The bacterial flagellar motor and its structural diversity

Trends Microbiol. 2015 May;23(5):267-74. doi: 10.1016/j.tim.2014.12.011. Epub 2015 Jan 20.


The bacterial flagellum is a reversible rotary motor powered by an electrochemical-potential difference of specific ions across the cytoplasmic membrane. The H(+)-driven motor of Salmonella spins at ∼300 Hz, whereas the Na(+)-driven motor of marine Vibrio spp. can rotate much faster, up to 1700 Hz. A highly conserved motor structure consists of the MS ring, C ring, rod, and export apparatus. The C ring and the export apparatus show dynamic properties for exerting their functional activities. Various additional structures surrounding the conserved motor structure are observed in different bacterial species. In this review we summarize our current understanding of the structure, function, and assembly of the flagellar motor in Salmonella and marine Vibrio.

Keywords: bacterial flagellum; flagellar assembly; protein export; rotary motor; stator assembly.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Bacteria / chemistry*
  • Bacteria / ultrastructure
  • Bacterial Physiological Phenomena*
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / physiology*
  • Cell Membrane / physiology
  • Escherichia coli / genetics
  • Escherichia coli / physiology
  • Flagella / chemistry*
  • Flagella / physiology*
  • Flagella / ultrastructure
  • Molecular Motor Proteins / chemistry
  • Molecular Motor Proteins / physiology*
  • Protons
  • Salmonella enterica / genetics
  • Salmonella enterica / physiology
  • Sodium


  • Bacterial Proteins
  • Molecular Motor Proteins
  • Protons
  • Sodium