title: NMR of Membrane Proteins: Beyond Crystals.
abstract: Membrane proteins are essential for the flow of signals, nutrients and energy between cells and between compartments of the cell. Their mechanisms can only be fully understood once the precise structures, dynamics and interactions involved are defined at atomic resolution. Through advances in solution and solid state NMR spectroscopy, this information is now available, as demonstrated by recent studies of stable peripheral and transmembrane proteins. Here we highlight recent cases of G-protein coupled receptors, outer membrane proteins, such as VDAC, phosphoinositide sensors, such as the FAPP-1 pleckstrin homology domain, and enzymes including the metalloproteinase MMP-12. The studies highlighted have resulted in the determination of the 3D structures, dynamical properties and interaction surfaces for membrane-associated proteins using advanced isotope labelling strategies, solubilisation systems and NMR experiments designed for very high field magnets. Solid state NMR offers further insights into the structure and multimeric assembly of membrane proteins in lipid bilayers, as well as into interactions with ligands and targets. Remaining challenges for wider application of NMR to membrane structural biology include the need for overexpression and purification systems for the production of isotope-labelled proteins with fragile folds, and the availability of only a few expensive perdeuterated detergents.Step changes that may transform the field include polymers, such as styrene maleic acid, which obviate the need for detergent altogether, and allow direct high yield purification from cells or membranes. Broader demand for NMR may be facilitated by MODA software, which instantly predicts membrane interactive residues that can subsequently be validated by NMR. In addition, recent developments in dynamic nuclear polarization NMR instrumentation offer a remarkable sensitivity enhancement from low molarity samples and cell surfaces. These advances illustrate the current capabilities and future potential of NMR for membrane protein structural biology and ligand discovery.
authors.affiliation: Henry Wellcome Building for Biomolecular NMR Spectroscopy, School of Cancer Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
authors.forename: Sundaresan
authors.initials: S
authors.lastname: Rajesh
authors.affiliation: Faculty of Medicine & Dentistry, Department of Biochemistry, University of Alberta, Edmonton, AB, T6G 2H7, Canada. overduin@ualberta.ca.
authors.forename: Michael
authors.initials: M
authors.lastname: Overduin
authors.affiliation: School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, NG7 2UH, UK. boyan.bonev@nottingham.ac.uk.
authors.forename: Boyan B
authors.initials: BB
authors.lastname: Bonev
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000737:chemistry / Q000648:ultrastructure; D006801:Humans; D007553:Isotope Labeling / Q000379:methods; D009682:Magnetic Resonance Spectroscopy / Q000295:instrumentation / Q000379:methods*; D008565:Membrane Proteins / Q000737:chemistry*; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D000072417:Protein Domains; D017510:Protein Folding; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D012984:Software
chemical_list: D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins
keywords: High resolution NMR; Membrane targets; Protein interactions; Protein structure; Solid state NMR