In Escherichia coli, FtsEX coordinates peptidoglycan (PG) synthesis and hydrolysis at the septum. It acts on FtsA in the cytoplasm to promote recruitment of septal PG synthetases and recruits EnvC, an activator of septal PG hydrolases, in the periplasm. Following recruitment, ATP hydrolysis by FtsEX is thought to regulate both PG synthesis and hydrolysis, but how it does this is not well understood. Here, we show that an ATPase mutant of FtsEX blocks septal PG synthesis similarly to cephalexin, suggesting that ATP hydrolysis by FtsEX is required throughout septation. Using mutants that uncouple the roles of FtsEX in septal PG synthesis and hydrolysis, we find that recruitment of EnvC to the septum by FtsEX, but not ATP hydrolysis, is required to promote cell separation when the NlpD-mediated cell separation system is present. However, ATP hydrolysis by FtsEX becomes necessary for efficient cell separation when the NlpD system is inactivated, suggesting that the ATPase activity of FtsEX is required for optimal activity of EnvC. Importantly, under conditions that suppress the role of FtsEX in cell division, disruption of the FtsEX-FtsA interaction delays cell separation, highlighting the importance of this interaction in coupling the cell separation system with the septal PG synthetic complex.

中文翻译：

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FtsEX水解ATP以及与FtsA相互作用在分隔肽聚糖合成和水解中的作用。

在大肠杆菌中，FtsEX协调隔膜中肽聚糖（PG）的合成和水解。它作用于细胞质中的FtsA，以促进间隔PG合成酶的募集，并在周质中募集EnvC（间隔PG水解酶的激活剂）。募集后，人们认为通过FtsEX进行的ATP水解既可以调节PG的合成又可以调节水解，但是如何做到这一点尚不清楚。在这里，我们显示FtsEX的ATPase突变体与头孢氨苄类似地阻止了间隔PG的合成，这表明在整个分离过程中都需要通过FtsEX进行ATP水解。使用解离FtsEX在间隔PG合成和水解中的作用的突变体，我们发现当存在NlpD介导的细胞分离系统时，通过FtsEX而不是ATP水解将EnvC募集到隔膜是促进细胞分离所必需的。然而，当NlpD系统失活时，通过FtsEX进行的ATP水解对于有效的细胞分离变得必要，这表明FtsEX的ATPase活性是EnvC最佳活性所必需的。重要的是，在抑制FtsEX在细胞分裂中的作用的条件下，FtsEX-FtsA相互作用的破坏会延迟细胞分离，突出了这种相互作用在将细胞分离系统与间隔PG合成复合物偶联中的重要性。