View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Elsevier - Publisher Connector Structure Article Cell-free Expressed Bacteriorhodopsin in Different Soluble Membrane Mimetics: Biophysical Properties and NMR Accessibility Manuel Etzkorn,1 Thomas Raschle,1 Franz Hagn,1 Vladimir Gelev,3 Amanda J. Rice,2 Thomas Walz,2 and Gerhard Wagner1,* 1Department of Biological Chemistry and Molecular Pharmacology 2Department of Cell Biology Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA 3FB Reagents, 267 Pearl Street, Cambridge, MA 02139, USA *Correspondence:
[email protected] http://dx.doi.org/10.1016/j.str.2013.01.005 SUMMARY polymers (amphipols) (Popot et al., 2011) or lipid bilayer nano- discs (Denisov et al., 2004) have lately received increased atten- Selecting a suitable membrane-mimicking environ- tion as promising tools for the investigation of membrane ment is of fundamental importance for the investiga- proteins (Gorzelle et al., 2002; Raschle et al., 2010; Zoonens tion of membrane proteins. Nonconventional surfac- et al., 2005). Advantages of using nonconventional membrane tants, such as amphipathic polymers (amphipols) mimetics include the exceptionally good refolding properties and lipid bilayer nanodiscs, have been introduced of amphipols for heptahelical membrane proteins such as as promising environments that may overcome G-protein-coupled receptors (GPCRs) (Dahmane et al., 2009) or the absence of detergent as well as the more native-like envi- intrinsic disadvantages of detergent micelle sys- ronment provided by nanodiscs. Additionally it has been demon- tems. However, structural insights into the effects strated that the use of nonconventional surfactants can increase of different environments on the embedded protein protein stability and improve the accessibility of the functional are limited.