革兰氏阴性菌脂多糖运输系统的构成及作用机制

Component and functions of lipopolysaccharide transport system in Gram-negative bacteria

摘要:

革兰氏阴性菌包含有两层组分不同的膜结构——内膜和外膜，对大多数革兰氏阴性菌而言，脂多糖（lipopolysaccharides，LPS）是其外膜上最主要的脂质成分，锚定在外膜小叶（the outer leaflet of the OM）上，是革兰氏阴性菌固有免疫的重要组成部分。脂多糖运输系统（lipopolysaccharide transport system，Lpt）将胞内装配完整的LPS正确装配到外膜，使得与脂多糖相关的阻渗、有机溶剂耐受性、疏水性抗生素耐受性、膜通透性等功能得以实现。该运输系统的正确作用主要依赖7个不同的脂多糖运输蛋白（LptABCDEFG）协同完成，整个系统贯穿细菌内膜至外膜，由内膜上ABC转运体复合物LptB2FG、胞质内转运协同蛋白LptA/C及被许多学者称作脂多糖运输的"命门"的外膜蛋白复合物LptDE共同构成。本文就革兰氏阴性菌脂多糖的具体结构功能进行简介，进而综述脂多糖运输系统的7个蛋白的构成和作用机制，以期为进一步研究该系统中每个蛋白的功能提供理论基础及参考。

Abstract:

Gram negative bacteria contain two layers of membranes:Inner membrane and Outer membrane. Lipopolysaccharides of most Gram-negative bacteria are the most important component of membrane lipid and anchored in the outer leaflet of the outer membrane, which play a role in inherent immune of Gram-negative bacteria. Lipopolysaccharide transport system assembles lipopolysaccharides into the outer membrane to achieve a variety of functions, including lipopolysaccharide associated barrier, organic solvent tolerance, hydrophobic antibiotic resistance, membrane permeability and other functions. The transport system mainly depends on 7 different lipopolysaccharides transport proteins (LptABCDEFG), which are composed of the ATP-binding cassette transporter complex LptB2FG, periplasm protein LptA/C, and "vital gate" outer membrane protein complex LptDE together. This paper describes the structure and functions of lipopolysaccharide transport system in Gram-negative bacteria, to provide information to further study the function of each protein in this system.