Interaction of Initiator Met-tRNAfMet (Escherichia coli) and Gly-tRNA1Gly (Staphylococcus epidermidis) with Bacterial Elongation Factor Tu: GTP Complex

Abstract
Jekowsky et al. reported recently that elongation factor Tu: GTP complex from Escherichia coli protected aminoacyl-tRNA from digestion by pancreatic RNase (1). 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× 10−7M for Ala-tRNA1Ala (Torulopsis utilis), 7.9× 10−8 M for Phe-tRNAphe (Escherichia coli), 8.1 × 10-7 M for initiator Met-tRNAfMet (Escherichia coli), and 5.4 × 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-tRNAIGly with EF-Tu: GTP even by the method of gel filtration.