Dimeric tRNA precursors in yeast

Publisher Website
Google Scholar
Abstract
Two DNA fragments, each containing a tRNA3Arg and a tRNAAsp gene in close conjunction, have been isolated from different genomic regions of Saccharomyces cerevisiae1. Nucleotide sequence analysis of the gene regions revealed that in both fragments the tRNA3Arg coding region is located 5′-proximal to the tRNAAsp coding region. They are separated by an identical spacer of 10 nucleotides. Although the 5′-flanking sequences are different in the two plasmids, some similarities are observed. To test the mode of expression of this gene configuration, we transcribed the DNA fragments in a Xenopus oocyte nuclear extract2,3. Specific transcription of the yeast tRNA genes took place in an RNA precursor which comprised both tRNA species. We report here that the precursor RNA was processed to the mature-sized tRNA molecules, indicating the presence of an enzyme activity in the Xenopus nucleus capable of cutting a dimeric tRNA precursor. This is the first observation of a eukaryotic dimeric tRNA precursor.