Structure of a protein determined by solid-state magic-angle-spinning NMR spectroscopy

The determination of a representative set of protein structures is a chief aim in structural genomics. Solid-state NMR may have a crucial role in structural investigations of those proteins that do not easily form crystals or are not accessible to solution NMR, such as amyloid systems 1 or membrane proteins(2-4). Here we present a protein structure determined by solid-state magic-angle-spinning (MAS) NMR. Almost complete C-13 and N-15 resonance assignments for a micro-crystalline preparation of the alpha-spectrin Src-homology 3 (SH3) domain(5) formed the basis for the extraction of a set of distance restraints. These restraints were derived from proton-driven spin diffusion (PDSD) spectra of biosynthetically site-directed, labelled samples obtained from bacteria grown using [1,3- C-13] glycerol or [2-C-13] glycerol as carbon sources. This allowed the observation of long-range distance correlations up to similar to7 Angstrom. The calculated global fold of the alpha-spectrin SH3 domain is based on 286 inter-residue C-13-C-13 and six N-15-N-15 restraints, all self-consistently obtained by solid-state MAS NMR. This MAS NMR procedure should be widely applicable to small membrane proteins that can be expressed in bacteria.