Lipoprotein LptE is required for the assembly of LptD by the β-barrel assembly machine in the outer membrane of Escherichia coli
Lipoprotein LptE is required for the assembly of LptD by the β-barrel assembly machine in the outer membrane of Escherichia coli
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DOI：
10.1073/pnas.1019089108
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发表时间：
2011-02-08
影响因子：
11.1
通讯作者：
Silhavy, Thomas J.
中科院分区：
文献类型：
--
作者：
Chimalakonda, Gitanjali;Ruiz, Natividad;Silhavy, Thomas J.
大多数革兰氏阴性细菌在外膜（OM）的外小叶中含有脂多糖（LPS），一种基于葡糖胺的磷脂。LPS是细菌OM所特有的，在大多数情况下，对细胞活力至关重要。LPS从其合成位点转运到细胞表面需要八种必需蛋白质，MsbA和LptABCDEFG。虽然已经确定了关键参与者，但LPS转运和组装的机制尚不清楚。稳定的LptD/E复合物存在于OM中，并在LPS组装的最后阶段发挥作用。在这里，我们已经确定了突变等位基因lptE 6，这导致两个氨基酸缺失的脂蛋白LptE，影响其与LptD的相互作用。高度特异性的抑制突变不仅在lptD中分离，而且在bamA中分离，bamA编码β-桶装配机的中心组件。我们发现，LptE 6和两个抑制突变的影响组装的LptD/E复合物，并建议脂蛋白LptE与LptD相互作用，而这种蛋白质正在组装的β-桶装配机。
Most Gram-negative bacteria contain lipopolysaccharide (LPS), a glucosamine-based phospholipid, in the outer leaflet of the outer membrane (OM). LPS is unique to the bacterial OM and, in most cases, essential for cell viability. Transport of LPS from its site of synthesis to the cell surface requires eight essential proteins, MsbA and LptABCDEFG. Although the key players have been identified, the mechanism of LPS transport and assembly is not clear. The stable LptD/E complex is present at the OM and functions in the final stages of LPS assembly. Here, we have identified the mutant allele lptE6, which causes a two-amino-acid deletion in the lipoprotein LptE that affects its interaction with LptD. Highly specific suppressor mutations were isolated not only in lptD but also in bamA, which encodes the central component of the beta-barrel assembly machine. We show that lptE6 and both suppressor mutations affect the assembly of the LptD/E complex and suggest that the lipoprotein LptE interacts with LptD while this protein is being assembled by the beta-barrel assembly machine.