The FliS chaperone selectively binds the disordered flagellin C-terminal D0 domain central to polymerisation

Assembly of each Salmonella typhimurium flagellum filament requires export and polymerisation of ca. 30000 flagellin (FliC) subunits. This is facilitated by the cytosolic chaperone FliS, which binds to the 494 residue FliC and inhibits its polymerisation. Yeast two-hybrid assays, co-purification and affinity blotting showed that His binds specifically to the C-terminal 40 amino acid component of the disordered D0 domain central to polymerisation. Without His binding, the C-terminus is degraded. Our data provide further support for the view that FliS is a domain-specific bodyguard preventing premature monomer interaction. (C) 2003 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.