Constraints on models for the flagellar rotary motor

Philos Trans R Soc Lond B Biol Sci. 2000 Apr 29;355(1396):491-501. doi: 10.1098/rstb.2000.0590.

Abstract

Most bacteria that swim are propelled by flagellar filaments, each driven at its base by a rotary motor embedded in the cell wall and cytoplasmic membrane. A motor is about 45 nm in diameter and made up of about 20 different kinds of parts. It is assembled from the inside out. It is powered by a proton (or in some species, a sodium-ion) flux. It steps at least 400 times per revolution. At low speeds and high torques, about 1000 protons are required per revolution, speed is proportional to protonmotive force, and torque varies little with temperature or hydrogen isotope. At high speeds and low torques, torque increases with temperature and is sensitive to hydrogen isotope. At room temperature, torque varies remarkably little with speed from about -100 Hz (the present limit of measurement) to about 200 Hz, and then it declines rapidly reaching zero at about 300 Hz. These are facts that motor models should explain. None of the existing models for the flagellar rotary motor completely do so.

Publication types

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

MeSH terms

  • Bacterial Physiological Phenomena*
  • Escherichia coli / genetics
  • Escherichia coli / physiology
  • Flagella / genetics
  • Flagella / physiology*
  • Molecular Motor Proteins / genetics
  • Molecular Motor Proteins / physiology*
  • Movement / physiology*
  • Salmonella typhimurium / genetics
  • Salmonella typhimurium / physiology

Substances

  • Molecular Motor Proteins