Department of Structural Biology, Weizmann Institute of Science, Herzl St. 234, 7610001, Rehovot, Israel.
Centre for Structural Systems Biology (CSSB), DESY and European Molecular Biology Laboratory Hamburg, Notkestrasse 85, 22607, Hamburg, Germany.
Angew Chem Int Ed Engl. 2020 Oct 19;59(43):19121-19128. doi: 10.1002/anie.202008226. Epub 2020 Sep 11.
Membrane proteins require lipid bilayers for function. While lipid compositions reach enormous complexities, high-resolution structures are usually obtained in artificial detergents. To understand whether and how lipids guide membrane protein function, we use single-molecule FRET to probe the dynamics of DtpA, a member of the proton-coupled oligopeptide transporter (POT) family, in various lipid environments. We show that detergents trap DtpA in a dynamic ensemble with cytoplasmic opening. Only reconstitutions in more native environments restore cooperativity, allowing an opening to the extracellular side and a sampling of all relevant states. Bilayer compositions tune the abundance of these states. A novel state with an extreme cytoplasmic opening is accessible in bilayers with anionic head groups. Hence, chemical diversity of membranes translates into structural diversity, with the current POT structures only sampling a portion of the full structural space.
膜蛋白的功能需要脂质双层。尽管脂质组成具有极高的复杂性，但通常在人工去污剂中获得高分辨率结构。为了了解脂质是否以及如何指导膜蛋白的功能，我们使用单分子 FRET 技术在各种脂质环境中探测质子偶联寡肽转运体（POT）家族成员 DtpA 的动力学。我们表明，去污剂将 DtpA 捕获在具有细胞质开口的动态集合体中。只有在更接近天然环境的重建中，才能恢复协同性，从而使细胞质外侧开放，并对所有相关状态进行采样。双层组成可以调节这些状态的丰度。带有阴离子头基的双层中可以进入一种具有极端细胞质开口的新状态。因此，膜的化学多样性转化为结构多样性，目前的 POT 结构仅采样了完整结构空间的一部分。
