Department of Biology, City College of New York, New York, New York, USA.
J Bacteriol. 2012 Jun;194(12):3189-98. doi: 10.1128/JB.00176-12. Epub 2012 Apr 13.
The tubulin homolog FtsZ forms a polymeric membrane-associated ring structure (Z ring) at midcell that establishes the site of division and provides an essential framework for the localization of a multiprotein molecular machine that promotes division in Escherichia coli. A number of regulatory proteins interact with FtsZ and modulate FtsZ assembly/disassembly processes, ensuring the spatiotemporal integrity of cytokinesis. The Z-associated proteins (ZapA, ZapB, and ZapC) belong to a group of FtsZ-regulatory proteins that exhibit functionally redundant roles in stabilizing FtsZ-ring assembly by binding and bundling polymeric FtsZ at midcell. In this study, we report the identification of ZapD (YacF) as a member of the E. coli midcell division machinery. Genetics and cell biological evidence indicate that ZapD requires FtsZ but not other downstream division proteins for localizing to midcell, where it promotes FtsZ-ring assembly via molecular mechanisms that overlap with ZapA. Biochemical evidence indicates that ZapD directly interacts with FtsZ and promotes bundling of FtsZ protofilaments. Similarly to ZapA, ZapB, and ZapC, ZapD is dispensable for division and therefore belongs to the growing group of FtsZ-associated proteins in E. coli that aid in the overall fitness of the division process.
微管同源物 FtsZ 在细胞中部形成一个与膜相关的聚合环结构（Z 环），该结构确定了分裂的位置，并为促进大肠杆菌分裂的多蛋白分子机器的定位提供了必要的框架。许多调节蛋白与 FtsZ 相互作用，并调节 FtsZ 的组装/拆卸过程，确保细胞分裂的时空完整性。Z 相关蛋白（ZapA、ZapB 和 ZapC）属于一组 FtsZ 调节蛋白，它们通过在细胞中部结合和束状聚合 FtsZ 来稳定 FtsZ 环组装，从而发挥功能冗余作用。在这项研究中，我们报告了 ZapD（YacF）作为大肠杆菌细胞中部分裂机制的一个成员的鉴定。遗传学和细胞生物学证据表明，ZapD 定位到细胞中部需要 FtsZ，但不需要其他下游分裂蛋白，在那里它通过与 ZapA 重叠的分子机制促进 FtsZ 环组装。生化证据表明，ZapD 直接与 FtsZ 相互作用，并促进 FtsZ 原丝的束状。与 ZapA、ZapB 和 ZapC 类似，ZapD 对于分裂不是必需的，因此属于大肠杆菌中越来越多的与 FtsZ 相关的蛋白质，它们有助于分裂过程的整体适应性。
