Fig. 6: Model describing how FlhF establishes flagellar localization of polar flagella.
From: Polar confinement of a macromolecular machine by an SRP-type GTPase
a The FID domain of FlhF binds to FliG, while the NG domain of FlhF interacts with the CTD of HubP. This configuration allows the FiD-bound FliG to capture the transmembrane protein FliF through its C-terminal domain. b FlhF hinders the interaction between FliG and its C-ring partners FliM/FliN, while permitting FliG to engage with FliF. c, d FlhG stimulates the GTPase activity of FlhF, initiating another round of FlhF-mediated diffusion-capture, which leads to the successive assembly of the C-ring. e When not engaged with FliM/FliN, FlhG can interact with the master transcriptional regulator FlrA. The color code is: FlhF with its NG, linker and FID domains (green, black and orange, respectively), HubP/FimV (yellow), flagella building blocks (grey tones), FlhG (red) and the cytoplasmic membrane (light brown). Further descriptions are given in the discussion.
