Yeast mitochondrial genomes consisting of only A.T base pairs replicate and exhibit suppressiveness.
Mutants, called p-, that result from extensive deletions of the 75-kilobase Saccharomyces cerevisiae mitochondrial genome arise at high frequency. The remaining mitochondrial DNA is amplified in the p- cells, often as head-to-tail multimers, producing a cell with the normal amount of mitochondrial DNA. In matings, some of these p- mutants exhibit zygotic hypersuppressiveness, excluding the wild-type mitochondrial genome (p+) from all the diploids that are produced. From a hypersuppressive p- strain, we isolated two mutants with reduced suppressiveness. These mutants, one moderately suppressive and one nonsuppressive, retain only 89 and 70 base pairs, respectively, of the wild-type mitochondrial genome. Their sequences consist of 100% A . T base pairs. Replication of DNA in the mitochondrion, formation and amplification of new deletion genomes, and exhibition of suppressiveness do not require a single G . C base pair.
D001483:Base Sequence; D004261:DNA Replication; D004271:DNA, Fungal / Q000235:genetics*; D004272:DNA, Mitochondrial / Q000235:genetics*; D005786:Gene Expression Regulation; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D013489:Suppression, Genetic
D004271:DNA, Fungal; D004272:DNA, Mitochondrial