Architectural features of the Salmonella typhimurium flagellar motor switch revealed by disrupted C-rings

Shahid Khan, Rongbao Zhao, Thomas S. Reese

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The three-dimensional surface topology of rapid-frozen Salmonella typhimurium flagellar hook basal body complexes was studied by stereo- examination of thin-film metal replicas. The complexes contained the extended cytoplasmic structure, composed of the switch complex proteins; FliG, FliM, and FliN. Distinct nanometer-scale element arrays, separated by grooves, defined the outer surface of the cytoplasmic (C-) ring. The number of array elements was comparable to previously determined FliG and FliM copy numbers in the basal body. In addition to basal body complexes lacking C-rings, complexes containing incomplete C-rings were identified. The incomplete C- rings had lost segments of the proximal array. Basal bodies with the distal C-ring array alone were not found. These findings are compatible with the spatial organization of the flagellar switch suggested by previous biochemical data.

Original languageEnglish (US)
Pages (from-to)311-319
Number of pages9
JournalJournal of Structural Biology
Issue number3
Publication statusPublished - Jan 1 1998


ASJC Scopus subject areas

  • Structural Biology

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