Properties of phenylalanine transfer ribonucleic acid with modified 3′-terminal end in protein biosynthesis using a rabbit reticulocyte cell-free system: effect of the replacement of cytidine residues from the CpCpA end of tRNA by 5-iodocytidine or 2-thiocytidine

Abstract

Phe-tRNA Phe from yeast containing 2-thiocytidine or 5-iodocytidine in position 75 of the polynucleotide chain or Phe-tRNA Phe in which both positions 74 and 75 were substituted by 5-iodocytidine were investigated in the poly U-dependent polyphenylalanine synthesis on ribosomes from rabbit reticulocytes. Phe-tRNA Phe-Cps2CpA was nearly as active as the native Phe-tRNA Phe-CpCpA in the overall process. Phe-tRNA Phe-Cpi 5CpA as well as Phe-tRNA Phe-i5Cpi 5CpA were considerably less active than the native species. Investigation of individual steps of protein biosynthesis with these modified substrates revealed that the donor activity of peptidyl-tRNAs which contain 5-iodocytidine in their 3'-terminus is strongly imparied suggesting exacting structural requirements for the interaction of the CpCpA end of tRNA with the ribosomal P-site.

Structural features in aminoacyl‐tRNAs required for recognition by elongation factor Tu

“…Phe-tRNAPhe-C?CA or PhetRNAPhe *' -1 Ci5CA are considerably less active [43] whereas Phe-tRNAPhe-C&A is nearly as active as native Phe-tRNAPhe-CCA in polypeptide synthesis [44]. Phe-tRNAPhe -Cn'CA and Phe-tRNAPhen5Cn5CA are both equally active in polypeptide synthesis [45].…”