Putative origins of replication in the mitochondrial genome of yeast

Zamaroczy, Miklos de; Baldacci, Giuseppe; Bernardi, Giorgio

doi:10.1016/0014-5793(79)80580-3

Cited by 44 publications

(18 citation statements)

References 11 publications

(11 reference statements)

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“…When a petite is crossed with a wild-type cell, the replication rate of its genome is the main factor in determining its level of transmission to the progeny. As expected, suppressivity can range from almost 100%, in the case of certain ori+ petites, which we have called super-suppressive, (de Zamaroczy et al, 1979;Goursot et al, 1980;Bernardi et al, 1980; these petites have been called hyper-suppressive by Blanc and Dujon, 1980) to almost 0% in the case of some orin petites. It is of interest to note that the different replication rates associated with different ori sequence situations are paralleled by similar changes in transcription; in particular, ori°genomes are transcribed at a minimal level, if at all (Baldacci and Bernardi, in preparation).…”

Section: Introductionsupporting

confidence: 69%

“…The last step is the segregation of defective genome units into the buds formed by the wild-type cell; further segregation of these genome units in the progeny leads to the formation of petite mutants, whose mitochondrial genome is formed by identical defective units. We have shown that the excised segment usually carries one (or more) of the seven canonical origins of replication that we have sequenced, localized, and oriented on the wildtype genome (de Zamaroczy et al, 1979; 1980; Bernardi et al, 1980;see Figure 1); in this case, ori+ petite genomes are produced.…”

Section: Introductionmentioning

confidence: 83%

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Surrogate origins of replication in the mitochondrial genomes of ori-zero petite mutants of yeast.

Goursot¹,

Mangin²,

Bernardi³

1982

The EMBO Journal

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We have investigated the mitochondrial genome of eight oril spontaneous petite mutants of Saccharomyces cerevisiae. The tandem repeat units of these genomes do not contain any of the seven canonical ori sequences of the wild-type genome. Instead, they contain one, or more, oris sequences. These 44-nucleotide long surrogate origins of replication are a subset of GC clusters characterized by a potential secondary fold with two sequences ATAG and GGAG, inserted in AT spacers, two AT base pairs just following them, a GC stem (broken in the middle, and, in most cases also near the base, by non-paired nucleotides), and a terminal loop. This structure is reminiscent of that of GC clusters A and B from canonical ori sequences and supports the view (Bernardi, 1982a) that the GC clusters of the mitochondrial genome arose, by an expansion process, from the canonical ori sequences. Like the latter, oris sequences are present in both orientations, are located in intergenic regions, and can be used as excision sequences when tandemly oriented. Again as in the case of canonical ori sequences, the density of orls sequences on the repeat units of petite genomes are correlated with the replication efficiency of the latter, as assessed by the outcome of crosses with wild-type or petite tester strains.

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Section: Introductionsupporting

confidence: 69%

Section: Introductionmentioning

confidence: 83%

Surrogate origins of replication in the mitochondrial genomes of ori-zero petite mutants of yeast.

Goursot¹,

Mangin²,

Bernardi³

1982

The EMBO Journal

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“…There is no evidence for plasmid integration into nuclear or mtDNA. Recombinant plasmids containing heterologous mtDNA from Xenopus laevis (29) (22,30,31). Crosses ofHS petiteswith p+ cells give rise to nearly 100% p-diploids containing amplified mtDNA contributed by the HS parent.…”

Section: Discussionmentioning

confidence: 99%

Properties of a Saccharomyces cerevisiae mtDNA segment conferring high-frequency yeast transformation.

Hyman¹,

Cramer²,

Rownd³

1982

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

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The bakers' yeast Saccharomyces cerevsiae is a facultative anaerobe, tolerant to mutations in its mitochondrial genome. Individual cytoplasmic petite mutants retain genetic information derived from any portion of the parental mtDNA, prompting questions concerning distribution of the DNA replication origin(s) on the yeast mitochondrial genome. The experiments described in this paper were designed to test the possibility of using high-frequency yeast transformation as a selection for yeast mtDNA sequences conferring autonomously replicating function. A complete petite mitochondrial genome was inserted into the yeast vector YIp5, and the hybrid plasmid (YRMpl) was used to transform yeast. YRMpl promoted high-frequency transformation ofboth wild-type yeast cells and petite mutant hosts lacking mtDNA and was maintained in each of these strains as a highcopy-number extrachromosomal element. The stability and copynumber properties of YRMpl are similar to those of YRp12, a recombinant plasmid containing a yeast chromosomal autonomously replicating sequence. sequence (ars) are able to transform yeast at high frequency, a readily selectable property (10). This rationale has been used to isolate putative DNA replication origins from yeast chromosomes (11,12) and from a wide variety of heterologous eukaryotic genomes (13).The experiments described here were undertaken to isolate and map yeast mtDNA sequences that are ars elements as assayed by high-frequency yeast transformation. Since many individual petite mtDNAs exist in vivo as amplified tandemly repeated segments (2), it was anticipated that the repetitive nature of these mitochondrial genomes might provide an enriched source ofDNA replication origins. We have shown that a cloned intact petite genome is capable of conferring ars characteristics to a nonreplicating vector and that ars properties of this cloned segment, such as mitotic stability and copy number, are similar to those of the chromosomal DNA sequence TRPl-arsl (7,8,10 Ag of DNA) as a result of stable integration into host cell chromosomal DNA. A few yeast sequences transform at high frequency (500-20,000 transformants per ,g of DNA) and are maintained within the cell as extrachromosomal elements. These properties result from the presence on the transforming plasmid of a DNA sequence conferring autonomously replicating functions (7-9). Hybrid molecules that combine a low-frequency transforming plasmid with an autonomously replicating MATERIALS AND METHODS Strains and Culture Conditions. The p-petite mutant A17-10 was isolated after ethidium bromide mutagenesis of S. cerevisiae strain A10 (a his ade p+). JHC8-24C (a ura3-52 his3-11 his3-15 leu2-3 leu2-112 inol -13 ino4-8 p+) and an ethidium bromide-induced p0 derivative served as hosts in yeast transformation experiments. Bacterial cloning was carried out in a thymine-requiring derivative ofEscherichia coli HB101 (14). Yeast culture media were used as described (15) Rapid Yeast DNA Preparation. High-molecular-weight total cellular DNA was prepared fr...

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“…Assuming that a close association between the DNA-synthesizing machinery and the enzymes rent mit+ alleles in providing the DNA precursors is needed, then if M80-4D) afer one and this association is not formed, the DNA-syntheformyl tetrahydrofo-sizing machinery will be deranged. Some DNA :titerationpture toh will still be formed, especially the DNA region D the different ts o containing the paromomycin resistance marker rol; td one genera-(which is included as one of the putative origins of replication [9]). This is seen by the preferential maintenance of the genetic markers pr and mit+ allele tscsl297 and by the preferential deletion of the region beginning with E, C, and be maintained as tscs9O2 and continuing to tscs983 and O.…”

Section: Discussionmentioning

confidence: 99%

Influence of the nuclear gene tmp3 on the loss of mitochondrial genes in Saccharomyces cerevisiae.

Zelikson¹,

Luzzati²

1982

Mol. Cell. Biol.

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The Saccharomyces cerevisiae tmp3 mutant is deficient in the mitochondrial enzyme complex that participates in the formation of one-carbon-group-tetrahydrofolate coenzymes, serine transhydroxymethylase, dihydrofolate reductase, and thymidylate synthetase, thus leading to multiple nutritional requirements of dTMP, adenine, histidine, and methionine. The tmp3 mutant quickly loses its mitochondrial genome even when grown on fully supplemented medium or on a high concentration of 5-formyl tetrahydrofolate, which replaces all the four requirements. A study of the loss of the mitochondrial genome by following several mitochondrial genetic markers showed that there was a preferential specific loss of a large region of the mitochondrial genome, covering mit ts983, E, Cr, and mit ts982 up to Or, and retention of the region of pr and mit tscs1297. A kinetic study showed that there was a preferentially rapid loss of the region covering the mit+ alleles ts983 to tscs9O2 at the rate of 10%o per generation.Inhibition of DNA synthesis in Saccharomyces cerevisiae cells, either by limitation of the precursor supply (4) or by deficiencies in other functions needed for its synthesis, such as cdc8 (19), results in the formation of respiratorydeficient cells.The loss of mitochondrial DNA and the formation of respiration-deficient strains in S. cerevisiae grown in the presence of antifolate drugs (5, 6, 22, 23) is due to the limitation of tetrahydrofolate formation and, hence, of 5,10-methylene tetrahydrofolate and l1-formyl tetrahydrofolate needed for the biosynthesis of both DNA and protein.A similar formation of respiratory-deficient cells by mutations leading to a limitation in the formation of thymidylate was described in mutants bearing tmpl allelic to cdc21 (4, 19) in fol mutants (15), and in tmp3 mutants (16).There are two types of mutants which are deficient in dTMP formation. The first one, tmpl, is deficient in thymidylate synthetase (2,12

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Putative origins of replication in the mitochondrial genome of yeast

Cited by 44 publications

References 11 publications

Surrogate origins of replication in the mitochondrial genomes of ori-zero petite mutants of yeast.

Surrogate origins of replication in the mitochondrial genomes of ori-zero petite mutants of yeast.

Properties of a Saccharomyces cerevisiae mtDNA segment conferring high-frequency yeast transformation.

Influence of the nuclear gene tmp3 on the loss of mitochondrial genes in Saccharomyces cerevisiae.

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