van den Ent F, Löwe J
MRC Laboratory of Molecular Biology, Hills Road, Cambridge, CB2 2QH, UK.
EMBO J. 2000 Oct 16;19(20):5300-7. doi: 10.1093/emboj/19.20.5300.
Bacterial cell division requires formation of a septal ring. A key step in septum formation is polymerization of FtsZ. FtsA directly interacts with FtsZ and probably targets other proteins to the septum. We have solved the crystal structure of FtsA from Thermotoga maritima in the apo and ATP-bound form. FtsA consists of two domains with the nucleotide-binding site in the interdomain cleft. Both domains have a common core that is also found in the actin family of proteins. Structurally, FtsA is most homologous to actin and heat-shock cognate protein (Hsc70). An important difference between FtsA and the actin family of proteins is the insertion of a subdomain in FtsA. Movement of this subdomain partially encloses a groove, which could bind the C-terminus of FtsZ. FtsZ is the bacterial homologue of tubulin, and the FtsZ ring is functionally similar to the contractile ring in dividing eukaryotic cells. Elucidation of the crystal structure of FtsA shows that another bacterial protein involved in cytokinesis is structurally related to a eukaryotic cytoskeletal protein involved in cytokinesis.
细菌细胞分裂需要形成一个隔膜环。隔膜形成的关键步骤是FtsZ的聚合。FtsA直接与FtsZ相互作用，可能将其他蛋白质靶向到隔膜。我们已经解析了嗜热栖热菌中apo形式和ATP结合形式的FtsA的晶体结构。FtsA由两个结构域组成，核苷酸结合位点位于结构域间的裂隙中。两个结构域都有一个共同的核心，在肌动蛋白家族的蛋白质中也能找到。在结构上，FtsA与肌动蛋白和热休克同源蛋白（Hsc70）最为同源。FtsA与肌动蛋白家族蛋白质的一个重要区别是FtsA中插入了一个亚结构域。这个亚结构域的移动部分封闭了一个凹槽，该凹槽可能结合FtsZ的C末端。FtsZ是微管蛋白在细菌中的同源物，FtsZ环在功能上类似于正在分裂的真核细胞中的收缩环。FtsA晶体结构的解析表明，另一种参与胞质分裂的细菌蛋白在结构上与一种参与胞质分裂的真核细胞骨架蛋白相关。
