Department of Chemical Biology and Organic Chemistry, Institute of Biomembranes, Bijvoet Center for Biomolecular Research, Faculty of Science, Utrecht University, Padualaan, Utrecht, The Netherlands.
EMBO J. 2011 Apr 20;30(8):1425-32. doi: 10.1038/emboj.2011.61. Epub 2011 Mar 8.
Bacterial cell growth necessitates synthesis of peptidoglycan. Assembly of this major constituent of the bacterial cell wall is a multistep process starting in the cytoplasm and ending in the exterior cell surface. The intracellular part of the pathway results in the production of the membrane-anchored cell wall precursor, Lipid II. After synthesis this lipid intermediate is translocated across the cell membrane. The translocation (flipping) step of Lipid II was demonstrated to require a specific protein (flippase). Here, we show that the integral membrane protein FtsW, an essential protein of the bacterial division machinery, is a transporter of the lipid-linked peptidoglycan precursors across the cytoplasmic membrane. Using Escherichia coli membrane vesicles we found that transport of Lipid II requires the presence of FtsW, and purified FtsW induced the transbilayer movement of Lipid II in model membranes. This study provides the first biochemical evidence for the involvement of an essential protein in the transport of lipid-linked cell wall precursors across biogenic membranes.
细菌细胞的生长需要合成肽聚糖。这种细菌细胞壁的主要成分的组装是一个从细胞质开始并在细胞外表面结束的多步过程。该途径的细胞内部分导致膜锚定细胞壁前体，脂质 II 的产生。合成后，这种脂质中间体穿过细胞膜转移。脂质 II 的易位（翻转）步骤被证明需要一种特定的蛋白质（翻转酶）。在这里，我们表明，整合膜蛋白 FtsW 是细菌分裂机制的必需蛋白，是脂质连接肽聚糖前体穿过细胞质膜的转运蛋白。使用大肠杆菌膜囊泡，我们发现脂质 II 的转运需要 FtsW 的存在，并且纯化的 FtsW 诱导脂质 II 在模型膜中的跨膜运动。这项研究为必需蛋白在生物源膜中脂质连接细胞壁前体的转运中的参与提供了第一个生化证据。
