FIG 1.

Flagellar basal body protein FliF of Vibrio alginolyticus. (A) Schematic representation of the polar flagellar motor of V. alginolyticus. Its basal body is composed of several rings, including the H ring and T ring, which are not observed in the well-characterized Salmonella and E. coli basal bodies. FliF forms the MS ring of the basal body, and the C-ring protein FliG binds to FliF at the cytoplasmic face of the MS ring. The rotor-stator interactions that couple Na⁺ influx through the stator channel generate torque. OM, outer membrane; IM, inner membrane. (B) Primary structure of V. alginolyticus FliF. It has a large periplasmic region and two cytoplasmic tails at the N and C termini. The putative FliG-binding site is located at the very end of the C terminus. TM, transmembrane segment. Amino acid residue numbers are shown at the top.