Architectural features of the Salmonella typhimurium flagellar motor switch revealed by disrupted C-rings.
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.
Department of Physiology & Biophysics, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York, 10461, USA.
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Khan
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Zhao
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Reese
D001426:Bacterial Proteins / Q000737:chemistry / Q000502:physiology / Q000648:ultrastructure; D020285:Cryoelectron Microscopy; D005407:Flagella / Q000737:chemistry / Q000502:physiology / Q000648:ultrastructure*; D020409:Molecular Motor Proteins / Q000737:chemistry / Q000502:physiology / Q000648:ultrastructure; D016628:Replica Techniques; D012486:Salmonella typhimurium / Q000737:chemistry / Q000502:physiology / Q000648:ultrastructure*
D001426:Bacterial Proteins; C077389:FliN protein, Bacteria; C075660:Flig protein, Bacteria; D020409:Molecular Motor Proteins; C066821:FliM protein, Bacteria