Unité de Microbiologie Structurale, Institut Pasteur, CNRS UMR 3528, Université de Paris, 75015, Paris, France.
Bioinformatics Unit, Institut Pasteur de Montevideo, Montevideo, 11400, Uruguay.
Nat Commun. 2020 Apr 2;11(1):1641. doi: 10.1038/s41467-020-15490-8.
The mechanisms of Z-ring assembly and regulation in bacteria are poorly understood, particularly in non-model organisms. Actinobacteria, a large bacterial phylum that includes the pathogen Mycobacterium tuberculosis, lack the canonical FtsZ-membrane anchors and Z-ring regulators described for E. coli. Here we investigate the physiological function of Corynebacterium glutamicum SepF, the only cell division-associated protein from Actinobacteria known to interact with the conserved C-terminal tail of FtsZ. We show an essential interdependence of FtsZ and SepF for formation of a functional Z-ring in C. glutamicum. The crystal structure of the SepF-FtsZ complex reveals a hydrophobic FtsZ-binding pocket, which defines the SepF homodimer as the functional unit, and suggests a reversible oligomerization interface. FtsZ filaments and lipid membranes have opposing effects on SepF polymerization, indicating that SepF has multiple roles at the cell division site, involving FtsZ bundling, Z-ring tethering and membrane reshaping activities that are needed for proper Z-ring assembly and function.
细菌中环 Z 组装和调控的机制尚未完全阐明，尤其是在非模式生物中。放线菌是一个庞大的细菌门，包括病原体结核分枝杆菌，它们缺乏与大肠杆菌中描述的典型 FtsZ-膜锚定和 Z 环调节剂。在这里，我们研究了谷氨酸棒状杆菌 SepF 的生理功能，它是放线菌中唯一已知与 FtsZ 保守 C 端尾部相互作用的细胞分裂相关蛋白。我们发现 FtsZ 和 SepF 的形成在功能环 Z 的形成中是必不可少的相互依存的。SepF-FtsZ 复合物的晶体结构揭示了一个疏水的 FtsZ 结合口袋，这定义了 SepF 同源二聚体作为功能单元，并提出了一个可逆的寡聚化界面。FtsZ 丝和脂质膜对 SepF 聚合有相反的影响，表明 SepF 在细胞分裂部位具有多种功能，涉及 FtsZ 束集、Z 环系留和膜重塑活动，这些活动对于适当的 Z 环组装和功能是必需的。
