8ftw
FliT-FliJ fusion complex
Structural highlights
FunctionA0A5K1UBM0_SALTM Flagellar protein that affects chemotactic events.[PIRNR:PIRNR019404]A0A0F7J9R1_SALTM Dual-function protein that regulates the transcription of class 2 flagellar operons and that also acts as an export chaperone for the filament-capping protein FliD. As a transcriptional regulator, acts as an anti-FlhDC factor; it directly binds FlhC, thus inhibiting the binding of the FlhC/FlhD complex to class 2 promoters, resulting in decreased expression of class 2 flagellar operons. As a chaperone, effects FliD transition to the membrane by preventing its premature polymerization, and by directing it to the export apparatus.[HAMAP-Rule:MF_01180] Publication Abstract from PubMedThe flagellum is a sophisticated nanomachine responsible for motility in Gram-negative bacteria. Flagellar assembly is a strictly choreographed process, in which the motor and export gate are formed first, followed by the extracellular propeller structure. Extracellular flagellar components are escorted to the export gate by dedicated molecular chaperones for secretion and self-assembly at the apex of the emerging structure. The detailed mechanisms of chaperone-substrate trafficking at the export gate remain poorly understood. Here, we structurally characterized the interaction of Salmonella enterica late-stage flagellar chaperones FliT and FlgN with the export controller protein FliJ. Previous studies showed that FliJ is absolutely required for flagellar assembly since its interaction with chaperone-client complexes controls substrate delivery to the export gate. Our biophysical and cell-based data show that FliT and FlgN bind FliJ cooperatively, with high affinity and on specific sites. Chaperone binding completely disrupts the FliJ coiled-coil structure and alters its interactions with the export gate. We propose that FliJ aids the release of substrates from the chaperone and forms the basis of chaperone recycling during late-stage flagellar assembly. Chaperone Recycling in Late-Stage Flagellar Assembly.,Rossi P, Xing Q, Bini E, Portaliou AG, Clay MC, Warren EM, Khanra NK, Economou A, Kalodimos CG J Mol Biol. 2023 Mar 1:167954. doi: 10.1016/j.jmb.2023.167954. PMID:37330284[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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