Enhanced expression of the DNA damage-inducible gene DIN7 results in increased mutagenesis of mitochondrial DNA in Saccharomyces cerevisiae
| Autor: | Piotr Koprowski, M. U. Fikus, J. Lazowska, Piotr Dzierzbicki, Zygmunt Ciesla, Piotr A. Mieczkowski |
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| Rok vydání: | 2003 |
| Předmět: |
Mitochondrial DNA
Saccharomyces cerevisiae Proteins Base Sequence DNA repair DNA damage Mutant Genes Fungal Mutagenesis (molecular biology technique) General Medicine Saccharomyces cerevisiae Mitochondrion Biology Molecular biology DNA Mitochondrial Exodeoxyribonucleases Mutagenesis Genetics DNAJA3 Molecular Biology Gene Sequence Alignment Conserved Sequence DNA Damage |
| Zdroj: | Molecular genetics and genomics : MGG. 269(5) |
| ISSN: | 1617-4615 |
| Popis: | We reported previously that the product of DIN7, a DNA damage-inducible gene of Saccharomyces cerevisiae, belongs to the XPG family of proteins, which are involved in DNA repair and replication. This family includes the S. cerevisiae protein Rad2p and its human homolog XPGC, Rad27p and its mammalian homolog FEN-1, and Exonuclease I (Exo I). Interestingly, Din7p is the only member of the XPG family which specifically functions in mitochondria. We reported previously that overexpression of DIN7 results in a mitochondrial mutator phenotype. In the present study we wished to test the hypothesis that this phenotype is dependent on the nuclease activity of Din7p. For this purpose, we constructed two alleles, din7-D78A and din7-D173A, which encode proteins in which highly conserved aspartates important for the nuclease activity of the XPG proteins have been replaced by alanines. Here, we report that overexpression of the mutant alleles, in contrast to DIN7, fails to increase the frequency of mitochondrial petite mutants or erythromycin-resistant (Er) mutants. Also, overproduction of din7-D78Ap does not result in destabilization of poly GT tracts in mitochondrial DNA (mtDNA), the phenotype observed in cells that overexpress Din7p. We also show that petite mutants induced by enhanced synthesis of wild-type Din7p exhibit gross rearrangements of mtDNA, and that this correlates with enhanced recombination within the mitochondrial cyt b gene. These results suggest that the stability of the mitochondrial genome of S. cerevisiae is modulated by the level of the nuclease Din7p. |
| Databáze: | OpenAIRE |
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