Mutations Targeting the C-Terminal Domain of FliG Can Disrupt Motor Assembly in the Na+-Driven Flagella of Vibrio alginolyticus

Characterization of PomA Mutants Defective in the Functional Assembly of the Na + -Driven Flagellar Motor in Vibrio alginolyticus

“…These fliG mutants prevent the polar localization of the PomA/B complex, which suggests that the interaction between FliG and PomA is necessary to fix the PomA/B stator complex around the rotor. We speculated that the PomA-FliG interaction induced a large conformational change at the periplasmic region of PomB and bound to the T ring and the peptidoglycan layer (12). In this study, we demonstrate that the cytoplasmic domain of PomA is also important for the stator to assemble around the rotor.…”

“…We have shown in a previous study that some fliG mutants, which have mutations in their C-terminal region, do not have defects in flagellation but do have impaired motor function (12). These fliG mutants prevent the polar localization of the PomA/B complex, which suggests that the interaction between FliG and PomA is necessary to fix the PomA/B stator complex around the rotor.…”

“…This dynamic property might be an adaptation to environmental conditions in which the coupling ion is abundant. In V. alginolyticus, it was suggested that the interaction between the T ring, which was recently found as a novel periplasmic basal structure of the motor composed of MotX and MotY, and the periplasmic region of PomB as well as the interaction between FliG and the cytoplasmic region of PomA is important for the stator assembly around the rotor (12,22). From those lines of evidence, we can infer that Na ϩ affects those interactions.…”

Distinct Roles of Highly Conserved Charged Residues at the MotA-FliG Interface in Bacterial Flagellar Motor Rotation

“…The N-terminal region of FliG directly binds to the MS ring (15). Because a specific interaction of the C-terminal domain of FliG (FliG C ) with MotA are required not only for flagellar motor rotation (16,17) but also for stator assembly around the rotor (18)(19)(20), FliG C is believed to be located at the upper part of the C ring (Fig. 1).…”

Contribution of Many Charged Residues at the Stator-Rotor Interface of the Na + -Driven Flagellar Motor to Torque Generation in Vibrio alginolyticus

“…Thus, it was suggested that the cytoplasmic region of PomA is involved not only in the interaction with FliG but also in the Na ϩ influx through the stator and that the region containing H136 is involved in the stator-rotor interaction, although this effect may be indirect. It has been shown that certain mutations in the core region of the FliG C-terminal domain, which contains conserved charged residues, also disrupt the motor function as well as the stator assembly around the rotor (24). These lines of evidence indicate that interactions between the cytoplasmic region of PomA and the C-terminal domain of FliG are involved in the function of the Na ϩ -driven motor as seen in the H ϩ -driven motor, but the detailed mechanism underlying this remains unclear.…”