Interaction of initiator Met-tRNArMet (Escherichia coli) and Gly-tRNAIGly (Staphylococcus epidermidis) with bacterial elongation factor Tu:GTP complex.

Jekowsky et al. reported recently that elongation factor Tu:GTP complex from Escherichia coli protected aminoacyl-tRNA from digestion by pancreatic RNase (I). On the basis of their finding, we have developed the "RNase-resistance assay" for determination of the dissociation constant of aminoacyl-tRNA from aminoacyl-tRNA:EF-Tu:GTP complex. By the use of this sensitive assay, the dissociation constants were estimated to be 3.6 x 10(-7) M for Ala-tRNA1Ala (Torulopsis utilis), 7.9 x 10(-8) M for Phe-tRNAPhe (Escherichia coli), 8.1 x 10(-7) M for initiator Met-tRNAfMet (Escherichia coli), and 5.4 x 10(-6) M for Gly-tRNA1Gly (Staphylococcus epidermidis) participating in cell wall biosynthesis. Moreover, using a relatively large amount of EF-Tu:GTP, we have been able to detect the ternary complexes of initiator Met-tRNAfMet and Gly-tRNA1Gly with EF-Tu:GTP even by the method of gel filtration.