Magic angle spinning carbon-13 NMR analysis of the complex of elongation factor Tu, GTP and (1-carbon-13) phenylalanyl-tRNA-Phe

The chemical environment of the single carbonyl 13C atom in the ternary complex EF-Tu cntdot GTP cntdot (1-13C)Phe-tRNA-Phe was studied with magic angle spinning NMR. This technique enables high-resolution NMR in solids or in frozen solutions, the latter permitting analysis of labile macromolecular complexes under -100 degree C storage conditions. We found indications for multiple conformations in the immediate vicinity of the aminoacyl ester bond in the complex at these low temperatures. In contrast to earlier thoughts, our data do not indicate a major role of the carbonyl oxygen in the binding of Phe-tRNA to EF-Tu cntdot GTP.