Localization of the Binding Site for the Oligosaccharide Moiety of Gb₃ on Verotoxin 1 Using NMR Residual Dipolar Coupling Measurements

Abstract

By use of NMR residual dipolar coupling measurements in a dilute liquid-crystalline solvent, the solution structure has been determined of the complex between the oligosaccharide moiety of globotriaosylceramide (Gb(3)-OS) and the B-subunit homopentamer of verotoxin 1 (VTB). The dipolar coupling data indicate that Gb(3)-OS binds in a single binding site per monomer, which is identical to one of three sites inferred from the X-ray structure of the same complex. We find no evidence within experimental error for occupancy at either of the two additional binding sites observed per monomer in the crystal structure.