Rotational symmetry of the C ring and a mechanism for the flagellar rotary motor

Proc Natl Acad Sci U S A. 1999 Aug 31;96(18):10134-9. doi: 10.1073/pnas.96.18.10134.

Abstract

FliG, FliM, and FliN, key proteins for torque generation, are located in two rings. The first protein is in the M ring and the last two are in the C ring. The rotational symmetries of the C and M rings have been determined to be about 34 (this paper) and 26 (previous work), respectively. The mechanism proposed here depends on the symmetry mismatch between the rings: the C ring extends 34 levers, of which 26 can bind to the 26 equivalent sites on the M ring. The remaining 8 levers bind to proton-pore complexes (studs) to form 8 torque generators. Movement results from the swapping of stud-bound levers with M ring-bound levers. The model predicts that both the M and C rings rotate in the same direction but at different speeds.

Publication types

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

MeSH terms

  • Bacterial Proteins / chemistry
  • Bacterial Proteins / physiology*
  • Bacterial Proteins / ultrastructure*
  • Flagella / physiology
  • Flagella / ultrastructure
  • Microscopy, Electron
  • Models, Molecular
  • Models, Structural
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / ultrastructure
  • Rotation
  • Torque

Substances

  • Bacterial Proteins
  • FliN protein, Bacteria
  • Flig protein, Bacteria
  • Recombinant Fusion Proteins
  • FliM protein, Bacteria