Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular...
-
Upload
garey-eaton -
Category
Documents
-
view
219 -
download
2
Transcript of Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular...
![Page 1: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/1.jpg)
Gene Expression
Eukaryotic Gene Transcription9/18/08
Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics
![Page 2: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/2.jpg)
Eukaryotic RNA Polymerases
• Three DNA dependent RNA polymerases: RNA Pol I, II, and III
• All 3 are big, multimeric proteins (500-700 kD)
• All have 2 large subunits with sequences similar to and ' in E. coli RNA polymerase, so catalytic site may be conserved
• All interact with general transcription factors-GTFs
• RNA Pol II is most sensitive to -amanitin
![Page 3: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/3.jpg)
RNA Polymerase II Inhibitor -Amanitin “The Destroying Angel” - Amanita phalloides
Bicyclic octapeptideBlocks elongation
pol II >> pol III >>> pol I
![Page 4: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/4.jpg)
Yeast RNA Polymerase II Subunits
![Page 5: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/5.jpg)
Transcription Factors
The three RNA polymerases (I, II and III) interact with their promoters via protein:protein and protein:DNA interactions
These proteins or transcription factors (TFs) recognize and initiate transcription at specific promoter sequences
Some transcription factors (TFIIIA and TFIIIC for RNA polymerase III) bind to specific recognition sequences within the coding region
![Page 6: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/6.jpg)
Helix-Turn-Helix Motif
![Page 7: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/7.jpg)
Zinc-Finger Motif: C2H2 Class
![Page 8: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/8.jpg)
Basic Region-Leucine Zipper Motif: bZIP
![Page 9: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/9.jpg)
bZIP Transcription Factor
![Page 10: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/10.jpg)
General Transcription Factors (GTFs)
• GTFs position RNAPs at transcription initiation sites, forming the preinitiation complex (PIC)
• Transcription-initiation complex = RNAP + general transcription factors (GTF) bound to promoter region
• Many of the GTFs that associate with RNAP II initiate transcription from TATA box-containing promoters have been identified– TFIIA, TFIIB, TFIID, TFIIE, TFIIF and TFIIH– TFII = “transcription factor RNAP II”
![Page 11: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/11.jpg)
General Transcription Factors
• TFIID is largest and consists of a TATA-box binding protein (TBP) and 8-10 TBP-associated factors (TAFIIs)
• TBP is a “universal transcription factor” – associates with promoters of all three RNAPs, and promoters with and without a TATA box
• Binding of TAFIIs extend the interactions of TFIID
• TFIID has two roles: – foundation for the transcriptional PIC complex– Prevents nucleosome stabilization in the promoter
region (antagonist to H1)
![Page 12: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/12.jpg)
TBP is used by all 3 RNA polymerases
• TBP is a subunit of an important GTF for each of the 3 RNA polymerases:
– TBP or TFIID for Pol II
– SL1 for Pol I
– TFIIIB for Pol III
• It does NOT always bind to TATA boxes; promoters for RNA Pol I and Pol III (and even some for Pol II) do not have TATA boxes, but TBP is still used.
• The GTFs that contain TBP may serve as positioning factors for their respective polymerases.
![Page 13: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/13.jpg)
Yeast TATA Binding Protein: TBPTBP binds in the minor groove of DNA
TBP binding bends the DNA
![Page 14: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/14.jpg)
• RNA Pol I transcribes genes for the large rRNA precursor
• There are hundreds of similar copies of this gene in each genome
• RNA Pol I promoters (called class I) have two components:
• Upstream control element: –156 to -107• Core element: –45 to +20
• Two different transcription factors bind these sequences co-operatively: SL1 and UBF (TBP is a component of SL1)
Promoters for RNAP I
![Page 15: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/15.jpg)
![Page 16: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/16.jpg)
Transcribes various small RNAs: 5S rRNA, tRNA precursors, U6 snRNA, etc
The 5S rRNA and tRNA genes have class III promoters
U6 snRNA and 7SL RNA gene have promoters that resemble RNAP II promoters
The 5S rRNA promoters are entirely within the coding region of the gene
The tRNA promoters contain two elements
The other promoters for U6 snRNA etc appear similar to RNAP II promoters (have TATA boxes) but -amanitin test indicates these are transcribed by RNAP III.
Promoters for RNAP III
![Page 17: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/17.jpg)
PIC Assembly for RNA Pol III Genes
TBP TBP
TBPTBP
![Page 18: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/18.jpg)
RNA Polymerase II General Transcription Factors
Factor Subunits FunctionTFIID - TBP 1 Recognize core promoter (TATA), Recruit TFIIBTFIID - TAFs 12 Recognize core promoter (non-TATA), Pos and Neg
regulatory functions, HAT activityTFIIA 3 Stabilize TFIID and promoter bindingTFIIB 1 Recruit RNA Pol II / TFIIF, Start site selectionTFIIF 2 Assist RNA Pol II to bind promoterRNA Pol II 12 Enzymatic synthesis of RNA, Recruit TFIIETFIIE 2 Recruit TFIIH, Modulate TFIIH helicase, ATPase,
and kinase activitiesTFIIH 9 Promoter melting using helicase, Promoter
clearance via CTD phosphorylation
Modified from Roeder, R.G., Trends in Biochem. Sci. 21:327-334
![Page 19: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/19.jpg)
• Important for helping TBP to bind to promoters that lack TATA boxes.
• There are different TAFs in different cells!
• In vivo these factors are associated with additional proteins forming a larger complex of about 50 polypeptides.
• It is hypothesized that this high MW complex may preassemble and interact with promoters in a single step.
TBP-associated Factors (TAFs or TAFIIs)
![Page 20: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/20.jpg)
TFIID binds TATA box via TBP subunit
TFIIA facilitates and stabilizes binding of TFIID complex
Eukaryotic RNA Pol II TranscriptionFormation of the PIC
![Page 21: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/21.jpg)
TFIIB binds to TFIID
TFIIB is a monomeric protein
C terminal domain contacts DNA and TBP
N terminal domain extends towards start site
Proximity of certain promoter- and enhancer-transcription factors (important for developmental regulation- their activation domain binds directly to TFIIB)
TFIIH close as well at this point, but not yet bound
Eukaryotic RNA Pol II TranscriptionFormation of the PIC
![Page 22: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/22.jpg)
TFIIF binds to RNAPII (preformed complex) – directs RNAPII to promoter
Binding of TFIIE to TFIIF/RNAPII complex and already positioned TFIIB helps positioning the RNAPII over start site:
Two large subunits of RNAP II interact with promoter DNA: CTD tail (unphsphorylated form) of RNAPII is in direct contact with TFIID
TFIIE is DNA-dependent ATPase- probably necessary for generating the energy for transcription
Eukaryotic RNA Pol II TranscriptionFormation of the PIC
![Page 23: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/23.jpg)
Binding of RNAP II/TFIIF/TFIIE to promoter activates TFIIH
TFIIH contains nine subunits
It has helicase activity- unwinds DNA downstream from the initiator site in the presence of ATP necessary for promoter clearance
It has protein kinase activity- phosphorylation of CTD tail of RNAPII
Phosphorylation detaches RNAPII from TFIID
Beginning of transcription by RNAPII
Eukaryotic RNA Pol II TranscriptionFormation of the PIC
![Page 24: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/24.jpg)
Carboxyl-Terminal Domain (CTD Tail)
• Stretch of 7 amino acids that is repeated multiple times (26-52 times): Tyr-Ser-Pro-Thr-Ser-Pro-Ser
• Critical for viability
• CTD tail becomes phosphorylated on ser and some tyr residues as the RNAP transcribes away from the promoter
![Page 25: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/25.jpg)
RNA Pol II PromotersConsist of two parts:
1. Core promoter: - TATA box (position at ~ -30)- initiator (on the transcription start site)
2. Proximal Promoter Elements (can be upstream, downstream or internal)
DownstreamElement
UpstreamElement
TATA Initiator
![Page 26: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/26.jpg)
Eukaryotic TATA Box
ConsensusSequence
TATA motif is usually located at position -25
![Page 27: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/27.jpg)
Eukaryotic Promoter Regions
Initiator
![Page 28: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/28.jpg)
RNA Polymerase II Promoter Consensus Sequences of Transcription Factor Binding Sites
![Page 29: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/29.jpg)
Proximal Control Elements of Genes
Modular Factor Binding Sites
![Page 30: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/30.jpg)
Coordinate Regulation Via Response Elements
Multiple genes are transcribed in response to different cues: for example, heat shock, hormone levels, developmental events, phorbol esters, heavy metals, metabolite concentrations, etc.
Similarly responsive genes will have a DNA sequence located in cis to the gene called a response element.
These response elements are binding sites for transacting factors that are activated in response to the environmental cue.
The location of these elements relative to the start site of transcription is not conserved between genes: eg. a cis element that leads to transcription in response to a hormone may be located at –300 in one gene and –175 in another
![Page 31: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/31.jpg)
Response Elements: Coordinate Regulation
Metallothionein Gene Promoter
![Page 32: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/32.jpg)
Coordinate Regulation by Hormones/Steroid Receptors
Adapted from Molecular Biology of the Cell, 4th Edition
![Page 33: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/33.jpg)
Steroid Receptors
Upon binding to the hormone cortisol, the cytoplasmic glucocorticoid receptor displaces an inhibitory protein (Hsp90) and moves to the nucleus where is can interact with glucocorticoid response elements (GREs) in the DNA affecting gene transcription.
Adapted from Molecular Biology of the Cell, 4th Edition
![Page 34: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/34.jpg)
Activation of Transacting Factors
![Page 35: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/35.jpg)
Control of Cellular Differentiation By TFs
![Page 36: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/36.jpg)
Enhancers
Control elements that stimulate transcriptionBind multiple different transcription factorsTranscription factors that recognize enhancer =
activators or enhancer binding proteinsActivators interact with general transcription factorsNegative enhancer is a silencer
![Page 37: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/37.jpg)
Stimulate expression of genes over long
disances (up to 50kb)Occur upstream, downstream, in introns
or in exonsOrientation independentMay be cell-type specific
Enhancers
![Page 38: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/38.jpg)
Activation of transcription initiation in eukaryotes by recruitment of the eukaryotic RNA polymerase II holoenzyme complex (100 protein subunits).
Enhancers: Action at a Distance
![Page 39: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/39.jpg)
Insulators / Boundary Elements
Boundary elements block encroachment of heterochromatin from neighboring loci. They also stop the unregulated enhancement or activation of neighboring genes outside of their chromosomal domain.
![Page 40: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/40.jpg)
Hypomethylation(Active)
Vs.Hypermethylation
(Silenced)
![Page 41: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/41.jpg)
Silencing: Histone Deacetylation HDAC
• Some repressors recruit histone deacetylase, which removes acetyl groups from histones resulting in gene silencing
![Page 42: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/42.jpg)
Histone Acetylation and Deacetylation
AcCoA
C
O
CHNHCH2
C
O
NH... ...CH2
CH2
CH2
CH2
NH 3+
C
O
CHNHCH2
C
O
NH... ...CH2
CH2
CH2
CH2
NH
Gly Lys
CCH3
O
CoA
AcPositive charge on amino group No charge on amide group
Histone acetyl transferases
Histone deacetylases
HAT
HDAC
![Page 43: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/43.jpg)
Histone tails are postranslationally modified by acetylation, methylation, phosphorylation and ubiquitination. These modifications have a profound effect on gene activity. The specific set of modifications is termed the “histone code” .
Histone Code
![Page 44: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/44.jpg)
Remodeling complexes allow access of replication and transcription factors to the DNA.
Remodeling requires ATP
Chromatin Remodeling
![Page 45: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/45.jpg)
Gene Activation By Chromatin Remodeling
Transcription Factor Access
![Page 46: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/46.jpg)
HATs open chromatin
Nucleosome remodelers
Transcription Factor Coactivators
![Page 47: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/47.jpg)
Assembly of preinitiation complex on
open chromatin
![Page 48: Gene Expression Eukaryotic Gene Transcription 9/18/08 Thomas Ryan, Ph.D. Biochemistry and Molecular Genetics tryan@uab.edu.](https://reader036.fdocuments.in/reader036/viewer/2022062320/56649f4f5503460f94c7162d/html5/thumbnails/48.jpg)
Chromatin remodeling of diploid somatic cell nucleus in the egg cytoplasm reprograms the nucleus to recapitulate development.