Lutkenhaus Joe, Du Shishen
University of Kansas Medical Center, Kansas City, KS, USA.
Subcell Biochem. 2017;84:27-65. doi: 10.1007/978-3-319-53047-5_2.
Cytokinesis in E. coli is organized by a cytoskeletal element designated the Z ring. The Z ring is formed at midcell by the coalescence of FtsZ filaments tethered to the membrane by interaction of FtsZ's conserved C-terminal peptide (CCTP) with two membrane-associated proteins, FtsA and ZipA. Although interaction between an FtsZ monomer and either of these proteins is of low affinity, high affinity is achieved through avidity - polymerization linked CCTPs interacting with the membrane tethers. The placement of the Z ring at midcell is ensured by antagonists of FtsZ polymerization that are positioned within the cell and target FtsZ filaments through the CCTP. The placement of the ring is reinforced by a protein network that extends from the terminus (Ter) region of the chromosome to the Z ring. Once the Z ring is established, additional proteins are recruited through interaction with FtsA, to form the divisome. The assembled divisome is then activated by FtsN to carry out septal peptidoglycan synthesis, with a dynamic Z ring serving as a guide for septum formation. As the septum forms, the cell wall is split by spatially regulated hydrolases and the outer membrane invaginates in step with the aid of a transenvelope complex to yield progeny cells.
大肠杆菌中的胞质分裂由一种称为Z环的细胞骨架元件组织。Z环在细胞中部形成，它是由FtsZ细丝聚集而成，FtsZ细丝通过其保守的C末端肽（CCTP）与两种膜相关蛋白FtsA和ZipA相互作用而与膜相连。虽然FtsZ单体与这些蛋白中的任何一种之间的相互作用亲和力较低，但通过亲合力可实现高亲和力——聚合连接的CCTP与膜系链相互作用。Z环在细胞中部的定位由FtsZ聚合的拮抗剂确保，这些拮抗剂位于细胞内，并通过CCTP靶向FtsZ细丝。环的定位由一个从染色体末端（Ter）区域延伸到Z环的蛋白质网络加强。一旦Z环形成，通过与FtsA相互作用招募其他蛋白质，形成分裂体。组装好的分裂体随后被FtsN激活，以进行隔膜肽聚糖合成，动态的Z环作为隔膜形成的导向。随着隔膜的形成，细胞壁被空间调节的水解酶裂解，外膜在跨包膜复合物的帮助下同步内陷，产生子代细胞。
