Max Planck Institute for Biophysical Chemistry(Karl Friedrich Bonhoeffer Institute)Am Faßberg 11 · 37077 GöttingenPhone: +49 551 201-0 · Fax: +49 551 201-1222www.mpibpc.mpg.de

Max Planck Institute for Biophysical Chemistry

Karl Friedrich Bonhoeffer Institute

Göttingen

Publishing information

Publisher Max Planck Institute for Biophysical ChemistryAm Faßberg 1137077 Göttingen

Texts Marcus Anhäuser, Diemut Klärner, Dr. Carmen Rotte; (in German) in cooperation with the scientists at the Max Planck Institute

for Biophysical ChemistryTranslation Baker & Harrison, Dr. Daniel Whybrew Language editing Jaydev Jethwa, Dr. Nathan PavlosFinal proof-reading Dr. Ulrich Kuhnt, Dr. Carmen RottePhotographs Irene Gajewski, Peter Goldmann (p. 10, bottom left, p. 17 top right),

Heidi Wegener (p. 85); Cover picture: Irene GajewskiLayout Rothe-Grafik, Georgsmarienhütte; Hartmut SebessePrinted at Druckhaus Fromm, OsnabrückCoordination Dr. Carmen Rotte

Press and public relations officeMax Planck Institute for Biophysical Chemistry pr@mpibpc.mpg.de

Internet address www.mpibpc.mpg.de

Located in Göttingen, home of one of Ger -many’s foremost universities, the Max Planck

Institute for Biophysical Chemistry has for manyyears been conducting cutting-edge research. Asone of the largest institutes of the Max Planck Society, it houses numerous research groups andprovides them with an elaborate network of work-shops and central facilities. Students and re-searchers from various disciplines and nationscollaborate not only with their colleagues at the in-stitute but also with a large number of expertsworldwide to shed light on complex life processes.

The novel insights gained from the basic re-search conducted here have continuously facilita-ted innovation and have led to many economicallysuccessful licensing agreements and spin-off com-panies. With this brochure, we would like to inviteyou to tour our institute and learn about our historyand current research activities. We hope it inspiresyou to take a closer look at our ongoing researchand, eventually, we can welcome you to one of ourvisitor and training programs

Helmut GrubmüllerManaging Director, October 2009

Preamble

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An expedition into the world of molecules 4

Research without constraints 6

Tradition and vision 8

Teaching and learning 10

When a new idea ignites something 12

Excellent service for cutting-edge research 14

Open doors 16

Emeritus Directors of the institute 18

NanoBiophotonics 22Prof. Dr. Stefan W. Hell

Structure and Dynamics of Mitochondria 24Dr. Stefan Jakobs

Biomolecular Spectroscopy and Single Molecule Detection 25Prof. Dr. Peter Jomo Walla

Laboratory of Cellular Dynamics 26Dr. Thomas M. Jovin

Biochemical Kinetics 27Prof. Dr. Manfred Eigen

Electron Spin Resonance Spectroscopy 28Dr. Marina Bennati

Biological Micro- and Nanotechnology 29Dr. Thomas Burg

Spectroscopy and Photochemical Kinetics 30Prof. Dr. Jürgen Troe

Reaction Dynamics 31Prof. Dr. Dirk Schwarzer

Structural Dynamics of (Bio)Chemical Processes 32Dr. Simone Techert

Laser-induced Chemistry 33Prof. Dr. Michael Stuke

Theoretical and Computational Biophysics 36Prof. Dr. Helmut Grubmüller

Computational Biomolecular Dynamics 38Prof. Dr. Bert de Groot

Structural Investigations of Protein Complexes 39Dr. Stefan Becker

NMR-based Structural Biology 40Prof. Dr. Christian Griesinger

Structure Determination of Proteins Using NMR 42Prof. Dr. Markus Zweckstetter

Solid-State NMR Spectroscopy 43Dr. Adam Lange

Systems Biology of Motor Proteins 44Dr. Martin Kollmar

Bioanalytical Mass Spectrometry 45Dr. Henning Urlaub

Enzyme Biochemistry 46Dr. Manfred Konrad

Nucleic Acid Chemistry 47Dr. Claudia Höbartner

Content

Introduction 4

Look deeper 20

Sophisticated molecules 34

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Cellular Biochemistry 50Prof. Dr. Reinhard Lührmann

3D Electron Cryo-Microscopy 52Prof. Dr. Holger Stark

Ribosome Dynamics 53Prof. Dr. Wolfgang Wintermeyer

Physical Biochemistry 54Prof. Marina Rodnina

Neurobiology 58Prof. Dr. Reinhard Jahn

Structural Biochemistry 60Dr. Dirk Fasshauer

Biophysics of Synaptic Transmission 61Dr. Takeshi Sakaba

Membrane Biophysics 62Prof. Dr. Erwin Neher

Cellular Logistics 66Prof. Dr. Dirk Görlich

Nuclear Architecture 68Dr. Volker Cordes

Chromatin Biochemistry 69Dr. Wolfgang Fischle

Molecular Developmental Biology 72Prof. Dr. Herbert Jäckle

Developmental Biology 74Prof. Dr. Michael Kessel

Molecular Organogenesis 75Prof. Dr. Reinhard Schuh

Molecular Cell Differentiation 76Prof. Dr. Ahmed Mansouri

Molecular Developmental Neurobiology 77Dr. Anastassia Stoykova

Biomedical NMR 78Prof. Dr. Jens Frahm

Gene Expression and Signaling 80Dr. Halyna Shcherbata

Sleep and Waking 81Dr. Henrik Bringmann

Genes and Behavior 82Prof. Dr. Gregor Eichele

Circadian Rhythms 84Dr. Henrik Oster

The institute at a glance 85

Reaching us 87

Pictures 88

Cellular machines 48

Talkative nerve cells 56

The cell nucleus as control center 64

From egg to organism 70

How do nerve cells talk to each other? Howdoes a complex organism evolve from a single

egg cell? How is our »biological clock« controlled?Scientists at the Max Planck Institute for Biophys -ical Chemistry are on the trail towards unravelingthe answers to these, and other, fundamental biol -ogical questions. However, observing the molecu-lar mechanisms that control and regulate these vi-tal cellular processes is no easy feat. They occurdeep within the nanocosmos of living cells and aretherefore invisible to the naked eye. Conventionalmicroscopes can detect bacteria or observe individ -ual body cell. However, what occurs deep withinthe inner workings of a living cell remains an un-solved mystery.

One focus of the institute's research is thedevelop ment of special methods that provide a closer look into the world of molecules. Ultra-highre solution fluorescence microscopy, nuclear magnet -ic resonance spectroscopy, cryo-electron micro -scopy and computer simulations are just a few ofthe methods that are successfully used to investi-gate proteins – the minute nanomachines of livingcells. The aim is to unravel the many tricks thatproteins play to fulfill their diverse cellular func -tions as molecular motors, chemical plants orphoto electric cells, for example. Cellular logisticsis also carefully managed by proteins. How specificproteins sort and transport different cargos be -tween the various compartments of a cell is one ofthe topics being explored in greater detail here.

Other scientists are investigating how a cell con-verts the basic blueprints of proteins into readable

An expedition into the world of molecules

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forms, and are revealing how the cellular proteinfactories – the ribosomes – function. Proteins canonly successfully fulfill their tasks when they arecorrectly assembled. The molecular mechanismsunderlying the quality control for protein productionare also being intensively studied at the institute.

Likewise, many phenomena of inanimate naturecan be traced back to molecular processes. Manymolecules, radicals and atoms in the atmospherereact with each other, for example, after they havebeen produced and excited by solar radiation.Another group of researchers is focusing on in -vesti gating these and other forms of internal mo -le cular dynamics.

At the Max Planck Institute for BiophysicalChemistry, scientists from various disciplines andof different nationalities work together to shed lighton complex life processes. Biologists, chemists,medical scientists and physicists collaborate notonly with their colleagues at the institute, but alsowith a large number of renowned experts worldwide.

Accordingly, many different languages can beheard on the campus as people exchange views onprojects, ideas and results. When the Max PlanckInstitute for Dynamics and Self-Organization moves from central Göttingen to the Faßberg siteat the end of 2010, more than 1,000 employeeswill be working on the newly established MaxPlanck Campus.

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Like all other Max Planck Institutes, the MaxPlanck Institute for Biophysical Chemistry

primarily pursues basic research. Here, researchersfollow up on fundamental new ideas. This »un -inhibited« research, the excellent working con -ditions and the outstanding international reputa -tion are the reasons why the Max Planck Institutefor Biophysical Chemistry has become a center ofattraction for both students and renowned re-searchers from all over the world.

The new findings gained from such scientific re-search have paved the way for many pioneering applications. For example, a chemical compoundcalled Miltefosine, which was synthesized here,turned out to be a cure for the tropical disease visceral leishmaniasis – also known as kalar-azar.If left untreated, the disease fatality rate can be ashigh as 100 percent within two years. The WorldHealth Organization (WHO) hopes to use this medicine to control leishmaniasis in the long-termand finally defeat it.

Other researchers have provided groundbreakingideas for improving optical microscopy to go wellbeyond current resolution barriers, thus revolu -tioni zing optical microscopy.

Many of the scientists at the institute have re-ceived awards and prizes for their work, includingthe seven recipients of the prestigious GottfriedWilhelm Leibniz Prize of the German ResearchFoundation. Currently, two of the 44 Nobel Lau-reates who studied or worked in Göttingen areconducting their research at the Max Planck Insti-tute for Biophysical Chemistry.

Manfred Eigen was awarded the Nobel Prize forChemistry in 1967. He succeeded in observing thecourse of very fast chemical reactions occurring inthe range of nanoseconds. He thus broke througha fundamental barrier as, until then, these very fastreaction processes had been considered unmeasur -able. His work is of fundamental importance farbeyond the scope of chemistry.

Erwin Neher and Bert Sakmann were awardedthe 1991 Nobel Prize for Physiology or Medicine.They explored the molecular structures that enablenerve cells to transmit electric signals. In 1976, thetwo Max Planck researchers developed a methodfor measuring the incredibly weak electric currentthat flows for extremely short time periods whensingle pores open up – the so-called patch clamp

Research without constraints

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technique. Miniscule ion channels – pore-formingproteins – are embedded within the outer mem-brane of nearly all cell types. They not only trans-mit the electrical activity of nerve and musclecells, but also translate physical and chemical sensory stimuli into neuronal signals. Blood cells,

immune cells and liver cells also use ion channelsfor communication. These »nanomachines« in themembrane are therefore not only involved in nervecell signaling; they also play a universal role in the»messaging systems« of organisms.

Erwin Neher (left) and Bert Sakmann (right) were awarded the 1991 Nobel Prize for Physiology or Medicine »for their discoveriesconcerning the function of single ion channels in cells«. This so-called patch clamp technique is now used by research laboratoriesall over the world. It provides the key to explaining numerous life processes on the cellular level.

Manfred Eigen received the 1967 Nobel Prize for Chemistry for investigations of »extremely fast chemical reactions, effected by disturbing the equilibrium by means of very short pulses of energy». Soon afterwards he became Director of the Göttingen MaxPlanck Institute for Physical Chemistry in the Bunsenstraße and initiated the founding of the Max Planck Institute for BiophysicalChemistry at the Faßberg site on the outskirts of Göttingen.

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The Max Planck Institute for Biophysical Chem -istry was founded at the Faßberg site on the

outskirts of Göttingen on the initiative of ManfredEigen, and was officially inaugurated in 1971. Itshistory can be traced back far beyond this date,how ever, extending back to the former Kaiser Wil-helm Institute for Physical Chemistry in Berlin. In1949, after the creation of the Max Planck Society,the physicochemist Karl Friedrich Bonhoeffer re-

established the Berlin institute as the Max PlanckInstitute for Physical Chemistry in Göttingen. Thisinstitute and the Göttingen Max Planck Institutefor Spectroscopy were then merged to form theMax Planck Institute for Biophysical Chemistry.

The focus of the newly founded institute on bio-logical research also has its roots in the work andinterests of Karl Friedrich Bonhoeffer. He pursueda strong interdisciplinary approach at a very earlystage and applied physical-chemical methods toresolve biological questions – a good reason to name the institute after him.

Manfred Eigen's vision for the newly-establishedinstitute was to use biological, chemical and physical methods to study complex life processes:a vision which has played a decisive role in the success of the institute, and which still standstoday in the departments and research groups.

Tradition and vision

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Karl Friedrich Bonhoeffer (1899-1957) was the founder and first Director of the Max Planck Institute for Physical Chemistryin Göttingen, which he had re-established in 1949 as the successor institute to the Kaiser Wilhelm Institute for PhysicalChemistry in Berlin.

At present, the Max Planck Institute for Bio -physical Chemistry comprises eleven departmentsand 30 research groups with their own research foci. With more than 830 staff members – in -cluding 470 scientists – it is not only one of thelargest institutes of the Max Planck Society, but isalso unique in its interdisciplinarity covering a uni-versal range of research areas.

The Directors of the individual departments areat the same time Scientific Members of the MaxPlanck Society and decide jointly on the course tobe taken by the institute. The current President ofthe Max Planck Society, Peter Gruss, and the VicePresident, Herbert Jäckle, are also Directors here.

The Max Planck Society for the Advancementof Science currently sustains 80 institutes with abroad spectrum of different fields ranging from thehumanities and law to the natural sciences and astronomy.

In order to ensure the maintenance of the insti-tute’s high quality research, a Scientific AdvisoryBoard of internationally renowned scientists re g -ularly assesses the research accomplished here. ABoard of Trustees, comprised of not only scientistsbut also prominent representatives from businessand politics, supports contact with the public at large.

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Science is based on more than just experience.The future of science depends on the young

scientists who drive the research forward. Manyresearchers at the Max Planck Institute for Bio-physical Chemistry teach as professors at the Uni-versity of Göttingen as well as other universities.They are actively involved in collaborative researchcenters and graduate schools, and thereby main-tain close contact with the students. Many stu-dents, on the other hand, come to the institute fortheir laboratory work during their bachelor andmaster courses or doctoral studies.

In the international competition for the bestyoung minds, the Max Planck Society and variousuniversities have established a special program ofeducation and training for outstanding students:The International Max Planck Research Schools.

The Max Planck Institutes for Biophysical Chem -istry, for Dynamics and Self-Organization and forExperimental Medicine have teamed up with theUniversity of Göttingen to establish the scientificprograms Molecular Biology, Neurosciences andPhysics of Complex and Biological Systems. Thestructured education and training, with excellentresearch and learning conditions, is tailored to pre-pare especially-talented German and foreign stu-dents for their doctoral studies.

The institute has also made a significant con -tribution to the success of the Georg August Uni-versity of Göttingen in the national Excellence Initiative with its Göttingen Graduate School forNeurosciences and Molecular Biosciences(GGNB). The GGNB, which is supported byfunds from the Excellence Initiative, creates thebest possible research and training conditions fordoctoral students and supports young scientistswith offers of intensive courses and tutoring.

There are also programs for young scientistswith in the framework of further cooperations be -tween the institute and the University, the MaxPlanck Institutes for Dynamics and Self-Organi-zation and for Experimental Medicine as well asthe German Primate Center. These include:

Teaching and learning

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– the European Neuroscience Institute (ENI),which concentrates on experimental researchinto functions and diseases of the nervous system,

– the Göttingen Center for Molecular Physiologyof the Brain (CMPB), where researchers fromvarious disciplines collaborate in the field ofbrain research in order to gain a better under-standing of the molecular processes and inter-actions between nerve cells,

– the Bernstein Center for Computational Neuro -science (BCCN Göttingen), where the neuronalbasis of our brain activity is investigated withthe aid of mathematical models,

– the Göttingen Microscopy in the NanometerRange Excellence Cluster, which develops in-novative microscopy methods with a resolutionin the nanometer range, making them availableon a practical level.

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Whether in the field of medical diagnostics,laser technology or microscopy – the find ings

of basic research solve many a practical problemthat applied research was not able to solve. Suchfindings are therefore also in high demand in in-dustry.

Many scientists at the institute hold promisingpatents and founded companies in the area of medical diagnostics and therapy, metrology and environmental technology or ultra-high resolutionmicroscopy, for example.

The newly developed FLASH (Fast Low AngleShot) method allows one to take magnetic re s -onance tomography images 100 times faster. Thisnew technique has revolutionized magnetic re s -onance tomography and is now routinely used inhospitals worldwide. The FLASH patent was oneof the most successful patents of the Max PlanckSociety for a long time.

The RNA interference (RNAi) technique wassuccessfully applied for the first time to mam -malian cells at the institute. Using this method, in-dividual genes can be switched to »mute«, therebyenabling their function to be specifically investi -gated. This technique should make it possible totreat certain hereditary diseases in the future.

The STED microscope developed at the instituteallows fluorescence microscopic images with adrastically-improved resolution in comparison toconventional optical microscopes. Minute detailsinside living cells can thus be observed and even»filmed« live. Since 2007, this ultra-high resolu tionmicroscope has also been commercially avail able.

When a new idea ignites something

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The revenue from patents and licenses is invested into new projects at theinstitute. The use of the patents creates new jobs for highly-qualified staff mem-bers. In addition, there is a broad spectrum of further cooperative ventures with in-dustrial companies, including pharmaceutical companies and companies that developindustrial measurement technology. Former and present employees of the institute havebeen involved in the founding of more than a dozen companies.

One of these spin-off companies is DIREVO (now Bayer HealthCare AG), where an automated»Evolution Machine« is used to quickly find and optimize biopharmaceutical active substances.

Another example is Lambda Physik (now Coherent), which specializes in developing lasers that operate withextremely short light pulses. As documented through several patents, the lasers have undergone continuousfurther development. They are now also used in medicine and research, in addition to printing technology.

The biotechnology company DeveloGen, ofwhich the Max Planck Society itself is a partner, is another successful spin-off from the institute.Two of the institute's scientists, Peter Gruss andHerbert Jäckle, founded the company in 1997. DeveloGen connects research on genetic controlprocesses in the development of different kinds ofbody tissues with the practical treatment of medicalconditions such as obesity and diabetes.

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STED+

Confocal

What happens if an important building-blockis missing – be it in a complicated experi-

ment or in one's own store of knowledge? Work-shops and a library are as important for successfulresearch as are well-equipped laboratories.

In order to reveal the processes deep inside livingcells, the performance and resolution of experi-ments and measuring instruments is constantlybeing improved. The scientists' ideas are put intopractice by the experts in the precision mechanicsand electronics workshops, whether for the patchclamp technique, for the freezing of biologicalsamples or for ultra-high resolution microscopy.

Some 50 workshop employees construct compli-cated new devices or optimize existing apparatusfor the respective experiments.

The shelves of the Otto Hahn Library hold morethan 70,000 volumes of journals and almost40,000 monographs. Current subscriptions includealmost 600 journals. In addition, the Otto HahnLibrary offers access to a multitude of electroniccatalogues and various databases, as well as the option of an inter-library loan from other specialistlibraries. This service is available to both institutemembers and all interested parties.

Excellent service for cutting-edge research

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Just as indispensable are the employees in thescientific and non-scientific central facilities. Inorder to provide all researchers at the institute withthe best analytical and measurement methods, andto keep them up-to-date, scientists in the centralcore facilities Electron Microscopy, Innovative Optical Microscopy, Mass Spectrometry and X-rayCrystallo graphy develop new procedures in theirown parti cular fields. Institute members can findhelp with sample preparation, data acquisition anddata analysis.

The IT & Electronics Service team assists inhardware and software problems, and also takescare of the trouble-free storage, archiving andtransmission of data internally, as well as to cooper -ating research facilities within and outside of Göt-tingen. Colleagues in the reprographic departmentensure that photographs and presentation mate -

rials or the internal newsletter, for example, arehandled professionally. The EU Liaison Office ad-vises researchers on the writing of applications andsupports them in contract negotiations with theEU Commission, as well as with complete projectcoordination. The workshops, IT & ElectronicsService, building services and ad ministration alsooffer a number of young people qualified training.Between four and six trainees complete their train -ing every year, often with above-average success.

Scientists can only push ahead with their re-search with commitment if their children are welllooked after during the day. Accordingly, the insti-tute offers childcare directly on the institute sitesince 2005. Some 30 children between one andfour years of age are professionally cared for – allday long.

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At the Max Planck Institute for BiophysicalChemistry anyone who is interested will find

that our doors are open. Whether a teacher, pupil,journalist or private individual, everyone is invitedto find out about current research projects duringguided tours through the institute and individualdepartments, presentations or discussions.

Since the only way to reach a general audienceis through the media, the institute not only issuespress releases on current topics but also welcomesjournalists to explore deeper by directly contactingexperts here. In addition, the institute offers a specialprogram for journalists: the European Initiative forCommunicators of Science (EICOS). Once a year,up to 14 selected journalists and editors from allover Europe and Israel are invited to gain a close-up view of our research activities. As a result, onefinds journalists working side by side with scien-tists at the bench or in front of the computer. Forone week – sometimes longer – they come to gripswith a pipette, use a gel chamber and operate a microscope in order to explore how proteins – the

cell’s »nano machines« – perform their tasks. Not only do the journalists obtain insights into the day-to-day workings of a scientist, the direct contactalso leads to intensive dialogue that benefits bothsides.

The Max Planck Institute for Biophysical Chem -istry is also highly committed to outreach activitiesfor pupils and teachers. It invites students and teachers from schools to explore research projectsduring guided tours and lectures with instructiveexperiments. The one-week program Science andYouth (Göttinger Woche Wissenschaft & Jugend), organized by the city of Göttingen every year, provides students an intimate glimpse of the insti-tute’s laboratories. During that time, some of thedepartments and research groups offer speciallectures, presentations and lab tours. One can learn something about our »biological clock«, ob-serve proteins »at work«, take a look through astate-of-the-art microscope or experience magneticresonance tomography first hand. The EducationOutreach Program (Schulkontaktprogramm) pro -

Open doors

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vides students with access to the institute all theyear round. The program includes a variety oflectures and lab visits, including experimentaldem onstrations.

In addition, teachers can expand their know -ledge in certain key areas. The institute offers ad-vanced training courses for teachers in cooperationwith XLAB – Göttingen Experimental Laboratoryfor Young People e.V. And if neither textbooks norresearches fail to help – pupils and teachers canpose their questions related to science directly to

the researchers at the institute and XLAB via theonline portal Schools ask Science (Schule fragt dieWissenschaft).

And finally, it should not be forgotten that al -though the main task of the institute is to pursuescientific research it also offers a home for the arts.It hosts regular art exhibitions and, last but not least, participates in the presentation of a scientificlectures series at the Göttingen Literature Festival(Göttinger Literaturherbst).

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Professor Dr. Otto-D. Creutzfeldt † 1971 – 1992 · Neurobiology (left)

Professor Dr. Leo C. M. De Maeyer1971 – 1996 · Experimental Methods(middle)

Professor Dr. Manfred Eigen1971 – 1995 · Biochemical Kinetics ·(right)

Professor Dr. Dieter Gallwitz1985 – 2004 · Molecular Genetics (left)

Professor Dr. Manfred Kahlweit1971 – 1996 · Kinetics of Phase

Transformations (middle)

Professor Dr. Hans Kuhn1971 – 1984 · Molecular Systems (right)

Emeritus Directors of the institute

Professor Dr. Bert Sakmann1985 – 1988 · Cell Physiology (left)

Professor Dr. Fritz Peter Schäfer1971 – 1994 · Laser Physics (middle)

Professor Dr. Hans Strehlow1971 – 1984 · Electrochemistry and Reaction Kinetics (right)

Professor Dr. Klaus Weber1973 – 2004 · Biochemistry

and Cell Biology (left)

Professor Dr. Albert Weller †1971 – 1990 · Spectroscopy (middle)

Professor Dr. Victor P. Whittaker1973 – 1987 · Neurochemistry (right)

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Research in focus

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Look deeper

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how the unseen becomes visible

Without X-ray structural analysis, Francis Crick andJames Watson would not have discovered that DNA– our prime genetic carrier – has a double helixstructure. And how would have Robert Koch, also aNobel Laureate, detected the anthrax bacillus with -out a good microscope at his disposal? Top scientificachievements require high-end equipment. There -fore, it is no wonder that many of the institute'sscientists are involved in methodical innovations.New spectroscopic and microscopic methods areneeded, for example, in order to determine structuraldetails at the single molecule level as well as to explore the dynamics of molecular processes.

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Making the smallest details visible using focusedvisible light – this is the objective of our ultra

high resolution light microscopes, in recent years coined nano scopes. Conventional microscopes reachtheir resolution limits when two similar objects arecloser than 0.2 micrometers (1/5000 of a millimeter)to each other because the diffraction of light blursthem to a single image feature. Even the best micro -scope lenses cannot change this. There fore, anyonewho desires to image at nanometer or even moleculardimensions must resort to electron or scanning probemicroscopy. However, the interior of living cells canonly be observed with focused visible light. Fluore s -cence microscopy, where the molecules (proteins, lipids, nuclei acids) of interest are highlighted by tag-ging them with specific fluorescent molecules (fluoro -phores), is the most important light microscopy modality in the life sciences. But like any other lightmicroscopy, standard fluorescence microscopy is alsolimited by diffraction.

Switching fluorescence off and on by lightIn order to outsmart the resolution limiting role of dif-fraction, we ensure that the adjacent (inseparable) mo-

lecules or groups of molecules emit their fluorescencesuccessively. To this end, we use transitions betweenfluorophore states that switch or modulate the fluores-cence of adjacent molecules for a brief period of time.Switching adjacent molecules consecutively off and onmakes them readily distinguishable.

Stimulated Emission Depletion (STED) microscopy,developed by our group, is the first focused light-microscopy method which is no longer fundamentallylimited by diffraction. In this approach the focal spotof the fluorescence excitation beam is accompaniedby a doughnut-shaped »STED beam« that switchesoff fluorophores at the spot periphery, by effectivelyconfining them to the ground state. In contrast, molecules at the doughnut center can dwell in thefluorescence »on« state and fluoresce freely. The re-solution is typically improved by up to ten times com-pared with conventional microscopes, meaning thatlabelled protein complexes with distances of only 15 to 50 nanometers can be discerned.

As the brightness of the STED beam is increased,the spot in which molecules can fluoresce is furtherreduced in size. As a consequence, the resolution ofthe system can be increased, in principle, to mol -

NanoBiophotonics

Two-color STED imageof a glioblastoma, themost frequent malig -nant brain tumor in adults. Clathrin protein is green; β-tubulin protein is stained red. In contrast to the blurred classical image (left),the STED image (right) shows considerably finer structures. (Picture and sample: J. Bückers, D. Wildanger, L. Kastrup, R. Medda)

Prof. Dr. Stefan W. Hell received his PhD in physics at theUniversity of Heidelberg in 1990and worked from 1991 to 1993 atthe European Laboratory forMolecular Biology in Heidelberg.From 1993 to 1996, he did re-search at the Universities ofTurku (Finland) and Oxford (GreatBritain). In 1997, he went to theMax Planck Institute for Biophys -ical Chemistry as head of a Ju-nior Research Group. Since 2002,he has headed the Department ofNanoBiophotonics. Stefan Hellhas received many awards for hisresearch, among them the Prizeof the International Commissionfor Optics (2000), the HelmholtzPrize (2001), the 10th German Fu -ture Prize of the Federal President(2006) and the Julius Springer Prize (2007). In 2008, he receivedthe Leibniz Prize as well as theState Prize of Lower Saxony. In2009, he was awarded the OttoHahn Prize of Physics.

ecular dimensions. Combined with fast beam scanning even rapid processes, suchas the diffusion of synaptic vesicles insidea neuron, have been followed with highresolution.

Using a (meta)stable switchSwitching fluorescence can also be per-formed in a different manner. In parti -cular, switching fluorophores betweenmetastable (long-lived) states allows oneto overcome the diffraction resolution lim -it with low levels of light. In a method called RESOLFT, one switches thesefluorophores with a spatially structured beam as in STED, but as has been shownmore recently, switching individual fluoro-phores randomly in space is very effectivefor pro ducing images with resolu tion on thenanometer scale. In this approach (calledSTORM, PALM, GSDIM) only one mol -ecule in the diffraction area is »on«, butat an unknown, random position. The ad-jacent molecules indeed lie within the dif-fraction spot, but are »off« for the periodof detection and therefore do not disturbthe registration of the single fluorophore.Imaging the fluorescence signal on a cam -era allows one to calculate the posi tion ofthat »on« state fluoro phore with an ac -curacy that is far beyond the resolution

lim it. This procedure is repeated again until each molecule has been registered.

In our variant of this approach, calledGSDIM, we switch ordinary fluorophoresbe tween a bright and a dark state differingin electron spin, thus making this methodapplicable for a wide range of fluorophores.

Ingeniously combinedAnother goal of our research is the develop -ment of innovative optical configurations.In the 4Pi microscope, two objectives aredirected at one point so that the wavefrontsof the two lenses improve focusing jointly.As a result, a sharpening of the focal lightspot by three to seven times is achievedalong the longitudinal axis of the micro -scope.

If one combines the 4Pi microscope withthe STED or single molecule switchingmethod, objects which are barely 20-30nano meters apart can be distinguished in3D. Until a few years ago this was con -sidered difficult to obtain in practice. Inprinciple even higher resolution is possible:down to the size range of the mole culesthemselves. Such »optical nanoscopes« areexpected to provide completely new in-sights into nano structured transparent ma-terials, such as polymers, and especially theinner workings of living cells.

S. W. Hell: Far-field optical nanoscopy. Science 316, 1153-1158 (2007).

S. W. Hell: Nanoskopie mit fokussiertemLicht. Physik Journal 6, 47-53 (2007).

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Contact:hell@4pi.dewww.mpibpc.mpg.de/groups/hell/

The STED microscopy (circular inset image) providesapproximately ten times sharper details of filamentstructures within a nerve cell compared to a con-ventional light microscope (outer image). (Picture: G. Donnert, S. W. Hell)

Structure and Dynamics of Mitochondria

Dr. Stefan Jakobs studied biologyin Kaiserslautern and Manchester(UK) and carried out his PhD atthe Max Planck Institute for PlantBreeding Research in Cologne.Subsequently, he first worked asa postdoctoral fellow in Cologne,then in the Department of Nano-Biophotonics at the Max PlanckInstitute for Biophysical Chemistry.Since 2005, he heads the Struc tureand Dynamics of Mito chondriaResearch Group. Stefan Jakobscompleted his habilitation at theUniversity of Göttingen in 2007.

Contact:sjakobs@gwdg.dewww.mitoweb.de

I. E. Suppanz, C. A. Wurm, D. Wenzel,S. Jakobs: The m-AAA protease proces-ses cytochrome c peroxidase preferenti-ally at the inner boundary membrane ofmitochondria. Mol. Biol. Cell 20, 572-580 (2009).

R. Schmidt, C. A. Wurm, A. Punge, A.Egner, S. Jakobs, S. W. Hell: Mitochon-drial cristae revealed with focused light.Nano Lett. 9, 2508-2510 (2009).

M. Andresen, A. C. Stiel, J. Fölling, D.Wenzel, A. Schönle, A. Egner, C. Egge-ling, S. W. Hell, S. Jakobs: Photoswit-chable fluorescent proteins enable mo-nochromatic multilabel imaging anddual color fluorescence nanoscopy. Na-ture Biotechnol. 26, 1035-1040 (2008).

M. Andresen, A. C. Stiel, S. Trowitzsch,G. Weber, C. Eggeling, M. C. Wahl, S.W. Hell, S. Jakobs: Structural basis forreversible photoswitching in Dronpa.Proc. Natl. Acad. Sci. USA 104, 13005-13009 (2007).

Mitochondria are the »power plants«of the cell. They provide the chemi-

cal energy required to keep cellular meta-bolism moving. When the mitochondria donot function properly, the consequencesare correspondingly fatal. Defective mito-chondria can lead to disorders such as can-cer, Parkinson's or Alzheimer's.

But how are the mitochondria construc -ted in detail, and which molecular mecha-nisms lie behind this architecture? Mito-chondria are so nanoscopically small thattheir internal structure could pre viously onlybe examined with electron micro scopes.However, in this context, cells must be firstchemically fixed and cut into ultra-thin sli-ces, which then are examined individually.We therefore know correspondingly littleabout what occurs in the mitochondria ofliving cells.

With light microscopes, even fully intactcells can be examined. However, even withthe best conventional microscopes, thespatial resolution is not nearly high enoughto examine the interior of these powerplants more closely. Consequently, we usenew light-microscopy methods, such asStim ulated Emission Depletion (STED)micro scopy, which increase the optical reso -lution many times.

A glimpse into the interior of the cellular power plantTo this end, selected proteins are labeledwith dyes or fluorescent proteins in order tobe able to subsequently localize them in themitochondria. In this manner, we have, forexample, discovered that some protein com-plexes are concentrated in a specific part ofthe mitochondrial inner membrane. At pre-sent we are exploring the functional meaningof this special localization.

In a second research focus we are strivingto improve our molecular tools. We are in-vestigating and developing fluorescent pro-teins which can be selectively switched »on«and »off« with light flashes. As a result of their particular properties, such photo-chromic proteins provide completely newpossibilities for exploring the inner workingsof cells and mitochondria.

Different protein complexes – in this case the »TOM complex« – accumulate in specific regions of the mitochondrial outer membrane. Left: image made with conventional laser scanningfluorescence microscopy, right: image made withSTED microscopy.

Mammalian cells in which mitochondria are labeled green, the microtubule cyto -skeleton red, and the cell nucleus blue.

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Confocal STED

1µm

10 µm

Prof. Dr. Peter Jomo Walla studiedchemistry at the Universities of Heidelberg and Göttingen, and sub -sequently moved to the Max PlanckInstitute for Biophysical Chemistryto complete his PhD. After researchstays at the CNRS in Bordeaux(France) and the University of California at Berkeley (USA) he wasinitially Department Head at theDIREVO Biotech AG (today: BayerHealthCare AG) in Cologne. In 2003,he received an Emmy Noether Fellow -ship that allowed him to establish aJunior Research Group at the insti-tute. Since 2007, he is a full univer -sity professor at the Technical Uni-versity of Brunswick and continuesto head the Research Group Bio -mole cular Spectroscopy and SingleMolecule Detection at the MaxPlanck Institute for BiophysicalChem istry. Peter Jomo Walla receiveda Research Prize of the Fund of theGerman Chemical Industry for selec -ted junior professors in chemistry(2003) and the Young InvestigatorsAward of the Gordon Conference onPhotosynthesis (2000) for his research.

In order to investigate the nanocosmos ofthe cell, scientists develop increasingly

sophisticated tools and techniques. Our re-search group is specialized in examiningbiomolecules that are usually of high inter -est for biologically oriented groups at theinstitute using advanced spectroscopic andmicroscopic methods and in further improv -ing these techniques.

For example, we study how nerve cellscan release extremely rapidly chemicalmessenger substances in order to transmitsignals to other nerve cells. Packed in»messenger packages« – the vesicles – thesemessenger substances wait inside the nervecells. When an electrical nerve stimulus in-dicates that a message is to be transmitted,several synaptic vesicles fuse with the cellmembrane and release their contents intothe surroundings so that an adjacent nervecell can immediately recog nize the stimu-lus. These vesicles are only 30 to 60 nano-meter (millionths of a millimeter) in size.Despite this we are able to even study in-dividual vesicles in the test tube at the moment when they fuse with arti ficialmem branes. We achieve this by means ofhighly sensitive microscope techniqueswhich are able to resolve even single fluor -escing marker molecules attached to themembranes.

Ultra short laser flashes shed light onphotosynthesisIn a further focus we investigate how the so-lar energy is captured and transformed intochemical energy during photosynthesis. This

transformation occurs, in part, so rapidly thateven state-of-the-art oscilloscopes cannot resolve this time scale. We therefore workwith ultra short laser flashes whith durationsin the order of femtoseconds (10-15 seconds),that is a thousand-millionth of a millionth ofa second. These are time scales, in whicheven light itself only travels distances that areshorter than the diameter of a human hair.In the long-term we would like to develop ar-tificial photosynthesis systems which trans-form solar energy into chemically storedenergy and thus have the potential to helpresolve the current global problems in energysupply.

In the Biomolecular Spectroscopy and Single Mole -cule Detection Research Group confocal microscopemethods with which even individual biomolecules canbe examined are used and developed.

P. J. Walla: Modern biophysical chemistry. Wiley-VCH Weinhein, Februar 2009.

S. Bode, C. C. Quentmeier, P-N. Liao,N. Hafi, T. Barros, L. Wilk, F. Bittner, P.J. Walla: On the regulation of photosyn-thesis by excitonic interactions betweencarotenoids and chlorophylls. Proc. Natl.Acad. Sci. 106, 12311-12316 (2009).

P. J. Walla, P. A. Linden, C.–P. Hsu, G.D. Scholes, G. R. Fleming: Femtoseconddynamics of the forbidden carotenoidS1 state in light-harvesting complexesof purple bacteria observed after two-photon excitation. Proc. Natl. Acad. Sci. 97, 10808-10813 (2000).

Contact:pwalla@gwdg.dewww.pci.tu-bs.de/agwalla/ Peter_Walla_Main_d.htm

An exactly tuned interaction of the energy flu-xes between chlorophyll and carotinoid mole-cules allows the photosynthetic appa ratus toutilize nearly every light quantum for electrontransfer processes that are finally used to generate biochemically stored energy.

Biomolecular Spectroscopy and Single Molecule Detection

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We concentrate our research activitieson two major areas. The first has to do

with the molecular mechanisms of signaltransduction controlled by external growthfactors in normal and tumor cells. The secondfocus is on the molecular mechanisms un-derlying the pathogenesis of Parkinson'sdisease (PD). Characteristic of this and otherrelated neurodegenerative diseases, forexample Alzheimer's disease (AD), is the ap-pearance of protein aggregates in and aroundneurons of affected areas in the brain. In PD,the protein in question is �-synuclein. Un-fortunately, how the so-called amyloid aggre-

gates are formed and how they exert their toxic effects is largely unknown. Answers tothese questions are required before we canrationally design drugs to inhibit or reversethe progress of PD and AD. We approachthis challenge with molecular and cellularbiological approaches and biophysical tech-niques that can be applied in vitro as well asin studies of cells and tissues.

Tracking molecules in living cellsFor the cellular studies, we develop and utilizespecific biosensors based on fluorescent semi-conductor nanocrystals (Quantum Dots), no-

ble metal clusters (Nano-dots), and organic com-pounds. These probes are in-troduced into biomoleculesby chemical or cell expressiontechniques. In parallel, wehave developed a Programm-able Array Microscope (PAM)that permits high-speed andsensitive imaging of livingcells with high spatial, tem-poral, and spectral resolution.Thus, the location and in -volvement of probes on andwithin cells can be followedin real-time, down to the levelof individual nanoparticles. Inthis manner, we have dis -covered a new mode of re-ceptor transport on mamma-lian cells.

Donna Arndt-Jovin is res -ponsible for the cell biologicalresearch focusing on growthfactors and chromatin-relatedfunctions in the cell nucleus.The basic research on signal -ing is being extended to usein the operating room, forexample, for detecting braintumor (glioma) cells, with theQuantum Dot ligands.

Laboratory of Cellular Dynamics

Dr. Thomas M. Jovinwas awardedan MD in 1964 by the Johns Hopkins Medical School (USA).He became a scientific memberof the Max Planck Society in 1969and functioned as director andchairman of the Department ofMolecular Biology at the MaxPlanck Institute for BiophysicalChemistry until 2007. Since then,as an Emeritus Director, he hasheaded the Laboratory of CellularDynamics at the institute and anassociated unit at the Universityof Buenos Aires (Argentina). Thomas Jovin has received honor -ary degrees from the LimburgUniversity (Belgium) and the Uni-versity Medical School, Debrecen(Hungary). He is an honorary pro-fessor of the University of BuenosAires, a member of the EuropeanMolecular Biology Organization(EMBO), and an honorary mem-ber of the Hungarian Academy of Science.

Contact:tjovin@gwdg.de www.mpibpc.mpg.de/groups/jovin/

M. Gralle Botelho, X. Wang, D. J. Arndt-Jovin, D. Becker, T.M. Jovin: Induction ofterminal differentiation in Melanomacells on downregulation of �-amyloidPrecursor Protein. J. Invest. Dermatol. |doi:10.1038/jid.2009.296 (2009).

M. S. Celej, W.Caarls, A. P. Demchenko,T. M. Jovin: A triple emission fluorescentprobe reveals distinctive amyloid fibrillarpolymorphism of wild-type �-synucleinand its familial Parkinson’s disease mutants. Biochemistry 48, 7465-7472(2009).

E. A. Jares-Erijman, T. M. Jovin: Reflec -tions on FRET imaging: formalism, probes, and implementation. In: »FRETand FLIM Imaging Techniques«. T. Ga-della, Jr. ed. S. 475-517. Elsevier (2009).

M. J. Roberti, M. Morgan, G. Menéndez,L. Pietrasanta, T. M. Jovin, E. A. Jares-Erijman: Quantum dots as ultrasensitivenanoactuators and sensors of amyloidaggregation in live cells. J. Am. Chem.Soc. 131, 8102-8107 (2009).

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Human epithelial tumor cells: Quantum dots (red) carrying the epidermal growth factor (EGF) bind tothe cell surface receptor, itself labeled with a green fluorescent protein. The image was acquired witha new microscope (Programmable Array Microscope) developed at the institute for high-speed opti-cally-sectioned imaging of living cells (G. M. Hagen, K. A Lidke, B. Rieger, W. Caarls, D. J. Arndt-Jovin,T. M. Jovin: Dynamics of membrane receptors: single molecule tracking of quantum dot liganded epi-dermal growth factor. In: Yanagida, T, Ishii, Y, Eds. Single Molecule Dynamics in Life Sciences. Orlan-do: Wiley. pp. 117-130 (2008)).

Prof. Dr. Manfred Eigen receivedhis doctorate from the Universityof Göttingen in 1951, where hesubsequently worked at the Insti-tute of Physical Chemistry. Afterjoining the Max Planck Institutefor Physical Chemistry in 1953, hebecame Director of its ChemicalKinetics Department in 1964. Onthe initiative of Manfred Eigen,this institute became part oftoday’s Max Planck Institute forBiophysical Chemistry in 1971.Even after his retirement in 1995,he has been active as EmeritusDirector of the Department ofBiochemical Kinetics to the present day. In 1967, Manfred Eigen was awarded the NobelPrize for Chemistry for his re-search on ultra-fast chemical re-actions in solutions.

A. Koltermann, U. Kettling, J. Bieschke,T. Winkler, M. Eigen: Rapid assay pro-cessing by integration of dual-colorfluorescence crosscorrelation spectros-copy: High throughput screening forenzyme activity. Proc. Natl. Acad. Sci.USA 95, 1421-1426 (1998).

M. Eigen, B. Lindemann, M. Tietze, R.Winkler-Oswatitsch, A. Dress, A. vonHae seler: How old is the genetic code?Statistical geometry of tRNA providesan answer. Science 244, 673-679(1989).

M. Eigen: Stufen zum Leben. Die frühe Evolution im Visier der Moleku lar bio lo -gie. R. Piper-Verlag, München (1987).

M. Eigen: Selforganization of matterand evolution of biological macromole-cules. Naturwissenschaften 58, 465-523(1971).

M. Eigen: Proton transfer acid-base ca-talysis, and enzymatic hydrolysis. I. Ele-mentary processes. Angewandte ChemieInt. Ed. 3, 1-19 (1964).

Biochemical Kinetics

Contact: www.mpibpc.mpg.de/groups/eigen/english.html

Alack of perfection during the repro-duction process – that is the main

reason for the fascinating variety of lifeforms on earth. Although DNA, our geneticinformation carrier, is an extremely stablemacromolecule, errors sometimes do occurwhen information is copied and duplicated.Since not all of these errors are correctedand repaired, new variants emerge all thetime. These variants form the basis for theevolution of organisms. All living speciesare subject to these transformations.

»Evolution machines«We can define evolution as a natural phenom -enon, but we may also re-enact it in a con-trolled setting to meet our own needs. In these experiments, bacteria, viruses, or singlenucleic acid molecules are encouraged to re-produce, and then selected according to spe-cific criteria. For this purpose, we have de-

veloped special equipment that can processmany thousand samples simultaneously. Inthis way, we can study basic mechanisms ofevolution, e.g. the tricks that HIV and othercunning pathogens use to outsmart our immune system. Moreover, such »evolutionmachines« can help developing the mo l -ecular agents needed for novel drugs.

These different applications have one crucial aspect in common: In all of these cases, tiny quantities of substances need tobe analyzed. This amounts to »finding aneedle in the haystack«. It also goes for diagnostic applications, such as the early diagnosis of BSE. Special spectroscopic methods enable us to detect even singlemole cules. This has lead to the developmentof evolutionary biotechnology that permitsthe recognition of single biomolecules in aspecific distribution as well as the optimiza-tion of their function.

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The pictures show the automated evolution andscreening device of DIREVO Biosystems AG / Cologne (now: Bayer HealthCare AG) viewed fromthe front (above) and back (left). The biotech com-pany grew out of the Department of Biochemical Kinetics at the Max Planck Institute for BiophysicalChemistry.

Regardless of whether one is consider -ing simple water or complicated pro-

teins, electrons usually occur pairwise inmolecules. By means of their spin – a formof angular momentum – electrons generatea microscopic magnetic field. However,since they rotate in opposite directions,their magnetic effects cancel each other.As a consequence, we are only interestedin unpaired electrons, which serve ashighly sensitive probes in our experiments.These so-called »paramagnetic centers«can provide us with information on howcomplex biomolecules change their struc -tures while they are fulfilling their specificfunction. With the methods of electronspin reso nance (ESR)(electron paramag -netic resonance (EPR)) spectroscopy wecan observe biomolecules under nearly natural conditions and learn about howthey act in the living cell.

Observing the interior of proteinsWe develop techniques to excite a para-magnetic center or simultaneously excite several paramagnetic centers with micro -

waves or radio frequency radiation in orderto manipulate their magnetic inter actions. Inthis manner, we can not only measure thedistances between the active centers of aprotein down to the nanometer range, but also learn about their orientation in the mole -cule. In addition, we use detec tion fre-quencies in the millimeter range, which notonly require polarizing superconductingmagnets, but also a more complex micro -wave technology. There fore, in our researchgroup, biophysical investigations are con-ducted hand-in-hand with methodo logicaland technical developments.

Paramagnetic centers are involved in manymetabolic processes. Representative exam-ples are provided in the process of the photo -synthesis or the respiratory chain, but also inproteins such as the enzyme ribonucleotidereductase (RNR). From bacteria up to humans RNR catalyzes the last step in theformation of the individual building blocksof desoxyribonucleic acid (DNA). In thisprocess, paramagnetic states are generatedas a result of the transfer of electrons. Withthe aid of different ESR techniques, we have

succeeded in elucidating severalinter mediate steps in the cata -lytic cycle. While paramagneticcenters occur naturally in pro-teins such as RNR, they have tobe inserted arti ficially into otherproteins. To achieve this, we in-troduce spin labels at selectivepositions of the proteins. Follow -ing this protocol, we have startedto investigate the structure ofnucleic acids and membraneproteins in collaboration with other research groups of the in-stitute.

Electron Spin Resonance Spectroscopy

Dr. Marina Bennati received herPhD in experimental physics atthe University of Stuttgart in 1995.She subsequently worked at theMassachusetts Institute of Tech-nology (MIT) and the MIT/Har-vard Center for Magnetic Reso-nance in Cambridge (USA). In2001, she moved to the Universityof Frankfurt am Main, where shehabili tated in 2006. She has beenleading the Electron Spin Reso-nance Spectroscopy ResearchGroup at the Max Planck Institutefor Biophysical Chemistry since2007. In 2002, Marina Bennati re-ceived the Young InvestigatorAward of the International EPRSociety for her research.

ContactBennati@mpibpc.mpg.dewww.mpibpc.mpg.de/english/research/ags/bennati/

V. Denysenkov, D. Biglino, W. Lubitz, T. Prisner, M. Bennati: Structure of thetyrosyl biradical of mouse R2 ribonu-cleotide reductase from high-field PEL-DOR. Angew. Chem. Int. Ed. 47, 1224-1227 (2008).

M. R. Seyedsayamdost, C. T. Y. Chan, V.Mugnaini, J. Stubbe, M. Bennati: PEL-DOR spectroscopy with DOPA-β2 andNH2Y-α2s: Distance measurementsbetween residues involved in the radi-cal propagation pathway of E. coliribonucleotide reductase. J. Am. Chem.Soc. 129, 15748-15749 (2007).

V. Denysenkov, T. Prisner, J. Stubbe, M. Bennati: High-field pulsed electron-electron double resonance spectroscopyto determine the orientation of the tyro-syl radicals in ribonucleotide reductase.Proc. Nat. Acad. Sci. 103, 13386-13390(2006).

A) Structure of the R2 dimer complex frommouse ribonucleotide reductase and orien-tation of the active tyrosyl radicals as determined by high frequency EPR spectro -scopy (Bennati et al., 2008). B) Typical magnetic field dependent dipolar spectraof two interacting radicals at high frequen-cy. The dipolar frequencies observed are afunction of the irradiated molecular orien-tations in the EPR spectrum.

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A

B

Dr. Thomas Burg studied physicsat the Swiss Federal Institute ofTechnology (ETH) Zurich (Switzer -land) and received his PhD in2005 at the Massachusetts Insti-tute of Technology (MIT) in Cam-bridge (USA). From 2005 to 2008,he conducted postdoctoral re-search in the Department of Bio -logical Engineering at MIT. Since2009, he has headed the MaxPlanck Research Group BiologicalMicro- and Nanotechnology atthe Max Planck Insti tute for Bio-physical Chemistry.

T. P. Burg, M. Godin, W. Shen, G. Carlson,J. S. Foster, K. Babcock, S. R. Manalis:Weighing of biomolecules, single cells,and single nanoparticles in fluid. Nature 446, 1066-1069 (2007).

T. P. Burg, S. R. Manalis: Suspended microchannel resonators for biomolecu-lar detec tion. Applied Physics Letters 83,2698-2700 (2003).

Biological Micro- and Nanotechnology

Contact: tburg@mpibpc.mpg.dewww.mpibpc.mpg.de/english/research/ags/burg/

Cells are microscopically small. Yet,they are gigantic compared to the tiny

molecular machines which drive the com-plex biological processes within them. Many such components are a few ten tohundred nanometers (millionths of a milli-meter) in size. Even simple parameters,such as the size, mass or number of suchnano particles, provide scientists with im-portant information. They can help us tobetter understand cellular processes or torecognize pathological changes. But how isit possible to count or weigh, for example,a group of proteins which are so infinite s -imally small? Conventional methods usedin the macroscopic world are of no help here.New micro- and nanotechological pro ce -dures, which we develop in our group, mayhelp to address this challenge.

Weighing with a »tuning fork«In order, for example, to weigh individualnano particles, we are developing so-calledmicromechanical resonators – a kind ofmini ature »tuning fork«, smaller than thediameter of a hair. A trick is required to beable to examine biological objects in solutionwith them. The resonator is located in a va-cuum and can oscillate practically unattenu -ated. Inside it there is a channel which is on-ly a few micrometers wide. If a particle pas-ses through the channel, the resonance fre-

quency – i.e. is the characteristic tone forthis tuning fork – changes. From this alter-nation in »pitch« we calculate the mass witha deviation of a millionth of a billionth of agram. In this manner we can, for example,weigh a single bacterium with an accuracyof approximately one percent.

With such physical measurements we aimto ultimately penetrate into the regime of in-dividual molecules. To achieve this, we arebundling the forces of different fields of re-search and utilize knowledge from biology,chemistry, engineering and physics. They allcontribute to the new methods and can also,in turn, profit from their application.

Micro- and nanofluidic systems enable complex bio-logical experiments in extremely small channels.Very small objects such as cells can be examined in them individually and under well controlled con -ditions.

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Highly sensitive sensors which are integrated on microchips can detect minute particles, such as a singlebacterium, directly on the basis of its mass.

Many phenomena of nature can be traced back to molecular processes.

For example, molecules, radicals and atomsreact with one another in the atmosphereafter they have been excited or producedby solar radiation. Amazingly enough, theseprocesses are very similar to those whichoccur in fire and in internal combustion en-gines. Even in the formation of new starsin interstellar molecular clouds, such pro-cesses play an important role. What’s more,ele men tary photobio logical processes, suchas photosynthesis, follow similar basic prin-ciples in their intra- and intermolecular dy-namics.

In order to investigate such molecularpro cesses, we initiate them by means ofphoto chemical activation. Molecules ab-sorb light and achieve highly active statesas a result of the added energy, or activeparticles, such as atoms or radicals, are for-med which trigger a chain of reactions. Weinvestigate the temporal course of these re-actions and the sub sequent, frequentlyvery rapid, processes by analyzing the veryspecific absorption of light by the molecu-les with spectroscopic methods.

On the basis of their respective spectra,we are even able to distinguish moleculeswhich only differ in their energy state.

Investigation in the femtosecond rangeWith the aid of modern optical methods theconcentrations of molecules and their energystates can be followed with a temporal reso-lution down to the femtosecond range – thisis the time scale for the movement of atoms.In this manner, even the »ultrafast« inter-and intramolecular dynamics becomes di-rectly »vi sible«. We analyze the theory be-hind these processes with the methods ofquantum chemistry, reaction dynamics andmolecular statistics.

At present we are increasingly focusing onreactions of electrons and molecular ions inso-called plasmas, i.e. the gaseous state ofmatter in which not only electrically neutralparticles, but also charged particles, existnext to one another. This state can be de-tected on the earth in the ionosphere or inelectrical discharges such as lightning. In ou-ter space the majority of all matter exists inthis state.

With these results we develop theoreticalmodels, which are useful in many areas:from astrochemistry and atmospheric chem -istry, plasma- and photochemistry to com-bustion chemistry. Even large-scale indus -trial processes can be optimized with them.

Spectroscopy and Photochemical Kinetics

Prof. Dr. Jürgen Troe received hisPhD at the University of Göttingenin 1965 and completed his habili-tation there in physical chemistry.In 1971, he was appointed as pro-fessor at the Swiss Federal Insti-tute of Technology in Lausanne(Switzerland). In 1975, he returnedto the University of Göttingen asDirector at the Institute for Physi-cal Chemistry. From 1990 to 2008,he additionally headed the De-partment of Spectroscopy andPhotochemical Kinetics at theMax Planck Institute for Biophys -ical Chemistry, where he con -tinues with his research in theframework of an emeritus group.In addition, since 2009, he worksat the University of Göttingen as a»Lower Saxony Research Profes-sor«. Jürgen Troe is an honoraryprofessor at the Swiss Federal In-stitute of Technology in Lausan-ne, an honorary doctor of the Uni-versities of Bordeaux and Karls-ruhe, and an honorary member ofthe German Bunsen Society.

Contact: idreger@gwdg.de andshoff@gwdg.dewww.uni-pc.gwdg.de/troe/

E. I. Dashevskaya, I. Litvin, E. E. Niki-tin, J. Troe: Modelling low-energy elect-ron-molecule capture processes. Phys.Chem. Chem. Phys. 10, 1270 (2008).

Ch. Müller, J. Schroeder, J. Troe: Intra-molecular hydrogen bonding in 1,8-dihydroxy anthraquinone, 1-aminoan-thraquinone, and 9-hydroxyphenalenonestudied by pico second time-resolvedfluorescence. J. Phys. Chem. B 110,19820 (2006).

Ch. Müller, M. Klöppel-Riech, F. Schrö-der, J. Schroeder, J. Troe: Fluorescenceand REMPI spectroscopy of jet-cooledisolated 2-phenylindene in the S1. J.Phys. Chem. A 110, 5017 (2006).

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Prof. Dr. Dirk Schwarzer receivedhis PhD in physical chemistry in 1989 at the University of Göttin-gen. After a research stay at theUniversity of Chicago (USA), hemoved in 1990 to the Max PlanckInstitute for Biophysical Chemis-try as head of a research group inthe Department of Spectroscopyand Photochemical Kinetics. Since 2006, he has headed theReaction Dynamics ResearchGroup there. Dirk Schwarzer habilitated in physical chemistryat the University of Göttingen in1999 und has taught there as anadjunct professor since 2002.

The erosion of rocks occurs over a pe-riod of many centuries. But as slowly

as the underlying chemical reactions appar -ently take place – at the level of atoms andmolecules they occur inconceivably rapid-ly: in fractions of pico seconds, i.e. the mil-lionth part of a millionth of a second, mol -ecules change their structure, chemicalbonds are dissolved or reformed becauseatoms in molecules move so rapidly.

In the process, the molecules passthrough different energy states. These pro-cesses are driven, on the one hand, by thetransport of energy within the molecule,but on the other hand, energy also movesfrom molecule to molecule, for examplewhen the reactants inter act with the sur-rounding solvent.

On the time scale of atomic movements We desire to make the individual steps ofthese molecular processes visible and un-

derstand them in detail. To achieve this weuse laser spectroscopy. It allows us to iden-tify the substances participating in a chem -ical reaction based on their typical lightspectra as if every substance had its ownparticular rainbow pattern. We also charac-terize the concentrations, energy contentsand other properties of these substances ateach point in time in a reaction using thismethod.

The dynamics of chemical reactions ingases, liquids and supercritical fluids is atthe focus of our interest. By changingmacro scopic parameters such as tempera-ture, density or viscosity, we alter thestrength of interactions between moleculesand the frequency of energy-transferringimpacts. In this manner we untangle thedifferent, superimposed factors which in-fluence the course of a chemical reaction.With our experimental methods we can penetrate down to the time scale of the

movements of atoms inmolecules. In this way,the intermolecular dy -namics becomes directly»visible«.

T. Schäfer, D. Schwarzer, J. Lindner, P.Vöhringer: ND-stretching vibrationalenergy relaxation of NH2D in liquid-to-supercritical ammonia studied by fem-tosecond midin frared spectroscopy. J.Chem. Phys. 128, 064502 (2008).

C. Reichardt, J. Schroeder, D. Schwar-zer: Femtosecond IR spectroscopy ofperoxycarbonate photodecomposition:S1-lifetime determines decarboxylationrate. J. Phys. Chem. A, 111, 10111(2007).

Reaction Dynamics

Contact: dschwar@gwdg.de www.mpibpc.mpg.de/groups/troe/schwarzer/

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Diiodomethane in chloroform – snapshots of a molecular dynamic computer simulation (iodine atoms are violet, chlorine atoms are orange in color).

How swift is a molecule and how agileis it? What happens when its freedom

of movement is restricted, for example, be-cause it is locked in a crystalline structure?How do the individual atoms move when amolecule interacts with another one, i.e.when a chemical reaction occurs? Theseare the questions we try to answer in ourStructural Dynamics Research Group.

When we observe atomic and molecularstructures, we use X-ray flashes, which onlylast 10-14 seconds – i.e. one hundred trillionth of a second. These extremelyshort flashes are deflected by the mole -cules and then detected (ultra-fast X-raydiffraction). In this manner, individualatoms can be localized, namely with an accuracy of one hundred-millionth of amilli meter. Since the investigated mole -cules are one hundred to one thousand times larger than this, we can thus followevery movement in molecules and in chem -ical reactions very exactly and on extreme lyrapid time scales.

Choreography of the moleculesIn addition, we observe the residual X-rayflash after a fraction of the light quanta hasbeen captured by the obstructing mol -ecules (ultra-fast X-ray spectroscopy). In thismanner, we can determine the movementswith which individual atoms of the investi-

gated molecules participate in the choreo-graphy of a chemical reaction. With thesemethods we hope to understand chemicalprocesses so exactly that we can manipu -late them in a targeted manner in order, forexample, to develop materials which trans-form electrical energy into light energy more efficiently. Such light-active materialscan be used, for example, in photovoltaicfacilities and biopower plants.

Structural Dynamics of (Bio)Chemical Processes

Dr. Simone Techert received herPhD at the University of Göttingenin 1997. From 1998 to 2000, sheworked as a postdoctoral re-searcher and scientist at the European Synchrotron RadiationSource in Grenoble (France) andwent from there to the ScrippsResearch Institute in La Jolla,(California, USA). From 2001 to2004, she headed an Emmy Noether Junior Research Groupat the Max Planck Institute forBiophysical Chemistry. In 2005,she habilitated in physical chem -istry and worked as a scientist atthe Stanford Synchrotron Radia -tion Light Source in Stanford, California. Since 2006, she hasheaded the Structural Dynamicsof (Bio)Chemical Processes Re-search Group at the institute. She is a member of the AdvancedStudy Group of the Max PlanckSociety at the Center of FreeElectron Laser Science, Ham-burg. Simone Techert’s work hasbeen honored with several prizes such as the ESRF-PdP Prize (1999), the Roentgen Prize(2005), and the Karl WinnackerFellowship (2006).

Contact: stecher@gwdg.dewww.mpibpc.mpg.de/english/research/ags/techert/

A. Debnarova, S. Techert: Ab initiotreatment of time-resolved X-ray scatte-ring. J. Chem. Phys. 125, 224101(2006).

A. M. Lindenberg, et al.: Atomic-scalevisualization of inertial dynamics. Science 308, 392-394 (2005).

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Molecular movements during a chemical reactionare examined with soft X-radiation of the fourthgeneration (free electron laser): Ultra-fast X-raydiffraction on lipids provides a typical diffractionpattern.

X-radiation and water chemistry – when extremely short X-ray flashes impinge on water, freeelectrons are created in a trillionth of a second.

X-ray flash off X-ray flash on

Prof. Dr. Michael Stuke studiedphysics at the Universities ofMarburg, Heidelberg and theTechnical University Munich. In1977, he received his PhD in phys -ical chemistry with a disserta tionon laser isotope separation, forwhich he was awarded the OttoHahn Medal of the Max PlanckSociety. Since 1981, he heads theLaser Chemistry Research Groupat the Max Planck Institute forBiophysical Chemistry.

Laser-induced Chemistry

Contact: mstuke@gwdg.dewww.mpibpc.mpg.de/english/research/ags/stuke/

The sun sends high-energy light to theearth and induces many processes,

which can be of thermal or photochemicalnature. We investi gate the interaction andcoupling of high-energy radiation – in par-ticular laser radiation – with or into ma -terials. In this way, we can understand howthis energy acts on surfaces, molecules andatoms, and how the desired induced effectscan be used for precise and selective chem -ical processing of advanced materials.

In a controlled manner, any material cangently and with high precision be removedby pulsed laser ablation – with materialsranging from soft organic, such as the cornea of the human eye, all the way tohard metals used in industrial applications,and even diamond.

Growth of sophisticated 3-dimensional filigree structuresLasers can also be used to create small fili-gree three-dimensional material structures

made, for example, of ceramics or/and metals. To achieve this, a laser beam is directed onto a substrate surface, which isin direct contact to a suitable gas mixturecontaining a gaseous precursor compound.This precursor compound is decomposedby the laser’s energy leading to depositionof, for example, aluminum or/and alu -minum oxide. As a consequence, fine alu-minum struc tures or aluminumoxide wiresand rings can grow into the gaseous en -vironment. In this way, the desired struc -tures are laser-written just like a drawingpen creates lines on – however flat – paper.In this manner, ring electrode systems forsmall cages can be formed. Inside these cages scientists can store and investigatesmall objects, including cells, freely sus-pended in aqueous solution, when smallhigh frequency repelling electric fields areapplied to those electrodes. Cells are notaffected by nearby surfaces.

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Small three-dimensional structures can be created by laser-direct-write from the gas phase. Metallic aluminum(left) and aluminum-oxide (above) structures are createdwith a writing speed in the range of 50-100 micrometersper second. The precursor gas contains dimethylethyl -amine-alane alone (left) or with added oxygen (above).The compound gently breaks up into the stable gaseousamine (CH3)2C2H5N and AlH3 alane, forming the desiredaluminum (left) or aluminumoxide (above) and stable hydrogen H2 gas.

M. Stuke, K. Mueller, T. Mueller et al.:Direct-writing of three-dimensionalstructures using laser-based processes.MRS BULLETIN 32, 32-39 (2007), invited paper.

Sophisticated molecules

34

how structure is related to functionThe right protein for every purpose – the human body hashundreds of thousands available. Just think of our immunesystem with its vast selection of antibodies, which pro-tect us from viruses and disease-causing bacteria. How -ever, for many if not most proteins, the exact biologicalfunction has not been determined. Even less is knownabout their specific functional details. There is much tobe discovered. On top of this, the scientists focus on yetanother category of macromolecules: Nucleic acids donot only carry genetic messages, they also function ascatalysts – for instance, in the production of proteins.

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36

Highly specialized proteins perform and con-troll essentially all processes in the human

body. They transport cellular cargo, receive andtransmit signals, convert energy, facilitate chemi-cal reactions or ensure growth and movement.These molecules can undoubtedly be characte r -ized as the biochemical »nanomachines« of thecell; they developed in the course of a thousandmillion years of evolution. Similar to man-mademachines, in many cases it is the motions of indi-vidual parts of a protein, which implement itsfunction. Accordingly, the internal protein dynam -ics is extremely well-orchestrated. In many casesthe movement of individual atoms is decisive.

No wonder that minute construction errors canhave fatal consequences. Some hereditary dis -eases, for example sickle cell anemia, arise be-cause a specific protein differs by only a fewatoms from the normal version – which is com-

posed of many ten thousands of atoms. Eventhough the exact structure of proteins can be

measured at atomic resolution in many cases, the movements of proteins at an

atomic level are very rapid and, there -fore, are extremely difficult to access

experimentally. In order to find out how these

nano-technological marvels func -tion, we use com puter simula -tions. State-of-the-art, high-per -for mance parallel computers andever increasingly sophisticatedalgorithms allow us to calculatethe movement of each indi -

vidual atom in a protein com-

Theoretical and Computational Biophysics

37

Prof. Dr. Helmut Grubmüller received his PhD in theoreticalphysics at the Technical Univer -sity of Munich in 1994. From 1994to 1998, he worked as a researchassistant at the Ludwig Maxi -milians University in Munich. In 1998, he moved to the MaxPlanck Institute for BiophysicalChemistry as research grouphead. He has headed the Depart-ment of Theoretical and Compu-tational Biophysics there since2003. Helmut Grubmüller is alsohonorary professor of physics atthe University of Göttingen.

plex with sufficient precision. To un-derstand in detail the complex proces-ses of life on the basis of the knownphysical laws, we cooperate closelywith experimental research groups.

Proteins at work – the smallest motor in the worldA particularly impressive example of a protein at work is the molecular motorATP synthase. This protein complex ofonly twenty nanometers (millionth of amillimeter) in size works in the »powerplants« of cells and supplies the re -quired energy for most processes in thebody. With the aid of this protein ma chine, the human body transformsapproximately 75 kilograms of theenergy storage molecule ATP daily, andeven more in peak physical activities. In fact, the similarity between ATP

synthase and an Otto engine isastonish ing: In both cases there areforce strokes, a turning »crankshaft«and moving »cylinders«. The decisivedifference is the efficiency: Whereasthe Otto engine achieves only a frac -tion of the thermodynamical efficiencylimit, ATP syn thase reaches nearly 100 percent. By means of computer simulations, we have been able to re-solve how this energy transfer occursin detail. The sim ula tions revealed true»nano-mechanics«. The rotary move-ment of the shaft is translated into anatomically coordinated movement atthe synthesis site such that the ATPmolecule is synthe sized through elabor -ate assembly.

M. Zink, H. Grubmüller: Mechanicalproperties of the icosahedral shell ofsouthern bean mosaic virus: a molecu-lar dynamics study. Biophys J. 96, 1350-1363 (2009).

L. V. Schäfer, E. M. Müller, H. E. Gaub, H. Grubmüller: Elastic properties ofphoto switchable azobenzene polymersfrom molecular dynamics simulations.Angew. Chemie Int. Ed. 46, 2232-2237(2007).

F. Gräter, J. Shen, H. Jiang, M. Gautel, H. Grubmüller: Mechanically inducedtitin kinase activation studied by force-probe molecular dynamics simulations.Biophys. J. 88, 790-804 (2005).

R. Böckmann, H. Grubmüller: Nano -seconds molecular dynamics simulationof primary mechanical energy transfersteps in ATP synthase. Nature Struct.Biol. 9, 198-202 (2002).

M. Rief, H. Grubmüller: Kraftspektro-skopie von einzelnen Biomolekülen.Physikalische Blätter, 55-61, Feb.,(2001).

Contact:hgrubmu@gwdg.dewww.mpibpc.mpg.de/home/grubmueller/

Internal Groups: Dr. Gerrit Grœnhof

� As a nanomachine par excellence ATP synthase produces the universal »fuel« ATP in the human body.The complete machine is just 20 millionth of a millimeter in size. In this computer-generated snapshot anATP molecule (red) has just been assembled in the top part (cyan/green). The energy required for this istransmitted by a rapidly rotating »crankshaft« (orange, yellow arrow), which in turn is driven by a bottompart in the mitochondrial membrane (green/ yellow). In a manner similar to an electric motor, this bottompart is driven by an electric current, which flows across the membrane along the bottom part and the redstator. In order to examine the nanomachine at work, the computer calculates the forces that act on everysingle atom, from which the detailed motion of every atom is derived. From these data, a super-resolutionvideo sequence is obtained revealing the tricks of nature.

Forces often play an important role in molecular nanomachines, but are extremely difficult to access bymeasurement. Our computer simulations thereby aid in understanding how proteins react to forces. Theimage shows a vitamin molecule which is being pulled out of a receptor binding pocket – the requiredforce can be measured using an atomic force microscope; the simulation reveals the underlying mechanism.

The function of a machine can be muchmore easily understood if we can ob-

serve it in action. The same is true for thetiny machines in our cells – the proteins.Billions of these nanomachines enable,control or support nearly all the processesoccurring in our body. Accordingly, the consequences are frequently severe whenproteins do not function properly. Manydiseases are caused by such dysfunctions.

Which interactions give rise to aggre -gation of proteins and thus cause disorderssuch as Alzheimer’s or Parkinson’s disease?How do cells regulate the influx and effluxof molecules such as water, ions and nu-trients? How does molecular recognitionfunction? These are some of the questionswe investigate in our research group.

In order to understand the function anddysfunction of proteins, it is usually in -sufficient to know their blueprints andtheir three-dimensional shape. Many pro-teins fulfill their respective task only by means of well-orchestrated movements.Our objective is to understand protein dynamics at the molecular level and to unravel the mechanisms underlying suchdynamics.

Water channels, which also filterOne class of proteins investigated in thegroup are aquaporins. They form pores in thecell membrane, which function as perfect,highly selective water filters. Only water mol -ecules can pass through; ions and larger mol -ecules are blocked. By means of moleculardynamics simulations we were able to resol-

ve the mechanism which allows aquaporinsto selectively filter in such a way; an electro-static barrier effectively prevents any ionfrom passing through.

In addition, we have a true multitalentamong the proteins under investigation: ubi-quitin. It is part of a sophisticated recyclingsystem in the cell which marks certain pro-teins as cellular »trash«. But how does ubi-quitin manage to recognize and bind to amultitude of different partner molecules?With the aid of molecular dynamics calcu -lations and experiments in cooperation withthe Department of NMR-based StructuralBiology we were able to demonstrate thatubiquitin is surprisingly mobile. Like a Swissarmy knife it continuously changes its shape,extremely rapidly – within a millionth of a second – until it accidentally fits its partner.

Computational Biomolecular Dynamics

Prof. Dr. Bert de Groot receivedhis PhD in biophysical chemistryat the University of Groningen(The Netherlands) in 1999. From1999 to 2003, he worked as a post-doctoral fellow in Helmut Grub-müller’s Theoretical MolecularBiophysics Research Group at theMax Planck Institute for Biophysi-cal Chemistry. He heads the Com-putational Biomolecular DynamicsGroup there since 2004. Bert deGroot is an adjunct professor of physics at the University of Göttingen since 2009.

Contact:bgroot@gwdg.dewww.mpibpc.mpg.de/groups/de_groot

O. F. Lange, N. A Lakomek, C. Fares, G.F. Schröder, K. F. A. Walter, S. Becker, J.Meiler, H. Grubmüller, C. Griesinger, B.L. de Groot: Recognition dynamics upto microseconds revealed from RDCderived ubiquitin ensemble in solution.Science 320, 1471-1475 (2008).

J. S. Hub, B. L. de Groot: Mechanismof selectivity in aquaporins and aqua-glyceroporins. Proc. Nat. Acad. Sci.105, 1198-1203 (2008).

D. Seeliger, J. Haas, B. L. de Groot:Geometry-based sampling of conforma-tional transitions in proteins. Structure15, 1482-1492 (2007).

Molecular recognition by ubiquitin. Since ubiquitincan rapidly assume other shapes, it recognizes many different binding partners. One can imagine it to be like a key ring with which different locks can be opened.

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Water flow through an aquaporin channel. Left: Water(red/white) does not pass through the lipid membrane(green/yellow), but rather through special pores,which aquaporin forms in the membrane (blue). Right: Path of the water molecules through the aqua-porin channel. Specific interactions allow the passageof water, but prevent larger molecules or ions frompassing through in an uncontrolled manner. Even tinyprotons (hydrogen ions) are excluded.

Dr. Stefan Becker received hisPhD in 1991 at the University ofSaarland in chemistry and sub -sequently went to the C.H. BestInstitute in Toronto (Canada). In1995, he moved to the GrenobleOutstation of the European Mole-cular Biology Laboratory. Since1999, Stefan Becker has headedthe Molecular Bio logy ProjectGroup in the Department of NMR-based Structural Biology at theMax Planck Insti tute for Biophys -ical Chemistry.

The adage »the communication must beright« also applies to cells. To survive,

bacterial cells must, exactly like our body'scells, react to an entire spectrum of stimuliin their environment. However, the stimulistill have a barrier to cross before they canenter the cell: the cell membrane. It shieldsthe cells inner workings effectively from theexternal environment. However, there is aconnection from the outside to the inside:Receiving antennas in the membrane – thesensor proteins – acquire the stimuli andconduct them across the membrane. In theprocess, they enter into close contact withtheir communication partners. Sensor pro-teins are switched on and off depending onthe cell's requirements. But, how can theybe switched from »on« to »off«?

To find the answer to this question, wegrow crystals of such sensor proteins – asome times tedious procedure. Then we sendhigh-energy X-ray radiation through such acrystal and thus acquire a complicated dif-fraction pattern, which provides a largeamount of information on the spatial struc -ture of the sensor protein. Admittedly, thismethod has a disadvantage. Inthe crystal the protein has prac -tically no freedom of move-ment. In order to understanddynamic processes such as theswitching processes, supple-mentary nuclear magnetic re s -onance (NMR) measurementsare there fore required becausethis procedure allows us to ex -amine molecules in solution –with much freedom of move-ment.

What enables proteins to switch?Structural changes are of central importancefor the »on« and »off« states. The differ -ences between the active and inactive statecan be small, as for example in the histidinekinase CitA. This protein is vital for bac teriabecause it allows them to react to changesin their environment. Our investi gationsshow that when citrate binds to the regionof the protein which protrudes outward, theprotein contracts at this location. This con-traction is ultimately crucial for the trans-mission of the signal into the cell’s interior.

In the case of the STAT proteins, on the other hand, the structural alterations are great.STAT proteins transmit signals from the cellmembrane into the interior of the cell nucleusand change the activity of certain genes. Admittedly, in this case always two STATproteins bind to each other regardless ofwhether the STAT is active or inactive. How -ever, the binding occurs in very differentways, sometimes arranged parallel to eachother and sometimes antiparallel.

Structural Investigations of Protein Complexes

Contact:sabe@nmr.mpibpc.mpg.dehttp://medusa.nmr.mpibpc.mpg.de

39

Only if citrate binds to the part of the histidine ki-nase CitA, which extends out of the cell surface,does the molecule contract. As a result the trans-membrane part of the histidine kinase is pulled»upwards«. This movement is the signal that is re-layed into the cell’s interior and triggers the activ -ation of the intracellular histidine kinase domain.

In the active form (A) the two STAT molecules are arranged parallel to each other andbind like a nutcracker to the DNA (red structure in central position). How ever, in theinactive form (B) the STATs are arranged antiparallel to each other; the structure resembles a boat, where the interaction with the DNA cannot take place any more.

citrate-free citrate-bound

M. Sevvana et al.: A ligand-inducedswitch in the periplasmic domain ofsensor histidine kinase CitA. J. Mol.Biol. 377, 512-523 (2008).

D. Neculai, A. M. Neculai, S. Verrier, K. Straub, K. Klumpp, E. Pfitzner, S. Becker: Structure of the unphosphory -lated STAT5a dimer. J. Biol. Chem.280, 40782-40787 (2005).

S. Becker, B. Groner, C.W. Müller:Three-dimensional structure of theStat3ß homodimer bound to DNA. Nature 394, 145-151 (1998).

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For our molecular inventory, the spatialstructure of a molecule is just as important

as its chemical composition. The lethal conse-quences of misfolding are evidenced by such in-curable pathological condi tions as Alzheimer’s,Parkinson’s or Creutzfeldt-Jakob diseases. In allthree diseases, misfolded protein molecules accumulate in brain cells and destroy them. Onlyproperly shaped (folded) proteins and nucleicacids can fulfill their biological function. In thiscontext, we are interested in the question as towhich structural details are crucial for properfunction applied in vitro as well as in studies ofcells and tissues.

Getting to the core of the matterOur method of choice is nuclear magnetic re -sonance (NMR) spectroscopy. NMR spectrosco-py uses a common property of most atomic nu-clei, namely that they exhibit magnetic properties.They can be con sidered to be a kind of electricallycharged top which is attempting to orient itself toan external magnetic field. Because of this pro-perty, nuclei can absorb electromagnetic radiationthat has a certain energy and frequency (E = hν).The frequency which is absorbed depends on theatomic nucleus’ chemical environment. In a mol -

ecule with many differently placed atomic nuclei,a corresponding number of different frequenciesis required. As a consequence, an NMR spectrumresults, which contains detailed informationabout the arrangement of the individual atom nu-clei and thus about the atoms’ location in three-dimen sional space.

However, the interpretation of this informationis an art in itself. And the larger the molecule under inves tigation is, the more difficult this taskbecomes. The use of so-called triple resonanceexperiments, which provide three-dimensionalspectra, is required. In protein molecules whichcomprise more than two hundred amino acids – thebuilding blocks of all proteins – even this type ofNMR spectroscopy reaches its limit. However, weare attempting to push these limits even further.

Pushing the limitsIn this context, we incorporate isotopes into themolecules. We replace, for example, some of thenormal nitrogen with a variant possessing a heavieratomic nucleus (an isotope). We can then makeeither one isotope or the other visible. In thismanner, proteins which are really too large forNMR spectroscopy can be analyzed section bysection. However, the first problem to be solved

NMR-based Structural Biology

Spatial reconstructionof a tubulin molecule.NMR spectroscopyshows how the anti-cancer drug penetratesinto this structure.

41

is how to produce such proteins in ade-quate numbers. Bacteria which havebeen equipped with the gene in ques-tion have proved helpful. If they are fedwith amino acids which contain a spe-cific isotope, they as semble the proteinaccording to our wishes – if everythingfunctions properly.

Electrons, which have a much largermag netic moment than nuclei, can alsobe attached to molecules. They provideaddi tional information, which we used,for example, to analyze the spatial struc -ture of one of the most frequent humanmembrane proteins. In addi tion, wewish to use electrons for signal amplifi-cation using so-called Dynamic NuclearPolarization (DNP).

Dynamic moleculesNMR spectroscopy can also be used to observe proteins in action. In solutionor embedded in a membrane, they canmove freely in a manner similar to thatin their natural environment during themeasurement. When they change theirspatial structure in the process, this fre-quently occurs extremely rapidly. Anew procedure enables us to measurethe movements of proteins which occurin a time window of between one thou-

sand-millionth and a millionth of a se-cond. In this manner, we obtain newknowledge of how proteins recognizeone another and what makes them ma-neuverable.

Focus on drug moleculesWe can now exactly examine how smallmol ecules act on large proteins. Thus,for example, it is possible to show howan active substance used in the chemo-therapy of cancer attaches to the pro-tein tubulin. The microtubuli, long na-no-tubes which the cell uses to main-tain its shape, are made of tubulin.When assembly and reassembly of thislattice does not function, the cells dieas soon as they attempt to reproduce.That affects cancer cells severely be-cause they normally reproduce continu-ously. A small molecule which we pre-pared can stop dis eases such as Alz -heimer’s, Parkinson’s and Creutzfeldt-Jakob – at least in our animal model.We are currently studying the spatialstructure of this extremely promisingmol ecule in a complex with its targetmolecule.

Prof. Dr. Christian Griesinger studied chemistry and physics atthe University of Frankfurt/Main,where he received his PhD in or-ganic chemistry in 1986. From 1986to 1989, he was a postdoctoral fel-low at the Laboratory for PhysicalChemistry at the ETH in Zurich(Switzerland). In 1990, he accept -ed a professorship at the Institutefor Orga nic Chemistry at the Uni-versity of Frankfurt, and since1999, he has headed the Depart-ment of NMR-based StructuralBiology at the Max Planck Institu-te for Biophysical Chemistry.Christian Griesinger has beenawarded a number of renownedprizes, among them the Sommer-feld prize (1997), the Leibniz prizeof the DFG (1998) and the Bayerprize (2003). He is member of theAkademie der Wissenschaften zuGöttingen and the German Acade-my of Sciences Leopoldina. He re ceived an ERC Advanced Grantin 2008.

O. Lange, N. A. Lakomek, C. Farès, G.Schröder, S. Becker, J. Meiler, H. Grub -müller, C. Griesinger, B. de Groot: Re-cognition dynamics up to microsecondsrevealed from an RDC-derived ubiqui-tin ensemble in solution. Science 320,1471-1475 (2008).

M. Reese, D. Lennartz, T. Marquardsen,P. Höfer, A. Tavernier, P. Carl, T.Schippmann, M. Bennati, T. Carlomag-no, F. Engelke, C. Griesinger: Con-struction of a liquid-state NMR DNPshuttle spectrometer: first experimentalresults and evaluation of optimal per-formance characteristics. Appl. Magn.Reson. 34, 301-311 (2008).

M. Bayrhuber, T. Meins, M. Habeck, S. Becker, K. Giller, S. Villinger, C. Von-rhein, C. Griesinger, M. Zweckstetter, K.Zeth: Struc ture of the human voltage-dependent anion channel. Proc. Natl.Acad. Sci. USA 105, 15370-5 (2008).

Contact:cigr@nmr.mpibpc.mpg.de/http://medusa.nmr.mpibpc.mpg.de

The spatial structure of a molecular channel whichpasses through the outer membrane of mitochondria– the »power plants« of cells. Via such channels, themitochondria provide chemical energy in the form of adenosine triphosphate, in the human body thisamounts to approximately 75 kg daily.

Form follows function – this platitudefor good product design is very fre-

quently also perfectly implemented in pro-teins. Depending on their task, they havea very specific shape. The amino acidchains of a muscle protein fold them selvesinto a different spatial struc ture than thosein a tunnel protein, which allows substan-ces to pass through a mem brane.

Proteins out of shapeIt thus appears even more surprising thatparticularly a large part of the human ge-nome contains plans for proteins whichare present in the cell in nearly an unfold -ed form. Biologists term these proteins»intrinsically disordered« or »natively un -folded«. They play an important role invar ious cellular processes, for example,when a gene is read, when a cell divides,or when signals are transmitted.

It is not exactly easy to investigate thisunusual protein group because such pro-teins are very flexible and mobile. Thishinders work using imaging methods asthe acquired images – as in photography –are out of focus. Only with nuclear mag-netic resonance spectro scopy are we able

to obtain information with atomic resolu-tion. Importantly, high mobility is highlybeneficial in the cell. It allows such dis -ordered proteins to bind to many differentpartners. Additionally, the cell can regulatethese proteins efficiently, for example, byattaching small phosphate groups.

In our group we use magnetic resonanceto study how these proteins change theirform when they recognize other proteinsand bind to them or when something goeswrong with their own folding. We investi-gate the con sequences of such misfoldingsof proteins such as �-synuclein, tau undamyloid-�, which play a central role in theParkinson’s and Alzheimer’s diseases. InParkinson’s and Alzheimer’s patients mis-folded tau and amyloid-� can be detectedin the brain tissue as »protein clumps«.But why are these improperly folded pro-teins so detrimental? According to our re-search results, a possible cause is that im-properly folded tau protein binds muchmore weakly to microtubule proteins – thecell’s »transport rails«. As a consequence,the material transport inside the nerve cellis disrupted, and nerve cell endings nolong er grow properly.

Structure Determination of Proteins Using NMR

Prof. Dr. Markus Zweckstetterstudied physics at the LudwigMaximilians University in Munich.He did his PhD under the super -vision of Tad Holak at the MaxPlanck Institute for Biochemistryin Martinsried and received hisPhD from the Technical Universityof Munich. Subsequently, from1999 to 2001, he worked as apostdoctoral fellow in Dr. AdrianBax’s group at the National In -stitutes of Health in Bethesda(Maryland, USA). Since 2001, hehas headed the Research GroupProtein Structure DeterminationUsing NMR at the Max Planck In-stitute for Biophysical Chemistry.Markus Zweckstetter has taughtas honorary professor of biologyat the University of Göttingen since 2008.

Contact:mzwecks@gwdg.dewww.mpibpc.mpg.de/groups/zweckstetter

D. P. Karpinar, M. B. Balija, S. Kügler,F. Opazo, N. Rezaei-Ghaleh, N. Wender,H. Y. Kim, G. Taschenberger, B. H. Fal-kenburger, H. Heise, A. Kumar, D. Rie-del, L. Fichtner, A. Voigt, G. H. Braus,K. Giller, S. Becker, A. Herzig, M. Bal-dus, H. Jäckle, S. Eimer, J. B. Schulz, C.Griesinger, M. Zweckstetter: Pre-fibrillaralpha-synuclein variants with impairedbeta-structure increase neurotoxicity inParkinson's disease models. EMBO J. |doi:10.1038/emboj.2009.257 (2009).

M. D. Mukrasch, S. Bibow, J. Korukot-tu, S. Jeganathan, J. Biernat, C. Griesin-ger, E. Mandelkow, M. Zweckstetter:Structural polymorphism of 441-resi-due tau at single residue resolution.PLoS Biol. 17, e34 (2009).

M. Bayrhuber, T. Meins, M. Habeck, S. Becker, K. Giller, S. Villinger, C. Von-rhein, C. Griesinger, M. Zweckstetter, K.Zeth: Structure of the human voltage-dependent anion channel. Proc. Natl.Acad. Sci. USA 105, 15370-15375(2008).

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Structure of the tau protein. Inthe background, an electronmicroscopic image of the microtubuli, the binding partnerof the tau protein, can be seen.

Dr. Adam Lange studied physicsin Göttingen and received hisPhD in 2006 at the Max Planck In-stitute for Biophysical Chemistryin cooperation with the NationalInstitutes of Health in Bethesda(Maryland, USA). Subsequently,he moved to the Swiss FederalInstitute of Technology (ETH) Zurich with an EMBO Fellowship.Since 2008, he has headed theSolid-State NMR SpectroscopyResearch Group at the MaxPlanck Institute for BiophysicalChemistry. In 2006, Adam Langewas awarded the Otto Hahn Medal of the Max Planck Societyand the R. R. Ernst Prize of theGerman Chemical Society.

Life without proteins is inconceivable.They manage and perform the majori-

ty of those tasks which ensure the sur vivalof bacteria as well as plants and animals.All proteins are constructed of amino acids,hundreds – sometimes even thousands – ofwhich must be correctly strung together.However, only when they have folded toform their correct three-dimensionalstructure can they fulfill their respectivefunc tion in the cell. But, if they are incor-rectly folded, they can cause great damage.

Indeed, two incorrectly folded proteinscan be detected in the brain tissues of Alz-heimer’s patients. Amyloid plaques (proteinclumps) are found scattered diffuselyamong nerve cells in the cerebral cortexand other regions of the brain. Inside thenerve cells, there are tau fibrils which haveagglutinated to form clusters. In inter actionwith genetic factors, the latter contributeto the disruption of the nerve cell meta -bolism and the communication be tweennerve cells. The nerve cells atrophy and ultimately die.

Why do the individual molecules accu-mulate in this way and why can the cellnot degrade them? To find answers to thesequestions, we are attempting to determine

the structure of individual proteins in thetau tangles.

Rotating moleculesHowever, conventional methods of structuredetermination do not function in this casebecause the plaques and tangles are simplytoo large and additionally insoluble in water.They are thus neither appropriate for liquid- state nuclear magnetic resonance (NMR)spectro scopy nor for X-ray structure analy-sis. We therefore use a special form ofNMR spectroscopy to investigate theseheavy, water-insoluble protein aggregates:solid-state NMR spectroscopy. And wecombine this with a trick: As the moleculesthemselves do not turn rapidly enough, werotate our entire sample up to 65,000 timesper second. With the aid of radio waves wecan then examine the structure of the taufibrils in the strong magnetic field of theNMR spectrometers.

However, we are also interested in thestructure of other proteins which are tightlyanchored in the cell membrane. For ex -ample, how does the structure of the mem-brane proteins change when other mole -cules, for example medicinal products,bind to them.

A. Lange, I. Scholz, T. Manolikas, M.Ernst, B. H. Meier: Low-power crosspolarization in fast magic-angle spin-ning NMR experiments. Chem. Phys.Lett. 468, 100-105 (2009).

C. Wasmer, A. Lange, H. Van Melckebeke,A. B. Siemer, R. Riek, B. H. Meier:Amyloid fibrils of the HET-s(218-289)prion form a �-solenoid with a triangu-lar hydrophobic core. Science 319,1523-1526 (2008).

A. Lange, K. Giller, S. Hornig, M. F.Martin-Eauclaire, O. Pongs, S. Becker,M. Baldus: Toxin-induced conformatio-nal changes in a potassium channel re-vealed by solid-state NMR. Nature440, 959-962 (2006).

Solid-State NMR Spectroscopy

Contact:adla@nmr.mpibpc.mpg.dewww.mpibpc.mpg.de/english/research/ags/lange/

43

The superconducting magnet generates amagnetic field which is approximately 400,000times as strong as the earth's magnetic field.

The cells of all organisms, whether ani-mals or plants, have an active inner

life. They have a molecular inventory –their motor proteins – with which they canselectively move diverse cell components.Even in the movement of muscles, duringcell division or intracellular logistics, suchmotor proteins are indispensable. We de -sire to find out how they function and howdifferent motor proteins collaborate in thecell as a complex network. To achieve this,we determine the spectrum of motor pro-teins which different organisms have attheir disposal.

In this context, we can draw upon a con -tinuously increasing number of completelysequenced genomes. To identify motor pro-tein genes, we compare the DNA sequen-ces from the genomes of many different or-ganisms, from mouse and human down tofly, round worm and yeast. However, justbecause the DNA sequence of the organ-isms is known does not mean that the genes coded in it are known – far from it.Therefore, we are developing special toolsfor screening databases and selectively de-tecting motor protein genes.

Giant in the realm of proteinsThe mode of operation of motor proteinscan only be understood if we are familiarwith the details of their spatial structure.We are currently studying the protein com-plex comprising dynein und dynactin. It isinvolved in both the transport of differentcell components and cell division, in whichthe chromosomes must be sorted and cor-rectly distributed between the daughtercells. Dynactin coordinates and regulatesthe cellular cargo transport, whereas dynein supplies the energy required in thisprocess. However, how this molecular machine transforms chemical energy intomechanical work is still largely unresolved.This is not surprising because cellular dynein is a true giant among proteins. It isapproximately twenty times larger than thered blood pigment hemoglobin and thuspoorly accessible for structural investiga -tions. As a consequence, it is a par ticularchallenge to decipher its spatial struc ture.

Systems Biology of Motor Proteins

Dr. Martin Kollmar received hisPhD in chemistry at the MaxPlanck Institute for Medical Research in Heidelberg in 2002.He has been head of the SystemsBiology of Motor Proteins ProjectGroup at the Max Planck Institutefor Biophysical Chemistry sincethat time. Martin Kollmar receiveda Liebig Fellowship in 2002 and was awarded the Sophie Bernthsen Prize in 1998.

Contact:mako@nmr.mpibpc.mpg.dewww.motorprotein.de

F. Odronitz, H. Pillmann, O. Keller, S. Waack, M. Kollmar: WebScipio: An online tool for the determination ofgene structures using protein sequences.BMC Genomics 9, 422 (2008).

F. Odronitz, M. Kollmar: Drawing thetree of eukaryotic life based on the ana-lysis of 2269 manually annotated myo-sins from 328 species. Genome Biology8, R196 (2007).

F. Odronitz, M. Hellkamp, K. Kollmar:diArk – a resource for eukaryotic genome research. BMC Genomics8, 103 (2007).

Foreground: schematic diagram of the organization of the subunits in thecytoplasmic dynein/dynactin complex.Known structures of subunits or frag-ments thereof are superimposed onthe schematic diagram. Background:Phylogenetic tree of the dyneins, inwhich the different dynein forms aremarked in color.

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Dr. Henning Urlaub studied bio-chemistry at the Free Universityof Berlin and received his PhD atthe Max Delbrück Center for Molecular Medicine in Berlin.From 1997 to 2004, he conductedresearch as a postdoctoral fellowin Reinhard Lührmann’s labora -tories in Marburg and Göttingen,a period that included for severalresearch stays at the EuropeanMolecular Biology Laboratory(EMBL) in Heidelberg. He hasheaded the Bioanalytical MassSpectrometry Research Group atthe Max Planck Institute for Bio-physical Chemistry since 2004.Henning Urlaub has organizedthe series of Summer Schools on»Proteomic Basics«, held annual-ly since 2004. He is a member of the Executive Board of the German Society for Proteome Research (DGPF).How much does a molecule weigh?

Mass spectrometry is used to deter-mine exactly the mass – and thus theweight – of molecules. The state-of-the-art »bioanalytical« mass spec tro metry ofproteins has become a fundamental ana-lysis technique in the life sciences. As aresult of new methods in bioanalyticalmass spectrometry, we can quantify theproteins in different cells and develop-mental stages of an organism, for howcells develop and how organisms age is also reflected in their protein patterns. Wedetermine and compare the protein patterns of protein complexes and cellularcompartments, but also entire cells and

tissues, in cooperation with other researchgroups. The differences which we observein this context not only help us to under-stand cellular processes. They also allowconclusions as to what is occurring in acell when it differentiates from a progeni-tor cell (for example in bone marrow) to ahighly specialized immune cell. Not least,we are interested in how such cellular pro-cesses change in certain diseases.

Manageable protein fragments To achieve this we do not analyze the in-tact proteins. On the contrary, we initiallycleave the proteins, which we have iso -lated from a cell, into smaller, moremanage able protein fragments (peptides).Subsequently, we determine exactly notonly their mass, but also the sequence oftheir individual building blocks, the aminoacids. As soon as we know the mass andamino-acid sequence of one or more ofthese peptides, we can reliably identify the corresponding intact protein in databasesand determine its quantity.

The properties of proteins change withthe sequence and degree of modificationof their amino acids. This must be takeninto consideration in the analysis. Thus,proteins that are components of cell mem-branes and possess, for example, sugar re -sidues require a different analysis pro -cedure compared with those that bearphosphate residues and can switch special genes »on« and »off«. A further objectiveof our research group is therefore to im-prove the existing analytical methods andto develop new procedures that will pro -vide even more de tailed insight into the diverse protein inventory of cells.

Bioanalytical Mass Spectrometry

Contact:henning.urlaub@mpibpc.mpg.dewww.mpibpc.mpg.de/home/urlaub

State-of-the-art Fourier-transform (FT) electrospray-ionization mass spectrometer for the quantitativeanalysis of molecules. Tiny quantities of proteinsand their fragments are separated by liquid chroma -tography and sprayed directly into the mass spectro -meter. The screen shows the position of the spraynozzle (capillary needle made of silica glass) fromwhich the molecules emerge in front of the openingof the mass spectrometer.

Ion source of an electrospray-ionization mass spectrometer. Between the nozzle (1/100 of a milli -meter) and the opening of the mass spectrometer avoltage of 1-2 kV is applied. In this way, tiny dropletsof liquid containing the molecules to be investigatedare sprayed into the mass spectrometer, like a jet ofliquid from a scent-spray. Once inside the massspectrometer, the solvent evaporates, leaving charged molecules, the exact mass of which canthen be determined.

T. Oellerich, M. Gronborg, K. Neumann,H. H. Hsiao, H. Urlaub, J. Wienands:SLP-65 phosphorylation dynamics reve-als a functional basis for signal integra-tion by receptor-proximal adaptor pro-teins. Mol. Cell. Proteomics 8, 1738-1750 (2009).

L. Weinmann, J. Hoeck, T. Ivacevic, T.Ohrt, J. Muetze, P. Schwille, E. Kremmer,V. Benes, H. Urlaub , G. Meister: Importin 8 is a gene silencing factorthat targets argonaute proteins to dis-tinct mRNAs. Cell 136, 496-507(2009).

E. Meulmeester, M. Kunze, H .H. Hsiao,H. Urlaub, F. Melchior: Mechanismand consequences for paralog-specificsumoylation of ubiquitin-specific pro-tease 25. Mol. Cell 30, 610-619(2008).

C. Lenz, E. Kuehn-Hoelsken, H. Urlaub:Detection of protein-RNA crosslinks bynanoLC-ESI-MS/MS using precursorion scanning and multiple reaction mo-nitoring (MRM) experiments. J. Am.Soc. Mass Spectrometry 18, 869-881(2007).

Without enzymes all life would abruptly come to a halt. These bio-

catalysts enable a wealth of chemical pro-cesses which could otherwise not occur inour body. They accelerate chemical re -actions to an incomprehensible extent, sometimes as much as a factor of 1020.In order to boost reactions to thatextent, the enzymes requirechemical energy in an ap-propriate form. Most en -zymes work with a smallmolecule named adeno sinetriphosphate (ATP), theuniversal currency of ener-gy supply of the cell. Onaverage a human beingforms and consumes about75 kilograms of this mole-cule daily.

The primary focus of ourwork is on enzymes which can activate theineffective precursors of a medication. Inchemotherapy of some cancers and virusinfections the patients are not given theactive substance itself but rather a chemi-cal precursor, termed pro-drug. In the hu-man body, in a best case scenario only inthe diseased cells, the medication then de-velops the desired destructive effect. Inthis process, enzymes which attach phos-phate groups to components of the geneticmaterial DNA frequently come into play.How ever, these enzymes accept – more orless readily – similar molecules which areadministered to the patient as pro-drugs.

Curbing viruses and tumors When three phosphate groupshave been at tached to these »false«building blocks, they are also incorpo-rated into new DNA molecules. However,since they do not fit optimally, the struc -

ture of the DNA becomes unstable, or thechain of building blocks breaks off prema-turely. In this manner, the false DNA buil-ding blocks slow down viral reproductionor hinder tumor growth.

We already know which molecularstructures are formed when the pro-drugscome into contact with these enzymes.This helps us to understand why the easeof phosphate group attachment varies fordifferent pharmaceuticals. On this basis,we want to construct enzyme variantswhich activate certain pro-drugs even bet-ter and more selectively. In this context, we are particularly interested in thestructural mirror images of normal DNAbuilding blocks in living cells.

Enzyme Biochemistry

Dr. Manfred Konrad studied bio l -ogy, mathematics and chemistry,and received his PhD from theUniversity of Heidelberg in 1981.From 1978 to 1979, he conductedresearch as a DAAD Fellow at theBoston University, School of Medicine (USA). In 1982, he wentto the University of Bristol (UnitedKingdom) as an EMBO Fellow. After having worked for the Gödecke Company (Freiburg), heinitially went to the University ofMarburg and then came to theMax Planck Institute for Bio -physical Chemistry. Manfred Konrad has headed the EnzymeBiochemistry Research Groupthere since 2005.

Contact:mkonrad@gwdg.dewww.mpibpc.mpg.de/english/research/ags/konrad

E. Sabini, S. Hazra, S. Ort, M. Konrad,A. Lavie: Structural basis for substratepromiscuity of deoxycytidine kinase. J.Mol. Biol. 378, 607-621 (2008).

B. M. Wöhrl, L. Loubière, R. Brundiers, R. S. Goody, D. Klatzmann, M. Konrad: Expressing engineered thymidylate ki-nase variants in human cells to improveAZT phosphorylation and human im-munodeficiency virus inhibition. J. Gen.Virol. 86, 757-764 (2005).

C. Monnerjahn, M. Konrad: Modulatednucleoside kinases as tools to improvethe activation of therapeutic nucleosideanalogues. Chem. Bio. Chem. 4, 143-146 (2003).

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� In human cells there are enzymes from the kinase family which attachphosphate groups to nucleosides (N) – the building blocks of DNA – inthree steps. Nucleoside analogues (NA), which are administered as medi-cine, are also readily accepted, but their incorporation destroys the DNAstructure.

The enzyme deoxycyti-dine kinase attachesphosphate groups to theDNA building block de-oxycytidine. In this con-text, image (D-deoxy -cytidine, D-dC) and mirror image (L-deoxy-cytidine, L-dC) areequally well accepted.

Dr. Claudia Höbartner studiedtechnical chemistry at the Techni -cal University of Vienna (Austria)and the Swiss Federal Institute ofTechnology (ETH) Zurich (Swit-zerland). She received her PhD inorganic chemistry from the Leo-pold Franzens University of Inns-bruck in 2004. From 2005 to 2007,she did research as an ErwinSchrödinger Postdoctoral Fellowof the Austrian Science Fund(FWF) at the University of Illinois at Urbana-Champaign(USA). In 2007, she returned tothe University of Innsbruck – funded by the Herta Firnberg Program of the Austrian Federal Ministry for Science and Re-search. She has headed the MaxPlanck Research Group NucleicAcid Chemistry at the Max PlanckInstitute for Biophysical Chem -istry since 2008.

Nucleic acids are essential buildingblocks of all organisms. The nucleic

acids DNA and RNA store and transmitgenetic information. However, this does

not nearly exhaust their functional reper-toire. Nucleic acids also perform taskswhich scientists have only known from pro-teins for a long time. For example, just likeproteins RNAs can act as catalysts (ribo-zymes) and accelerate various chemical re -actions in nature. RNAs also regulate theac tivities of genes by means of ribo switchesor RNA interference.

DNA and RNA enzymes We want to understand how RNA func -tions as an enzyme or a gene regulator. Toachieve this we must first chemically mod ify the RNA. Thus, we furnish it forexample with chemical markers, which wecan site-specifically attach to the nucleicacid. We analyze the properties of this modified RNA in cooperation with otherresearch groups in the institute.

It has only been known for a few yearsthat DNA also has catalytic ability. TheseDNA catalysts (deoxyribozymes) have putour know ledge about catalytic nucleicacids on a new foundation. Today scien-tists already use DNA enzymes in researchand are investigating their possible use asmedicine or as alternative biosensors.

In our group we develop DNA enzymeswith which we can manipulate and chemi -cally modify RNA in a desired manner.However, to construct such custom-tailoredtools out of deoxyribozymes, we must havevery detailed knowledge of how they func -tion. Which of the thousands of atoms ina DNA enzyme participate in the cataly-sis? Where does the driving force requiredto accelerate a reaction come from? In orderto answer these questions, we analyze themolecular details of the structure, func -tion and mechanisms of DNA catalystswith an entire arsenal of methods fromchemistry, biochemistry and biophysics.

R. Rieder, C. Höbartner, R. Micura:Enzy matic ligation strategies for thepreparation of purine riboswitches withsite-specific chemical modifications. In: Riboswitches (Ed. A. Serganov). Methods Mol. Biol. 540, 15-24 (2009).

C. Höbartner, S. K. Silverman: Recentad vances in DNA catalysis. Biopolymers87, 279-292 (2007).

Nucleic Acid Chemistry

Contact:claudia.hoebartner@mpibpc.mpg.dewww.mpibpc.mpg.de/english/research/ags/hoebartner

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In vitro selection is the procedure with which catalytic nucleic acids arefound in the laboratory. In this method, a library of different nucleic acids isrepeatedly sorted and amplified until a (deoxy)ribozyme with the desiredproperties is obtained.

The primary structure of ribonucleic acid (RNA).Chemical modifications can be added to the nucleobases, the sugar unit (ribose) or the phosphate backbone.

Cellular machines

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how molecules divide up the workYeast fungi are organisms that consist of a single cell. Butmany body cells in multi-cellular organisms, such as miceand humans, function autonomously as well. In order forthe cells to reliably fulfill their various functions, a largenumber of different proteins – the cell’s nanomachines –must smoothly work together. Which molecular machinesare at work in different cell types, how do they function indetail, and how do they interact? These are some of thequestions that several departments and research groupsaddress by employing biochemical, molecular genetic, microscopic and fluorescence spectroscopic methods.

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Regardless of whether muscle, skin or liver, inevery tissue there is an abundance of diverse

proteins. The blueprints for all of these protein mol -ecules are present in encoded form in the genesfound in the cell nucleus.

In order to be able to produce proteins accordingto these blueprints, a gene is initially transcribed intoa precursor messenger ribonucleic acid (pre-mRNA).However, this precursor form (draft version) cannotbe immediately utilized for protein production, be-cause the blueprint for a protein is not normally present in one piece, but rather in several segments –the exons. Between these exons there are regionsthat have to be excised from the precursor version –the introns. Only after this operational step (termedsplicing) has occurred are all of the required exonscontiguously connected in a ready-to-use messengerRNA.

This appears to be unnecessarily complicated, butit has a decisive advantage: Different exons can beselected and assembled to form different messengerRNAs as required. As a consequence, a single genecan provide the blueprints for many different pro-teins. This process, which is termed »alternative splicing«, explains how human beings can producemore than 100,000 different proteins from a rathermodest complement of approximately 25,000 genes.

Cutting to measure In order to transform the precursor version of amessen ger RNA into a functional end product, splicing must occur very precisely. Thus, it is no won-der that this process is performed by a very compli-cated molecular machine, the splicesosome. This

machine is comprised of more than 150 proteins andfive small RNA molecules (the snRNAs U1, U2, U4,U5 und U6). Many of these spliceosomal proteinsare not scattered around the cell nucleus in an un-orderly manner, but form precisely organized com-plexes. Thus, for example, approximately 50 of theseproteins associate with the snRNAs to form RNA-protein particles. These so-called snRNPs (pro-nounced »snurps«) bind to the pre-mRNA as pre -fabricated complexes and are the main subunits ofthe splice osome.

A molecular editing tableThe spliceosome is assembled on site for each splicing event. To achieve this, snRNPs and otherhelper proteins are successively assembled on thepre-mRNA. Each of these five RNA-protein particlesperforms specific tasks. Thus, for example, the

Spliceosomes remove introns from a pre-mRNA to produce mature mRNA which serves outside the nucleus as a template for protein production.

A catalytically activespliceosome has a

complex three-dimen-sional structure.

Cellular Biochemistry

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Prof. Dr. Reinhard Lührmann received his PhD in chemistry atthe University of Münster in 1975.He went from there to the MaxPlanck Institute for MolecularGenetics in Berlin where heheaded an independent researchgroup at the Otto Warburg Labora -tory from 1981 to 1988. In 1982, he acquired his professorshipqualifications (habilitation) in molecular biology and biochemis-try at the Free University of Ber-lin. In 1988, he accepted a pro -fessorship for physiological chemistry and molecular biologywith the School of Medicine atthe University of Marburg. He has headed the Department ofCellular Biochemistry at the MaxPlanck Institute for BiophysicalChemistry since 1999. ReinhardLührmann has been awarded numerous scientific prizes,among them the Max Planck Research Prize (1990), the LeibnizPrize (1996), the Feldberg Prize(2002), and the Ernst Jung Prizefor Medicine (2003). He is an honorary professor at the Uni -versities of Göttingen and Marburg.

M. C. Wahl, C. L. Will, R. Lührmann:The spliceosome: design principles of adynamic RNP machine. Cell 136, 701-718 (2009).

S. Bessonov, M. Anokhina, C. L. Will,H. Urlaub, R. Lührmann: Isolation ofan active step 1 spliceosome and com-position of its RNP core. Nature 452,846-850 (2008).

H. Stark, R. Lührmann: Electron cryo-microscopy of spliceosomal compo-nents. Ann. Rev. Biophys. Biomol.Structure 35, 435-457 (2006).

Contact:reinhard.luehrmann@mpibpc.mpg.dewww.mpibpc.mpg.de/english/research/dep/luehrmann

beginning and end of an intron must berecognized and brought closer to each other in order to im mediately splice outthe intron and couple the two exons origi-nally separated by the intron. The mole-cular »scissors«, which ex cises the intron,is successively acti vated during this pro-cess. In the course of splicing a brisk com -ing and going of snRNAs and proteins occurs; the timing of these mole cular ex-changes is exactly controlled. Presum ably,this complex procedure en sures the exactexcision of an intron and hence error-freeassembly instructions for each protein.

Our objective is to record the dramaticstructural dynamics of the spliceosome togenerate a movie of the splicing process.Concomitantly, we would like to under-stand how the spliceosome’s molecularscissors – its catalytic center – is assembledand would like to observe this pair of scissorsduring the excision of an intron. To achievethis, we have stopped the spliceosome atdifferent operational steps, isolated it inthese states and analyzed its components.

In addition, we are able to reassemblebiologically active spliceosomes from iso -lated components. By selectively remov -ing or modifying individual components,we can observe how these manipulationsaffect the spliceosome.

In order to understand this fascinatingmolecular machine's mode of operationin detail, we use an interdisciplinary ap-proach. In addition to biochemical and

biophysical methods, we primarily usehigh-resolution electron microscopy andX-ray crystal structure analysis. They pro-vide us with three-dimensional models ofindi vidual snRNPs and entire spliceo -somes, as well as details of the partici -pating macromolecules.

Errors with grave consequences The molecular analysis of the spliceo -some, which is the focus of our inter -disciplinary approach, will not only pro -

vide information about the causes ofmole cular disorders that result from errors in the splicing of messenger RNA,but will also allow new therapeutic ap-proaches for the treatment for such dis -eases. New estimates suggest that morethan 20 percent of human genetic dis -eases are the result of mutations that im-pair the function of spliceosomes.

Active spliceosomes (stained red) are only present in distinct regions of the cell nucleus.

At the heart of the spliceosome: An RNase H-like domain in the Prp8 protein (as revealed by X-ray crystallography) suggests thatthe spliceosome is an RNP enzyme.

The cell keeps its metabolism runningwith molecular machines. Frequently,

the latter are very complex structures com-prising a large number of different com -ponents. In order to observe these machinesdirectly in action in the nanocosmos of thecell scientists must how ever expend a greatdeal of effort.

Snapshots in a state of shockIn our group we investigate macromole -cules in a shock-frozen state with the aidof the electron cryo-microscope. Thatsounds perhaps para doxical, but the mole-cular machinery can be stopped in verydiffe rent operational steps by means offlash freezing. The electron micro scopeprovides us with a complete series ofimages of a single macromolecule with thesesamples from different spatial perspectivesand at different points in time. From theseindi vidual images we ultimately assemblethe three-dimensional structure with theaid of special computer programs. Theyshow us what the molecular machine lookslike and how it changes during theirfunctional cycle – and does so in 3D.

We apply this technique to a large num-ber of different molecular machines, which

are located at important switching pointsof cellular information processing. Thesemachines frequently comprise not onlyproteins but rather are complex associa -tions of proteins and nucleic acids. Forexample, we investigate how the cell’s pro-tein factory – the ribosome – produces pro-teins by reading out the genetic informa -tion. At present we are also observingsplice osomes. They go into action after theblueprints for proteins have been copiedinto the draft version of a messenger RNA.Splice osomes cut the unnecessary partsout of the messenger RNA and thus con-vert the blueprints into a legible form. Inaddition, we are studying a vital proteincomplex, which plays an important role during cell division: the so-called AnaphasePromoting Complex. It en sures that the genetic information is correctly distributedto the two daughter cells.

With the aid of electron cryo-microscopywe can observe the spatial structure andmovements of such different molecularmachines directly at work. In this manner,we learn to understand their functioning indetail.

3D Electron Cryo-Microscopy

Prof. Dr. Holger Stark studied bio-chemistry at the Free UniversityBerlin and received his PhD atthe Fritz Haber Institute in Berlinin 1997. Subsequently, he did re-search at Imperial College Lon-don (United Kingdom) and, from1998 to 1999, was a group leaderat the University of Marburg. In2000, he relocated to the MaxPlanck Institute for BiophysicalChemistry as research grouphead. He has been a professorfor molecular electron cryo-microscopy at the University ofGöttingen since 2008. HolgerStark has received many awardsfor his research, among them theOtto Hahn Medal of the MaxPlanck Society (1997), the Ad -vancement Award of the Ger man Society for Electron Microscopy (1998) as well as the BioFuture Prize (2005).

Contact:hstark1@gwdg.dewww.mpibpc.mpg.de/groups/stark/

F. Herzog, I. Primorac, P. Dube, P. Len-art, B. Sander, K. Mechtler, H. Stark, J.M. Peters: Structure of the anaphasepromoting complex/cyclosome inter -acting with a mitotic checkpoint com-plex. Science 323, 1477-1481 (2009).

A. Chari, M. M. Golas, M. Klingenhager, N. Neuenkirchen, B. Sander, C. Engl-brecht, A. Sickmann, H. Stark, U. Fischer:An assembly chaperone collaborateswith the SMN complex to generate spliceosomal SnRNPs. Cell 135, 497-509 (2008).

B. Kastner, N. Fischer, M. M. Golas, B.Sander, P. Dube, D. Boehringer, K. Hart-muth, J. Deckert, F. Hauer, E. Wolf, H.Uchtenhagen, H. Urlaub, F. Herzog, J.M. Peters, D. Poerschke, R. Luhrmann,H. Stark: GraFix: sample preparation forsingle-particle electron cryomicroscopy.Nat. Methods 5, 53-55 (2008).

B. Sander, M. M. Golas, E. M. Makarov,H. Brahms, B. Kastner, R. Luhrmann, H.Stark: Organization of core spliceosomalcom ponents U5 snRNA loop I andU4/U6 Di-snRNP within U4/U6.U5Tri-snRNP as revealed by electron cryo-microscopy. Mol. Cell 24, 267 (2006).

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The ribosome »at work!«

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Prof. Dr. Wolfgang Wintermeyerreceived his PhD in chemistry atthe Ludwig Maximilians Univer -sity of Munich. Subsequent to hishabilitation in 1979, he conductedresearch on a Heisenberg Fellow -ship from the German ResearchFoundation at the University ofMunich, at the Karolinska Insti -tutet in Stockholm (Sweden) andat the Massachusetts Institute ofTechnology in Cambridge(Massa chusetts, USA). From 1987until he became an emeritus pro-fessor in 2009, he held the Chairfor Molecular Biology at the Private University of Witten/ Herdecke. From 1991 until 2007,he was also the Dean of the Faculty of Life Sciences there.Since 2009, Wolfgang Winter -meyer has been a Max PlanckFellow and head of the RibosomeDynamics Research Group in theDepartment of Physical Chem -istry at the Max Planck Institutefor Biophysical Chemistry.

Label for membrane proteinsAll living cells are enclosed in a membrane,which separates the cell’s interior from itsexternal environment. The membranecomprises a double layer of fat-like mol -ecules, in which many proteins are embed-ded; the latter fulfill very specific functions.Some of them function as »receiving an-tennae« for the reception of signals. Othersserve as channels, which only allow certainsubstances to pass into the cell. But howare such proteins inserted into the cellmembrane?

For the most part their incorporation intothe cell membrane occurs while the pro-tein is being assembled on the ribosome.Ribosomes, which assemble membraneproteins, must there fore be directed to the

cell membrane. But how is a membraneprotein recognized and how are the ribo -somes that are involved in the assembly re-cruited?

When a membrane protein is assembledon ribosomes, a specific label (»signal sequence») is incorporated, mostly in theearly part of the protein. This signal is recognized by a ribonucleic acid-proteincomplex – the signal recognition particle(SRP) – which directs the ribosome as-sembling the membrane protein to the cell

membrane. Interactions of the ribosomewith the signal recognition particle and the helper proteins ultimately result in thedeve l op ing protein being integrated in themembrane during the further course of syn-thesis. The molecular events occurring inthis process are one focus of our research.

Ribosomes in motionIn a second project we are investigating, incooperation with Marina Rodnina and Holger Stark, the molecular movements of molecules on the ribosome during proteinsynthesis. The energy required for this is stored in the energy-storage molecule GTPand is released when GTP is cleaved. Inthis context, the task of the elongationfactor G is to transfer this energy selec -

tively to the ribosome. We aim to find outhow these movements on the ribosome areinitiated: directly, by means of a mechani-cal coupling comparable to the shaft in amotor, or indirectly, via a mechanism whichuses the spontaneous movement of themolecules – the Brownian motion. In orderto reach this goal, we are combining physical biochemistry methods, includingrapid kinetics and single-molecule ap-proaches as well as electron cryo-micro -scopy.

Schematic of membrane targeting of a translating ribo -some. Depicted is a cut-away picture of the 50S ribosomalsubunit. The modeled nascent peptide inside the peptideexit tunnel of the ribosome is colored blue, the exposed signal sequence is red. The SRP binding site includes pro-tein L23 (yellow). The contact of the nascent peptide withprotein L23 induces a conformational change that promotesSRP binding to the translating ribosome. Subsequently, SRPbinds to the SRP receptor which mediates the contact ofthe ribosome with the membrane and the protein trans -locat ing pore (translocon), as indicated schematically.

T. Bornemann, J. Jöckel, M. V. Rodnina,W. Wintermeyer: Signal sequence-inde-pendent membrane targeting of riboso-mes containing short nascent peptideswithin the exit tunnel. Nat. Struct. Mol.Biol. 15, 494-499 (2008).

A. Savelsbergh, V. I. Katunin, D. Mohr,F. Peske, M. V. Rodnina, W. Winter -meyer: An elongation factor G-inducedribosome rearrangement preceedstRNA-mRNA translocation. Mol. Cell11, 1517-1523 (2003).

Ribosome Dynamics

Contact:Wolfgang.Wintermeyer@mpibpc.mpg.dewww.mpibpc.mpg.de/home/wintermeyer/

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In the cell nothing occurs without proteins. Theymaintain the cell’s shape, provide for mobility, for

transport and for communication, and finally theyare involved in all constructive, degradative, re -organization processes. Proteins are produced accord -ing to blueprints, which are stored in the geneticmaterial, desoxyribonucleic acid (DNA). Complexmolecular machines (ribosomes) are responsible forputting together the individual building blocks of

the proteins – the amino acids – in the sequencedictated by the blueprint. Composed of more thanfifty protein components and three to four ribo -nucleic acid molecules, ribo somes, with dimensionsof 10 to 20 nanometers, are approximately as largeas the smallest viruses. In order to observe thesemolecular complexes at work, we use different bio-physical methods such as fluorescence spectro -scopy and fast kinetic techniques.

Physical Biochemistry

Structural model of a bacterial ribosome. The two transfer ribo -nucleic acids which dock on itbring appropriate amino acids.

Prof. Marina Rodnina studiedbiology in Kiev and received herPhD there in 1989. Subsequently,she went to the University of Witten/Herdecke on a researchfellowship from the Alexandervon Humboldt Foundation. Sheworked there as a research assistant from 1992 to 1997. Afterher habilitation in 1997, she wasappointed university professorthere and, from 2000 to 2009, sheheld the Chair of Physical Bio -chemistry. Marina Rodnina hasheaded the Department of Phy s -ical Biochemistry at the MaxPlanck Institute for BiophysicalChemistry as a Director since2008. She has also been a memberof the German Academy of NaturalScientists Leopoldina in Halle since that year.

P. Milon, A. L. Konevega, C. O. Gualerzi, M. V. Rodnina: Kinetic checkpoint at alate step in translation initiation. Mol.Cell 30, 712-720 (2008).

A. L. Konevega, N. Fischer, Y. P. Semen-kov, H. Stark, W. Wintermeyer, M. V.Rodnina: Spontaneous reverse move-ment of tRNA-mRNA through the ribo-some. Nat. Struct. Mol. Biol. 14, 318-324 (2007).

M. Diaconu, U. Kothe, F. Schlünzen, N.Fischer, J. Harms, A. G. Tonevitski, H.Stark, M. V. Rodnina, M. C. Wahl:Structural basis for the function of theribosomal L7/L12 stalk in factor bindingand activation of GTP hydrolysis. Cell121, 991-1004 (2005).

Contact:rodnina@mpibpc.mpg.dewww.mpibpc.mpg.de/english/research/dep/rodnina/

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Precision workEven when hundreds, sometimes thou-sands, of amino acids are linked to eachother, every one of them is important. Asingle false building block can render theprotein non-functional. In the worst casea defective protein can even cause damage.How ribosomes manage to keep the errorfrequency so astonishingly low is there-fore of particular interest to us. It is al -ready known that ribosomes do not nor-mally react if they are confronted with anin correct building block. Only when thecorrect building block docks on, doesthis trigger a structural change, whichulti mately results in the linking of theamino acids. The ribosome brings twoamino acids into such a position thatthey are readily connected. Thus, theribo some is a catalyst which acceleratesthe link ing of amino acids by ten million times. We are currently attempting tofind out which molecular processes playa role in inducing the structural changeand how the catalytic mechanism func -tions in detail.

Programmed »errors«Normally, the production of a protein goes according to plan. A blueprint madeof ribonucleic acid dictates exactlywhich of the twenty standard aminoacids have to be linked in which sequence.Errors rarely occur, but they are occasion -

ally even necessary to obtain the desiredprotein. Only when the ribosome seem -ingly makes an error, can it indeed in -corporate special amino acids, such asselenocysteine, which do not belong tothe standard repertoire of the aminoacids. But which mechanisms allowsuch exceptions to the rule? When weunderstand that, we hope to simultane-ously better understand how errors arenormally avoided. Conceivably, one daysuch knowledge may also be used in amedical context.

Continuously restructuredWhile the ribosome is progressivelyassemb ling a protein, it changes itsthree-dimensional structure. In this pro-cess, specific protein factors come intoplay. For example, the elongation factor Guses chemical energy to bring about aprofound restructuring of the ribosome,similar to the manner in which motorproteins in muscle cells transform chem -ical energy into mechanical work. To -gether with Wolfgang Winter meyer's re-search group we are studying this processwith biochemical and biophysical meth -ods. In co-operation with Holger Stark’sresearch group we attempt to visualizethese struc tural changes of the ribosomeusing electron cryo-microscopy.

Talkative nerve cells

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To catch a ball, recognize danger in time, remembersomething or solve an arithmetical problem – our nervous system stores experiences from earliest child-hood, controls complicated movements and creates ourconsciousness, all seemingly without effort. The humannervous system consists of approximately one hundredbillion nerve cells, and each of these individual nervecells can make contact with thousands of neighboringcells. Tiny membrane storage vesicles release specialmessenger substances that affect the behavior of ad -jacent cells. The researchers aim to shed light on themolecular processes that give nerve cells their abilityto collect and process information – including suchcomplex brain functions as learning and memory.

how signals are transmitted

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Nerve cells (or neurons) are communicationspecia lists. They receive and process signals

and transmit them to recipient cells such as musclecells or other neurons. Transmission is mediatedby specialized signaling molecules, the neuro-transmitters. Within nerve endings, neurotrans-mitters are stored in small membrane-enclosedcontainers termed synaptic vesicles. If electricalsignals indicate that a message is to be sent, someof the synaptic vesicles fuse with the cell mem-brane and release their content, which in turn isrecognized by the receiving cell.

Sociable SNARESThe molecular makeup of synaptic vesicles hasrecently been unraveled. They contain a fascinat -ing array of proteins that execute all the jobs thatthe vesicles must perform. Synaptic vesicles notonly need to sequester and store neurotrans -mitters, but they also respond to signals and undergo fusion with the plasma membrane. Fusion is mediated by a group of specialized pro-teins termed SNAREs.

Together with other research groups we want tofind out how exactly the SNAREs bring about

Neurobiology

� Model of a synaptic vesicle, sliced open, depicting the circular

vesicle membrane in which proteins are embedded. The

neurotransmitter glutamate is stored inside the vesicle (red).

Prof. Dr. Reinhard Jahn studiedbiology and chemistry, and ob -tained his PhD at the University of Göttingen in 1981. Between1983 and 1986, he worked at theRockefeller University (USA), andthereafter at the Max Planck Institute for Psychiatry (today:Neurobiology) in Munich. In 1991,he became professor at Yale University in New Haven (Con-necticut, USA). In 1997, he wasappointed head of the Depart-ment of Neurobiology at the MaxPlanck Institute for BiophysicalChemistry. He is an adjunct pro-fessor of biology at the Universityof Göttingen, and he is the Deanof the Göttingen Graduate Schoolfor Neurosciences and MolecularBiosciences (GGNB). ReinhardJahn has received numerousawards including the Max PlanckResearch Prize (1990), the LeibnizPrize of the German ResearchFoundation (2000), and the ErnstJung Prize for Medicine (2006).

A. Stein, A. Radhakrishnan, D. Riedel,D. Fasshauer, R. Jahn: Synaptotagminactivates membrane fusion through aCa2+-dependent trans-interaction withphospholipids. Nature Struct. Mol. Biol.14, 904-911 (2007).

D. Zwilling, A. Cypionka, W. Pohl, D.Fasshauer, P. J. Walla, M. C. Wahl, R.Jahn: Early endosomal SNAREs form astructurally conserved SNARE complexand fuse liposomes with multiple topo-logies. EMBO J. 26, 9-18 (2007).

S. Takamori, M. Holt, K. Stenius, E. A.Lemke, M. Grønborg, D. Riedel, H. Ur-laub, S. Schenck, B. Brügger, P. Ringler,S. A. Müller, B. Rammner, F. Gräter, J.S. Hub, B. L. De Groot, G. Mieskes, Y.Moriyama, J. Klingauf, H. Grubmüller,J. Heuser, F. Wieland, R. Jahn: Molecu-lar anatomy of a trafficking organelle.Cell 127, 831-846 (2006).

Contact:rjahn@gwdg.dewww.mpibpc.mpg.de/research/english/dep/jahn

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membrane fusion. Indeed, we alreadyhave a very good idea of how theyachieve this goal: If SNAREs that areattached to the vesicle and the plasmamembrane meet, they become entan-gled and change their conformation. Asresult, they exert a pulling force thatpushes the membranes against each other until they fuse. This process,which is controlled by many additionalproteins, can be reconstituted in thetest tube. In our research, we want tofind out how these proteins work to -gether to achieve the precision andspeed of synaptic vesicle fusion.

SNAREs are not only needed forneurotransmitter release. They are alsoinvolved in the countless membranefusion reactions that occur in every cellof our body. Bio logical membranes turnover continuously. They shed small ves -icles that are then transported to othermembranes where they fuse. We wantto understand how these fusion re -actions are controlled. After all, vesiclesonly fuse with their specific targetmembrane, and they only fuse if theyare told to do so. Synaptic vesicles, forinstance, only fuse if they need totransmit a signal. One of our objectivesis to find out what these fusions havein common and how they differ fromeach other.

Hans Dieter Schmitt and colleaguesalso work on SNAREs. As model organ -ism they use bakers yeast because it is

easy to introduce or delete individualgenes in this unicellular organism.Their main interest is focused on intra-cellular transport vesicles. These vesicleshave to be covered by a protein coat inorder to form and to detach from theprecursor membrane. Intriguingly, uponarrival at their destination, help by theSNAREs in the target membrane isneeded to get rid of the coat. Only afterthe coat proteins are shed, can theSNAREs do their job and fuse themembranes.

Karin Kühnel studies a destructiveprocess that also involves membranes.If cells are starving they begin to digestparts of themselves. To this end, theyform membrane vesicles that randomlyenclose parts of the cell’s interior. Thevesicle content is in turn delivered tothe cell’s »stomach«, the lysosome,where it is digested. This process, termed autophagocytosis, not onlyhelps cells to survive periods of star -vation but also participates in routineclean-ups. For instance, damaged oraggregated cell components are dis -posed of by this mechanism. The re-search group is primarily interested indetermining the three-dimensionalstructures of the participating proteins.

Research group:Dr. Karin KühnelDr. Hans Dieter Schmitt

The fusion of membranes is mediated by SNARE proteins (blue, red, and green).

The cells of our bodies – as also thoseof other animals, plants, fungi and

many unicellular organisms – have a muchmore complex structure than the cells ofbacteria. In our complex eukaryotic cellsthere are many separate reaction compart-ments in which different tasks are per -formed. The cell manufactures proteins inthe so-called endoplasmatic reticulum, aparticularly large branched area. It digestsmaterial foreign to the cell in the muchsmaller lysosomes. A characteristic set ofmolecules performs specific functions ineach membrane-enclosed compartment.

In order for these tasks to be smoothlycarried out, it is essential for cell survivalthat these molecules are available in suffi -cient quantities and at the correct time.They are therefore distributed to the differ - ent areas by a complex transport system.

Transport in vesiclesIn this context the molecules are trans -ported in small, membrane-enclosed sacks,the vesicles, from compartment to com-partment. When a cargo is ready, the vesiclebuds off the membrane of one compart-ment, the donor orga nelle. Then the loadedvesicle migrates through the main cell

space, the cytosol, and ultimately mergeswith the membrane of the target compart-ment, in which the molecule is required.

When the transport vesicle fuses withthe membrane, so-called SNARE proteinsplay the main role. This is a group of rela-tively small membrane-bound proteins. Todate it has been assumed that a stablecomplex is formed between the mem -branes of the transport vesicle and the tar-get compartment in a zipper-like process.

We are investigating exactly what happenswhen the SNARE proteins form this com-plex. We also want to know which otherfactors control and catalyze this processand how the stable complex is disassem -bled into its components when the processhas been completed. Ultimately, we are in-terested in the evolutionary developmentof this transport system because it hasbeen shown that the molecular machinesinvolved in the basic process of the trans-port process can be found in all eukaryoticcells. This is an indication of their com-mon descent, which we are studying.There fore, we combine not only structuraland biophysical approaches, but also in -corporate the phylogenetic relationshipsbetween the protein machines.

Structural Biochemistry

Dr. Dirk Fasshauer studied bio l -ogy and received his doctorate atthe University of Göttingen in1994. He conducted research atYale Uni versity, New Haven (Con-necticut, USA) from 1995 to 1997and moved from there to the MaxPlanck Institute for BiophysicalChemistry. He has headed theStructural Biochemistry ResearchGroup in the Department ofNeuro biology there since 2002.

Contact:dfassha@gwdg.dewww.mpibpc.mpg.de/groups/fasshauer/fassh_main.htm

T. H. Kloepper, C. N. Kienle, D. Fass-hauer: SNAREing the basis of multicel-lularity: Consequences of protein fami-ly expansion during evolution. Mol.Biol. Evol. 25, 2055-2068 (2008).

P. Burkhardt, D. A. Hattendorf, W. Weis, D. Fasshauer: Munc18a controls SNARE assembly through its interaction withthe syntaxin N-peptide. EMBO J. 27,923-933 (2008).

A. Pobbati, A. Stein, D. Fasshauer: N- toC-terminal SNARE complex assemblypromotes rapid membrane fusion. Science 313, 673-676 (2006).

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Phylogenetic tree of thesecretory syntaxin pro-teins of animals (left).Using isothermal titrationcalorimetry it is possibleto determine the strongtendency of the two pro-teins Munc18a and syn -taxin 1a to bind to each other. This complex formsduring the release of themessenger substancesfrom synaptic vesicles(right).

Dr. Takeshi Sakaba received hisPhD in psychology at the Univer -sity of Tokyo (Japan) in 1998. From1998 to 2006, he did research as apostdoctoral fellow under ErwinNeher in the Department ofMembrane Biophysics at the Max Planck Institute for Biophys -ical Chemistry. Since 2006, he hasheaded the Max Planck ResearchGroup Biophysics of SynapticTransmission there.

When a nerve cell transmits a signalto the next one, this signal is nor-

mally transformed twice. The »transmit-ting« cell translates its electrical signal intoa chemical one, and the »receiving« cell, inturn, transforms the chemical signal into an electrical one. Why does this haveto be so complicated?

The chemical communication via neuro -transmitters offers a decisive advantage. Incontrast to electrical signals neurotransmit-ters can not only activate, but also inhibitthe next nerve cell. Additionally, the neces-sary contact locations between the nervecells – the synapses – are remarkably adap-table. Depending on the position, they cantransmit electrical signals in attenuatedform, but they can also amplify them. Thissynaptic dynamics is of extreme importancefor information processing in the brain. Wewould like to know what the underlyingmolecular mechanisms are.

To this end, we compare various synapse types from different areas of the brain, forexample, from the cerebellum, the cerebralcortex and the brainstem. We investigate

these synapses by combining electro physiol -ogical methods with imaging pro ceduresand molecular biological tech niques. As wenow know, the recycling of the synapticvesicles filled with chemical messengers onthe sides of the transmitting nerve cell contributes decisively to the diversity of synaptic dynamics among different synapsetypes.

Determining the rules of interconnectivityBut, which role do the dynamic propertiesof the synapses play when the nerve cellscongregate to form complex neuronal net-works in our brain? It may be possible thatnerve cells connect completely randomlywith different synapse types. But theseinter connectivities could also follow veryspecific rules. It may, for example, be thecase that a group of neurons only connectseach other to facilitating synapses. We areon the track of the »connectivity rules«which the nerve cells have to follow in theneuronal connectivity between the cerebralcortex and the brainstem.

N. Hosoi, M. Holt, T. Sakaba: Calciumdependence of exo- and endocytoticcoupling at a glutamatergic synapse.Neuron 63, 216-229 (2009).

T. Sakaba: Two Ca-dependent stepscontrolling synaptic vesicle fusion andreplenishment at the cerebellar basketcell terminal. Neuron 57, 406-419(2008).

K. Wadel, E. Neher, T. Sakaba: Thecoupling between synaptic vesicles andCa2+ channels determines fast neuro-transmitter release. Neuron 53, 563-575 (2007).

Biophysics of Synaptic Transmission

Contact:tsakaba@gwdg.dewww.mpibpc.mpg.de/english/research/ags/sakaba

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Fluorescence image of a Purkinje cell in the cerebellum; many nerve endings of other nerve cells impinge on its process (the dendrites) and form synapses there.

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Many vital processes rely on the exchange of sig-nals between sub-cellular structures, but also

between our body’s cells. In this context biologicalmembranes occupy a key position because they notonly compartmentalize tissues and organs, but alsoprovide for the communication between the com-partments. We use biophysical and molecular ap-proaches to study the relevant signaling mechanisms.In this endeavor we increasingly rely on fluorescentmolecules in order to label specific proteins, whichparticipate in the signal flow.

Flexible circuits in the brainSynapses are the contact points for information flowin our brain, where signals are exchanged betweenindividual neurons. Contrary to the circuit elementsin electronic computers where connections are hard - wired, synaptic strength – the electrical response ofthe receiving neuron to a nerve impulse in the trans-mitting one – is not constant, but is use-dependent.It varies depending on the information being pro -cessed. Each type of synapse has its own »perso -nality« with regard to this so-called »synaptic plastic -ity«. Changes, which are caused by short, intensivebursts of activity may be only transient or else persistfor hours and days. Neuroscientists consider the verylong-term changes as the basis of learning and mem -ory. Likewise, the short-term changes in synapticstrength have an important role in the second-by-second information processing, for instance duringadaptation of sensory signals.

The research projects of the department concen-trate on short-term plasticity and its molecular andphysiological mechanisms. A nerve impulse causesthe liberation of a signal substance from the nerveending of the transmitting neuron. The immediatetrigger for the release of this »neurotransmitter« isan increase in the presynaptic concentration of cal-cium ions. This causes the fusion of storage vesicles,which contain the neurotransmitter, with the cellmembrane. Thereby neurotransmitter is released in-to a narrow gap between the transmitting and the re-ceiving neuron. But calcium ions can do even more.They promote the delivery of new vesicles, which holdneurotransmitter ready for release. Synapse strengththen depends on how many synaptic vesicles thetransmitting cell uses per nerve impulse and how rapidly they can be replenished. In addition to calciumions, other signal substances, for example cyclicAMP, are involved in the regulation of replenishment.Short-term synaptic plasticity is thus the result ofnumerous processes, which intertwine.

How is it possible that one and the same signalingsubstance – calcium ions – can control several pro-cesses in different ways? The answer resides inquantitative detail, as we could show by biophysicalinvestiga tions: The triggering of neurotransmitter re-lease by calcium is a highly cooperative process,which sets in only at rather high calcium concentra-tions, but then accelerates greatly. The re-supply ofvesicles accelerates linearly with increased calcium,reaching adequate rates already below the threshold,at which release commences. Depending on the cal-cium level, either one or the other one of these pro-cesses will be preferentially activated.

Allowing contacts to matureThe calyx of Held synapse, an important synapticjunction in the mammalian auditory pathway, hasbeen at the focus of our research for a long time. Itscup-shaped synaptic terminal is so generously dimen -sioned that it can be easily manipulated. HolgerTaschen berger was able to show that, as is the case

Membrane Biophysics

The calyx of Held is an exceptionally large nerve ending,which makes contact with a compact postsynaptic nervecell body. It is an important connection in the auditory path-way and is particularly well suited for biophysical investi -gations because it is accessible for electrophysiologicalmeasurements (patch-clamp) due to its size.

Prof. Dr. Erwin Neher studiedphysics in Munich and at the University of Wisconsin (USA).He redirected his interests to bio-physics and performed a PhDproject at the Max Planck Insti -tute for Psychiatry (now: MaxPlanck Institute for Neurobiology)in Munich. He joined the MaxPlanck Institute for BiophysicalChemistry in 1972, worked for ayear at Yale University in NewHaven (Connecticut, USA) andhas headed the Department ofMembrane Biophysics at the institute since 1983. Erwin Neheris a honorary professor at theUniversity of Göttingen. For hisresearch on ionic currents flowingthrough individual membrane pores he received the Nobel Prize for Medicine and Physio l -ogy jointly with Bert Sakmann in 1991.

R. A. Neher, M. Mitkovski, F. Kirchhoff,E. Neher, F. J. Theis, A. Zeug: Blindsource separation techniques for thedecomposition of multiply labeled fluo-rescence images. Biophys. J. 96, 1-10(2009).

E. Neher, T. Sakaba: Multiple roles ofcalcium ions in the regulation of neuro-transmitter release. Neuron 59, 861-872 (2008).

J. Wlodarczyk, A. Woehler, F. Kobe, E.Ponimaskin, A. Zeug, E. Neher: Analysisof FRET-signals in the presence of freedonors and acceptors. Biophys J. 94,986-1000 (2008).

E. Neher: A comparison between exocy-tic control mechanisms in adrenal chro-maffin cells and a glutamatergic synap-se. Pflügers Arch. 453, 261-268 (2006).

T. Sakaba, A. Stein, R. Jahn, E. Neher. Distinct kinetic changes in neurotrans-mitter release after SNARE-proteincleavage. Science 309, 491-494 (2005).

Contact:eneher@gwdg.dewww.mpibpc.mpg.de/english/research/dep/neher/

Internal Research Groups:Dr. Meike PedersenDr. Holger TaschenbergerDr. Samuel Young

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with the majority of other synapses in ourbrain, the calyx undergoes a functionalmaturation process. More mature synap-ses use their supply of synaptic vesiclesmore sparingly. In comparison with ayounger synapse, a single nerve impulsereleases a much smaller fraction of theavailable vesicles. As a result, the synapticstrength decreases much less rapidly dur -ing repeated stimulation. In addition, mature synapses optimize their use of cal-cium ions. They require less calcium in-flux for triggering vesicle fusion becausethe calcium channels there are locatedcloser to those vesicles, which are readyto release their contents. On the otherhand, these synapses produce proteins,which bind calcium ions such that theirconcentration is rapidly reduced to a basal level.

Viral gene expression of synaptic proteinsThe calyx of Held is ideally suited for bio-physical studies on synaptic transmissionin brain slices. However, it was not pre-viously possible to selectively change therelevant proteins in this preparation. There -fore, Samuel Young developed custom-tailored high expression recombinant adenoviruses and a method to deliver these recombinant viruses into the nervecells. The synaptic calcium sensor synapto -tagmin and a variant carrying site-specificmutations were cloned into the viral ge-

nome. After infec tion of the nerve cellswith such viruses, it was possible to ob-serve how the modified calcium sensoraffected the synaptic func tion.

Colorful proteinsHow do the different signal processes atthe nerve ending interact? In order to makethis machinery visible, it is necessary tosimultaneously display the distributionand temporal changes of as many signalcarriers as possible. Today, molecular biol -ogy provides excellent tools for selectivelylabeling proteins with multi-color fluores-cent tags. When analyzing spectrally re-solved images of multiply labeled prep - arations, one has to separate the indi -vidual contributions of labels, which arepresent at a given pixel. To achieve this,we developed an algorithm of so-called»blind source separation«, which allowsdetermination of both the spectral charac -teristics of the dyes involved and their individual contributions to the overallimage.

Triply labeled fibroblast cells. The proteins of the cytoskeleton and the nucleic acids of these cells aremarked with fluorescent dyes (actin: green; tubulin: blue; nucleic acids: red). The spectral analysis oftheir fluorescence allows separation of the three components on the basis of a single image acquisi -tion (in cooperation within the DFG Research Center Molecular Physiology of the Brain).

The cell nucleusas control center

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Communication must work: this also applies to livingcells. In order for the cells to fulfill their duties, theyrequire communication paths between their individualcompartments – from packaging and sorting stationsvia the power plants to the cell nucleus. Minute poresin the nuclear envelope serve as vital transport andcommunication channels that control the delivery ofmolecular cargos between the cell nucleus and othercellular compartments. These nuclear pores are highlyselective gates: While small molecules usually passunhindered, larger ones rely on a cellular shuttle service for their transport. Scientists at the instituteare attempting to reveal the underlying highly complexprocesses on the molecular level.

active information storage with input and output control

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An export complex atatomic resolution. Theexportin CRMI (blue)with its cargo moleculesnurportin (orange) andRan (red) bound. Ran isa molecular switch,which determines thedirection into which thecargo is carried (in thiscase from the cell nucleus to the cytosol).CRM1 exports, forexample, the riboso-mes mentioned aboveas well as hundreds ofregulatory factors outof the cell nucleus. Viruses such as HIV misuse CRM1 to export their genetic material from the nucleus to the cytoplasm, where it is packed in viral particles. In the background, a scanning electron microscopic image of nuclear pore complexes – the giant transport channels in the nuclear envelope – is shown.

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Recipe for success – division of laborEukaryotic life forms, such as plants or animals,are characterized by a division of labor in their cells.The cell nucleus focuses on the administration ofthe genome, mitochondria on supplying energy tothe cell, whereas the so-called cytosol has special -ized in protein synthesis. The advantages of thisorganization can be impressively summarized bythe fact that only eukaryotes have evolved to com-plex, multicellular organisms. But this also has itsprice and must be maintained by a sophisticatedlogistic system. Cell nuclei lack protein synthesisand must therefore import all required enzymesand structural proteins from the cytosol. In return,nuclei produce and export decisive components ofthe protein synthesis machinery (for example ribo-somes) to the cyto sol and thus enable cytosolic pro-tein synthesis.

Gates and transportersThe cell nucleus is enclosed in two membranesthat are impermeable for proteins and other macro -molecules. An exchange of material can thereforenot occur directly through these membranes. In -stead, so-called nuclear pore complexes are em-bedded in the nuclear envelope. One can imaginethem as highly selective gates, which make up thestationary part of an entire transport machinerysystem.

The mobile part of this transport machinery iscomprised of nuclear import receptors (importins)and exportins. Although the nuclear pores appeartightly closed to the majority of macromoleculesabove a certain size limit, importins and exportinshave the privilege of being able to pass nearlyunimpeded through the permeability barrier of nu-clear pores. In this context, the decisive point is

Cellular Logistics

Prof. Dr. Dirk Görlich studied biochemistry in Halle (Saale) andreceived his PhD at the HumboldtUniversity in Berlin in 1993. Aftera two-year research period at the Wellcome/CRC Institute inCambridge (United Kingdom), he was first appointed head of a re-search group in 1996 and then, in2001, professor for molecular biol -ogy at the Center for MolecularBiology of the University of Hei-delberg (ZMBH). Since 2007, hehas been heading the Depart-ment of Cellular Logistics at theMax Planck Institute for Bio -physical Chemistry. Dirk Görlichhas received numerous scientificawards, among them the KarlLohmann Prize of the German Society for Biological Chemistry(1993), the Heinz Maier LeibnitzPrize (1997), the EMBO Gold Medal (1997), and the AlfriedKrupp Promotion Prize (2001).

T. Monecke, T. Güttler, P. Neumann, A.Dickmanns, D. Görlich, R. Ficner:Crystal structure of the nuclear exportreceptor CRM1 in complex with snur-portin1 and RanGTP. Science 324,1087-1091 (2009).

S. Frey, D. Görlich: A saturated FG-repeat hydrogel can reproduce the per-meability pro perties of nuclear porecomplexes. Cell 130, 512-523 (2007).

S. Frey, R. P. Richter, D. Görlich: FG-rich repeats of nuclear pore proteinsform a three-dimensional meshworkwith hydrogel-like properties. Science314, 815-817 (2006).

Contact:goerlich@mpibpc.mpg.dewww.mpibpc.mpg.de/english/research/dep/goerlich

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that they can also carry cargo or passen-gers on their passage through the pores.Not every passenger is allowed on board;instead, importins and exportins recog-nize with molecular preci sion whichmolecule is to be imported into the nu-cleus and which is to be exported. Themechanisms of these recognition pro-cesses are the focus of our research.

How does the sorting unit of nuclearpores work?Nuclear pores are extremely effectivesorting machines and each of them cantransport up to 1000 cargo complexesper second. Nuclear pores have an ex-tremely complex structure, and each ofthem comprises about 700 proteinmole cules or approximately 20 millionindividual atoms. In order to compre-hend the functional principle of such acomplex system, it has to be reduced toessentials. As a decisive step in this di-rection, we were recently able to recon-stitute the nuclear pore’s perme abilitybarrier in a test tube. It consists of so-called »FG repeats« and forms an »in-telligent« hydrogel with amazing mate-rial properties. It suppresses the passageof »normal« macromolecules, but allowsan up to 20,000 times faster influx of the same molecules when they are

bound to an appropriate importin or ex-portin. The efficiency of the influx ofimportins and exportins into this gelreaches the limits of what is physicallypossible and is only limited by the speedof transport to the barrier. We are cur-rently intensively investigating the chem -ical and physical bases of this uniquephenomenon. We not only expect togain a deep understanding of a processthat is essential for eukaryotic life, butalso impulses for the development ofnew materials.

Permeability properties of an FG hydrogel. A) An optical section through a fluorescence-labeled FG hydrogel. Light-colored areas correspondto the gel; dark ones to the surrounding buffer.B) The same region, imaged in another fluorescencechannel, shows the influx of a green fluorescentimportin·cargo complex at three different points intime. The complex penetrates rapidly into the gel,accumulates there 100 to 1000-fold and moves sorapidly into the gel that it could traverse a nuclearpore within 10 milliseconds. C) A red fluorescentcontrol substrate in comparison. It does not bind theimportin and therefore cannot penetrate into the gel.

C

B

A

Direction of influx

Gel

Cont

rol s

ubst

rate

Importin•

carg

o co

mpl

ex

Buffer side FG hydrogel

30 min

10 min

30 sec

30 min

10 min

30 sec

50 µm

The permeability barrier of the nuclear pore is a hydrogel, i.e. an elastic solid, which consists primarily of water, similar to gummy bears or thevitreous body of the eye. The translucent red pattern of lines on the background provides an impression of the transparency of the object. Since the hydrogel comprises FG repeats, it is termed FG hydrogel. The in vitro reconstituted FG hydrogel shown here is several millimeters insize. In contrast, the barriers of the nuclear poremeasure only about 50 nanometers.

Higher vertebrates, such as the humanbeing, are comprised of more than

200 diffe rent cell types. With only a few ex-ceptions, these cell types all have a nu-cleus, which is the cell’s control centerand which contains the hereditary infor-mation stored in the chromosomes. Thisgenetic material is separated from the restof the cell by a membrane jacket, the nu-clear envelope. To still allow extremely di-verse mole cules to be exchanged betweenthe nucleus and the cytoplasm, the nucle-ar envelope is traversed by many nuclearpores, through which the entire cargotransport takes place.

Even though the cell nucleus is normal-ly depicted as a sphere, it can assume verydifferent shapes depending on the cell type. In many cell types it is actuallyspheri cal or ellipsoid, where as in others itcan be tubular, lobed or even segmented.The architecture in the interior of suchnuclei sometimes also appears just as dif-ferent. Why this is the case and whichmolecules play a role in such nuclear or-ganization is still largely unclear. Nor ismuch known as to whether the nuclear ar-chitecture influences the function of a celltype.

Nuclear basket made of thread-like proteinsTo be able to answer these questions, we are attempting to identify the proteins thatare involved in the construction and infra-structure of the cell nucleus. The startingpoint of our investiga tions are thread-likebuilding blocks, which are anchored to theinner side of the nuclear pores and formstructures which are reminiscent of roundbaskets. We have discovered that a majorcomponent of these nuclear baskets is alarge rod-shaped protein, which we havebeen able to detect at the nuclear peri -phery in many cell types. There it alsofunctions as a docking site for other nu-clear components, which can differ de-pending on the cell type.

At least in some of these cell types, thisrod-shaped protein plays an important rolein the distribution of the genetic materialin the proximity of the nuclear envelope.There it con tributes substantially to theinternal architec ture of the cell nucleus.However, the nuclear basket and this pro-tein probably also have other functions,which we desire to elucidate.

Nuclear Architecture

Dr. Volker Cordes received hisPhD in cell biology at the Univer-sity of Heidelberg in 1992. From1992 to 1997, he worked as a research associate at the Bio-center of the University of Würz-burg and at the German CancerResearch Center in Heidelberg. In1997, he relocated to the Institutefor Cell and Molecular Biology atthe Karolinska Institutet in Stock-holm (Sweden). There he was initially head of a junior researchgroup, and after his habilita tion,he became a university lecturer.In 2004, he returned to Germanyas head of a research group atthe University of Heidelberg. In2007, he moved to the MaxPlanck Institute for BiophysicalChemistry, where he has headedthe Nuclear Architecture Re-search Group ever since.

Contact:vcordes@gwdg.dewww.mpibpc.mpg.de/english/research/ags/cordes

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Scanning electron microscopic image of the inner side of a cleaned oocyte nuclearenvelope from the clawed frog Xenopus laevis. Thread-like structures, similar toround baskets, are located directly over the nuclear pores. The diameter of such nuclear baskets is approximately 120 nano-meters (millionth of a millimeter).

Dr. Wolfgang Fischle studied biochemistry at the University ofTübingen. Thereafter he went tothe University of California at SanFrancisco (USA) as a scholar ofthe Boehringer Ingelheim Foun -da tion and received his PhD inthe field of biochemistry in 2002.As a postdoctoral fellow on a fellowship of the Damon RunyonCancer Research Foundation heworked at the University of Virgi-nia at Charlottesville and at theRockefeller University in NewYork (USA) from 2002 to 2005. He heads the Max Planck ResearchGroup Chromatin Biochemistry atthe institute since 2006. WolfgangFischle received a fellowship of the European Network of Ex-cellence »Epigenome« in 2006.

Everyone is familiar with the structuralimage of DNA: The carrier of here d -

itary information looks like a rope ladderthat has been twisted to form a double helix. In living cells it is stored in the cellnucleus, the »command center« of the cell.However, the DNA does not occur there asisolated molecules. In conjunction withspecific proteins it forms chromatin. At re-gular intervals short segments of the DNAare wound around a complex of histoneproteins, forming the nucleosome. Theseconstitute the fundamental repetitive unitof chromatin. While all nucleosomes areessentially assembled in the same manner, there are fine molecular differences whichare primarily due to chemical alterations inthe histone proteins. These alterations aretermed post-translational histone modifi -cations. Today we assume that the cell usesthese alter ations in nucleosomes as signalsor markers in order to recognize and definedifferent regions of chromatin. Apparentlythey play an important role in cellular he-reditary.

Not only the product of our genesHereditable differences between individualcells and entire organisms are not only theresult of different gene sequences, but arealso due to the same hereditary informationbeing read differently. Deviating characters

arise, for example, because the same geneis more active in certain cells of an organ-ism than in others. At the chromatin levelthe cell executes this control over the dif-ferential reading of genes via stable pat-terns of histone modifications. These so-called epigenetic effects play, for example,a role in cell differentiation, in the develop-ment of the embryo, but also when cellsundergo cancerous changes.

We want to find out in detail how thesehistone modifications influence the organi-zation and dynamics of chromatin and to

understand how they control the read-out ofthe genome. In order to achieve this we com-bine experimental approaches from diffe-rent disciplines such as biochemistry, bio-physics, cell biology, and molecular biology.

K. Zhang, K. Mosch , W. Fischle, S. I. Grewal: Roles of the Clr4 methyltrans-ferase complex in nucleation, spreadingand maintenance of heterochromatin.Nat. Struct. Mol. Biol. 15, 381-388(2008).

W. Fischle, H. Franz, S. A. Jacobs, C. D.Allis, S. Khorasanizadeh: Specificity ofthe CDY family of chromodomains forlysine-methylated ARKS/T motifs. J.Biol. Chem. 283, 19626-19635 (2008).

W. Fischle: Talk is cheap – Crosstalk inthe establishment, maintenance, andreadout of chromatin marks. Genes Dev.22, 3375-3382 (2008).

Chromatin Biochemistry

Contact:wfischl@gwdg.dewww.mpibpc.mpg.de/english/research/ags/fischle/

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Organization ofchromatin.

Chromatin segments are present in different states,which are controlled by post-translational histone modifications. The images were taken with an atomicforce microscope.

From egg to organism

how living beings are formed and controlled

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Heart and brain, liver and lung– all parts of our body can betraced back to a single egg cell. But exactly how does theegg cell evolve into so many different cell types? And howdo the cells in the embryo form complex organs that interactsuccessfully? The researchers unravel these enigmatic pro-cesses on the molecular level, in flies and also in mice.Despite their obvious anatomical differences their embryonicdevelopment follows fairly similar rules. Thus, the resultsobtained from this research permit us to gain insights into

the earliest stage of human life. These findings help us tobetter understand and treat diseases that can be tracedback to malformations at this early stage of life.

A large portion of our life is spent asleep – but why is this?How is our »biological clock« controlled, causing us to be-come tired in the evening and awake again in the morning?Scientists at the institute are also investigating thesefascin ating questions.

A »live broadcast« of a beating heart or »images of thinking« – last but not least, the researchers continuouslyimprove imaging methods like magnetic resonance tomo-graphy in order to provide detailed insights into the inner life of human beings and animals.

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The fruit fly Drosophila is a very popular scien-tific research object for good reasons. Un -

demanding and immensely prolific, despite its di-minutive size, it is a very complex organism – absolutely comparable to a mammal. As is the casein all animals this fly develops from a single, smallegg cell. But how does a complex body with ex -treme ly diverse cell types and organs develop fromthis one cell? To answer this great biological riddle,we delve deeply into the molecular control mechan -isms which regulate such developmental pro -cesses from egg to fly. Frequently, the controlfactors which we found in the fly are present in similar form in the human genome. They are notsome special achievement of flies, but rather acommon genetic legacy of all animals. Drosophila’sgenetic inventory is correspondingly informative in medical questions: When developmental pro-cesses derail in humans, genes and entire controlsystems, which we have al ready known in the flyfor a long time, are presumably often disturbed.

Early settings of the courseThe body structure of the fly has already been determined before the egg cell is fertilized. The female flies not only supply their eggs with nutrients, they also provide proteins and theirblueprints, which intervene as control factors indevelopment. These factors are asymmetricallydistributed in the egg and consequently stipulatethe body axes. In the process they activate a genecascade which subdivides the embryo into increas -ingly smaller segments. As in an architect’s blue-prints, the basic structural plan of the body withits segments and organs, which only become vi s -ible much later, are nearly invisibly sketched, andthe areas in which body parts develop are stipu -lated. In this context, communication processesbetween the cells play a role. They define the respective developmental fate of a cell at exact positions in the body via the interaction of signalsubstances and corresponding receptor molecules.

Additional facetsAlf Herzig and his research group focus on veryspecial cells: the so-called stem cells. These cellsdivide in the same manner as their geneticallyidentical sister cells, but do not initially developinto a specific cell type. Indeed, that is not evendesired because stem cells are the body’s silent re-serves. They subsequently develop into exactlythose cells which the organism has lost due to cell

Molecular Developmental Biology

All five fruit fly embryos are at the same developmental stage. However,by using a special staining technique the products of different genes have been made visible. They show that a fruit fly embryo, which is only two hours old, is already divided into specific areas (blue) and – although not yet morphologically visible – already exhibits segmentalunits.

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M. Beller, C. Sztalryd, N. Southall, M. Bell, H. Jäckle, D. S. Auld,B. Oliver: COPI complex is a regulatorof lipid homeostasis. PloS Biology 6,2530-2549 (2008).

S. Grönke, A. Mildner, S. Fellert, N.Tennagels, S. Petry, G. Müller, H. Jäckle,R. P. Kühnlein: Brummer lipase is anevolutionary conserved fat storage re -gulator in Drosophila. Cell Metab.1, 323-330 (2005).

R. Rivera-Pomar, H. Jäckle: From gradients to stripes in Drosophila em-bryogenesis: filling in the gaps. TrendsGenet. 12, 478-483 (1996).

Contact:hjaeckl@gwdg.dewww.mpibpc.mpg.de/english/research/dep/jaeckle

death. But how does the organism pre-vent these cells from differentiating simultaneously with the other cells? Apparently, the genes of the stem cellsare specially packaged and stored in thecell nucleus. Consequently, Herzig’steam studies the packaging characteris-tics – i.e., the histone modifications –and the position of the genes in the cellnucleus, and compares them with ad -jacent cells which differentiate.

Gerd Vorbrüggen’s research group isconcerned with a specialist among thedifferentiated cells, a cell which every -one is familiar with: the muscle cell.The scientists investigate how musclecells are formed and how they unerringlyposition themselves into an exactlystipu lated overall pattern in the body.

In order for muscles to be able towork they need energy. Ronald Kühn-lein, Mathias Beller and Ralf Pflanz’s re-search groups are working on the ques-

tion of how the fly controls its energybudget. They want to understand howan organism knows how much energy itmust store in the form of fat deposits tocover its energy requirements even in times of famine. These projects willhelp us to better understand human obesity, which in the meantime with itscon sequences such as cardiovasculardis eases, dia betes and certain types ofcancer has become a worldwide healthproblem. These researchers expect thefly, as a biomedical model, to make acontribution to the diagnosis of and tonew therapies for obesity in the long-term.

� The fruit fly Drosophila melanogaster.

Prof. Dr. Herbert Jäckle receivedhis PhD in biology from the Uni-versity of Freiburg in 1977. Hesubsequently worked at the Uni-versity of Texas at Austin (USA),the European Molecular BiologyLaboratory in Heidelberg, and theMax Planck Institute of Develop-mental Biology in Tübingen. In1987, he became a university pro-fessor for genetics at the LudwigMaximilians University in Munich.He has headed the Department ofMolecular Developmental Biol-ogy at the Max Planck Institute forBiophysical Chemistry since 1991.In 2002, he became the Vice-President of the Max Planck Society. Herbert Jäckle has re-ceived numerous renowned science awards, among them theLeibniz Prize in 1986, the FeldbergPrize in 1990, the Otto Bayer Prizein 1992, the Louis Jeantet Prizeand the German Future Prize in1999. He has taught as an honor -ary professor at the University of Göttingen since 1993.

The fruit fly embryo shortlybefore larva formation.

Internal groups:Dr. Mathias Beller, Dr. Alf Herzig,Dr. Ronald Kühnlein, Dr. RalfPflanz, Dr. Gerd Vorbrüggen;the research group of Dr. ReinhardSchuh is associated with the department.

When a complex or-ganism develops

from a single egg cell,even ex perienced bio l -ogists are amazed timeand again. In humans, asin mice, the blueprints ofdevelopment are encodedin the genes, which arepassed on from the par -ents to their offspring.With each cell divi sionthe embryo ap proa chesits goal: to become acompletely de veloped or-ganism. On the way tothis objective, the samecycle repeats itself timeand time again. First, thegenetic material is dupli-cated, and then it is dis-tributed among the de -veloping daughter cells.

During embryogenesis,and tightly coupled to thecell divisions, a multitudeof molecular switches de-termining cell fates areset. Thus, for example, adecision may be taken as to whether a cellkeeps many developmental options open orwhether its prospective destiny has alreadybeen determined. Whether or not it will liein the forward or rear part of the body, orwhether it will have a career as a muscle ora nerve cell may also be decided. When thefinal state has been reached, the cell cycleis terminated and the fully-differentiatedcell concentrates completely on its special -ized task, for example signal transmission inthe nervous system. However, many organsalso retain cells which further divide and inthe process renew themselves. These stemcells, which act as the body’s silent reserve,can deliver the necessary replenishment ofdifferentiated cells and ensure that the cellrepertoire is maintained.

Gene »on«, gene »off«We want to understand how the two ele-mentary gear systems, cell division and celldifferentiation, interact. Which molecular

mechanisms are the bases of these pro -cesses, which genes are involved, and howare their functions coordinated? We investi -gate these questions using the mouse as ourmodel. Although this rodent appears com-pletely different from a human being, theirorgans and tissues are similar, and for an im-pressive 99 percent of the mouse genes there are similar sequences in the humangenome. To plumb the depths of thesemecha nisms at a molecular level, we search for genes which are involved in both pro -cesses. In order to get on their track we attempt to activate or switch them off withthe precisely targeting instruments of gen -etic engineering. Based on the consequencesof such experiments we can determinewhich role a gene plays under normal con-ditions. With the information ob tained, wewant to contribute to a molecular under-standing of mammalian de velopment.

Developmental Biology

Prof. Dr. Michael Kessel receivedhis PhD at the University of Kiel inBiology in 1981. From 1981 to1983, he worked at the NationalCancer Institute in Bethesda(Maryland, USA) and from 1983 to1986 at the Center for MolecularBiology in Heidelberg. Since 1986,he has been a member of the De-partment of Molecular Cell Biol -ogy at the Max Planck Institutefor Biophysical Chemistry andhas headed the DevelopmentalBio logy Research Group theresince 1992. Concurrently, MichaelKessel also teaches as a seniorlecturer on the Biological Facultyof the University of Göttingen.

Contact:mkessel1@gwdg.de www.mpibpc.mpg.de/groups/gruss/en/mkessel.htm

L. Luo, Y. Uerlings, N. Happel, N. S. Asli, H. Knoetgen, M. Kessel: Regulationof ge minin functions by cell cycle de-pendent nuclear-cytoplasmic shuttling.Mol. Cell. Biol. 27, 4737-4744 (2007).

M. Pitulescu, M. Kessel, L. Luo: The regulation of embryonic patterning andDNA replication by Geminin. Cell.Mol. Life Sci. 62, 1425-1433 (2005).

L. Luo, X. Yang, Y. Takihara, H. Knoetgen,M. Kessel: The cell-cycle regulator geminin inhibits Hox function throughdirect and polycomb-mediated inter -actions. Nature 427, 749-753 (2004).

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Neural stem cells which have differentiated into so-called astrocytes(green) are obtained from the embryonic mouse brain. Cell nuclei arestained blue.

We breathe in and out ap -proxi mately 20,000 times

a day without thinking about it.Each time the respiratory airflows through the delicate tubesystem of our lungs, which con-tain five to six liters of air, and ex-change appro ximately half a literof air with every breath. Like thecrown of a tree, the system tran-sitions into increasingly finerbranches down to the alveoliwhere oxygen migrates into thecirculatory system

Our research group wants to understandhow the installation of these highly branchedpathways for the respiratory air occurs.How ever, the examination of the underlyingmolecular mechanisms is very difficult andtime-consuming to examine in mammals. Asa consequence, we investigate our complexques tions on biology’s model organism parexcellence: the fruit fly Drosophila melano-gaster.

Drying out the respiratory systemThe fly and the human being are more simi-lar in many aspects than one might think.From a total of 13,600 Drosophila genes ap-proximately 7,000 genes are also present insimilar form in the human genome. Thefruit fly indeed has no lungs, but instead asystem of arboreally branched tubular path-ways for the respiratory air, the trachea. In

the meantime we know that the installationof this system of tubes is very similarly or-ganized to the development of the lungs. Anumber of closely related steps during em-bryonic development ensure that the tubesbranch at the proper locations and that theyare not too narrow or too wide at the end.

Common to both, flies and mammals, isalso that they have respiratory tubes that areinitially filled with liquid during the devel -opmental phase. Therefore, they must bedried out at the proper time, otherwise thedeveloping organism will display severe res -piratory problems. In babies born prema -turely, for example, there is danger of the res -piratory distress syndrome (RDS). Even inadult humans liquid in the lungs can resultin life-threatening edemas.

Among the 7,000 genes that are similar inhumans and flies, we have dis covered 20 genes which ensure that the tubes de velopproperly and are dried out at the right time.Now, we want to determine the mo lec ularmechanisms in which these genes are em-bedded and whether they have kept theirfunctions across the species boundaries.

Molecular Organogenesis

Prof. Dr. Reinhard Schuh received his PhD at the EberhardKarls University, Tübingen, in biol -ogy in 1986. From 1986 to 1988, heworked as a scientific staff mem-ber at the Max Planck Institute forDevelopmental Biology in Tübin-gen and from 1988 to 1991 aslecturer at the Institute for Gen -etics and Microbiology at the Ludwig Maximilians University inMunich. Since 1992, he has been amember in the Department of Molecular Developmental Biologyat the Max Planck Institute forBiophysical Chemistry. He hasheaded the Molecular Organo -genesis Research Group theresince 2005. Reinhard Schuh alsoteaches as an adjunct professoron the Biological Faculty of theUniversity of Göttingen.

M. Behr, C. Wingen, C. Wolf, R. Schuh,M. Hoch: Wurst is essential for airway clearance and respiratory-tube size control. Nature Cell Biol. 9, 847-853(2007).

C. Krause, C. Wolf, J. Hemphälä, C. Samakovlis, R. Schuh: Distinct functionsof the leucine-rich repeat transmem-brane proteins capricious and tartan inthe Drosophila tracheal morphogenesis.Dev. Biol. 296, 253-264 (2006).

M. Behr, D. Riedel, R. Schuh: The claudin-like megatrachea is essential in septate junctions for the epithelial barrier function in Drosophila. Dev. Cell5, 611-620 (2003).

C. Wolf, R. Schuh: Single meso dermalcells guide outgrowth of ectodermal tubular structures in Drosophila. GenesDev. 14, 2140-2145 (2000).

Contact:rschuh@gwdg.dewww.mpibpc.mpg.de/groups/schuh/

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The lung of the insects, the tracheal system, permeates the entireembryo of the fly.

The cross-linkage of tracheal cell groups (red marking)is enabled by closely associated bridge cells (blue marking and designated by arrows). Right: During development, the bridge cells (blue; arrow) stretch and connect the tracheal cell groups(red). The tracheal cells migrate along the bridge celland thus form a connecting network.

Whether heart or kidney, pancreas orbrain – the organs in our body are

the equivalents of small factories, in whichspecialized »units« perform specific tasks.In the pancreas there are primarily two celltypes which share the work. While themajo rity of them produces digestive juices,the smaller cell group produces hormonessuch as insulin, which regulates the bloodsugar level. The mesen cephalon (mid-brain) also comprises highly specializedcells, for example nerve cells, which pro-duce the messenger substance dopamine.

But as different as the cellular specialistsare – they all evolve during the de vel -opment of an organ from nearly identicalprogenitor cells. In our group we are study-ing the underlying mechanisms behind thisprocess.

We already know that certain genes con-trol the maturation of an organ and thusdetermine the subsequent fate of the cells.These control genes provide the blueprintfor specific proteins, so-called transcriptionfactors. These factors selectively switch ongenetic programs or suppress them andthus transform pro genitor cells into cellswith specific characteristics. This has beenshown by tests in which these genes wereinactivated. For example, with out the con-

trol gene Pax4, no insulin-producing cellsdevelop in the pancreas. Other factors cause cells to produce glucagon, insulin’santagonist. The situation in the mid-brainis very similar. There, for example, thefactor lmx1a activates the characteristics ofa specific group of nerve cells, whichshould produce the messenger substancedopamine. In order for cells with differenttasks to be formed in the correct propor -tions in an organ, the respective factorsinter act with each other and thus tare outthe required balance.

Mouse research for human beingsWe investigate the maturation of an organin mice because we can very easily modifythis small rodent genetically and can thusselec tively examine the role of the partici-pating factors. The information obtained inour research is also of fundamental impor-tance for human medicine. It can be usedto generate dopamine-producing cells fromhuman embryonic stem cells – the cellswhich die in the mid-brain of Parkinson’spatients. Dopamine-producing cells are notlimited to being cul tured in a culture dishto test the efficacy of potential medicines.In the future they may also be used forstem cell therapies.

Molecular Cell Differentiation

Prof. Dr. Ahmed Mansourireceived his PhD at the TechnicalUniversity of Brunswick in chem -is try in 1978. Subsequently, he didresearch as a postdoctoral fellowin the Institute for Human Geneticsat the University of Göttingen, in the Friedrich Miescher Labora -to ry of the Max Planck Society inTübingen and at the Max PlanckInstitute for Immunobiology inFrei burg. In 1989, he became astaff scientist at the Max PlanckInstitute for Biophysical Chemistryin the Department of MolecularCell Biology. In 1999, he habilita-ted in the Medical Faculty of theUniversity of Göttingen and since2002, he has been head of theMolecular Cell Differentiation Re-search Group. Ahmed Mansourihas held the professorship of theDr. Helmut Storz Foundation atthe University Medical School inGöttingen since 2005.

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Contact:amansou@gwdg.dewww.mpibpc.mpg.de/groups/gruss/en/amansouri.htm

P. Collombat, X. Xu, P. Ravassard, B. Sosa-Pineda, S. Dussaud, N. Billestrup,O. D. Madsen, P. Serup, H. Heimberg,A. Mansouri: The ectopic expression ofPax4 in the mouse pancreas convertsprogenitor cells into α- and sub -sequent ly β-cells. Cell 138, 449-462(2009).

R. Dressel, J. Schindehütte, T. Kuhl-mann, L. Elsner, P. Novota, P. C. Baier,A. Schillert, H. Bickeböller, T. Herr-mann, C. Trenkwalder, W. Paulus, A.Mansouri: The tumorigenicity of mouseembryonic stem cells and in vitro diffe-rentiated neuronal cells is controlled bythe recipients' immune response. PLoSONE 3:e2622 (2008).

In the mouse embryo (A) the activity of the lmx1a factor can be made visible with the aid of a reporter (B). Thelmx1a factor determines the fate of the labeled cells in the mid-brain (arrow). With this factor they becomenerve cells which specialize in the production of dopamine.

A B

Dr. Anastassia Stoykova receivedher PhD in neurochemistry at theInstitute for Molecular Biology of the Bulgarian Academy of Sciences in Sofia (Bulgaria).From 1973 to 1989, she worked atthe Regeneration Research Labo-ratory and the Institute for Mol -ecular Biology, interrupted by a re-search stay as an Alexander vonHumboldt Fellow at the GöttingenMax Planck Institutes for Experi-mental Medicine (1980-1981) andfor Biophysical Chemistry (1988-1989). After her habilitation in1989, she worked as a researchassistant professor at the Insti -tute for Molecular Biology, Sofia.Sub sequently, she returned toGöttingen and worked as a staffscientist in the Department of Mol -ecular Cell Biology at the MaxPlanck Institute for BiophysicalChemistry (1992-2002). In 2002, shebecame a group leader in the Mol -ecular Cell Biology Department.Since 2008, she has headed theMolecular De velopmental Neuro-biology Research Group in thescope of the Minerva Program atthe institute.

The human brain is both fascinatingand puzzling. Hundreds of billions of

neurons and many more glia cells are linked to form a complex network in it. Despite the vast number and variety ofcells, the mammalian brain develops fromastonishingly few original cells, the stemcells. We are investigating how this occursin the developing cerebral cortex, the outerregion of the mammalian cerebrum, inwhich environmental stimuli converge, mo-tion sequences are planned and initiated,and perceptions and cognitions develop.

The complexity of the cerebral cortex arises only in the course of its develop-ment. Com pletely developed, it comprisessix cellular layers and many functionally di-verse areas, each with its own responsibili-ties. The nerve cells of the different layersare born at particular developmental stages;they have a typical morphology, function,and make connections with diverse regionsof the brain and spinal cord. These pro -cesses are controlled by the expression ofspecific genes in the progenitors and/ornerve cells. In addition, the combina torialexpression of sets of transcription factorsin the progenitors develops a sort of mapwithin the germinative zone which anti -cipates the subsequent functional areali -zation.

We study the molecular mechanismswhich control the development of the cerebral cortex in mouse models. The transcription factor Pax6, for example,plays a decisive role in the development ofbrain and eye. If the Pax6 gene is inactive,fewer nerve cells form in the cortex, the

layers and functional areas exhibit abnormaldevelopment, and Pax6-deficient miceshow cognitive disabilities. Defect in the human PAX6 causes similar cortical abnor-malities and behavioral deficiency (aniridiasyndrome). We investigate how Pax6, to -gether with its interacting partners and target genes, regulates the differentiation

of cortical pro genitors in the developingbrain. In the adult brain only limited neuro -genesis occurs. Given the neurogenic prop -erties of Pax6, we are attempting to understand whether activation of this geneor its partners in the normal or damagedbrain – for example, under inadequateblood supply – could promote generationof more neuronal cells for eventual repair.

T. C. Tuoc, K. Radyushkin, A. B. Tonchev, M. C. Piñon, R. Ashery-Padan, Z. Molnar, M. S. Davidoff, A. Stoykova: Selectivecortical layering abnormalities and beha-vioral deficits in cortex-specific Pax6knock-out mice. J. Neurosci. 29, 8335-8349 (2009).

T. C. Tuoc, A. Stoykova: Trim11 modu -lates the function of neurogeneic tran-scription factor Pax6 through ubiquitinproteosome system. Genes Dev. 22,1972-1986 (2008).

G. M. Fimia, A. Stoykova, A. Romagnoli, L. Giunta, S. Di Bartolomeo, R. Nar dacci,M. Corazzari, C. Fuoco, A. Ucar, P.Schwartz, P. Gruss, M. Pieacentini, K. Chowdhury, F. Cecconi: AMBRA1 re-gulates autophagy and development ofthe nervous system. Nature 447, 1121-1125 (2007).

Molecular Developmental Neurobiology

Contact:astoyko@gwdg.dewww.mpibpc.mpg.de/groups/gruss/en/astoykova.htm

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Autoregulatory feedback loop between Trim11 and Pax6maintains the Pax6 dosage at a physiological level neces-sary to assure normal neurogenesis.

A) If Pax6 is not active, more deep layer (L6, L5) but al-most no upper-layer (L4 to L2) neurons are produced inthe cortex, due to a premature stop of the progenitor division that deplete the progenitor pool.B) Although the motor area is distinctly shrunken in mice with an inactive Pax6 gene, major axonal trajectories arepreserved.

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The visualization of structures and functionsby imaging plays an increasingly important

role in biological and medical research. In this respect magnetic resonance imaging (MRI) offersdetailed and completely noninvasive insights intothe body of animals and humans. MRI is there-fore widely used in diag nostic imaging, but alsoemerges as an indispensable research tool in thebiomedical sciences. It allows us to link advancesin molecular biology and genetics to anatomical,biochemical, and physiologic properties in the in-tact organism. Thus, MRI contributes to a trans-lation of new biological findings in animals intofuture diagnostic methods and therapies for humans.

The primary aim of our team is the further de-velopment of MRI methods and applications. Asearly as in the mid-eighties we invented a newprinciple for the acquisition of rapid images(FLASH) that revolutio nized the scientific poten-tial and clinical impact of MRI. Currently, wework on non-Cartesian strategies for encoding thespatial information as well as on novel mathe -matical approaches for image reconstruction.Such techniques represent major advances for avariety of applications including »parallel« MRI,which relies on the simultaneous data acquisitionwith multiple receive coils, and »real-time« MRI.As another example, we have made great progressby combining radial encodings with the FLASHtechnique. Such applications resulted in the re-cording of high-quality MRI movies in real time,which acquire, reconstruct, and visualize organmotions such as the beating heart without any detectable delay.

Access to the »thinking« brainA second major focus addresses neuroimagingtechniques that allow us to investigate the centralnervous system in a more specific manner beyondthe mere imaging of anatomy. For example, by

Biomedical NMR

Nerve fiber tracks in the human (top) and rhesus monkey brain (bottom). MRI measurements that probedifferences in the directed mobility of water molecules in brain tissue allow for a reconstruction of white matter fiber tracts. The figure depicts major fiber pathways, which cross the corpus callosum inthe center of the brain and mainly connect cortical areas of similar function in both hemispheres. Green= prefrontal, light blue = premotor, dark blue = motor, red = sensory, orange =parietal, magenta = tem-poral, yellow = occipital.

Prof. Dr. Jens Frahm received hisPhD in physical chemistry fromthe University of Göttingen in1977. The same year, he becamea scientific assistant at the MaxPlanck Institute for BiophysicalChemistry, where he subsequentlyheaded his own independent re-search group from 1982 to 1992funded by major grants of the Ministry for Research and Tech-nology. Since 1993, Jens Frahmhas been Director of the Biomedi-zinische NMR Forschungs GmbH,a non-profit company financed bythe Max Planck Society from royalties of the group’s patents. In 1994, he obtained his habilita -tion from the University of Göttin-gen, where he has been teach ingas an adjunct professor since1997. In 1991, Jens Frahm wasawarded the Gold Medal of theSociety for Magnetic Resonancein Medicine, followed by the KarlHeinz Beckurts Award (1993), theState Award of Lower Saxony(1996), and the Sobek ResearchAward (2005). In 2005, he waselected as an Ordinary Memberof the Academy of Sciences atGöttingen.

S. Boretius, T. Michaelis, R. Tammer, A.Tonchev, R. Ashery-Padan, J. Frahm, A.Stoy kova: In vivo MRI of altered brainanatomy and fiber connectivity in adultPax6 deficient mice. Cerebr. Cortex,doi: 10.1093/cercor/bhp057 (2009).

M. Uecker, T. Hohage, K. T. Block, J.Frahm: Image reconstruction by regula-rized nonlinear inversion – Applicationsto parallel imaging. Magn. Reson. Med.60, 674-682 (2008).

S. Hofer, J. Frahm: Topography of thehuman corpus callosum revisited –Comprehensive fiber tractographyusing magnetic resonance diffusiontensor imaging. NeuroImage 32, 989-994 (2006).

Contact:jfrahm@gwdg.dewww.biomednmr.mpg.de

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exploiting the directional mobility ofwater molecules in gray and white mat-ter, we can virtually reconstruct thethree-dimensional pathways of nerve fi-ber bundles in the brain. In this man-ner we redefined the topography of fi-bers passing through the central whitematter structure (corpus callosum) ofthe human and rhesus monkey brain.Other MRI sequences provide accessto the »thinking« brain. They are sen-sitive to changes of the intravascularconcentration of paramagnetic deoxy-hemoglobin which in turn reflectchanges in neural activity. Applicationsrange from information processing in

primary sensory systems to cognitionand even extend to the establishmentof a method for immediate functionalfeedback (neurofeedback), so that sub-jects can learn how to control the activ -ity of selected systems of their ownbrain.

A third important part of our re-search is devoted to MRI of animals,which mainly refers to brain studies ofgenetically modified mice. In collabor -ation with other researchers we ex -amine models of human brain dis orderssuch as neurodegenerative diseasesand multiple sclerosis. A benefit ofMRI is the fact that we can look atdisease progression and response totreat ment in individual animals. Re-cent studies of the mouse brain at veryhigh spatial resolution complementhistological analyses with tissue cha r -ac terizations in living animals.

High-resolution MRI of the mouse brain. A resolutionof 30 micrometers identifies cellular layers in the cortex and subcortical regions of an anesthetizedmouse. Contrasts are mainly due to differences in cellular density and degree of myelination. The insertsdepict enlarged sections of the cortex (top), hippo-campus (middle), and cerebellum (bottom).

Real-time MRI of the human heart. RadialFLASH techniques allow us to visualize thebeating heart during free breathing and without synchronization to the electrocardio-gram. The figure depicts 15 consecutiveimages (top left to bottom right) with a tem-poral separation of 30 milliseconds (corres-ponding to a frame rate of 33 images per second). The 450 millisecond movie sectioncovers the systolic phase of a single heart-beat, which is characterized by a thickeningand contraction of the myocardial wall.

Muscular dystrophy in the fruit flyIn Western Europe more than 70,000 peoplesuffer from severe forms of muscular dys -trophy. Those patients have pro gressivemuscle weakening and loss and so far nocure exists to treat these fatal dis orders.Drosophila’s easy-to-manipulate geneticsystem, relatively short life cycle, low cost,and biological complexity make the fruit flya perfect system to investigate these hered -itary muscle diseases. Pre viously we havedeveloped a Drosophila model for studyingmuscular dystrophies and shown that thephenotypes caused by Drosophila Dystro-glycan and Dystrophin mutations areremark ably similar to phenotypes observedin human muscular dystrophy patients. Mu-tant flies show de creased mobility, age-de-pendent muscle degeneration and braindefects.

With the aid of our fly model we investi -gate the molecular components and sig nal -ing pathways which regulate these genes.This should provide a better understandingof the causes of muscular dystrophy andcould contribute to the development of newtherapeutic approaches in the future.

Stem cells as a silent reserveStem cells are one of our additional researchfocuses. There are two types of stem cells:embryonic stem cells and adult stem cells.Adult stem cells form the body’s reserve tosupply the tissues with the required re -plenishment of new cells. To prevent stemcells from becoming depleted, they divideasymmetrically into another stem cell and

a daughter that differentiates. Stem cellsdo not work autonomously in their tissues,but rather they are regulated by signalsfrom their surroundings – their stem cellniche. Only in its special niche can a stemcell re generate itself. We are interested tofind out how the stem cell division andmaintenance is controlled and morespecifi cally how microRNAs – miRNAs –are involved in the process. Since Droso-phila has good markers for stem cells andniche cells, we are able to use geneticscreens in order to discover novel genes,which interact with miRNAs in the processof stem cell self-renewal and cell to cellcommunication in the adult stem cell niche. Given that miRNAs regulate geneexpression and enter readily into cells, theyhave a potential as therapeutics in regener -ative medi cine and cancer therapies.

Gene Expression and Signaling

Dr. (Univ. Kiev) Halyna Shcherbatastudied biology at the NationalUniversity of Lviv (Ukraine) andreceived her PhD from the Insti-tute of Plant Physiology and Genetics of the National Acad -emy of Sciences of Ukraine inKiev in 1996. From 2000 to 2003,she was assistant professor atthe Department of Genetics andBiotechnology at the NationalUniversity of Lviv, followed by apostdoctoral stay at the Depart-ment of Biochemistry, Universityof Washington (Seattle, USA). Halyna Shcherbata has beenhead of the Max Planck ResearchGroup Gene Expression and Signaling at the Max Planck Institute for Biophysical Chem -istry since 2008.

Contact:halyna.shcherbata@mpibpc.mpg.dewww.mpibpc.mpg.de/english/research/ags/shcherbata/

H. R. Shcherbata, A. S. Yatsenko, L. Pat-terson, V. D. Sood, U. Nudel, D. Yaffe,D. Baker, H. Ruohola-Baker: Dissectingmuscle and neuronal disorders in aDrosophila model of muscular dystro-phy. EMBO J. 26, 481-493 (2007).

H. R. Shcherbata, E. J. Ward, K. A. Fischer, J. Y. Yu, S. H. Reynolds, C. H.Chen, P. Xu, B. A. Hay, H. Ruohola-Baker: Stage-specific differences in therequirements for germline stem cellmaintenance in the Drosophila ovary.Cell Stem Cell 1, 698-709 (2007).

� Drosophila develops an age-dependent musculardystrophy phenotype that was used to screen for modifiers. (A) Architecture of wild type transversemuscle section. (B) Dg mutants show severe muscledystrophy.

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(A) Drosophila adult germ-line stem cells (outlinedwith white lines) and theirstem cell niche (markedwith arrows, pink). (B) Mutant enlarged stemcell niche can host morestem cells.

Dr. Henrik Bringmann studiedbiology in Göttingen and Heidel-berg and received his PhD at theMax Planck Institute for Cell Biol -ogy and Genetics in Dresden in2007. Subsequently, he worked asa postdoctoral fellow at the Lab -oratory of Molecular Biology inCambridge (United Kingdom). Since 2009, he has been headingthe Sleep and Waking Max PlanckResearch Group at the MaxPlanck Institute for BiophysicalChemistry. Henrik Bringmann wasawarded the Otto Hahn Medal ofthe Max Planck Society in 2008.

Sleep and waking are part of the life ofevery animal and every human being.

Why we are awake appears obvious. Butwhy do we sleep? One moves less and isbarely aware while asleep. Anyone whosleeps is more vulnerable. So why do ani-mals enter such a hazardous state?

Without sleep we feel tired and are in -efficient. Today researchers believe thatsleep is not only important for energy con-servation but also for the nervous system,which has time to regenerate. But what isregenerated in the nerve cells during sleep?

Our research group is trying to find outwhat happens in nerve cells during sleep.We want to know how a nervous systemfalls asleep and wakes up, how it knowsthat it is tired and has to sleep, and wewould like to understand the essentialfunctions of sleep, which make it im -possible for animals not to sleep.

The sleeping wormWe study sleep and waking on one of thesimplest animal models that has a sleep-like state: the round worm (nematode)Caenorhabditis elegans. In most animals,which are exposed to sunlight, the sleep-wake rhythm is coordinated with the ex -ternal day-night cycle. In contrast, C. elegansis a ground-dwelling animal. Its sleep-wakerhythm is controlled by an exactly pre -determined internal developmental pro-gram. C. elegans larvae experience exactlyfour distinctive sleep waking cycles duringtheir development. After each sleep phasethe animals moult.

A great advantage for our investigationsis the simple nervous system of C. elegans.Because the animals are transparent, wecan observe and manipulate the nervoussystem in intact animals both during sleepand waking.

We will subsequently test the resultsfrom our worm sleep studies in more com-plex animal models and also in humanbeings in order to learn about the differ -ences and similarities.

H. Bringmann: Mechanical and geneticseparation of aster- and midzone-posi-tioned cytokinesis. Biochem. Soc. Trans.36, 381-383 (2008).

H. Bringmann, C. R. Cowan, J. Kong,A. A. Hyman: LET-99, GOA-1/GPA-16,and GPR-1/2 are required for aster-po-sitioned cytokinesis. Curr. Biol. 17,185-191 (2007).

H. Bringmann, A. A. Hyman: A cyto -kinesis furrow is positioned by two con-secutive signals. Nature 436, 731-734(2005).

H. Bringmann, G. Skiniotis, A. Spilker,S. Kandels-Lewis, I. Vernos, T. Surrey: A kinesin-like motor inhibits micro -tubule dynamic instability. Science 303,1519-1522 (2004).

Sleep and Waking

Contact:henrik.bringmann@mpibpc.mpg.dewww.mpibpc.mpg.de/english/research/ags/bringmann/

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Photomontage of two pictures of the sameworm. The photograph shows connectionsbetween nerve cells (the synapses) duringwaking (red) and sleep (green).

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Anyone who has flown across several time zones knows the feeling in the first days

there after. During the day one is lamed by leadenfatigue, and at night one tosses and turns, wideawake in bed – a clear case of jetlag. Our circa -dian clock requires a few days until it has re -adjusted to our shifted circadian rhythm. But itworks: After a few days we again »tick« synchron -ously with the outside world. The circadian clockhas a period of nearly 24 hours, hence the term»circadian« which means approximately one day(derived from Latin circa, »around«, and dies,»day«).

The problems which occur in jetlag are a vividexample of how external influences disturb ourcircadian clock. In this context, it is really correctto speak of many clocks for the physiological pro-cesses in our body – up to our behavior – are co -ordinated by an entire network of molecular »zeit-gebers«. The individual organs each accom -modate their own peripheral oscillators, which areunder the central control of the circadian pace-maker in the hypothalamus, the supra chiasmaticnucleus (SCN).

The circadian clocks of the or-gans adapt to altered external in-fluences at different rates. In thiscontext, the adrenal gland’s clockplays a decisive role, as we wereable to show in experiments withmice. This organ normally secretesthe hormone cortisol and therebyhas a decisive influence on theclocks of other organs. If one inhibitscortisol synthesis, the body adapts more rapidly to the new time zone. Thisknowledge opens a pathway to hormonetherapy of jetlag.

An atlas of the clock genesWe obtain insights of this type by analyzing the genes relevant to the circadian clock. An exten sive,unique source of clock gene candidates are the at-lases of gene activity in the brain (www.brain-map.org, www.gene atlas.org), which we helped todevelop. In order to construct these molecularmaps, we developed high-resolution, automatedtechniques. In this manner, we can identify genes

Genes and Behavior

�In the Down syndromethree copies of the PCP4and Col18a1 genes, in addition to many others,are present. PCP4 (left) is effective in the nervoussystem, whereas Col18a1 –a collagen gene (right) –is active in the connec tivetissue of the mouse em-bryo.

Prof. Dr. Gregor Eichele studiedchemistry and structural biologyand received his doctorate in 1980at the University of Basel (Switzer -land). Subsequently, he did re-search in the field of de velop men -tal biology from 1981 to 1984 as apostdoctoral fellow at the Univer-sity of California at San Francisco(USA). From 1985 to 1990, he wasa faculty member at the HarvardUniversity School of Medicine inBoston (USA) und worked at theBaylor College of Medicine(Houston, USA) from 1991 to 1998.In 1997, he became a scientificmember of the Max Planck Societyand, in late 1998, he became a Director at the Max Planck Institutefor Experimental Endocrinology.Gregor Eichele has been a Director at the institute and head of the Department of Genes andBehavior since 2006. For his re-search he has received numerousawards, among them the FriedrichMiescher Prize, the McKnightNeuroscience Develop mentAward in 1991 as well as the Innovation Award in FunctionalGenomics in 2000.

V. Jakubcakova, H. Oster, F. Tamanini, C. Cadenas, M. Leitges, G. T. van derHorst, G. Eichele: Light entrainment ofthe mammalian circadian clock by aPRKCA-dependent posttranslational mechanism. Neuron 54, 831-843 (2007).

E. S. Lein, M. J. Hawrylycz, N. Ao, et al.: Genome-wide atlas of gene expression inthe adult mouse brain. Nature 445, 168-176 (2007).

A. Visel, J. Carson, J. Oldekamp, M.Warnecke, V. Jakubcakova, X. Zhou, C. A.Shaw, G. Alvarez-Bolado, G. Eichele: Re-gulatory pathway analysis by high-throughput in situ hybridization. PLoSGenet. 3, 1867-1883 (2007).

J. P. Carson, T. Ju, H. C. Lu, C. Thaller,M. Xu, S. L. Pallas, M. C. Crair, J. Warren,W. Chiu, G. Eichele: A digital atlas tocharacterize the mouse brain transcripto-me. PLoS Comput. Biol. 1, e41 (2005).

Contact:gregor.eichele@mpibpc.mpg.dehttp://genesandbehavior.mpibpc.mpg.de

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which, for example, are activated in a cir-cadian fashion in the SCN, the body’smaster clock. We then remove such can-didate genes from the SCN of mice anddetermine by means of running wheeland molecular experiments whether thecircadian clock is defective.

The expression atlas also provides uswith new insights into the metabo lome,the totality of all molecules involved inthe metabolism of an organism. Many ofthese molecules exhibit concentra tionfluctuations in the course of a day. In themean time we know, for example, theactivity pattern of all 360 solute carrier(SLC) genes. They contain the blue-prints for the SLC proteins, im portantpore proteins in biological membranes.They transport small mole cules such asnutri ents, vitamins, hormones and min -erals, in and out – between cells and with -in cells. If we know when which genesare active, we can construct a high-resol -ution atlas of substance exchangethroughout the entire mammalian organ-ism with a particular emphasis on thecirca dian aspects of meta bolism.

Developmental genes under the magnifying glassOur atlases of gene expression (www.genepaint.org, www.eurexpress.org) are also animportant resource for investigating how

genes influence the develop - ment of the brain in theembryo – the second largeresearch focus in our de-partment. We concentrateprimarily on those geneswhich coordinate thegrowth and structure ofthe cerebral cortex.

An example is the Esco2gene, which is active fora brief period in the stemcells of the cerebral cortexand which regulates the

cohesion of the chromo -somes during cell division. If

this gene is removed from thegrowth zone of the cerebral

cortex of mice, the animals areborn without this part of the brain.

People, in whom the Esco2 gene hasmutated, suffer from a severe hereditarydisease, which is termed the Robertssyndrom. We use our Esco2 mutants tostudy both the molecular processes ofcell division and the cause of the Roberts syndrom.

In the figure the activity strength (green to red) ofthe 36 solute carrier genes (SLCs) in the adrenalgland of the mouse is shown. The earlier in the dayan SLC reaches its activity maximum (red), the clo-ser it is to the top of the diagram. It is easy to seethat even in a SLC subset of merely 36 genes thereis a definite preference for peak expression at aspecific time of day.

Life on earth is shaped by multiple en-vironmental cycles. One of the most

influential of these is the succession of dayand night. In most species – from pro -karyotes to humans – internal timekeepers(so-called circadian clocks) that anticipatethese daily events and fine-tune physiologyto the varying demands of activity and resthave evolved. Circadian clocks are genetic -ally encoded and, thus, do not cease func -tioning in the absence of external time cuessuch as the sun. Our clock makes us feeltired in the evening, wakes us again everymorning, and regulates the secretion of various hormones with a 24 hour rhythm.

Our group is interested in the molecularmechanisms behind these phenomena. Forthis purpose, we have generated mice inwhich we have specifically disrupted someof those genes that regulate circadian time-keeping – which, by the way, are remark -ably similar in mice and men. We study thechanges in daily rhythms in these mice,with a focus on sleep-wake regulation andthe interaction between internal clocks andthe uptake/metabolism of food.

Visualizing the ticking of the clockBy providing our mice with a runningwheel we can very precisely measure theirdaily activity rhythms. In some animals, wehave genetically tagged the clock with thefirefly’s light-producing protein. By measur -ing light emission we can now follow themolecular »ticking« of the circadian clockin living tissue and observe how it reacts todifferent external stimuli.

We hope that our findings will lead tonew approaches for the treatment of»rhythm dis eases« such as sleep disruption,winter depression, and the so-called »nighteating syndrome«.

Circadian Rhythms

Dr. Henrik Oster received his PhDin biochemistry from the Univer -sity of Fribourg (Switzerland) in2002. From 2002 to 2007, he workedas a postdoctoral fellow at theMax Planck Institute for Experi-mental Endocrinology in Hanover und at the WellcomeTrust Centre for Human Geneticsat the University of Oxford (UnitedKingdom). In 2007, he received anEmmy Noether Grant from theGerman Research Foundation.Since then, he has headed theCircadian Rhythms ResearchGroup at the Max Planck Institutefor Biophysical Chemistry. HenrikOster received the Faculty Prizeof the University of Fribourg in2002 and was awarded the OttoHahn Medal of the Max PlanckSociety in 2003.

Contact:henrik.oster@mpibpc.mpg.dehttp://circadianrhythms.mpibpc.mpg.de

D. Lupi , H. Oster, S. Thompson, R. G.Foster: The acute light-induction ofsleep is mediated by OPN4-based pho-toreception. Nat. Neurosci. 11, 1068-1073 (2008).

H. Oster, S. Damerow, S. Kiessling, V.Jakubcakova, D. Abraham, J. Tian, M.W. Hoffmann, G. Eichele: The circadi-an rhythm of glucocorticoids is regula-ted by a gating mechanism residing inthe adrenal cortical clock. Cell Metab.4, 163-173 (2006).

H. Oster, S. Baeriswyl, G. T. van derHorst, U. Albrecht: Loss of circadianrhythmicity in aging mPer1-/-mCry2-/-mutant mice. Genes Dev. 17, 1366-1379 (2003).

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Wheel-running activity of a Cry1mutant mouse under light/dark (LD)and constant darkness (DD) con -ditions. In DD, the activity rhythmshows a period length of ~22 hours,whereas in LD the internal clock issynchronized to the external lightcycle of 24 hours.

Top: When we couple the clock protein PER2 to thelight-producing enzyme luciferase we can visualizethe rhythm of the internal clock by monitoring thelight signal produced by the oxidation of the luciferinmolecule. Bottom: Light emission rhythm from liverslice of a mouse bearing the PER2-lucife rase fusionprotein.

Institute staff members:837, including 473 scientists

Managing Director:Professor Dr. Helmut Grubmüller (2009 – 2010)

Assistant to the Managing Director:Eva-Maria Hölscher

Head of administration:Manfred Messerschmidt

Contact: Max Planck Institute for Biophysical Chemistry(Karl Friedrich Bonhoeffer Institute)Am Faßberg 11 · 37077 GöttingenPhone: +49 551 201-0 · Fax: +49 551 201-1222www.mpibpc.mpg.de

DepartmentsCellular Biochemistry (Professor Dr. Reinhard Lührmann)

Cellular Logistics (Professor Dr. Dirk Görlich)

Genes and Behavior (Professor Dr. Gregor Eichele)

Membrane Biophysics (Professor Dr. Erwin Neher)

Molecular Cell Biology (Professor Dr. Peter Gruss; on leave of absence; President of the Max Planck Society)

Molecular Developmental Biology (Professor Dr. Herbert Jäckle)

NanoBiophotonics (Professor Dr. Stefan W. Hell)

Neurobiology (Professor Dr. Reinhard Jahn)

NMR-based Structural Biology (Professor Dr. Christian Griesinger)

Physical Biochemistry (Professor Marina Rodnina)

Theoretical and Computational Biophysics (Professor Dr. Helmut Grubmüller)

Biomedical NMR (Professor Dr. Jens Frahm)

Board of Trustees

Ralf O. H. Kähler · CEO Volksbank Göttingen

Thomas Keidel · CEO Mahr GmbH, Göttingen

Dr. Joachim Kreuzburg · CEO Sartorius AG, Göttingen

Dr. Wilhelm Krull · Secretary General of the Volkswagen Foundation, Hannover

Dr. Peter Lange · Federal Ministry of Education and Research, Berlin

Professor Dr. Gerd Litfin (Chair) · former CEO LINOS AG, Göttingen

Wolfgang Meyer · Mayor of the City of Göttingen

Thomas Oppermann · Member of the German Federal Parliament, Berlin

Gerhard Scharner · former CEO Sparkasse Göttingen

Reinhard Schermann · Chief Councillor City of Göttingen

Dr. Herbert Stadler · CEO Affectis Pharmaceuticals AG, München

Ilse Stein · Editor-in-Chief Göttinger Tageblatt

Volker Stollorz · Editorial Journalist Frankfurter Allgemeine Sonntagszeitung, Köln

Lutz Stratmann · Minister of Science and Culture of Lower Saxony, Hannover

Professor Dr. Rita Süssmuth · former President of the German Federal Parliament, Berlin

Professor Dr. Kurt von Figura · President of the University of Göttingen

The institute at a glance

85

Scientific Advisory BoardProfessor Dr. Hugo BellenHoward Hughes Medical Institute, Baylor College of Medicine (Houston, USA)

Professor Dr. Carmen Birchmeier-KohlerMax Delbrück Center for Molecular Medicine (Berlin)

Professor Dr. Sir David CaseBioMaPS Institute and Department of Chemistry & Chemical Biology, Rutgers University (Piscataway, USA)

Professor Dr. Christopher DobsonUniversity of Cambridge (Cambridge, UK)

Professor Dr. Gideon DreyfussHoward Hughes Medical Institute, University of Pennsylvania (Philadelphia, USA)

Professor Dr. Mary Beth HattenRockefeller University (New York, USA)

Professor Dr. Peter JonasUniversity of Freiburg (Freiburg)

Professor Dr. Michael LevittStanford University (Stanford, USA)

Professor Dr. David NesbittUniversity of Colorado at Boulder (Boulder, USA)

Professor Dr. Peter SoMassachusetts Institute of Technology (Cambridge, USA)

Professor Dr. Joan SteitzYale University (New Haven, USA)

Professor Dr. Joseph TakahashiHoward Hughes Medical Institute, University of Texas (Dallas, USA)

Professor Dr. Peter WalterUniversity of California (San Francisco, USA))

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... by car Autobahn A7 Kassel-Hannover, Göttingen NordExit. Continue straight on at the first traffic lightfollowing the B27 in the direction of Braunlage.After about 2 km turn left in the direction of Ni-kolausberg (signposted). The third road junction onthe left-hand side leads onto the institute’s campus.

... by trainTake a taxi from the Göttingen train station to theinstitute or the city bus number 8 or 13 in the direction of downtown. Transfer to bus number 5in the direction of Nikolausberg at one of the firstfour bus stops. The »Am Faßberg« bus stop is located across the street from the institute site.

Reaching us …

... by planeVia the Frankfurt or Hannover airports.From the Frankfurt Airport, direct trains to Göt-tingen leave every two hours at the long-distancetrain station. Alternatively, from the regional trainstation, take the train or urban railway (S-Bahn) tothe Central Station (Frankfurt/Hbf) (trains to Göt-tingen at half hour intervals). Travel time with acar to Göttingen is approximately 3 hours.

From the Hannover Airport, take the urban rail-way (S-Bahn) to the Hannover Central Station.From their take an ICE or an IC train to Göttingen(travel time approximately 30 minutes). Travel time with a car to Göttingen is approximately 1.5 hours.

87

Page 5 (bottom, left): Medial nucleus of the trapezoid body (MNTB) in the brain injected withGFP adenovirus (green). The vesi cular glutamatetransporter VGLUT1 is stained red. (Meike Peder-sen, Department of Membrane Biophysics)

Page 5 (bottom, second from left): Structure of bacte-riorhodopsin, a protein used by archaea which actsas a proton pump. (Helmut Grubmüller, Departmentof Theoretical and Computational Biophysics)

Page 5 (bottom, second from right): Neural stem cellsoriginating from the embryonic brain of mice whichhave differentiated into star-shaped glial cells, so-called astrocytes (green). Cell nuclei are stainedblue. (Michael Kessel, Research Group Develop-mental Biology)

Page 5 (bottom, right): The insuline hormone in two different schema tizations. (Helmut Grubmül-ler, Department of Computational and TheoreticalBiophysics)

Page 6: Confocal fluorescence micrograph showingthe tubulin cytoskeleton of rat kan garoo cells.(Christian Wurm, Stefan Jakobs; Research GroupMitochondrial Structure and Dynamics)

Page 7 (bottom, right): Max Planck Institute for Neurobiology

Page 8 (left): Archives of the Max Planck Society

Page 9 (top): Spatial structure of the molecular force sensor titin kinase. (Helmut Grubmüller, Department of Theoretical and Computational Biophysics)

Page 9 (bottom): Dirk Bockelmann, Department ofNMR-based Structural Biology

Page 12 (top): Deutscher Zukunftspreis, Ansgar Pudenz

Page 13: Filament structures within a nerve cell.The STED microscope provides much sharper details compared to a conventional microscope.(Stefan W. Hell, Department of NanoBiophotonics)

Page 21: Confocal fluorescence micrograph showingthe actin cytoskeleton (red), the tubulin cytoskeleton(green) and the cell nucleus (blue) of rat kangaroocells. (Christian Wurm, Stefan Jakobs; ResearchGroup Mitochondrial Structure and Dynamics)

Page 30: Federico Neri, fotolia.com

Page 33: Inter-Stilist, fotolia.com

Page 34: The head-tail connector of the phi29 DNApolymerase. The blue part in the middle representsDNA. The connector is involved in DNA packagingduring virus reproduction, where virus DNA is pushed into an empty virus shell. (Matthias Popp;Department of Theoretical and Computational Biophysics)

Page 48/49: Three-dimensional structure of the largest subunit of the spliceosome, the »tri-snRNP«(left) and four more structures of its flexible com -ponent (»U5 snRNP«). (Holger Stark, former Re-search Group 3D Electron Cryo-Microscopy)

Page 54/55 (top): Bacterial cells. (Irochka, fotolia.com)

Page 56/57: Hundreds of billions of neurons are linked to form a complex network in our brain. (Sebastian Kaulitzki, fotolia.com)

Page 64: Confocal fluorescence micrograph showingthe tubulin cyto skeleton (red) and the cell nucleus(blue) of rat kangaroo cells. (Christian Wurm, Stefan Jakobs; Research Group MitochondrialStructure and Dynamics)

Page 65: Alexander Egner, Facility for InnovativeLight Microscopy

Page 70/71: A section through the mouse brainshows star-shaped glial cells (astrocytes, green) inthe upper layer and neurons in the lower layer(red). Cell nuclei are stained blue. (Michael Kessel,Research Group Developmental Biology)

Page 76/77: Emilia Stasiak, fotolia.com

Page 82/83: FinePix, fotolia.com (old clock)

Page 84: Kyslynskyy, fotolia.com

Pictures

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Publishing information

Publisher Max Planck Institute for Biophysical ChemistryAm Faßberg 1137077 Göttingen

Texts Marcus Anhäuser, Diemut Klärner, Dr. Carmen Rotte; (in German) in cooperation with the scientists at the Max Planck Institute

for Biophysical ChemistryTranslation Baker & Harrison, Dr. Daniel Whybrew Language editing Jaydev Jethwa, Dr. Nathan PavlosFinal proof-reading Dr. Ulrich Kuhnt, Dr. Carmen RottePhotographs Irene Gajewski, Peter Goldmann (p. 10, bottom left, p. 17 top right),

Heidi Wegener (p. 85); Cover picture: Irene GajewskiLayout Rothe-Grafik, Georgsmarienhütte; Hartmut SebessePrinted at Druckhaus Fromm, OsnabrückCoordination Dr. Carmen Rotte

Press and public relations officeMax Planck Institute for Biophysical Chemistry pr@mpibpc.mpg.de

Internet address www.mpibpc.mpg.de

Max Planck Institute for Biophysical Chemistry(Karl Friedrich Bonhoeffer Institute)Am Faßberg 11 · 37077 GöttingenPhone: +49 551 201-0 · Fax: +49 551 201-1222www.mpibpc.mpg.de

Max Planck Institute for Biophysical Chemistry

Karl Friedrich Bonhoeffer Institute

Göttingen