School of Life Sciences and Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230027, People's Republic of China.
School of Life Sciences and Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230027, People's Republic of China
Biochem J. 2019 May 21;476(10):1433-1444. doi: 10.1042/BCJ20190138.
The tubulin-like GTPase protein FtsZ, which forms a discontinuous cytokinetic ring at mid-cell, is a central player to recruit the division machinery to orchestrate cell division. To guarantee the production of two identical daughter cells, the assembly of FtsZ, namely Z-ring, and its precise positioning should be finely regulated. In , the positioning of Z-ring at the division site is mediated by a bitopic membrane protein MapZ (mid-cell-anchored protein Z) through direct interactions between the intracellular domain (termed MapZ-N (the intracellular domain of MapZ)) and FtsZ. Using nuclear magnetic resonance titration experiments, we clearly assigned the key residues involved in the interactions. In the presence of MapZ-N, FtsZ gains a shortened activation delay, a lower critical concentration for polymerization and a higher cooperativity towards GTP hydrolysis. On the other hand, MapZ-N antagonizes the lateral interactions of single-stranded filaments of FtsZ, thus slows down the formation of highly bundled FtsZ polymers and eventually maintains FtsZ at a dynamic state. Altogether, we conclude that MapZ is not only an accelerator to trigger the polymerization of FtsZ, but also a brake to tune the velocity to form the end-product, FtsZ bundles. These findings suggest that MapZ is a multi-functional regulator towards FtsZ that controls both the precise positioning and proper timing of FtsZ polymerization.
微管样 GTP 酶蛋白 FtsZ 在细胞中部形成不连续的有丝分裂环，是招募分裂机制来协调细胞分裂的核心参与者。为了保证产生两个相同的子细胞，FtsZ（即 Z 环）的组装及其精确定位应该得到精细的调节。在本文中，通过细胞间锚定蛋白 MapZ（中细胞锚定蛋白 Z）与 FtsZ 之间的直接相互作用，Z 环在分裂部位的定位由双位膜蛋白 MapZ 介导。利用核磁共振滴定实验，我们清楚地确定了参与相互作用的关键残基。在 MapZ-N 的存在下，FtsZ 的激活延迟缩短，聚合的临界浓度降低，对 GTP 水解的协同性增加。另一方面，MapZ-N 拮抗 FtsZ 单链丝的侧向相互作用，从而减缓高度束状 FtsZ 聚合物的形成，并最终使 FtsZ 保持动态状态。总之，我们得出结论，MapZ 不仅是触发 FtsZ 聚合的加速器，也是调节形成最终产物 FtsZ 束的速度的制动器。这些发现表明，MapZ 是 FtsZ 的多功能调节剂，控制 FtsZ 聚合的精确定位和适当时间。
