Evidence for symmetry in the elementary process of bidirectional torque generation by the bacterial flagellar motor

Shuichi Nakamura, Nobunori Kami-ike, Jun Ichi P. Yokota, Tohru Minamino, Keiichi Namba

Research output: Contribution to journalArticlepeer-review

44 Citations (Scopus)

Abstract

The bacterial flagellar motor can rotate in both counterclockwise (CCW) and clockwise (CW) directions. It has been shown that the sodium ion-driven chimeric flagellar motor rotates with 26 steps per revolution, which corresponds to the number of FliG subunits that form part of the rotor ring, but the size of the backward step is smaller than the forward one. Here we report that the proton-driven flagellar motor of Salmonella also rotates with 26 steps per revolution but symmetrical in both CCW and CW directions with occasional smaller backward steps in both directions. Occasional shift in the stepping positions is also observed, suggesting the frequent exchange of stators in one of the 11-12 possible anchoring positions around the rotor. These observations indicate that the elementary process of torque generation by the cyclic association/dissociation of the stator with every FliG subunit along the circumference of the rotor is symmetric in CCW and CW rotation even though the structure of FliG is highly asymmetric and suggests a 180° rotation of a FliG domain for the rotor-stator interaction to reverse the direction of rotation.

Original languageEnglish
Pages (from-to)17616-17620
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume107
Issue number41
DOIs
Publication statusPublished - 2010 Oct 12
Externally publishedYes

Keywords

  • FliG
  • MotAB stator complex
  • Salmonella
  • Stepping rotation
  • Switch

ASJC Scopus subject areas

  • General

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