G-protein-coupled receptor solubilization and purification for biophysical analysis and functional studies, in the total absence of detergent

Abstract

G-protein coupled receptors (GPCRs) constitute the largest class of membrane proteins and are a major drug target. A serious obstacle to studying GPCR structure/function characteristics is the requirement to extract the receptors from their native environment in the plasma membrane, coupled with the inherent instability of GPCRs in the detergents required for their solubilization. In the present study, we report the first solubilization and purification of a functional GPCR [human adenosine A<inf>2A</inf> receptor (A<inf>2A</inf>R)], in the total absence of detergent at any stage, by exploiting spontaneous encapsulation by styrene maleic acid (SMA) co-polymer direct from the membrane into a nanoscale SMA lipid particle (SMALP). Furthermore, the A<inf>2A</inf>R-SMALP, generated from yeast (Pichia pastoris) or mammalian cells, exhibited increased thermostability (∼5°C) compared with detergent [DDM (n-dodecyl-β-D-maltopyranoside)]-solubilized A<inf>2A</inf>R controls. The A<inf>2A</inf>R-SMALP was also stable when stored for prolonged periods at 4°C and was resistant to multiple freeze-thaw cycles, in marked contrast with the detergent-solubilized receptor. These properties establish the potential for using GPCR-SMALP in receptor-based drug discovery assays. Moreover, in contrast with nanodiscs stabilized by scaffold proteins, the non-proteinaceous nature of the SMA polymer allowed unobscured biophysical characterization of the embedded receptor. Consequently, CD spectroscopy was used to relate changes in secondary structure to loss of ligand binding ([<sup>3</sup>H]ZM241385) capability. SMALP-solubilization of GPCRs, retaining the annular lipid environment, will enable a wide range of therapeutic targets to be prepared in native-like state to aid drug discovery and understanding of GPCR molecular mechanisms.

Publication DOI: https://doi.org/10.1042/BSR20140171
Divisions: College of Health & Life Sciences > School of Biosciences
College of Health & Life Sciences
College of Health & Life Sciences > School of Biosciences > Cellular and Molecular Biomedicine
College of Health & Life Sciences > Aston Pharmacy School
College of Health & Life Sciences > Chronic and Communicable Conditions
Additional Information: ©2015 The Author(s) This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (CC-BY) (http://creativecommons.org/licenses/by/3.0/) which permits unrestricted use, distribution and reproduction in any medium, provided the original work is properly cited. Funding: BBSRC (BB/I020349/1; BB/I019960/1; BB/J010812/1; BB/J017310/1; and MRC/Astra Zeneca (G1001610).
Uncontrolled Keywords: adenosine receptor,detergent-free,g-protein coupled receptor (GPCR),protein thermostability,structure,Biochemistry,Biophysics,Cell Biology,Molecular Biology
Full Text Link: http://www.bios ... /bsr035e188.htm
Related URLs: http://www.scop ... tnerID=8YFLogxK (Scopus URL)
PURE Output Type: Article
Published Date: 2015-02-27
Authors: Jamshad, Mohammed
Charlton, Jack
Lin, Yu-Pin
Routledge, Sarah J
Bawa, Zharain
Knowles, Timothy J.
Overduin, Michael
Dekker, Niek
Dafforn, Tim R.
Bill, Roslyn M. (ORCID Profile 0000-0003-1331-0852)
Poyner, David R. (ORCID Profile 0000-0003-1590-112X)
Wheatley, Mark

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