Coupling ion specificity of chimeras between H(+)- and Na(+)-driven motor proteins, MotB and PomB, in Vibrio polar flagella.
We have shown that a hybrid motor consisting of proton-type Rhodobacter sphaeroides MotA and sodium-type VIBRIO: alginolyticus PomB, MotX and MotY, can work as a sodium-driven motor in VIBRIO: cells. In this study, we tried to substitute the B subunits, which contain a putative ion-binding site in the transmembrane region. Rhodobacter sphaeroides MotB did not work with either MotA or PomA in Vibrio cells. Therefore, we constructed chimeric proteins (MomB), which had N-terminal MotB and C-terminal PomB. MomB proteins, with the entire transmembrane region derived from the H(+)-type MotB, gave rise to an Na(+) motor with MotA. The other two MomB proteins, in which the junction sites were within the transmembrane region, also formed Na(+) motors with PomA, but were changed for Na(+) or Li(+) specificity. These results show that the channel part consisting of the transmembrane regions from the A and B subunits can interchange Na(+)- and H(+)-type subunits and this can affect the ion specificity. This is the first report to have changed the specificity of the coupling ions in a bacterial flagellar motor.
Asai
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Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-Ku, Nagoya 464-8602, Japan.
Kawagishi
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Sockett
R E
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Homma
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D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002414:Cations, Monovalent / Q000378:metabolism / Q000494:pharmacology; D005407:Flagella / Q000187:drug effects / Q000378:metabolism*; D005838:Genotype; D006859:Hydrogen / Q000378:metabolism / Q000494:pharmacology; D008094:Lithium / Q000378:metabolism / Q000494:pharmacology; D008124:Locomotion / Q000187:drug effects; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D020409:Molecular Motor Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D011522:Protons; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012242:Rhodobacter sphaeroides / Q000235:genetics; D016415:Sequence Alignment; D012964:Sodium / Q000378:metabolism / Q000494:pharmacology; D015222:Sodium Channels / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013379:Substrate Specificity; D014733:Vibrio / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*
D001426:Bacterial Proteins; D002414:Cations, Monovalent; D008565:Membrane Proteins; D020409:Molecular Motor Proteins; C063010:MotA protein, Bacteria; C064779:MotB protein, Bacteria; C107540:PomA protein, Vibrio; C107541:PomB protein, Vibrio; D011522:Protons; D011993:Recombinant Fusion Proteins; D015222:Sodium Channels; D006859:Hydrogen; D008094:Lithium; D012964:Sodium