Structural Effects of Mutations inSalmonella typhimuriumFlagellar Switch Complex

Rongbao Zhao, Stephan C. Schuster, Shahid Khan

Research output: Contribution to journalArticle

34 Scopus citations

Abstract

Mutations inSalmonella typhimurium fliG, fliMandfliNgive rise either to non-flagellate, non-motile or non-chemotactic mutant bacteria. The FliG, FliM and FliN proteins form part of recently characterized extended flagellar basal structures, and have been postulated to form a mutually interacting structural complex. We have examined basal body preparations from non-motile or non-chemotacticfliG, fliMandfliNmutant strains by electron microscopy and immunoblot gel analysis. Most flagellar preparations isolated from the non-motile mutants lacked FliM, but contained FliG. The basal bodies lacked the belled morphology characteristic of the wild-type structures, but had protrusions which could be labelled with anti-FliG. Non-motile mutant preparations severely depleted of FliG but containing FliM were also obtained. These preparations contained extended, belled flagellar structures that were labelled with anti-FliM. Thus, FliM is part of the shell of the extended structures responsible for the belled morphology, while FliG may be part of the inner substructure. The extended basal structures from a FliG temperature-sensitive mutant strain rapidly lost FliM, as well as FliG, upon a shift to a non-permissive temperature, implying interaction between the FliG- and FliM-containing substructures. In dramatic contrast to non-motile mutants, extended basal structures isolated from non-chemotactic mutants were indistinguishable from wild-type structures. This difference may reflect the energetics of the different protein-protein interactions operative during torque generation and the switching of rotation sense.

Original languageEnglish (US)
Pages (from-to)400-412
Number of pages13
JournalJournal of Molecular Biology
Volume251
Issue number3
DOIs
StatePublished - Jan 1 1995

Keywords

  • Bacterial chemotaxis
  • Flagellar basal body
  • Immunoelectron microscopy
  • Molecular motor
  • Protein-protein interactions

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology

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