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

• Published in: Journal of structural biology Vol. 122; no. 3; pp. 311 - 319
• Main Authors: Khan, S, Zhao, R, Reese, T S
• Format: Journal Article
• Language: English
• Published: United States 1998
• Subjects: Bacterial Proteins - chemistry; Bacterial Proteins - physiology; Bacterial Proteins - ultrastructure; Cryoelectron Microscopy; Flagella - chemistry; Flagella - physiology; Flagella - ultrastructure; Molecular Motor Proteins - chemistry; Molecular Motor Proteins - physiology; Molecular Motor Proteins - ultrastructure; Replica Techniques; Salmonella typhimurium - chemistry; Salmonella typhimurium - physiology; Salmonella typhimurium - ultrastructure
• ISSN: 1047-8477
• DOI: 10.1006/jsbi.1998.3999

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.