Centre for Structural Systems Biology (CSSB), DESY, Notkestrasse 85, 22607 Hamburg, Germany; European Molecular Biology Laboratory Hamburg, Notkestrasse 85, 22607 Hamburg, Germany.
European Molecular Biology Laboratory Hamburg, Notkestrasse 85, 22607 Hamburg, Germany.
Structure. 2018 Feb 6;26(2):345-355.e5. doi: 10.1016/j.str.2018.01.007.
Saposin-derived lipid nanoparticles (SapNPs) are a new alternative tool for membrane protein reconstitution. Here we demonstrate the potential and advantages of SapNPs. We show that SapA has the lowest lipid specificity for SapNP formation. These nanoparticles are modular and offer a tunable range of size and composition depending on the stoichiometric ratio of lipid and saposin components. They are stable and exhibit features typical of lipid-bilayer systems. Our data suggest that SapNPs are versatile and can adapt to membrane proteins of various sizes and architectures. Using SapA and various types of lipids we could reconstitute membrane proteins of different transmembrane cross-sectional areas (from 14 to 56 transmembrane α helices). SapNP-reconstituted proteins bound their respective ligands and were more heat stable compared with the detergent-solubilized form. Moreover, SapNPs encircle membrane proteins in a compact way, allowing structural investigations of small membrane proteins in a detergent-free environment using small-angle X-ray scattering.
类脂囊泡（SapNPs）是一种新型的膜蛋白重构替代工具。在此，我们展示了 SapNPs 的潜力和优势。我们发现 SapA 对 SapNP 形成的脂质特异性最低。这些纳米颗粒具有模块化特性，可根据脂质和类脂结合蛋白成分的比例调节大小和组成范围。它们稳定，表现出典型的双层脂系统特征。我们的数据表明 SapNPs 具有多功能性，可以适应各种大小和结构的膜蛋白。使用 SapA 和各种类型的脂质，我们可以重构不同跨膜截面积的膜蛋白（从 14 到 56 个跨膜α螺旋）。与去污剂溶解形式相比，SapNP 重构的蛋白与其各自的配体结合更稳定，且热稳定性更高。此外，SapNPs 以紧凑的方式包围膜蛋白，允许使用小角度 X 射线散射在无去污剂的环境中对小膜蛋白进行结构研究。
