Novel hybrid maturases in unstable pseudorevertants of maturaseless mutants of yeast mitochondrial DNA

Abstract

Unstable pseudorevertants of mitochondrial mutants of Saccharomyces cerevisiae lacking the maturase function encoded by the fourth intron of the cytochrome b gene (bl4) were isolated. They were found to be heteroplasmic cells owing their regained ability to respire (and grow on glycerol medium) to the presence of a rearranged (rho) mtDNA that contains an in-frame fusion of the reading frames of the group I introns bl4 and intron 4a of the coxl gene encoding subunit I of cytochrome c oxidase (al4