title: Mutation in the a-subunit of F(1)F(O)-ATPase causes an increased motility phenotype through the sodium-driven flagella of Vibrio.
abstract: Bacterial flagellar motors exploit the electrochemical potential gradient of a coupling ion as energy source and are composed of stator and rotor proteins. Vibrio alginolyticus has a Na(+)-driven motor and its stator is composed of PomA and PomB. Recently, we isolated increased motility strains (sp1-sp4) from the PomA-N194D/PomB-D24N mutant whose motility was quite weak. To detect the responsible mutation, we have used a next-generation sequencer and determined the entire genome sequences of the sp1 and sp2 strains. Candidate mutations were identified in the gene encoding the a-subunit of F1Fo-ATPase (uncB). To confirm this, we constructed a deletion strain, which gave the increased motility phenotype. The amount of membrane-bound ATPase was reduced in the sp2 and ΔuncB mutants. From these results, we conclude that a mutation in the uncB gene causes the increased motility phenotype in V. alginolyticus. They confer faster motility in low concentrations of sodium than in the parental strain and this phenotype is suppressed in the presence of KCN. Those results may suggest that the proton gradient generated by the respiratory chain is increased by the uncB mutation, consequently the sodium motive force is increased and causes the increased motility phenotype.
authors.affiliation: Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-Ku, Nagoya 464-8602, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Terashima
authors.forename: Takashi
authors.initials: T
authors.lastname: Terauchi
authors.forename: Kunio
authors.initials: K
authors.lastname: Ihara
authors.forename: Noriko
authors.initials: N
authors.lastname: Nishioka
authors.forename: Seiji
authors.initials: S
authors.lastname: Kojima
authors.forename: Michio
authors.initials: M
authors.lastname: Homma
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D025243:Bacterial Proton-Translocating ATPases / Q000235:genetics / Q000378:metabolism*; D005407:Flagella / Q000235:genetics / Q000378:metabolism*; D020125:Mutation, Missense; D015222:Sodium Channels / Q000235:genetics / Q000378:metabolism; D044149:Vibrio alginolyticus / Q000201:enzymology* / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; C107540:PomA protein, Vibrio; C107541:PomB protein, Vibrio; D015222:Sodium Channels; D025243:Bacterial Proton-Translocating ATPases
keywords: ATPase; flagellar motor; membrane potential; polar flagella; proton motive force