Department of Microbiology, The Ohio State University, Columbus, OH, USA.
Department of Microbiology, The Ohio State University, Columbus, OH, USA.
Curr Opin Microbiol. 2021 Apr;60:51-57. doi: 10.1016/j.mib.2021.01.006. Epub 2021 Feb 15.
Cells must build and maintain at least one membrane that surrounds essential cellular components and provides structural integrity. Gram-negative bacteria possess an inner membrane, which separates the aqueous cytoplasmic and periplasmic compartments, and an outer membrane, which surrounds the periplasm. The outer membrane is an asymmetric bilayer with phospholipids in its inner leaflet and lipopolysaccharides in its outer leaflet. This structure provides cellular integrity and prevents the entry of many toxic compounds into the cell. Constructing the outer membrane is challenging, since its lipid constituents must be synthesized within the inner membrane, transported across the periplasm, and ultimately assembled into an asymmetric structure. This review highlights major recent advances in our understanding of the mechanism and structure of the intermembrane, multi-protein machine that transports lipopolysaccharide across the cell envelope. Although our understanding of phospholipid transport is very limited, we also provide a brief update on this topic.
细胞必须构建和维持至少一层膜，以包围基本的细胞成分并提供结构完整性。革兰氏阴性细菌具有内膜，将水细胞质和周质隔室分开，以及外膜，包围周质。外膜是一个不对称的双层，其内层含有磷脂，外层含有脂多糖。这种结构提供了细胞的完整性，并防止许多有毒化合物进入细胞。构建外膜是具有挑战性的，因为其脂质成分必须在内膜内合成，穿过周质运输，最终组装成不对称结构。这篇综述强调了我们对跨细胞膜运输脂多糖的膜间、多蛋白机器的机制和结构的主要最新理解。尽管我们对磷脂转运的理解非常有限，但我们也简要介绍了这个主题的最新进展。
