Department of Medicinal Chemistry and Institute for Structural Biology, Drug Discovery and Development, Virginia Commonwealth University, Richmond, VA 23298-0540, USA.
Biochem Soc Trans. 2021 Jun 30;49(3):1361-1374. doi: 10.1042/BST20201080.
Membrane proteins play vital roles in living organisms, serving as targets for most currently prescribed drugs. Membrane protein structural biology aims to provide accurate structural information to understand their mechanisms of action. The advance of membrane protein structural biology has primarily relied on detergent-based methods over the past several decades. However, detergent-based approaches have significant drawbacks because detergents often damage the native protein-lipid interactions, which are often crucial for maintaining the natural structure and function of membrane proteins. Detergent-free methods recently have emerged as alternatives with a great promise, e.g. for high-resolution structure determinations of membrane proteins in their native cell membrane lipid environments. This minireview critically examines the current status of detergent-free methods by a comparative analysis of five groups of membrane protein structures determined using detergent-free and detergent-based methods. This analysis reveals that current detergent-free systems, such as the styrene-maleic acid lipid particles (SMALP), the diisobutyl maleic acid lipid particles (DIBMALP), and the cycloalkane-modified amphiphile polymer (CyclAPol) technologies are not better than detergent-based approaches in terms of maintenance of native cell membrane lipids on the transmembrane domain and high-resolution structure determination. However, another detergent-free technology, the native cell membrane nanoparticles (NCMN) system, demonstrated improved maintenance of native cell membrane lipids with the studied membrane proteins, and produced particles that were suitable for high-resolution structural analysis. The ongoing development of new membrane-active polymers and their optimization will facilitate the maturation of these new detergent-free systems.
膜蛋白在生物体内发挥着至关重要的作用,它们是大多数目前处方药物的作用靶点。膜蛋白结构生物学旨在提供准确的结构信息,以了解其作用机制。在过去的几十年中,膜蛋白结构生物学的发展主要依赖于基于去污剂的方法。然而,基于去污剂的方法存在显著的缺点,因为去污剂经常破坏天然的蛋白-脂质相互作用,而这些相互作用对于维持膜蛋白的天然结构和功能往往至关重要。近年来,无去污剂方法作为一种很有前途的替代方法出现了,例如在天然细胞膜脂质环境中对膜蛋白进行高分辨率结构测定。本文通过对使用无去污剂和基于去污剂方法测定的五组膜蛋白结构进行比较分析,批判性地评估了无去污剂方法的当前现状。该分析表明,目前的无去污剂系统,如苯乙烯-马来酸脂粒(SMALP)、二异丁基马来酸脂粒(DIBMALP)和环烷烃修饰的两亲聚合物(CyclAPol)技术,在维持跨膜域的天然细胞膜脂质和高分辨率结构测定方面并不优于基于去污剂的方法。然而,另一种无去污剂技术——天然细胞膜纳米颗粒(NCMN)系统,在研究的膜蛋白中表现出对天然细胞膜脂质更好的维持能力,并产生了适合高分辨率结构分析的颗粒。新型膜活性聚合物的不断发展及其优化将促进这些新型无去污剂系统的成熟。