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Requirement of the Saccharomyces cerevisiae APN1 gene for the repair of mitochondrial DNA alkylation damage
Author(s) -
AcevedoTorres Karina,
FonsecaWilliams Sharon,
AyalaTorres Sylvette,
TorresRamos Carlos A.
Publication year - 2009
Publication title -
environmental and molecular mutagenesis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1
H-Index - 87
eISSN - 1098-2280
pISSN - 0893-6692
DOI - 10.1002/em.20462
Subject(s) - mitochondrial dna , biology , dna repair , methyl methanesulfonate , dna damage , microbiology and biotechnology , genetics , base excision repair , mutation , dna glycosylase , mitochondrion , dna , gene
The Saccharomyces cerevisiae APN1 gene that participates in base excision repair has been localized both in the nucleus and the mitochondria. APN1 deficient cells ( apn1 Δ) show increased mutation frequencies in mitochondrial DNA (mtDNA) suggesting that APN1 is also important for mtDNA stability. To understand APN1 ‐dependent mtDNA repair processes we studied the formation and repair of mtDNA lesions in cells exposed to methyl methanesulfonate (MMS). We show that MMS induces mtDNA damage in a dose‐dependent fashion and that deletion of the APN1 gene enhances the susceptibility of mtDNA to MMS. Repair kinetic experiments demonstrate that in wild‐type cells (WT) it takes 4 hr to repair the damage induced by 0.1% MMS, whereas in the apn1 Δ strain there is a lag in mtDNA repair that results in significant differences in the repair capacity between the two yeast strains. Analysis of lesions in nuclear DNA (nDNA) after treatment with 0.1% MMS shows a significant difference in the amount of nDNA lesions between WT and apn1 Δ cells. Interestingly, comparisons between nDNA and mtDNA damage show that nDNA is more sensitive to the effects of MMS treatment. However, both strains are able to repair the nDNA lesions, contrary to mtDNA repair, which is compromised in the apn1 Δ mutant strain. Therefore, although nDNA is more sensitive than mtDNA to the effects of MMS, deletion of APN1 has a stronger phenotype in mtDNA repair than in nDNA. These results highlight the prominent role of APN1 in the repair of environmentally induced mtDNA damage. Environ. Mol. Mutagen., 2009. © 2009 Wiley‐Liss, Inc.