Study of the interaction between uncharged yeast tRNAPhe and elongation factor Tu from Bacillus stearothermophilis

Proton NMR studies are presented on the interaction of nonaminoacylated yeast tRNAPhe and elongation factor Tu X GTP from Bacillus stearothermophilis. From experiments in which transfer of magnetization is observed between proton spins of tRNA and the protein, it is concluded that complex formation takes place. Amino acid residues of the protein come into close contact with the base pair A5U68 and/or U52A62 of the acceptor T psi C limb of the tRNA molecule. From the line broadening of tRNA resonances, associated with complex formation, an association constant of 10(3)-10(4) M-1 is estimated. The NMR experiments do not monitor a significant conformational change of the tRNA molecule upon interaction with the protein. However, at times long after the onset of complex formation, spectral changes indicate that the upper part of the acceptor helix becomes distorted.