Salmonella enterica serovar Typhi flagellar filament

The flagella of Salmonella enterica serovar Typhi are complex, rotary nanomachines on the bacterial surface that enable swimming and swarming motility through viscous environments like host mucosa, facilitating host cell adhesion and invasion during infection. Composed of a basal body motor powered by proton motive force, a flexible hook, and a long helical filament primarily made of FliC (H1) or FljB (H2) flagellin proteins via phase variation, they allow antigenic switching to evade host immunity. Flagellar motility is essential for biofilm initiation and maturation on surfaces, aiding persistence in hostile environments. Key components include the MS-ring (FliF), rod (FlgB-G), export apparatus (FlhA/B, FliO/R), and stator units (MotA/B). In pathogenesis, flagella promote systemic infection like typhoid fever by enabling tissue penetration and immune modulation. No approved drugs directly target Typhi flagella, though mutants in genes like fliC or flgE impair virulence, suggesting potential as anti-infective targets. Structural studies reveal domain-specific roles, with D3 domains influencing antigenicity and propeller efficiency. Phase variation occurs at 10^-3 to 10^-4 frequency per generation, enhancing bacterial fitness. Overall, these flagella represent a conserved virulence organelle across Salmonella serovars.

Other names

Typhi flagellaS. Typhi flagellumflagellin filament (FliC/FljB)H antigen