Crystallogenesis of Membrane Proteins Mediated by Polymer-Bounded Lipid Nanodiscs.
Broecker, J., Eger, B.T., Ernst, O.P.(2017) Structure 25: 384-392
- PubMed: 28089451 
- DOI: https://doi.org/10.1016/j.str.2016.12.004
- Primary Citation of Related Structures:  
5ITC, 5ITE - PubMed Abstract: 
For some membrane proteins, detergent-mediated solubilization compromises protein stability and functionality, often impairing biophysical and structural analyses. Hence, membrane-protein structure determination is a continuing bottleneck in the field of protein crystallography. Here, as an alternative to approaches mediated by conventional detergents, we report the crystallogenesis of a recombinantly produced membrane protein that never left a lipid bilayer environment. We used styrene-maleic acid (SMA) copolymers to solubilize lipid-embedded proteins into SMA nanodiscs, purified these discs by affinity and size-exclusion chromatography, and transferred proteins into the lipidic cubic phase (LCP) for in meso crystallization. The 2.0-Å structure of an α-helical seven-transmembrane microbial rhodopsin thus obtained is of high quality and virtually identical to the 2.2-Å structure obtained from traditional detergent-based purification and subsequent LCP crystallization.
Organizational Affiliation: 
Structural Neurobiology, Department of Biochemistry, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada. Electronic address: jana.broecker@utoronto.ca.