Weart Richard B, Nakano Shunji, Lane Brooke E, Zuber Peter, Levin Petra Anne
Department of Biology, Washington University, St Louis, MO 63130, USA.
Mol Microbiol. 2005 Jul;57(1):238-49. doi: 10.1111/j.1365-2958.2005.04673.x.
Summary Assembly of the tubulin-like cytoskeletal protein FtsZ into a ring structure establishes the location of the nascent division site in prokaryotes. Factors that modulate FtsZ assembly are essential for ensuring the precise spatial and temporal regulation of cytokinesis. We have identified ClpX, the substrate recognition subunit of the ClpXP protease, as an inhibitor of FtsZ assembly in Bacillus subtilis. Genetic data indicate that ClpX but not ClpP inhibits FtsZ-ring formation in vivo. In vitro, ClpX inhibits FtsZ assembly in a ClpP-independent manner through a mechanism that does not require ATP hydrolysis. Together our data support a model in which ClpX helps maintain the cytoplasmic pool of unassembled FtsZ that is required for the dynamic nature of the cytokinetic ring. ClpX is conserved throughout bacteria and has been shown to interact directly with FtsZ in Escherichia coli. Thus, we speculate that ClpX functions as a general regulator of FtsZ assembly and cell division in a wide variety of bacteria.
微管蛋白样细胞骨架蛋白FtsZ组装成环状结构确定了原核生物中新生分裂位点的位置。调节FtsZ组装的因子对于确保胞质分裂精确的空间和时间调控至关重要。我们已确定ClpXP蛋白酶的底物识别亚基ClpX是枯草芽孢杆菌中FtsZ组装的抑制剂。遗传数据表明，在体内ClpX而非ClpP抑制FtsZ环的形成。在体外，ClpX通过一种不需要ATP水解的机制以ClpP非依赖的方式抑制FtsZ组装。我们的数据共同支持一个模型，即ClpX有助于维持未组装的FtsZ的细胞质池，这是细胞分裂环动态性质所必需的。ClpX在整个细菌中保守，并且已证明在大肠杆菌中可直接与FtsZ相互作用。因此，我们推测ClpX在多种细菌中作为FtsZ组装和细胞分裂的一般调节因子发挥作用。
