Department of Biosystems Science and Engineering, Eidgenössische Technische Hochschule (ETH) Zurich , 4058 Basel, Switzerland.
Nano Lett. 2017 Jul 12;17(7):4478-4488. doi: 10.1021/acs.nanolett.7b01844. Epub 2017 Jun 23.
How complex cytoplasmic membrane proteins insert and fold into cellular membranes is not fully understood. One problem is the lack of suitable approaches that allow investigating the process by which polypeptides insert and fold into membranes. Here, we introduce a method to mechanically unfold and extract a single polytopic α-helical membrane protein, the lactose permease (LacY), from a phospholipid membrane, transport the fully unfolded polypeptide to another membrane and insert and refold the polypeptide into the native structure. Insertion and refolding of LacY is facilitated by the transmembrane chaperone/insertase YidC in the absence of the SecYEG translocon. Insertion into the membrane occurs in a stepwise, stochastic manner employing multiple coexisting pathways to complete the folding process. We anticipate that our approach will provide new means of studying the insertion and folding of membrane proteins and to mechanically reconstitute membrane proteins at high spatial precision and stoichiometric control, thus allowing the functional programming of synthetic and biological membranes.
细胞质膜蛋白如何插入和折叠到细胞膜中尚不完全清楚。一个问题是缺乏合适的方法来研究多肽插入和折叠到膜中的过程。在这里，我们介绍了一种方法，可以机械地展开和提取单个多拓扑α-螺旋膜蛋白乳糖通透酶（LacY）从磷脂膜中，将完全展开的多肽运送到另一个膜中，并将多肽插入并重新折叠成天然结构。在没有 SecYEG 转运体的情况下，跨膜伴侣/插入酶 YidC 促进 LacY 的插入和重折叠。插入到膜中是一个逐步的、随机的过程，采用多种共存的途径来完成折叠过程。我们预计，我们的方法将为研究膜蛋白的插入和折叠提供新的手段，并以高空间精度和化学计量控制机械地重建膜蛋白，从而允许对合成和生物膜进行功能编程。
