Antifungal proteins copy
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ANTIFUNGAL PROTEINSBY SREE REMYA.S
II MSC BIOTECHNOLOGY
CONTENTS• INTRODUCTION
• FUNGAL CELL WALL
• ANTIFUNGAL PROTEINS
• CLASSES OF ANTIFUNGAL PROTEINS & THEIR MECHANISMS
• CONCLUSION
INRODUCTIONFungi are amazing organisms, which can
grow in any surfaceFungi are proficient at colonizing & using
plants, humans & animals as substrateThe fungal cell wall protects the organisms
& relays signals for invasion& infection of a plant, animal or a human host
Fungi are extremely diverse group of organisms &some plants have antifungal activity
FUNGAL CELL WALL
ANTIFUNGAL PROTEINSPlants are exposed to large number of
pathogenic fungiAlthough plants do not have an immune
system, but they have a defense mechanism including antifungal activity
There are hundred’s of antifungal peptides & proteins known, with more being discovered almost daily
CLASSES OF ANTIFUNGAL PROTEINSo 13 CLASSES OF ANTIFUNGAL PROTEINS
ARE PRESENT: PR PROTEINSPR-1 PROTEINSPR-2 PROTEINS (beta glucanases)PR-3 PROTEINS(chitinases)PR-4 PROTEINS(chitin binding ) proteinsPR-5 PROTEINS(TL)DEFENSINSCYCLOPHILIN- LIKE PROTEINS
CONT….RIPsKILLER PROTEINS (KILLER TOXINS)PROTEASE INHIBITORSOTHER PROTEINS
ANTIFUNGAL PROTEIN
PR PROTEINSPlants exposed to pathogens such as
fungi& viruses produce low molecular weight antimicrobial compounds called phytoalexins
These plant proteins called pathogenesis related (PR) proteins , are divided into 5 groups, PR-1,-2,-3,-4,-5, based on serological& amino acid sequence analysis
The 5 classical groups of PR proteins has 2 subclasses:
Cont….A basic subclass found in plant cell vacuoleAn acidic subclass found in the
extracellular space
PR-1 proteins PR-1 proteins accumulates to high levels
after pathogen infection& are antifungal both in plants& in vitro
PR-1proteins have been found in wheat, rice , maize, tobacco
PR-1proteins cont….PR-1 proteins have antifungal activity at
the micro molar level against no: of plant pathogenic fungi including Uromyces fabae, Phytophthora infestans,Erysiphe graminis
PR-1proteins mechanismis unknownPR-2 PROTEINSPR-2 have(1,3)beta glucanase activity in
vitro & are grouped into 3 classes on the basis of aminoacid sequence analysis
PR-2 PROTEINSThis proteins found in plants like tobacco,
peas, grains & fruitsThe proteins are active at wide range of
fungi including human& plant pathogen(Rhizoctonia solani, C. albicans, A. fumigatus)
The antifungal activity of PR-2proteins are demonstrated by no: of invitro enzymes
BETA GLUCANASES
PR-3 PROTEINS(chitinase)A no: of enzymatic assays describes PR-
3proteins to have in vitro chitinase activityChitinases are isolated from fungi, plants
(tobacco, cucumber, beans)& bacteria have potent antifungal activity against human& plant pathogens including T. reesi, Alternia solani, A.radicina,F.oxysporum)
PR-4(chitin binding ) proteinsPR-4proteins have
molecular mass of 13- 14.5 KDa
PR-4proteins are isolated from potato, tobacco, barley , pumpkins& many other plant
PR-4 PROTEINS CONT….Chitin binding proteins& have antifungal
activity but are not PR proteins have been isolated from bacteria, plants, insects
Fungi inhibited by these proteins include plant& human pathogens eg: Paecilomyces variotii, F.oxysporum, Aspergillus.sp,A. brassicola
PR-5 ( TL) PROTEINSPR-5 proteins share significant homology
to thaumatin & are known as TLproteins
Cont…TL proteins have been isolated from A.
thaliana, pumpkin, wheat ,riceThe highly stabilized structure of PR-5 are
resistant to protease degradationMechanism is not knownThese proteins they are fungicidal against
a wide no: of plant& human pathogens, zeamatin protein has shown efficacy in murine vaginal model of C. albicans
DEFENSINSDefensins are low molecular mass
cysteine rich proteins found in mammals, fungi ,insects & plants
The insecect & mammalian defensins are quiet small & form voltage depedent ion channels in plasma membrane
The treatement of hyphae with the defensins from radish & dhalia cause k+ efflux & Ca+ uptake through binding to specific cell membrane receptors
COND…. Defensins have the ability to inhibit human&
fungal pathogens including B.cinerea, F.oxysporoum,F.solani & C.albicans at micromolar levels
CYCLOPHILIN LIKE PROTEIN Cyclophilins are conserved group of proteins –
that are intracellular receptors for cyclosporin & is found in bacteria, plant, animal,fungi
A protein isolated from mung bean is called mungin. Antifungal mechanism is not known
RIPsRIPs are RNA N- glucosidase that
depurinates Rrna,result inarrest of protein synthesis due to ribosome damage
Plant RIPs inhibit mammalian,bacterial, plant, fungal protein synthesis
RIPs have been isolated from Pisum sativum, Viscum album, & from fungi – A.giganteus
RIPs have intrinsic antifungal activity – have ability to inactivate fungal ribosomes invitro.
KILLER PROTEINS (KILLER TOXINS)A no: of yeast secrete proteins that are
lethal to sensitive fungal cells.These proteins are killer toxins are encoded by either by double stranded DNA,linear double stranded plasmid DNA
CONT… Fungal cells secrete a killer toxin are
resistant to their own toxin but are sensitive to other toxin
Kulveromyces lactis& several Pichia species secrete a no: of killer toxin
Killer proteins can disrupt cell wall synthesis ,DNA synthesis,& k+ channel activity – any of these effect leads to inhibition of fungal cell growth
PROTEIN INHIBITORSProtein inhibitors of serine & cysteine
protease have emerged as antifungal proteins that have potent activity against plant & animal pathogens.
GRAPH SHOWING THE POTENT ACTIVITY
CONT….Cysteine protease inhibitors are isolated
from a no: of plants & from a group of cystatins, the phytocystatins
Phytocystatins are active against plant pathogens such as F. solani,T.reesi
CURRENT INVENTIONSAntifungal activity work is carried out
world wideViridin a novel protein isolated from
culture protein T. viridae –molecular mass 65 kDa is active against fungi at 6 micrometer
Snakin -1 is such a novel protein isolated from potato
CONCLUSIONAntifungal proteins & polypeptides have
been isolated from diverse group of organisms
The range of fungi inhibited by antifungal proteins are extremely broad, & studies about antifungal proteins are carried out widely