Infectious Disease Biology, Institute of Life Sciences, Nalco Square, Bhubaneswar, Odisha 751023, India.
Manipal Academy of Higher Education, Manipal, Karnataka 576104, India.
Biosci Rep. 2021 Jan 29;41(1). doi: 10.1042/BSR20203034.
The peptidoglycan (PG) layer is an intricate and dynamic component of the bacterial cell wall, which requires a constant balance between its synthesis and hydrolysis. FtsEX complex present on the inner membrane is shown to transduce signals to induce PG hydrolysis. FtsE has sequence similarity with the nucleotide-binding domains (NBDs) of ABC transporters. The NBDs in most of the ABC transporters couple ATP hydrolysis to transport molecules inside or outside the cell. Also, this reaction cycle is driven by the dimerization of NBDs. Though extensive studies have been carried out on the Escherchia coli FtsEX complex, it remains elusive regarding how FtsEX complex helps in signal transduction or transportation of molecules. Also, very little is known about the biochemical properties and ATPase activities of FtsE. Because of its strong interaction with the membrane-bound protein FtsX, FtsE stays insoluble upon overexpression in E. coli, and thus, most studies on E. coli FtsE (FtsEEc) in the past have used refolded FtsE. Here in the present paper, for the first time, we report the soluble expression, purification, and biochemical characterization of FtsE from E. coli. The purified soluble FtsE exhibits high thermal stability, exhibits ATPase activity and has more than one ATP-binding site. We have also demonstrated a direct interaction between FtsE and the cytoplasmic loop of FtsX. Together, our findings suggest that during bacterial division, the ATPase cycle of FtsE and its interaction with the FtsX cytoplasmic loop may help to regulate the PG hydrolysis at the mid cell.
肽聚糖 (PG) 层是细菌细胞壁的一个复杂而动态的组成部分，其合成和水解需要保持平衡。在内膜上存在的 FtsEX 复合物被证明可以传递信号以诱导 PG 水解。FtsE 与 ABC 转运体的核苷酸结合结构域 (NBD) 具有序列相似性。大多数 ABC 转运体中的 NBD 将 ATP 水解与细胞内外的分子运输偶联。此外，这个反应循环由 NBD 的二聚化驱动。尽管已经对大肠杆菌 FtsEX 复合物进行了广泛的研究，但关于 FtsEX 复合物如何帮助信号转导或分子运输，仍然难以捉摸。此外，关于 FtsE 的生化特性和 ATPase 活性知之甚少。由于 FtsE 与膜结合蛋白 FtsX 之间的强烈相互作用，FtsE 在大肠杆菌中的过表达时是不可溶的，因此，过去对大肠杆菌 FtsE（FtsEEc）的大多数研究都使用了重折叠的 FtsE。在本文中，我们首次报道了大肠杆菌 FtsE 的可溶性表达、纯化和生化特性。纯化的可溶性 FtsE 表现出高热稳定性、ATPase 活性和一个以上的 ATP 结合位点。我们还证明了 FtsE 与 FtsX 细胞质环之间的直接相互作用。总之，我们的研究结果表明，在细菌分裂过程中，FtsE 的 ATPase 循环及其与 FtsX 细胞质环的相互作用可能有助于调节细胞中部的 PG 水解。
