Structure and transcription of the mitochondrial genome in heteroplasmic strains of<i>Saccharomyces cerevisiae</i>

Kang, Yijun; Miller, Donald E.

doi:10.1093/nar/17.21.8595

Cited by 5 publications

(1 citation statement)

References 43 publications

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“…Even when grown on a non-fermentable substrate, some progeny having only one or the other genome result during each culture doubling so that the pseudorevertants are unstable for respiratory growth. More recently, rare unstable pseudorevertants of a mitochondrial tRNA gene mutation were reported (7); in that case the mutant tRNA gene is evidently amplified so that its expression at a high level suppresses the original phenotypic defect. During our studies of a group of mitochondrial point mutations affecting the maturase encoded by the open reading frame of the fourth intron of the cytochrome b (cob) gene, we noted that such mutants yield numerous unstable pseudorevertants, as well as more rare stable revertants. In this paper we characterize examples of such pseudorevertants.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 1990

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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.

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Section: Introductionmentioning

confidence: 99%

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

et al. 1990

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Ordered processing of the polygenic transcripts from a mitochondrial tRNA gene cluster in K. lactis

Ragnini-Wilson

Frontali

1994

Curr Genet

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In Saccharomyces cerevisiae, transcription of the mitochondrial genome starts at multiple initiation sites and is followed by the processing of multigenic transcripts at the 5' and 3' termini of tRNA sequences and in some intergenic regions. We have used a comparative approach to investigate the structure and function of the latter processing sites. We present here an analysis of the transcripts of a cluster of tRNA genes from the mitochondrial genome of Kluyveromyces lactis. The gene order of this cluster is the same as that of the cluster in S. cerevisiae but the sequence of the intergenic regions is different. A detailed analysis of transcripts has been performed using S1 mapping and primer extension techniques. The results can be summarized as follows: (1) transcription of the cluster very probably starts at initiation sites having the nonanucleotide sequence TTATAAGTA (which acts as a promoter in S. cerevisiae) and yields polygenic transcripts; (2) processing of these transcripts seems to occur through an ordered pathway of endonucleolytic events in which some tRNA sequences are preferentially excised and some endonucleolytic cuts occur more readily than others; (3) in two intergenic regions, strong signals indicate the existence of processing events. The sequences around these sites are similar in sequence and localization to S. cerevisiae intergenic processing sites, indicating a possible functional importance in maintaining a conserved order of tRNA genes in different species of yeasts.

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Mitochondrial DNA rearrangements associated with mF plasmid integration and plasmodial longevity in Physarum polycephalum

1998

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Plasmodial cultures of Physarum polycephalum have defined life spans and undergo a reproducible decline (senescence) before losing the ability to be subcultured. Studies of the mtDNA of a long-lived Physarum strain, which does not undergo senescence, revealed a 7. 9-kb insertion in its mtDNA. This insertion is derived from a mitochondrial plasmid which enhances mitochondrial fusion and mtDNA recombination. Four different recombination events are required to convert the parental mtDNA to the form found in the long-lived strain. An additional recombination event, which deletes a 2.4-kb region of the insert from the long-lived strain, has been identified in the mtDNA of a normally senescing strain. These observations imply a mitochondrial involvement in the process of plasmodial senescence and implicate a region of the DNA derived from the mitochondrial plasmid as being necessary for plasmodial longevity.

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Structure and transcription of the mitochondrial genome in heteroplasmic strains ofSaccharomyces cerevisiae

Cited by 5 publications

References 43 publications

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

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

Ordered processing of the polygenic transcripts from a mitochondrial tRNA gene cluster in K. lactis

Mitochondrial DNA rearrangements associated with mF plasmid integration and plasmodial longevity in Physarum polycephalum

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