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Flagellin polymerisation control by a cytosolic export chaperone
F Auvray1, J Thomas, G M Fraser
1Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK.
Journal of Molecular Biology
|May 1, 2001
Summary
A cytosolic protein, FliS, specifically facilitates bacterial flagellin (FliC) export by binding to FliC subunits. This chaperone action prevents premature polymerization, ensuring proper flagellar filament assembly.
Area of Science:
- Microbiology
- Molecular Biology
- Structural Biology
Background:
- Bacterial flagellar assembly involves the polymerization of approximately 20,000 flagellin (FliC) subunits.
- The precise mechanism of flagellin export and subunit stabilization remains an area of investigation.
Purpose of the Study:
- To investigate the role of the cytosolic protein FliS in the export and polymerization of Salmonella flagellin (FliC).
- To elucidate the interaction between FliS and FliC and its impact on flagellar filament formation.
Main Methods:
- In vitro assembly of stable FliS-FliC complexes.
- Analysis of FliS binding to the C-terminal helical domain of FliC.
- Assessment of FliS's ability to prevent FliC polymerization.
Main Results:
- FliS specifically facilitates the export of Salmonella flagellin (FliC).
- FliS binds to the C-terminal helical domain of FliC, stabilizing subunit interactions.
- FliS homodimers efficiently bind FliC monomers, forming stable complexes in vitro.
- FliS acts as a substrate-specific chaperone, preventing premature FliC subunit interactions in the cytosol.
- FliS inhibits in vitro polymerization of FliC into filaments.
Conclusions:
- FliS is a crucial chaperone for bacterial flagellin export and polymerization.
- FliS binding to FliC prevents premature subunit interactions, ensuring ordered flagellar filament assembly.