INSERTED SEQUENCE IN THE MITOCHONDRIAL 23S RIBOSOMAL-RNA GENE OF THE YEAST SACCHAROMYCES-CEREVISIAE

The sequence organization of the yeast mit-DNA region carrying the large ribosomal RNA gene and the polar locus ω was examined. Hybridization studies using rho- deletion mutants and electron microscopy of the heteroduplexes formed between 23S rRNA and the appropriate restriction fragments, lead to the conclusion that the 23S rRNA1 gene of the ω+ strains is split by an insertion sequence of 1,000-1,100 bp. In contrast, no detactable insertion was found in the 23S rRNA gene of the ω- strains. The size and the location of the insert found in the 23S rRNA gene of the ω+ strains appear to be identical to those of the sequence Δ which had previously been found to characterize the difference (at the ω locus) between the mitDNA of the wild type strains carrying the ω+ or ω- alleles (Jacq et al., 1977). © 1979 Springer-Verlag.