The nucleotide sequence of a serine transfer ribonucleic acid from Escherichia coli.

Several approaches have yielded information on those features of tRNA structure responsible for the specific recognition of a tRNA by its cognate aminoacyl-tRNA synthetase (l-3). One method has involved comparison of the nucleotide sequences of different tRNAs (isoaccepting species) which are recognized by a single enzyme (4). Thus, a comparison of the sequences of those homologous and heterologous tRNA species which are charged by the yeast phenylalanyl-tRNA synthetase has suggested a possible recognition sequence for this enzyme (5, 6). However, the optimal conditions and rates of reaction of mischarging experiments are, in many cases, very different from those of the homologous aminoacylation. The existence of iso-accepting tRNA species from the same organism enables’ a comparison of tRNAs which undergo the same specific in vivo aminoacylation. Escherichia coli contains three serine accepting tRNAs, recognizing the codons [UCY],l [UCR], and [AGY]. The nucleotide sequence of the first species tRNArSe’, decoding [UCY], has been determined (7) and we report here the determination of the sequence of tRNAaser which decodes [AGY].