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Updated: Feb 14, 2026

Biophysical Characterization of Flagellar Motor Functions
06:08

Biophysical Characterization of Flagellar Motor Functions

Published on: January 18, 2017

8.7K

Effect of a clockwise-locked deletion in FliG on the FliG ring structure of the bacterial flagellar motor

Miki Kinoshita1, Keiichi Namba1,2, Tohru Minamino1

  • 1Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan.

Genes to Cells : Devoted to Molecular & Cellular Mechanisms
|February 7, 2018
PubMed

Insights

Bacterial flagellar motor protein FliG

Area of Science:

  • Microbiology
  • Structural Biology
  • Biochemistry

Background:

  • FliG is a crucial rotor protein in the bacterial flagellar motor, essential for motility.
  • FliG comprises N, M, and C domains, with FliG M- FliG C interactions driving ring formation.
  • Conformational changes in the Helix MC region mediate the switch between counterclockwise (CCW) and clockwise (CW) rotation.

Purpose of the Study:

  • To investigate the structural impact of a CW-locked deletion (∆PAA) in FliG on the FliG ring structure.
  • To elucidate the mechanism of conformational changes in Helix MC during flagellar motor switching.

Main Methods:

  • In vivo disulfide cross-linking experiments in Salmonella enterica.
  • Analysis of FliG structure in strains with specific mutations (∆PAA, G166C/G194C, E174C).
  • Oxidation with iodine to induce cross-linking and observe oligomer formation.

Main Results:

  • The ∆PAA deletion did not prevent domain-swap polymerization of FliG.
  • FliG(∆PAA + E174C) formed a cross-linked homodimer, unlike FliG(E174C).
  • This suggests Glu174 in Helix MC is closer to its neighbor in the CW motor state.

Conclusions:

  • The PAA deletion does not inhibit FliG polymerization.
  • The proximity of Glu174 in the CW motor indicates a structural rearrangement in Helix MC .
  • These findings provide insights into the structural basis of flagellar motor switching.
Keywords:
FliGbacterial flagellar motorchemotaxisdomain swapself-assemblysite-directed disulfide cross-linking

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