A method for solution NMR structural studies of large integral membrane proteins: reverse micelle encapsulation.
The structural study of membrane proteins perhaps represents one of the greatest challenges of the post-genomic era. While membrane proteins comprise over 50% of current and potential drug targets, their structural characterization lags far behind that of soluble proteins. Nuclear magnetic resonance (NMR) offers great potential not only with respect to structural characterization of integral membrane proteins but may also provide the ability to study the details of small ligand interactions. However, the size limitations of solution NMR have restricted comprehensive structural characterization of membrane protein NMR structures to the relatively small beta-barrel proteins or helical proteins of relatively simple topology. In an effort to escape the barriers presented by slow molecular reorientation of large integral membrane proteins solubilized by detergent micelles in water, we have adapted the reverse micelle encapsulation strategy originally developed for the study of large soluble proteins by solution NMR methods. Here we review a novel approach to the solubilization of large integral membrane proteins in reverse micelle surfactants dissolved in low viscosity alkane solvents. The procedure is illustrated with a 54kDa construct of the homotetrameric KcsA potassium channel.
Kielec
Joseph M
JM
Johnson Research Foundation and Department of Biochemistry & Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania, USA 19104-6059.
Valentine
Kathleen G
KG
Wand
A Joshua
AJ
D000818:Animals; D003902:Detergents / Q000737:chemistry*; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry*; D008823:Micelles; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D017433:Protein Structure, Secondary / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology
D003902:Detergents; D008565:Membrane Proteins; D008823:Micelles