Molecular characterization of the flagellar hook in Bacillus subtilis

J Bacteriol. 2012 Sep;194(17):4619-29. doi: 10.1128/JB.00444-12. Epub 2012 Jun 22.

Abstract

The structure of the Gram-positive flagellum is poorly understood, and Bacillus subtilis encodes three proteins homologous to the flagellar hook protein from Salmonella enterica. Here we generated a modified B. subtilis hook protein that could be fluorescently stained using a cysteine-reactive dye. We used the fluorescently labeled hook to demonstrate that FlgE is the hook structural protein and that FliK regulated hook length. We further demonstrate that two proteins of unknown function, FlhO and FlhP, and the putative hook cap, FlgD, were required for hook assembly, such that when flhO, flhP, or flgD was mutated, hook protein was secreted into the supernatant. All mutants defective in hook completion resulted in homogeneously reduced σ(D)-dependent gene expression due to the action of the anti-sigma factor FlgM.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Bacillus subtilis / genetics*
  • Bacillus subtilis / metabolism
  • Bacillus subtilis / ultrastructure*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Flagella / genetics
  • Flagella / metabolism*
  • Flagella / ultrastructure
  • Gene Expression Regulation, Bacterial
  • Promoter Regions, Genetic
  • Sigma Factor / genetics
  • Sigma Factor / metabolism

Substances

  • Bacterial Proteins
  • FlgE protein, Bacteria
  • FliK protein, Bacteria
  • Sigma Factor
  • FlgM protein, Bacteria