9n4z

CCW Flagellar Switch Complex - FliF, FliG, FliM, and FliN forming 34-mer C-ring from Salmonella

spinqualitylabelsall models 9n4z, resolution 3.00Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 9n4z is a 204 chain structure with sequence from Salmonella enterica subsp. enterica serovar Typhimurium. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Electron Microscopy, Resolution 3Å Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function FLIG_SALTY FliG is one of three proteins (FliG, FliN, FliM) that forms the rotor-mounted switch complex (C ring), located at the base of the basal body. This complex interacts with the CheY and CheZ chemotaxis proteins, in addition to contacting components of the motor that determine the direction of flagellar rotation (By similarity). Publication Abstract from PubMed Advances in cryo-electron microscopy instrumentation and sample preparation have significantly improved the ability to collect quality data for biomolecular structures. However, achieving resolutions consistent with data quality remains challenging in structures with symmetry mismatches. As a case study, the bacterial flagellar motor is a large complex essential for bacterial chemotaxis and virulence. This motor contains a smaller membrane-supramembrane ring (MS-ring) and a larger cytoplasmic ring (C-ring). These two features have a 33:34 symmetry mismatch when expressed in E. coli. Because close symmetry mismatches are the most difficult to deconvolute, this makes the flagellar motor an excellent model system to evaluate refinement strategies for symmetry mismatch. We compared the performance of masked refinement, local refinement, and particle subtracted refinement on the same data. We found that particle subtraction prior to refinement was critical for approaching the smaller MS-ring. Additional processing resulted in final resolutions of 3.1 A for the MS-ring and 3.0 A for the C-ring, which improves the resolution of the MS-ring by 0.3 A and the resolution of the C-ring by 1.0 A as compared to past work. Although particle subtraction is fairly well-established, it is rarely applied to problems of symmetry mismatch, making this case study a valuable demonstration of its utility in this context. Improving CryoEM maps of symmetry-mismatched macromolecular assemblies: A case study on the flagellar motor.,Singh PK, Iverson TM J Struct Biol. 2025 Mar 5;217(2):108184. doi: 10.1016/j.jsb.2025.108184. PMID:40054642 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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