Membrane proteins are essential for cellular growth, signalling and homeostasis, making up a large proportion of therapeutic targets. However, the necessity for a solubilising agent to extract them from the membrane creates challenges in their structural and functional study. Although amphipols have been very effective for single-particle electron cryo-microscopy (cryoEM) and mass spectrometry, they rely on initial detergent extraction before exchange into the amphipol environment. Therefore, circumventing this pre-requirement would be a big advantage. Here we use an alternative type of amphipol: a cycloalkane-modified amphiphile polymer (CyclAPol) to extract Escherichia coli AcrB directly from the membrane and demonstrate that the protein can be isolated in a one-step purification with the resultant cryoEM structure achieving 3.2 Å resolution. Together this work shows that cycloalkane amphipols provide a powerful approach for the study of membrane proteins, allowing native extraction and high-resolution structure determination by cryoEM.
Organizational Affiliation:
School of Biomedical Sciences, Faculty of Biological Sciences & Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK.
Université de Paris, Laboratoire de Biologie Physico-Chimique des Protéines Membranaires, CNRS, UMR 7099, F-75005, Paris, France.
Institut de Biologie Physico-Chimique, Fondation Edmond de Rothschild pour le dévelopement de la recherche scientifique, F-75005, Paris, France.
Wellcome Centre for Anti-Infectives Research, Drug Discovery Unit, Division of Biological Chemistry and Drug Discovery, University of Dundee, Dundee, DD1 5EH, UK.
Université de Paris, Laboratoire de Biologie Physico-Chimique des Protéines Membranaires, CNRS, UMR 7099, F-75005, Paris, France. zoonens@ibpc.fr.
Institut de Biologie Physico-Chimique, Fondation Edmond de Rothschild pour le dévelopement de la recherche scientifique, F-75005, Paris, France. zoonens@ibpc.fr.
School of Molecular and Cellular Biology, Faculty of Biological Sciences & Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK. f.sobott@leeds.ac.uk.
School of Biomedical Sciences, Faculty of Biological Sciences & Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds, LS2 9JT, UK. s.p.muench@leeds.ac.uk.