The structure of the β-barrel assembly machinery complex.
The structure of the β-barrel assembly machinery complex.
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DOI：
10.1126/science.aad3460
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发表时间：
2016-01-08
期刊：
影响因子：
--
通讯作者：
Noinaj N
中科院分区：
文献类型：
--
作者：
Bakelar J;Buchanan SK;Noinaj N
β-桶外膜蛋白（β-barrel outer membrane proteins，OMPs）存在于革兰氏阴性菌的外膜（outer membrane，OM）中，是营养物质输入、信号传导和粘附所必需的。虽然确切的机制是未知的，一个200 kDa的五组分复合物称为β-桶组装机（BAM）复合物已涉及OMP的生物成因。在这里，我们报告的BAM复合物的结构，从E。结果表明，辅助蛋白BamCDE的结合可调节BAM复合物的中心组分BamA的构象，从而调节BAM复合物的功能。BamA的周质结构域被发现处于封闭状态，其阻止从周质进入桶腔，表明底物OMP在生物发生期间可能不进入桶。此外，β-桶结构域的前八条链经历前所未有的构象转变，导致出口孔的打开和在侧门处的重排。
β-barrel outer membrane proteins (OMPs) are found within the outer membranes (OM) of Gram-negative bacteria and are essential for nutrient import, signaling, and adhesion. While the exact mechanism is unknown, a 200 kDa five component complex called the β-barrel assembly machinery (BAM) complex has been implicated in the biogenesis of OMPs. Here, we report the structure of the BAM complex from E. coli, revealing that binding of the accessory proteins BamCDE modulates the conformation of BamA, the central component of the complex, which may regulate the function of the BAM complex. The periplasmic domain of BamA was found in a closed state that prevents access to the barrel lumen from the periplasm, indicating substrate OMPs likely do not enter the barrel during biogenesis. Further, the first eight strands of the β-barrel domain undergo an unprecedented conformational shift leading to opening of the exit pore and rearrangement at the lateral gate.