Philipps-University Marburg, Center for Synthetic Microbiology (SYNMIKRO) and Department of Chemistry, Hans-Meerwein-Strasse 6, C07, 35043, Marburg, Germany.
Justus-Liebig-Universität, Department of Microbiology and Molecular Biology, Heinrich-Buff-Ring 26, 35392, Giessen, Germany.
Nat Commun. 2024 Jul 10;15(1):5797. doi: 10.1038/s41467-024-50274-4.
The basal structure of the bacterial flagellum includes a membrane embedded MS-ring (formed by multiple copies of FliF) and a cytoplasmic C-ring (composed of proteins FliG, FliM and FliN). The SRP-type GTPase FlhF is required for directing the initial flagellar protein FliF to the cell pole, but the mechanisms are unclear. Here, we show that FlhF anchors developing flagellar structures to the polar landmark protein HubP/FimV, thereby restricting their formation to the cell pole. Specifically, the GTPase domain of FlhF interacts with HubP, while a structured domain at the N-terminus of FlhF binds to FliG. FlhF-bound FliG subsequently engages with the MS-ring protein FliF. Thus, the interaction of FlhF with HubP and FliG recruits a FliF-FliG complex to the cell pole. In addition, the modulation of FlhF activity by the MinD-type ATPase FlhG controls the interaction of FliG with FliM-FliN, thereby regulating the progression of flagellar assembly at the pole.
细菌鞭毛的基本结构包括一个嵌入膜的 MS 环（由多个 FliF 组成）和一个细胞质 C 环（由 FliG、FliM 和 FliN 蛋白组成）。SRP 型 GTP 酶 FlhF 对于指导初始鞭毛蛋白 FliF 到达细胞极点是必需的，但机制尚不清楚。在这里，我们表明 FlhF 将发育中的鞭毛结构锚定在极地标志性蛋白 HubP/FimV 上，从而将其形成限制在细胞极点。具体来说，FlhF 的 GTPase 结构域与 HubP 相互作用，而 FlhF N 端的一个结构域与 FliG 结合。FlhF 结合的 FliG 随后与 MS 环蛋白 FliF 结合。因此，FlhF 与 HubP 和 FliG 的相互作用将 FliF-FliG 复合物募集到细胞极点。此外，MinD 型 ATP 酶 FlhG 对 FlhF 活性的调节控制着 FliG 与 FliM-FliN 的相互作用，从而调节极点处鞭毛组装的进展。
