[Poly(U)-dependent interaction of yeast tRNA(Phe) and its fragments with Escherichia coli ribosomes. II. Localization of tRNA binding centers with a P-site].

Poli(U)-dependent binding of yeast tRNA(Phe) lacking the 3'-terminal CA or CCA residues, and fragments of tRNA prepared by splitting the tRNA(Phe) at the G18 or 7mG46 nucleotides, to the 70S ribosomal P-site was studied. Equilibrium binding constants and free energies of binding were measured. The contribution of C74 and C75 was estimated at 3.9 kJ/mol and 3.0 kJ/mol, respectively, at 10 mM Mg2+ and 30 degrees C. The free energies of the binding of the anticodon arm the tRNA lacking its CCA terminus, and the tRNA fragment containing bases N1-N45 were found to be nearly equal. These results indicate that only the anticodon arm and the CCA terminus take part in deacylated tRNA-P-site interaction.