Identification of a protein complex that assembles lipopolysaccharide in the outer membrane of Escherichia coli
Identification of a protein complex that assembles lipopolysaccharide in the outer membrane of Escherichia coli
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DOI：
10.1073/pnas.0604744103
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发表时间：
2006-08-01
影响因子：
11.1
通讯作者：
Kahne, Daniel
中科院分区：
文献类型：
--
作者：
Wu, Tao;McCandlish, Andrew C.;Kahne, Daniel
大多数革兰氏阴性菌的外膜是由LIPS组成的，在几乎所有含有LIPS的细菌中，它对生物体的生命至关重要。这个分子的脂质部分，脂质A，也被称为内毒素，是先天免疫反应的有效激活剂。合成LIPS并将其组装在细胞表面需要50多个基因。在阐明LPS的结构和生物合成方面已经取得了巨大的进展，但直到最近，将其从内膜合成位点运输到细胞表面的最终细胞位置所需的细胞成分仍然难以捉摸。在这里，我们描述了一种蛋白质复合物的鉴定，其功能是在细胞表面组装LPS。该复合物包含两种蛋白质：Imp，已被确定为参与LPS组装的重要外膜蛋白；另一种蛋白质RlpB，迄今为止只被确定为一种罕见的脂蛋白。我们发现RlpB对细胞活力也至关重要，Imp/RlpB复合物负责lip到达外膜的外表面。
The outer membrane of most Gram-negative bacteria is made up of LIPS, and in nearly all bacteria that contain LIPS it is essential for the life of the organism. The lipid portion of this molecule, lipid A, also known as endotoxin, is a potent activator of the innate immune response. More than 50 genes are required to synthesize LIPS and assemble it at the cell surface. Enormous progress has been made in elucidating the structure and biosynthesis of LPS, but until recently the cellular components required for its transport from its site of synthesis in the inner membrane to its final cellular location at the cell surface remained elusive. Here we describe the identification of a protein complex that functions to assemble LPS at the surface of the cell. This complex contains two proteins: Imp, already identified as an essential outer-membrane protein implicated in LPS assembly; and another protein, RlpB, heretofore identified only as a rare lipoprotein. We show that RlpB is also essential for cell viability and that the Imp/RlpB complex is responsible for LIPS reaching the outer surface of the outer membrane.