title: Na+ conductivity of the Na+-driven flagellar motor complex composed of unplugged wild-type or mutant PomB with PomA.
abstract: PomA and PomB form the stator complex, which functions as a Na(+) channel, in the Na(+)-driven flagellar motor of Vibrio alginolyticus. The plug region of PomB is thought to regulate the Na(+) flow and to suppress massive ion influx through the stator channel. In this study, in order to measure the Na(+) conductivity of the unplugged stator, we over-produced a plug-deleted stator of the Na(+)-driven flagellar motor in Escherichia coli. The over-production of the plug-deleted stator in E. coli cells caused more severe growth inhibition than in Vibrio cells and that growth inhibition depended on the Na(+) concentration in the growth medium. Measurement of intracellular Na(+) concentration by flame photometry and fluorescent analysis with a Na(+) indicator, Sodium Green, revealed that over-production of the plug-deleted stator increased the Na(+) concentration in cell. Some mutations in the channel region of PomB or in the cytoplasmic region of PomA suppressed both the growth inhibition and the increase in intracellular Na(+) concentration. These results suggest that the level of growth inhibition correlates with the intracellular Na(+) concentration, probably due to the Na(+) conductivity through the stator due to the mutations.
authors: Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan.
authors: Norihiro
authors: N
authors: Takekawa
authors: Takashi
authors: T
authors: Terauchi
authors: Yusuke V
authors: YV
authors: Morimoto
authors: Tohru
authors: T
authors: Minamino
authors: Chien-Jung
authors: CJ
authors: Lo
authors: Seiji
authors: S
authors: Kojima
authors: Michio
authors: M
authors: Homma
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism; D005407:Flagella / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*; D015222:Sodium Channels / Q000378:metabolism; D044149:Vibrio alginolyticus / Q000235:genetics / Q000378:metabolism*
chemical_list: D001425:Bacterial Outer Membrane Proteins; C103352:PomA protein, bacteria; C103353:PomB protein, bacteria; D015222:Sodium Channels; D012964:Sodium