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Lookup NU author(s): Helen Glenwright,
Dr Phillip Aldridge
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FlgN chaperone acts as a bodyguard to protect its cognate substrates, FlgK and FlgL, from proteolysis in the cytoplasm. Docking of the FlgNFlgK complex with the FliI ATPase of the flagellar type III export apparatus is key to the protein export process. However, a ?fliH-fliI flhB(P28T) mutant forms some flagella even in the absence of FliH and FliI, raising the question of how FlgN promotes the export of its cognate substrates. Here, we report that the interaction of FlgN with an integral membrane export protein, FlhA, is directly involved in efficient protein export. A ?fliH-fliI flhB(P28T) ?flgN mutant caused extragenic suppressor mutations in the C-terminal domain of FlhA (FlhAC). Pull-down assays using GST affinity chromatography showed an interaction between FlgN and FlhAC. The FlgNFlgK complex bound to FlhAC and FliJ to form the FlgNFlgKFliJFlhAC complex. The FlgNFlhAC interaction was enhanced by FlgK but not by FliJ. FlgN120 missing the last 20 residues still bound to FlgK and FliJ but not to FlhAC. A highly conserved Tyr-122 residue was required for the interaction with FlhAC. These results suggest that FlgN efficiently transfers FlgK/L subunits to FlhAC to promote their export.
Author(s): Minamino T, Kinoshita M, Hara N, Takeuchi S, Hida A, Koya S, Glenwright H, Imada K, Aldridge PD, Namba K
Publication type: Article
Publication status: Published
Journal: Molecular Microbiology
Print publication date: 11/01/2012
ISSN (print): 0950-382X
ISSN (electronic): 1365-2958
Publisher: Wiley-Blackwell Publishing Ltd.
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