A synthetic peptide corresponding to the 550-585 region of α-dystroglycan binds β-dystroglycan as revealed by NMR spectroscopy

We have probed the binding of a synthetic peptide corresponding to the region 550-585 of the alpha subunit of dystroglycan with a recombinant protein fragment corresponding to the N-terminal extracellular region of beta -dystroglycan (654-750), using NMR in solution. In a 30:1 molar ratio, the peptide binds to the recombinant protein fragment in the fast/intermediate exchange regime, By monitoring the peptide intraresidue HN-H alpha peak volumes of the 2D TOCSY NMR spectra, both in the absence and in the presence of the recombinant fragment, we determined the differential binding affinities of each amino acid. We found that the residues in the region 550-565 (SWVQFNSNSQLMYGLP) are more influenced by the presence of the protein, whereas the C-terminal portion is marginally involved. These NMR results hale been confirmed by solid-phase binding assays. (C) 2001 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.