MOLECULAR RECOGNITION AND EVOLUTION OF Escherichia coli TYROSINE tRNA BY TYROSYL-tRNA SYNTHETASE

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Identity determinants of Escherichia coli tRNA^Tyr were examined using in vitro transcripts. The first and second anticodon nucleotides were base-specifically involved in tRNA recognition of tyrosyl-tRNA synthetase, whereas the third anticodon nucleotide was not. None of the identity determinants were found in the acceptor stem, except the discriminator base A73. With respect to the long variable arm, a stem of three base pairs in length was required for tyrosylation, while the sequence of the arm was not essential. From the results of identity conversion experiments, the discrimination modes of tRNA^Tyr from other amino acid specific tRNAs sharing some of the identity determinants of tRNA^Tyr were discussed.