Encyclopedia of Biophysics

Living Edition
| Editors: Gordon Roberts, Anthony Watts, European Biophysical Societies

Sodium-Driven Flagellar Motor: Structure and Mechanisms

  • Michio HommaEmail author
  • Seiji Kojima
Living reference work entry
DOI: https://doi.org/10.1007/978-3-642-35943-9_197-1



Ion-driven motor of flagella is very unique and is a force generation nanomachine which is a supramolecular complex. The flagellar motor, which is a molecular machine composed of many proteins, is embedded in inner membrane of bacteria and generates torque by ion flux.


Many motile bacteria move by rotating flagella. These are filamentous organs extending from the cell body. A flagellum consists of three parts, the filament, the hook, and the basal body. The filament functions as a helical propeller, and the basal body acts as a rotary motor embedded in the cell membranes. The hook works as a universal joint between these two structures that transmit torque smoothly. The motor can run reversibly in both directions: clockwise (CW) and counterclockwise (CCW). Energy for rotation of the motor comes from the electrochemical gradient of specific ions across the cytoplasmic membrane, and motors are classified...

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Copyright information

© European Biophysical Societies' Association (EBSA) 2018

Authors and Affiliations

  1. 1.Division of Biological Science, Graduate School of ScienceNagoya UniversityNagoyaJapan

Section editors and affiliations

  • Judith P. Armitage
    • 1
  1. 1.OCISB, Department of BiochemistryUniversity of OxfordOxfordUK