Role of Yeast Peptide Elongation Factor 3 (EF-3) at the AA-tRNA Binding Step1

Abstract

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)

Functional interactions of an Escherichia coli ribosomal ATPase

“…According to the`allosteric three-site' model of elongation, this would also increase aminoacyl-tRNA binding at the A site. EF-3 was shown previously to facilitate EF-1 A (EF-Tu)-dependent binding of aminoacyl-tRNA to the A site [38].…”

Moonlighting Functions of Polypeptide Elongation Factor 1: From Actin Bundling to Zinc Finger Protein R1-Associated Nuclear Localization

“… Animal:``GDP W GTP exchange'' S1 [12] EF-1b (eEF1Ba) ``GDP W GTP exchange'' S1, 3 [12,35]  Fungi: stimulation of``aa-tRNA binding'' S1 [13][14][15] * New nomenclature of EF is shown in parentheses.…”

“…EF-3 has been detected only in fungi. 14) It has a molecular mass of 116 kDa in yeast and has ribosome-dependent ATPase activity. EF-3 stimulates the binding of EF-1a・GTP・aa-tRNA to the ribosomal A-site 14) by facilitating release of deacylated tRNA from the E-site on the ribosome.…”

“…14) It has a molecular mass of 116 kDa in yeast and has ribosome-dependent ATPase activity. EF-3 stimulates the binding of EF-1a・GTP・aa-tRNA to the ribosomal A-site 14) by facilitating release of deacylated tRNA from the E-site on the ribosome. 15) In the last decade, EF-1a was shown to have remarkable functions in addition to its role in translation (Table 1).…”

A monoclonal antibody specific for carboxy‐terminal region of yeast translation elongation factor‐3 inhibits ribosome‐activated ATPase activity but not intrinsic ATPase activity

“…EF-3 is specific to yeasts and fungi, while EF-1 and EF-2 are common to all organisms (in prokaryotes, the counterparts of EF-1 and EF-2 are referred to as EFT and EF-G, respectively). Biochemical characterization of purified EF-3 from Saccharomyces (1,(6)(7)(8)(9)(10)(11), Schizosaccharomyces (7) and Candida (12) has clarified the following points. EF-3 is-a single polypeptide with a molecular weight of about 125,000.…”