title: Serine suppresses the motor function of a periplasmic PomB mutation in the Vibrio flagella stator.
abstract: The flagellar motor of Vibrio alginolyticus is made of two parts: a stator consisting of proteins PomA and PomB, and a rotor whose main component is FliG. The interaction between FliG and PomA generates torque for flagellar rotation. Based on cross-linking experiments of double-Cys mutants of PomB, we previously proposed that a conformational change in the periplasmic region of PomB caused stator activation. Double-Cys mutants lost their motility due to an intramolecular disulfide bridge. In this study, we found that the addition of serine, a chemotactic attractant, to a PomB(L160C/I186C) mutant restored motility without cleaving the disulfide bridge. We speculate that serine changed the rotor (FliG) conformation, affecting rotational direction. Combined with the counterclockwise (CCW)-biased mutation FliG(G214S), motility of PomB(L160C/I186C) was restored without the addition of serine. Likewise, motility was restored without serine in Che(-) mutants, in either a CCW-locked or clockwise (CW)-locked strain. In contrast, in a ΔcheY (CCW-locked) strain, Vibrio (L160C/I186C) required serine to be rescued. We speculate that CheY affects stator conformation and motility restoration by serine is independent on the chemotaxis signaling pathway.
authors.affiliation: Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, 464-8602, Japan.
authors.forename: Tatsuro
authors.initials: T
authors.lastname: Nishikino
authors.affiliation: Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, 464-8602, Japan.
authors.forename: Shiwei
authors.initials: S
authors.lastname: Zhu
authors.affiliation: Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, 464-8602, Japan.
authors.forename: Norihiro
authors.initials: N
authors.lastname: Takekawa
authors.affiliation: Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, 464-8602, Japan.
authors.forename: Seiji
authors.initials: S
authors.lastname: Kojima
authors.affiliation: Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, 464-8602, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Onoue
authors.affiliation: Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, 464-8602, Japan.
authors.forename: Michio
authors.initials: M
authors.lastname: Homma
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism; D005407:Flagella / Q000187:drug effects / Q000378:metabolism*; D020409:Molecular Motor Proteins / Q000378:metabolism; D009154:Mutation; D012694:Serine / Q000494:pharmacology*; D044149:Vibrio alginolyticus / Q000235:genetics / Q000378:metabolism*
chemical_list: D001425:Bacterial Outer Membrane Proteins; D020409:Molecular Motor Proteins; C103353:PomB protein, bacteria; D012694:Serine