Role of yeast peptide elongation factor 3 (EF-3) at the AA-tRNA binding step.
The stimulatory effect of peptide elongation factor 3 (EF-3), which is uniquely required for the yeast elongation cycle, on the step of binding of aminoacyl-tRNA (AA-tRNA) to ribosomes has been investigated in detail. Yeast EF-1 alpha apparently functions in a stoichiometric manner in the binding reaction of AA-tRNA to the ribosomes. The addition of EF-3 and ATP to this binding system strikingly stimulated the binding reaction, and the stimulated reaction proceeded catalytically with respect to both EF-1 alpha and EF-3, accompanied by ATP hydrolysis, indicating that EF-3 stimulated the AA-tRNA binding reaction by releasing EF-1 alpha from the ribosomal complex, thus recycling it. This binding stimulation by EF-3 was in many respects distinct from that by EF-1 beta gamma. The idea that EF-3 may participate in the regeneration of GTP from ATP and the formed GDP, as indicated by the findings that the addition of EF-3 along with ATP allowed the AA-tRNA binding and Phe polymerization reactions to proceed even in the presence of GDP in place of GTP, was not verified by the results of direct measurement of [32P]GTP formation from [gamma-32P]ATP and GDP under various conditions. Examination of the stability of the bound AA-tRNA disclosed the different binding states of AA-tRNA on ribosomes between in the cases of the complexes formed with EF-1 alpha alone, or factor-independently, and with EF-1 alpha and EF-3.(ABSTRACT TRUNCATED AT 250 WORDS)
Uritani
M
M
Department of Molecular Biology, School of Science, Nagoya University, Aichi.
Miyazaki
M
M
D005656:Fungal Proteins; D007700:Kinetics; D010303:Paromomycin / Q000494:pharmacology; D010445:Peptide Elongation Factors / Q000378:metabolism*; D011072:Poly U; D011485:Protein Binding; D012346:RNA, Transfer, Amino Acyl / Q000378:metabolism*; D012360:RNA, Transfer, Phe / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D046249:Transfer RNA Aminoacylation
D005656:Fungal Proteins; D010445:Peptide Elongation Factors; D012346:RNA, Transfer, Amino Acyl; D012360:RNA, Transfer, Phe; D029701:Saccharomyces cerevisiae Proteins; C111584:YEF3 protein, S cerevisiae; D011072:Poly U; D010303:Paromomycin