Styrene maleic-acid lipid particles (SMALPs) into detergent or amphipols: An exchange protocol for membrane protein characterisation

作者：Sophie J. Hesketh, David P. Klebl, A.J. Higgins, Maren Thomsen, Isabelle B. Pickles, Frank Sobott, Asipu Sivaprasadarao, Vincent L. G. Postis, Stephen P. Muench · 发表于：Biochimica et Biophysica Acta (BBA) - Biomembranes · 年份：2020 · DOI：10.1016/j.bbamem.2020.183192 · 被引用次数：39 · 研究领域：RNA and protein synthesis mechanisms、Lipid Membrane Structure and Behavior、RNA Interference and Gene Delivery

Membrane proteins are traditionally extracted and purified in detergent for biochemical and structural characterisation. This process is often costly and laborious, and the stripping away of potentially stabilising lipids from the membrane protein of interest can have detrimental effects on protein integrity. Recently, styrene-maleic acid (SMA) co-polymers have offered a solution to this problem by extracting membrane proteins directly from their native membrane, while retaining their naturally associated lipids in the form of stable SMA lipid particles (SMALPs). However, the inherent nature and heterogeneity of the polymer renders their use challenging for some downstream applications - particularly mass spectrometry (MS). While advances in cryo-electron microscopy (cryo-EM) have enhanced our understanding of membrane protein:lipid interactions in both SMALPs and detergent, the resolution obtained with this technique is often insufficient to accurately identify closely associated lipids within the transmembrane annulus. Native-MS has the power to fill this knowledge gap, but the SMA polymer itself remains largely incompatible with this technique. To increase sample homogeneity and allow characterisation of membrane protein:lipid complexes by native-MS, we have developed a novel SMA-exchange method; whereby the membrane protein of interest is first solubilised and purified in SMA, then transferred into amphipols or detergents. This allows the membrane protein and endogenously...