Structure and processing of yeast precursor tRNAs containing intervening sequences

Abstract

We have isolated a precursor of yeast tRNA^Tyr and shown that it contains an intervening sequence identical to that found in the gene for tRNA^Tyr. The conformation of pre-tRNA^Tyr is similar to that of mature tRNA^Tyr except for the anticodon loop. The loop is sensitive to endonucleolytic cleavage by S₁ nuclease near to the ends of the intervening sequence. This pre-tRNA is functionally inactive as it cannot be aminoacylated and the anticodon is not accessible for hydrogen bonding. A crude nuclear extract from yeast contains an excision-ligase activity which will process pre-tRNA^Tyr into mature tRNA^Tyr.