Intermolecular Cross-linking between the Periplasmic Loop3–4 Regions of PomA, a Component of the Na+-driven Flagellar Motor of Vibrio alginolyticus

Yorimitsu, Tomohiro; Asai, Yukako; Sato, Ken; Homma, Michio

doi:10.1074/jbc.m000848200

Cited by 18 publications

(11 citation statements)

References 34 publications

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“…22 -24 Crosslinking studies indicate that periplasmic loop 3 -4 , which joins transmembrane helices 3 and 4, of one PomA subunit is close to loop 3 -4 of an adjacent PomA subunit within the stator complex. 24,25 We have shown that MotA/B from the protondriven motor of Rhodobacter sphaeroides do not complement a DpomAB mutant of V. alginolyticus, 26,27 nor do PomA/B support flagellar rotation without MotX and MotY. However, a DpomABmotXY strain of V. cholerae can swim using E. coli MotA/B and proton motive force.…”

Section: Namentioning

confidence: 99%

Ion-coupling Determinants of Na+-driven and H+-driven Flagellar Motors

Asai

Yakushi

Kawagishi

et al. 2003

Journal of Molecular Biology

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122

114

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The bacterial flagellar motor is a tiny molecular machine that uses a transmembrane flux of H þ or Na þ ions to drive flagellar rotation. In protondriven motors, the membrane proteins MotA and MotB interact via their transmembrane regions to form a proton channel. The sodium-driven motors that power the polar flagellum of Vibrio species contain homologs of MotA and MotB, called PomA and PomB. They require the unique proteins MotX and MotY. In this study, we investigated how ion selectivity is determined in proton and sodium motors. We found that Escherichia coli MotA/B restore motility in DpomAB Vibrio alginolyticus. Most hypermotile segregants isolated from this weakly motile strain contain mutations in motB. We constructed proteins in which segments of MotB were fused to complementary portions of PomB. A chimera joining the N terminus of PomB to the periplasmic C terminus of MotB (PotB7 E ) functioned with PomA as the stator of a sodium motor, with or without MotX/Y. This stator (PomA/PotB7 E ) supported sodium-driven motility in motA or motB E. coli cells, and the swimming speed was even higher than with the original stator of E. coli MotA/B. We conclude that the cytoplasmic and transmembrane domains of PomA/B are sufficient for sodium-driven motility. However, MotA expressed with a B subunit containing the N terminus of MotB fused to the periplasmic domain of PomB (MomB7 E ) supported sodium-driven motility in a MotX/Y-dependent fashion. Thus, although the periplasmic domain of PomB is not necessary for sodium-driven motility in a PomA/B motor, it can convert a MotA/B proton motor into a sodium motor.

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Section: Namentioning

confidence: 99%

Ion-coupling Determinants of Na+-driven and H+-driven Flagellar Motors

Asai

Yakushi

Kawagishi

et al. 2003

Journal of Molecular Biology

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122

114

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“…It appears that PomA forms a stable homodimer and the two subunits function together (Sato and Homma, 2000b). A periplasmic loop region of PomA is considered important for dimer formation (Yorimitsu et al ., 2000).…”

Section: Introductionmentioning

confidence: 99%

MotX and MotY, specific components of the sodium‐driven flagellar motor, colocalize to the outer membrane in Vibrio alginolyticus

Okabe

Yakushi²,

Kojima

et al. 2002

Molecular Microbiology

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SummaryRotation of the sodium-driven polar flagella of Vibrio alginolyticus requires four motor proteins: PomA, PomB, MotX and MotY. MotX and MotY, which are unique components of the sodium-driven motor of Vibrio , have been believed to be localized in the inner (cytoplasmic) membrane via their N-terminal hydrophobic segments. Here we show that MotX and MotY colocalize to the outer membrane. Both proteins, when expressed together, were detected in the outer membrane fraction separated by sucrose density gradient centrifugation. As mature MotX and MotY proteins do not have N-terminal hydrophobic segments, the N-termini of the primary translation products must have signal sequences that are removed upon translocation across the inner membrane. Moreover, MotX and MotY require each other for efficient localization to the outer membrane. Based on these lines of evidence, we propose that MotX and MotY form a complex in the outer membrane. This is the first case that describes motor proteins function in the outer membrane for flagellar rotation.

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“…Interestingly, the molar ratio of MotA to MotB was calculated to be 2:1. Intermolecular cross-linking studies using cysteine substitutions within the periplasmic loop between the third and fourth transmembrane domains of MotA also suggested that adjacent MotA molecules were physically close within the motor (201). To further probe the stoichiometry of the torque generator, a chimeric construct was designed to produce a fused dimer of MotA molecules (158).…”

Section: The Mota-motb Complex Translocates Sodium Ionsmentioning

confidence: 99%

Polar Flagellar Motility of the Vibrionaceae

McCarter

2001

Microbiol Mol Biol Rev

313

356

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Polar flagella of Vibrio species can rotate at speeds as high as 100,000 rpm and effectively propel the bacteria in liquid as fast as 60 μm/s. The sodium motive force powers rotation of the filament, which acts as a propeller. The filament is complex, composed of multiple subunits, and sheathed by an extension of the cell outer membrane. The regulatory circuitry controlling expression of the polar flagellar genes of members of the Vibrionaceae is different from the peritrichous system of enteric bacteria or the polar system of Caulobacter crescentus. The scheme of gene control is also pertinent to other members of the gamma purple bacteria, in particular to Pseudomonas species. This review uses the framework of the polar flagellar system of Vibrio parahaemolyticus to provide a synthesis of what is known about polar motility systems of the Vibrionaceae. In addition to its propulsive role, the single polar flagellum of V. parahaemolyticus is believed to act as a tactile sensor controlling surface-induced gene expression. Under conditions that impede rotation of the polar flagellum, an alternate, lateral flagellar motility system is induced that enables movement through viscous environments and over surfaces. Although the dual flagellar systems possess no shared structural components and although distinct type III secretion systems direct the simultaneous placement and assembly of polar and lateral organelles, movement is coordinated by shared chemotaxis machinery

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Intermolecular Cross-linking between the Periplasmic Loop3–4 Regions of PomA, a Component of the Na+-driven Flagellar Motor of Vibrio alginolyticus

Cited by 18 publications

References 34 publications

Ion-coupling Determinants of Na+-driven and H+-driven Flagellar Motors

Ion-coupling Determinants of Na+-driven and H+-driven Flagellar Motors

MotX and MotY, specific components of the sodium‐driven flagellar motor, colocalize to the outer membrane in Vibrio alginolyticus

Polar Flagellar Motility of the Vibrionaceae

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