An acid-compatible co-polymer for the solubilization of membranes and proteins into lipid bilayer-containing nanoparticles

Hall, Stephen C.L., Tognoloni, Cecilia, Charlton, Jack, Bragginton, Éilís C., Rothnie, Alice J, Sridhar, Pooja, Wheatley, Mark, Knowles, Timothy J., Arnold, Thomas, Edler, Karen J. and Dafforn, Timothy R. (2018). An acid-compatible co-polymer for the solubilization of membranes and proteins into lipid bilayer-containing nanoparticles. Nanoscale , pp. 10609-10619.

Abstract

The fundamental importance of membrane proteins in drug discovery has meant that membrane mimetic systems for studying membrane proteins are of increasing interest. One such system has been the amphipathic, negatively charged poly(styrene-co-maleic acid) (SMA) polymer to form “SMA Lipid Particles” (SMALPs) which have been widely adopted to solubilize membrane proteins directly from the cell membrane. However, SMALPs are only soluble under basic conditions and precipitate in the presence of divalent cations required for many downstream applications. Here, we show that the positively charged poly(styrene-co-maleimide) (SMI) forms similar nanoparticles with comparable efficiency to SMA, whilst remaining functional at acidic pH and compatible with high concentrations of divalent cations. We have performed a detailed characterization of the performance of SMI that enables a direct comparison with similar data published for SMA. We also demonstrate that SMI is capable of extracting proteins directly from the cell membrane and can solubilize functional human G-protein coupled receptors (GPCRs) expressed in cultured HEK 293T cells. “SMILPs” thus provide an alternative membrane solubilization method that successfully overcomes some of the limitations of the SMALP method.

Publication DOI: https://doi.org/10.1039/C8NR01322E
Divisions: Life & Health Sciences > Biosciences
Life & Health Sciences
Life & Health Sciences > Cellular and Molecular Biomedicine
Additional Information: This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. Funding: This work has been supported by an Engineering and Physical Sciences Research Council (EPSRC: EP/M506461/1) and Diamond Light Source studentship for SCLH and funding from the Biotechnology and Biological Sciences Research Council (BBSRC: BB/M018261/1 [TRD], BB/J017310/1 [TRD and MW], BB/1020349/1 [MW and TRD], BB/P009840/1 [TJK] and BB/L00335X/1 [TJK]). CT acknowledges STFC BioMedNet (studentship agreement #2990) and the University of Bath for PhD studentship funding. The Medical Research Council (MRC) and AstraZeneca are thanked for supporting JC with a CASE award to MW. ECB thanks the University of Bristol for PhD studentship funding.
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Related URLs: http://pubs.rsc ... 2e#!divAbstract (Publisher URL)
Published Online Date: 2018-05-24
Authors: Hall, Stephen C.L.
Tognoloni, Cecilia
Charlton, Jack
Bragginton, Éilís C.
Rothnie, Alice J ( 0000-0002-4259-7015)
Sridhar, Pooja
Wheatley, Mark
Knowles, Timothy J.
Arnold, Thomas
Edler, Karen J.
Dafforn, Timothy R.

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