[ODP-030] 海洋性ビブリオ菌の極べん毛本数を制御するFlhGのC末端領域の役割
The polar flagellar number of Vibrio alginolyticus is negatively regulated by FlhG, a MinD/ParA family ATPase. Although FlhG is structurally similar to MinD, we found that FlhG has a biochemical property distinct from canonical family proteins: ATP-induced dimer formation is not observed for FlhG. Here we examined another common property of this family: the membrane binding via the C-terminal amphipathic helix (CTAH) to exhibit their biological activities. We deleted the C-terminal 20 residues of FlhG that contains the conserved CTAH. Expression of this FlhGΔC20 mutant allowed motility and single flagellar generation comparable to the wild type, although the protein level was reduced. Purified FlhGΔC20 exhibited slightly higher ATPase activity than wild type, and the ATPase stimulation level by FlhG-D171A mutation was about one third of wild type. In the presence of lipid, the ATPase activity of wild-type FlhG was stimulated a little but that of ΔC20 mutant was almost not. Furthermore, co-sedimentation with lipid vesicles was not affected by ΔC20 mutation. These results suggest that the CTAH of FlhG is not essential for function. Since the polar localization of FlhG is dependent on HubP, the polar landmark membrane protein, we assume that the FlhG function is achieved by binding to HubP, but not by binding to membrane with CTAH as shown for other family members.