1.4 yves gaudin
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Understanding the rhabdovirus fusion machinery
Perspectives opened by dynamic structural virology
Molecular and Structural Virology Laboratory CNRS – Gif sur Yvette
Yves Gaudin
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Rhabdovirus entry into the host cell
Endosome acidification
Membrane fusion
Virion endocytosis
Receptor recognition
Prototypes : rabies virus and VSV
Enveloped viruses with a typical bullet shape
Glycoprotein G mediates viral entry
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The membrane fusion pathwayComplete
fusion
Stalk Hemifusion Fusion Pore
Class IParamyxovirus F
Influenza HAHIV gp160
Class IIAlphavirus E1Flavivirus E
Native or prefusion conformation
Energy
Final or postfusion conformation
Fusion machineries
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Rhabdovirus glycoprotein G: The prototype of the third class
Internal fusion loops
Transmembrane domain
446 466 495CHO CHO
pH-dependent equilibrium between these different states
How does it work ?
Prefusion state
Activated state
Postfusion state
Receptor recognition
Membrane interaction
pH >7 pH < 6.5
pH 7.5 pH 5.5One glycoprotein
Several conformations
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pH 5.5pH 7.5
Identification of two distinct steps during membrane fusion
Libersou et al. J. Cell Biol. 2010
Visualization of individual fusion events
LIPO
LIPO
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Crystalline structures of VSV G
TM
Trimers
Prefusion Postfusion
Forme préfusion
Protomers
Prefusion Postfusion
Roche et al. Science 2006 ; Science 2007
Membrane
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Target membrane
Viral membrane
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The conformational change pathway
Trimeric prefusion
state(high pH)
Trimeric postfusion
state(low pH)
Fusion loopsTransmembrane domains
**
TomographyCristallography
TomographyCristallography
EMSAXS
Decreasing pH
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First structure of intermediates• Chandipura virus (outbreaks of deadly encephalitis in India)
Two different monomers in the asymetric unit !
1 1
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VSV G postfusion
Late intermediate
VSV G prefusion
Fusion loops.TM domains.
Early intermediate
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Structural virology: a french « savoir faire »
- Class II fusion proteins of Chikungunya virus (Felix Rey, Institut Pasteur)
- Replication complex of influenza and Mononegavirales, HIV structural biology (Rob Ruigrok, Winfried Weissenhorn, UVHCI, Grenoble)
- Replication complex of positive strand RNA viruses such as Dengue virus, West Nile virus, SARS coronavirus (Bruno Canard, AFMB, Marseille)
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Perspectives
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Powerful hybrid approaches (Cristallography, EM, SAXS, NMR…) in structural virology allow:
•Access to the dynamics of complex viral machineries
•Determination of the structure of intermediates that can constitute new targets for antiviral strategies