A 5 kb intergenic region containing ori1 in the mitochondrial DNA of Saccharomyces cerevisiae is dispensable for expression of the respiratory phenotype.

A mutant mitochondrial DNA of Saccharomyces cerevisiae strain R 0.54 has been shown to have a 5 kb deletion which removes the ori1 sequence and its surrounding intergenic sequences between the pro tRNA and 15 S rRNA genes. The deleted DNA has been sequenced and is found to be flanked by two 11 bp direct repeats. The deletion mutant displays a normal phenotype in non-fermentable media. This implies that the intergenic sequence is not required for expression of the respiratory phenotype.