title: 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 (bI4) 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 bI4 and intron 4 alpha of the coxl gene encoding subunit I of cytochrome c oxidase (aI4 alpha). The products of those gene fusions suppress the bI4 maturase deficiency still present in those heteroplasmic cells. Similar heteroplasmic pseudorevertants of a group II maturaseless mutant of the first intron of the coxI gene were characterized; they result from partial deletion of the coxI gene that fuses the reading frames of introns 1 and 2. These heteroplasms provide independent support for the existence of RNA maturases encoded by group I and group II introns. Also, since the petite/mit- heteroplasms arise spontaneously at very high frequencies they provide a system that can be used to obtain mutants unable to form or maintain heteroplasmic cells.
authors.affiliation: Molecular Cellular and Developmental Biology Program, Ohio State University, Columbus 43210-1292.
authors.forename: P Q
authors.initials: PQ
authors.lastname: Anziano
authors.forename: J V
authors.initials: JV
authors.lastname: Moran
authors.forename: D
authors.initials: D
authors.lastname: Gerber
authors.forename: P S
authors.initials: PS
authors.lastname: Perlman
mesh_terms: D001483:Base Sequence; D003470:Culture Media; D003573:Cytochrome b Group / Q000235:genetics*; D004271:DNA, Fungal / Q000235:genetics; D004272:DNA, Mitochondrial / Q000235:genetics*; D004722:Endoribonucleases / Q000235:genetics*; D005800:Genes, Fungal; D007438:Introns; D008969:Molecular Sequence Data; D009154:Mutation; D009713:Nucleotidyltransferases / Q000235:genetics*; D012150:Polymorphism, Restriction Fragment Length; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000254:growth & development
chemical_list: D003470:Culture Media; D003573:Cytochrome b Group; D004271:DNA, Fungal; D004272:DNA, Mitochondrial; D009713:Nucleotidyltransferases; C034038:mRNA maturase; D004722:Endoribonucleases