Cloning,sequencing and expression of the flagellin core protein and other genes encoding structural proteins of the Vibrio cholerae flagellum

Vibrio cholerae is a Gram-negative bacterium with a single polar flagellum. Motility is an important virulence factor for this non-invasive pathogen. We cloned and sequenced a locus in V. cholerae V86 (El Tor, Inaba) that contained five different structural genes of the flagellum. The cloned genes and their products were assigned names and functions based on homology with sequences of similar genes and their products from other related bacteria. All of these genes of V. cholerae V86, namely, flgI, J, M, L and flaA, were transcribed in the same direction. These genes respectively encoded the P- and L-ring proteins, the hook-associated proteins 1 and 3 and the flagellin core protein of the flagellum. Our data indicated the presence of more than one flagellar locus in V. cholerae which could provide a means of immunoavoidance during infection. When compared with homologs in other bacteria, the flagellin core protein of V. cholerae exhibited conservation in the N- and C-termini, but had diverged in the central region.