Structural highlights
Function[FLHA_SALTY] Required for formation of the rod structure of the flagellar apparatus. Together with FliI and FliH, may constitute the export apparatus of flagellin. [FLID_SALTY] Required for the 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. Publication Abstract from PubMedThe flagellum and the injectisome enable bacterial locomotion and pathogenesis, respectively. These nanomachines assemble and function using a type III secretion system (T3SS). Exported proteins are delivered to the export apparatus by dedicated cytoplasmic chaperones for their transport through the membrane. The structural and mechanistic basis of this process is poorly understood. Here we report the structures of two ternary complexes among flagellar chaperones (FliT and FliS), protein substrates (the filament-capping FliD and flagellin FliC), and the export gate platform protein FlhA. The substrates do not interact directly with FlhA; however, they are required to induce a binding-competent conformation to the chaperone that exposes the recognition motif featuring a highly conserved sequence recognized by FlhA. The structural data reveal the recognition signal in a class of T3SS proteins and provide new insight into the assembly of key protein complexes at the export gate. Structures of chaperone-substrate complexes docked onto the export gate in a type III secretion system.,Xing Q, Shi K, Portaliou A, Rossi P, Economou A, Kalodimos CG Nat Commun. 2018 May 2;9(1):1773. doi: 10.1038/s41467-018-04137-4. PMID:29720631[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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