The Variable Mitochondrial Genome of Ascomycetes: Organization, Mutational Alterations, and Expression

Wolf, Klaus; L, Del Giudice

doi:10.1016/s0065-2660(08)60460-5

Cited by 55 publications

(23 citation statements)

References 819 publications

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“…On the other hand, mtDNA molecules among diverse species are highly variable in size and organization (5,36). The yeast Saccharomyces cerevisiae has played the central role in studies of mtDNA heredity (for reviews, see 9, 28).…”

Section: Introductionmentioning

confidence: 99%

Structure and genetic stability of mitochondrial genomes vary among yeasts of the genus Saccharomyces

Piškur

Smole

Groth

et al. 1998

International Journal of Systematic Bacteriology

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~~Several yeast species/isolates belonging to the genus Saccharomyces were examined for the organization of their mtDNAs and ability to generate petite mutants. A general characteristic for all of the mtDNAs tested was that they were very A+T-rich. However, restriction patterns and inducibility of petite mutations revealed a great diversity in the organization and genetic behaviour of mtDNAs. One group of yeasts, Saccharomyces sensu stricto, contains mtDNA ranging in size from 64 to 85 kb. mtDNAs from these yeasts contain a high number of restriction sites that are recognized by the enzymes Haelll and Mspl, which cut specifically in G+C clusters. There are three to nine o r i h p sequences per genome. These yeasts spontaneously generate respiration deficient mutants. Ethidium bromide (Et-Br), a t low concentrations, induces a majority of cells to give rise to petites. A second group of yeasts, Saccharomyces sensu lato, contains smaller mtDNAs, ranging in size from 23 to 48 kb, and probably only a f e w intergenic G+C clusters and no ori/rep sequences. These yeasts also generate petite clones spontaneously, but Et-Br, even when present a t high concentrations, does not substantially increase the frequency of petites. In most petite clones from these yeasts only a small fragment of the wild-type molecule is retained and apparently multiplied. A third group, represented by Saccharomyces kluyveri, does not give rise to petite mutants either spontaneously or after induction.Keywords : yeast, mitochondrial genome, petite mutation, intergenic sequences, taxonomy INTRODUCTIONA remarkable aspect of mitochondrial genomes of all organisms is that they contain a very similar set of genes. On the other hand, mtDNA molecules among diverse species are highly variable in size and organization (5,36). The yeast Saccharomyces cerevisiae has played the central role in studies of mtDNA heredity (for reviews, see 9, 28). This is due mainly to the property that this yeast is a facultative anaerobe; i.e. it can survive without active mitochondria. The average cell of S. cerevisiae contains as many as 50 mtDNA molecules, but the number varies J. Piikur and others almost half of the genome, and they are usually separated from each other by over 200 G + C clusters (38). A large fraction of G + C clusters contains recognition sites for restriction enzymes splitting target sequences which contain only G and C residues, i.e.HaeIII and HpaIIIMspI (38). A special class of G + C clusters are orilrep sequences which are about 300 bp long and are present in eight copies scattered around the genome (4,40). G + C clusters can be grouped into eight families which presumably originated from a proto-G+ C cluster (38). Therefore, mtDNA contains a variety of short duplications which potentially can be involved in intramolecular recombination.S. cerevisiae spontaneously produces mutants, petites, which are deficient in the ability to respire aerobically. The spontaneous frequency is about 1 %, but upon induction with chemical mutagens, e.g. ethidium bro...

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Section: Introductionmentioning

confidence: 99%

Structure and genetic stability of mitochondrial genomes vary among yeasts of the genus Saccharomyces

Piškur

Smole

Groth

et al. 1998

International Journal of Systematic Bacteriology

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“…Indeed, such changes are prevalent in mitochondrial genomes of lower eukaryotes (2) and flowering plants (3,4). Moreover, chloroplast genomes of algae and some higher plants also show variability in size and gene order (5,6 As stated above, a special facet of the subgenomicrecombination pathway is that the original wild-type molecule must contain at least one segment that is dispensable.…”

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confidence: 99%

In vivo rearrangement of mitochondrial DNA in Saccharomyces cerevisiae.

Clark-Walker

1989

Proc. Natl. Acad. Sci. U.S.A.

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A revertant (SPR1) from a high-frequency petite strain of Saccharomyces cerevisiae has been shown by mapping and sequence analysis to have a rearranged mitochondrial genome. In vivo rearrangement has occurred through a subgenomic-recombination pathway involving the initial formation of subgenomic molecules in nascent petite mutants, recombination between these molecules to form an intermediate with direct repeats, and subsequent excision of the resident or symposed duplication to yield a molecule with three novel junctions and a changed gene order. Sequencing of the novel junctions shows that intramolecular recombination in each case occurs by means of G+C-rich short direct repeats of 40-51 base pairs. Mapping and sequence analysis also reveal that the SPR1 mitochondrial genome lacks three sectors of the wild-type molecule of 4.4, 1.7, and 0.5 kilobases. Each of these sectors occurs in nontemplate, base-biased DNA, that is over 90% A+T. Absence of these sectors together with a rearranged gene order does not appear to affect the phenotype of SPR1, as colony morphology and growth rate on a number of different substrates are not detectably different from the wild type. Lack of phenotypic change suggests that mitochondrial gene expression has not been noticeably disrupted in SPR1 despite deletion of the consensus nonomer promoter upstream from the glutamic acid tRNA gene. Dispensability of DNA sectors and the presence of recombinogenic short, direct repeats are mandatory features of the subgenomic-recombination pathway for creating rearrangements in baker's yeast mtDNA. It is proposed that, in other organisms, organelle genomes containing these elements may undergo rearrangement by the same steps.Mapping of mitochondrial genomes in yeasts has revealed that both rearrangements and length mutations are widespread (1). Indeed, such changes are prevalent in mitochondrial genomes of lower eukaryotes (2) As stated above, a special facet of the subgenomicrecombination pathway is that the original wild-type molecule must contain at least one segment that is dispensable. Potentially dispensable sectors of yeast mtDNA are the base-biased regions that comprise over half the 80-kb molecule (2, 7). These regions, up to 7 kb long in one instance, are greater than 90% A+T. Interspersed in these stretches of A+T are various G+C "clusters" of 20-50 base pairs (bp) (8). As described below, three dispensable base-biased sectors and six G+C clusters are involved in the creation of a rearranged mitochondrial genome.Formation of a mitochondrial genome containing direct duplications has been inferred from studies on high-frequency pelite-(hfp)-forming strains of Saccharomyces cerevisiae (9, 10). These respiratory competent strains have been obtained by mating nascent spontaneous petites (11). Characterization of mtDNA in hfp strains has suggested that the mitochondrial genome is composed of two subgenomic molecules (originating in the nascent petites) in equilibrium with a cointegrate (10). However, due to the large number of pet...

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“…In fungi, differences in the mitochondrial genome are much larger than those in animals . Among ascomycetes, mitochondrial DNA varies in size from 17 .6 kbp in Schizosaccharomyces pombe to 115 kbp in Cochliobolus heterostrophus (Wolf and Del Guidice 1988). In Physarum, the size of the mitochondrial genome is about 80 kbp and the copy number of the DNA molecule is about 32 per mitochondrion (Kuroiwa 1982) .…”

Section: Discussionmentioning

confidence: 99%

Direct Evidence of Mitochondrial Nuclear Division in the Ultra-micro Alga Cyanidioschyzon merolae.

et al. 1993

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Plant cells have three independent genomes: i .e., the cell-nuclear, mitochondrial and plastid genomes. Each organelle synthesizes its own DNA and divides regularly during the mitotic cycle. Studies regarding the timing of DNA synthesis and the division of mitochondria have been performed in many organisms. Kawano et al . (1983) demonstrated the presence of a mitochondrial division cycle, including mitochondrial M, G1 , S and G2 periods in the slime mold Physarum polycephalum, which clearly shows a rod-shaped mitochondrial nuclei. During the plasmodium phase, most of the mitochondria synthesized mt-DNA during the G2 period and divided semi-synchronously during the S period of the nuclear mitotic cycle . However, during the spore formation, the mitochondria only divided and did not synthesize mt-DNA .

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The Variable Mitochondrial Genome of Ascomycetes: Organization, Mutational Alterations, and Expression

Cited by 55 publications

References 819 publications

Structure and genetic stability of mitochondrial genomes vary among yeasts of the genus Saccharomyces

Structure and genetic stability of mitochondrial genomes vary among yeasts of the genus Saccharomyces

In vivo rearrangement of mitochondrial DNA in Saccharomyces cerevisiae.

Direct Evidence of Mitochondrial Nuclear Division in the Ultra-micro Alga Cyanidioschyzon merolae.

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