Efficient aminoacylation of a yeast tRNAAsptranscript with a 5' extension

A yeast aspartic acid tRNA with a 5' extension of 14 nucleotides was obtained by in vitro transcription with T7 DNA dependent RNA polymerase. This transcript, called extended tRNA Asp transcript, retains its aspartylation capacity with the same K m and only three times reduced k cal values as compared to those measured for canonical tRNA Asp . This result indicates that the 5' extension of the amino acid acceptor stem of tRNA Asp does not interfere with recognition by aspartyl-tRNA synthetase. However, in contrast to the wild-type tRNA Asp transcript, the 5' extended molecule presents a reduced capacity to be mischarged by arginyl-tRNA synthetase, suggesting the existence of different structural requirements in aspartyland arginyl-tRNA synthetases for tRNA Asp recognition.