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Structure of bacterial flagellar capping protein FliD
Structural highlights
FunctionA0A3I4YJR7_CAMJU Required for morphogenesis and for the elongation of the flagellar filament by facilitating polymerization of the flagellin monomers at the tip of growing filament. Forms a capping structure, which prevents flagellin subunits (transported through the central channel of the flagellum) from leaking out without polymerization at the distal end.[RuleBase:RU362066] Publication Abstract from PubMedThe bacterial flagellum is a remarkable molecular motor, whose primary function in bacteria is to facilitate motility through the rotation of a filament protruding from the bacterial cell. A cap complex, consisting of an oligomer of the protein FliD, is localized at the tip of the flagellum, and is essential for filament assembly, as well as adherence to surfaces in some bacteria. However, the structure of the intact cap complex, and the molecular basis for its interaction with the filament, remains elusive. Here we report the cryo-EM structure of the Campylobacter jejuni cap complex, which reveals that FliD is pentameric, with the N-terminal region of the protomer forming an extensive set of contacts across several subunits, that contribute to FliD oligomerization. We also demonstrate that the native C. jejuni flagellum filament is 11-stranded, contrary to a previously published cryo-EM structure, and propose a molecular model for the filament-cap interaction. The cryo-EM structure of the bacterial flagellum cap complex suggests a molecular mechanism for filament elongation.,Al-Otaibi NS, Taylor AJ, Farrell DP, Tzokov SB, DiMaio F, Kelly DJ, Bergeron JRC Nat Commun. 2020 Jun 25;11(1):3210. doi: 10.1038/s41467-020-16981-4. PMID:32587243[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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