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Regulation of bacterial Type III Secretion System export gate opening by substrates and the FliJ stalk of the flagellar ATPase
Author(s) -
Bryant Owain J.,
Fraser Gillian M.
Publication year - 2022
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/febs.16294
Subject(s) - secretion , microbiology and biotechnology , stalk , atpase , flagellum , type three secretion system , biophysics , cytosol , substrate (aquarium) , biology , chemistry , biochemistry , bacteria , enzyme , virulence , genetics , gene , horticulture , ecology
Type III Secretion Systems (T3SS) transport proteins from the bacterial cytosol for assembly into cell surface nanomachines or direct delivery into target eukaryotic cells. At the core of the flagellar T3SS, the FlhAB‐FliPQR export gate regulates protein entry into the export channel whilst maintaining the integrity of the cell membrane. Here, we identify critical residues in the export gate FliR plug that stabilise the closed conformation, preserving the membrane permeability barrier, and we show that the gate opens and closes in response to export substrate availability. Our data indicate that FlhAB‐FliPQR gate opening, which is triggered by substrate export signals, is energised by FlhA in a proton motive force‐dependent manner. We present evidence that the export substrate and the FliJ stalk of the flagellar ATPase provide mechanistically distinct, non‐redundant gate‐activating signals that are critical for efficient export.