Processing of transcripts of a dimeric tRNA gene in yeast uses the nuclease responsible for maturation of the 3′ termini upon 5 S and 37 S precursor rRNAs

The rna82 mutation of Saccharomyces cerevisiae inactivates an RNA processing activity responsible for maturation of 3′-terminal sequences upon 5 S and 37 S ribosomal RNA precursors. This study describes a difference in the processing of transcripts of an S. cerevisiae dimeric tRNA gene (tRNA Arg-tRNA Asp) in RNA polymerase III in vitro transcription extracts prepared from rna82 and wild-type cells. The mutant extract accumulated additional processing intermediates containing tRNA Arg sequences as compared to the extract from wild-type cells. The structure of these intermediates revealed a defect in removal of the 10 nucleotides left 3′ to the tRNA Arg sequence by the RNase P cleavage immediately 5′ to tRNA Asp. This is the first demonstration of a mutational defect affecting maturation of 3′ sequences upon a eukaryotic tRNA precursor.