Alterations at the 3′-CCA end of Escherichia coli and Thermus thermophilus tRNAPhe do not abolish their acceptor activity

Abstract The 3′-CCA end of tRNA Phe from Escherichia coli and Thermus thermophilus was changed to AAA, CCC, UUU and UUA by the stepwise degradation procedure of the 3′-CCA end of tRNA Phe followed by the ligation with oligoribotrinucleotides. Substrate activity of tRNAU Phe UUA and tRNA Phe CCC in tRNA aminoacylation was shown. tRNA Phe AAA is a bad substrate for E. coli and Th. thermophilus phenylalanyl-tRNA synthetases. tRNA Phe UUU has no detectable activity in tRNA aminoacylation. Therefore the nature of the 3′-end of tRNA Phe plays an important role in tRNA binding and its substrate efficiency. Nevertheless the CCA sequence at the 3′-end of tRNA Phe does not seem to be an absolute requirement for tRNA aminoacylation.