Biomedical Research Centre, Norwich Medical School, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK.
Biomedical Research Centre, Norwich Medical School, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK.
Biochim Biophys Acta Mol Cell Biol Lipids. 2017 Nov;1862(11):1461-1467. doi: 10.1016/j.bbalip.2017.08.003. Epub 2017 Aug 15.
Lipopolysaccharide (LPS) is an important component of the outer membrane (OM) of Gram-negative bacteria, playing essential roles in protecting bacteria from harsh environments, in drug resistance and in pathogenesis. LPS is synthesized in the cytoplasm and translocated to the periplasmic side of the inner membrane (IM), where it matures. Seven lipopolysaccharide transport proteins, LptA-G, form a trans‑envelope complex that is responsible for LPS extraction from the IM and transporting it across the periplasm to the OM. The LptD/E of the complex transports LPS across the OM and inserts it into the outer leaflet of the OM. In this review we focus upon structural and mechanistic studies of LPS transport proteins, with a particular focus upon the LPS ABC transporter LptBFG. This ATP binding cassette transporter complex consists of twelve transmembrane segments and has a unique mechanism whereby it extracts LPS from the periplasmic face of the IM through a pair of lateral gates and then powers trans‑periplasmic transport to the OM through a slide formed by either of the periplasmic domains of LptF or LptG, LptC, LptA and the N-terminal domain of LptD. The structural and functional studies of the seven lipopolysaccharide transport proteins provide a platform to explore the unusual mechanisms of LPS extraction, transport and insertion from the inner membrane to the outer membrane. This article is part of a Special Issue entitled: Bacterial Lipids edited by Russell E. Bishop.
脂多糖（LPS）是革兰氏阴性细菌外膜（OM）的重要组成部分，在保护细菌免受恶劣环境、耐药性和发病机制方面发挥着重要作用。LPS 在细胞质中合成，并易位到内膜（IM）的周质侧，在那里成熟。七种脂多糖转运蛋白（LptA-G）形成一个跨膜复合物，负责从 IM 中提取 LPS 并将其穿过周质运送到 OM。该复合物的 LptD/E 将 LPS 穿过 OM 并将其插入 OM 的外叶。在这篇综述中，我们重点介绍 LPS 转运蛋白的结构和机制研究，特别关注 LPS ABC 转运体 LptBFG。该 ATP 结合盒转运体复合物由十二个跨膜片段组成，具有独特的机制，通过一对侧门从 IM 的周质面提取 LPS，然后通过 LptF 或 LptG、LptC、LptA 的周质结构域之一或 LptD 的 N 末端结构域形成的滑动，为跨周质转运提供动力，转运到 OM。对七种脂多糖转运蛋白的结构和功能研究为探索 LPS 从内膜提取、运输和插入到外膜的异常机制提供了一个平台。本文是由 Russell E. Bishop 编辑的题为“细菌脂类”的特刊的一部分。
