Inserted sequence in the mitochondrial 23S ribosomal RNA gene of the yeast Saccharomyces cerevisiae

Abstract

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).