Evidence for phospholipid export from the bacterial inner membrane by the Mla ABC transport system
Evidence for phospholipid export from the bacterial inner membrane by the Mla ABC transport system
复制标题
DOI：
10.1038/s41564-019-0481-y
复制
发表时间：
2019-10-01
影响因子：
28.3
通讯作者：
Knowles, Timothy J.
中科院分区：
文献类型：
--
作者：
Hughes, Gareth W.;Hall, Stephen C. L.;Knowles, Timothy J.
Mla途径被认为通过逆行磷脂转运参与维持不对称的革兰氏阴性外膜。该途径由三个组分组成：外膜MlaA-OmpC/F复合物、可溶性周质蛋白MlaC和内膜ATP酶MlaFEDB复合物。在这里，我们解决了MlaC的晶体结构在其无磷脂封闭的载脂蛋白构象，揭示了一个旋转的β-片机制，其功能是打开和关闭磷脂结合口袋。使用载脂蛋白形式的MlaC，我们提供的证据表明，内膜MlaFEDB机械出口磷脂MlaC在周质。此外，我们确认磷脂输出过程通过MlaFEDB复合物的MlaD组分发生，并且该过程不依赖于ATP。我们的数据提供了证据的装置脂质出口远离内膜，并建议Mla途径可能有一个作用，在顺行磷脂运输。
The Mla pathway is believed to be involved in maintaining the asymmetrical Gram-negative outer membrane via retrograde phospholipid transport. The pathway is composed of three components: the outer membrane MlaA-OmpC/F complex, a soluble periplasmic protein, MlaC, and the inner membrane ATPase, MlaFEDB complex. Here, we solve the crystal structure of MlaC in its phospholipid-free closed apo conformation, revealing a pivoting beta-sheet mechanism that functions to open and close the phospholipid-binding pocket. Using the apo form of MlaC, we provide evidence that the inner-membrane MlaFEDB machinery exports phospholipids to MlaC in the periplasm. Furthermore, we confirm that the phospholipid export process occurs through the MlaD component of the MlaFEDB complex and that this process is independent of ATP. Our data provide evidence of an apparatus for lipid export away from the inner membrane and suggest that the Mla pathway may have a role in anterograde phospholipid transport.