Torque-speed relationship of the Na+-driven flagellar motor of Vibrio alginolyticus

Yoshiyuki Sowa, Hiroyuki Hotta, Michio Homma, Akihiko Ishijima

Research output: Contribution to journalArticlepeer-review

96 Citations (Scopus)


The torque-speed relationship of the Na+-driven flagellar motor of Vibrio alginolyticus was investigated. The rotation rate of the motor was measured by following the position of a bead, attached to a flagellar filament, using optical nanometry. In the presence of 50mM NaCl, the generated torque was relatively constant (∼3800pNnm) at lower speeds (speeds up to ∼300Hz) and then decreased steeply, similar to the H+-driven flagellar motor of Escherichia coli. When the external NaCl concentration was varied, the generated torque of the flagellar motor was changed over a wide range of speeds. This result could be reproduced using a simple kinetic model, which takes into consideration the association and dissociation of Na+ onto the motor. These results imply that for a complete understanding of the mechanism of flagellar rotation it is essential to consider both the electrochemical gradient and the absolute concentration of the coupling ion.

Original languageEnglish
Pages (from-to)1043-1051
Number of pages9
JournalJournal of Molecular Biology
Issue number5
Publication statusPublished - 2003 Apr 11


  • Energy transduction
  • Flagella
  • Molecular machine
  • Rotary motor
  • Vibrio

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology


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