Dornes Anita, Bedrunka Patrica, Pillet Benjamin, Kressler Dieter, Heimerl Thomas, Pané-Farré Jan, Bange Gert
Center for Synthetic Microbiology (SYNMIKRO) and Department of Chemistry, Philipps-University Marburg, Marburg, Germany.
Department of Biology, University of Fribourg, Fribourg, Switzerland.
Mol Microbiol. 2025 Aug;124(2):131-140. doi: 10.1111/mmi.15375. Epub 2025 May 19.
Number and arrangement of flagella, the bacterial locomotion organelles, are species-specific and serve as key taxonomic markers. The FlhG ATPase (also: YlxH, FleN), along with FlhF, plays pivotal roles in determining flagellation patterns. In Bacillus subtilis , FlhG and FlhF govern the spatial arrangement of peritrichous flagella. FlhG aids in flagellar assembly by interacting with the flagellar C-ring protein FliY, yet the molecular implications of this interaction have been unclear. Our study reveals that the ATP-dependent FlhG homodimer interacts with the C-terminal domain of GpsB, a cell cycle regulator, which recruits the peptidoglycan synthase PBP1 (also: ponA) to sites of cell wall elongation. A deletion of gpsB leads to dysregulation of the flagellation pattern mimicking the effects of a flhG deletion strain. The finding that GpsB can interact simultaneously with FlhG and PBP1, combined with the observation that GpsB and FliY can simultaneously interact with FlhG, strongly argues for a model in which FlhG confines flagella biosynthesis to regions of active cell wall biosynthesis. Thus, the FlhG-GpsB interaction appears to enable the locally restrained stimulation of the GTPase FlhF, known for its role to localize flagella in various bacterial species.
鞭毛是细菌的运动细胞器，其数量和排列具有物种特异性，是关键的分类学标记。FlhG ATP酶（也称为YlxH、FleN）与FlhF一起，在决定鞭毛形成模式中起关键作用。在枯草芽孢杆菌中，FlhG和FlhF控制周生鞭毛的空间排列。FlhG通过与鞭毛C环蛋白FliY相互作用来辅助鞭毛组装，然而这种相互作用的分子机制尚不清楚。我们的研究表明，依赖ATP的FlhG同型二聚体与细胞周期调节因子GpsB的C末端结构域相互作用，后者将肽聚糖合酶PBP1（也称为ponA）招募到细胞壁延伸部位。缺失gpsB会导致鞭毛形成模式失调，类似于flhG缺失菌株的效应。GpsB能同时与FlhG和PBP1相互作用，以及GpsB和FliY能同时与FlhG相互作用的发现，有力地支持了一种模型，即FlhG将鞭毛生物合成限制在活跃的细胞壁生物合成区域。因此，FlhG - GpsB相互作用似乎能够局部限制对GTP酶FlhF的刺激，FlhF以在各种细菌物种中定位鞭毛的作用而闻名。
