The interaction between EF-Tu X GTP and aminoacyl-tRNA is shown to be influenced by mutations at site 375 of this three-domain protein. Site 375 is located in domain II near the interface with domain I [(1984) EMBO J. 3, 113-120]. Replacement of the alanine at this site by a threonine or valine residue results in lower binding constants with Phe-tRNA and Tyr-tRNA, as was evaluated by the hydrolysis protection technique. The data are discussed in the light of what is known about the three-dimensional structure of the protein and its interaction sites with aminoacyl-tRNA.
Amino Acid Sequence Escherichia coli