Divergent transcription in the yeast ribosomal RNA coding region as shown by hybridization to separated strands and sequence analysis of cloned DNA.

λ-yeast DNA hybrids containing the coding sequences for all four ribosomal RNAs from the yeast Saccharomyces cerevisiae were strand separated by the poly(rU, rG)-CsCl method. Hybridization of yeast rRNA to the separated strands indicated that the arrangement of the RNAs in the precursor transcript is 5′-18 S.5.8 S.25 S.3′ and that the 5 S rRNA, which hybridizes to the opposite strand, must be synthesized separately and in the opposite direction. The location and direction of the 5 S rRNA transcript was independently established by DNA sequence analysis. The presumptive promoter region adjacent to the 5′ end of the 5 S rRNA coding region was also sequenced.