title: Oxidative DNA damage causes mitochondrial genomic instability in Saccharomyces cerevisiae.
abstract: Mitochondria contain their own genome, the integrity of which is required for normal cellular energy metabolism. Reactive oxygen species (ROS) produced by normal mitochondrial respiration can damage cellular macromolecules, including mitochondrial DNA (mtDNA), and have been implicated in degenerative diseases, cancer, and aging. We developed strategies to elevate mitochondrial oxidative stress by exposure to antimycin and H(2)O(2) or utilizing mutants lacking mitochondrial superoxide dismutase (sod2Delta). Experiments were conducted with strains compromised in mitochondrial base excision repair (ntg1Delta) and oxidative damage resistance (pif1Delta) in order to delineate the relationship between these pathways. We observed enhanced ROS production, resulting in a direct increase in oxidative mtDNA damage and mutagenesis. Repair-deficient mutants exposed to oxidative stress conditions exhibited profound genomic instability. Elimination of Ntg1p and Pif1p resulted in a synergistic corruption of respiratory competency upon exposure to antimycin and H(2)O(2). Mitochondrial genomic integrity was substantially compromised in ntg1Delta pif1Delta sod2Delta strains, since these cells exhibit a total loss of mtDNA. A stable respiration-defective strain, possessing a normal complement of mtDNA damage resistance pathways, exhibited a complete loss of mtDNA upon exposure to antimycin and H(2)O(2). This loss was preventable by Sod2p overexpression. These results provide direct evidence that oxidative mtDNA damage can be a major contributor to mitochondrial genomic instability and demonstrate cooperation of Ntg1p and Pif1p to resist the introduction of lesions into the mitochondrial genome.
authors.affiliation: Department of Biochemistry, Graduate Program in Genetic and Molecular Biology, Emory University School of Medicine, 4013 Rollins Research Center, Atlanta, GA 30322, USA.
authors.forename: Nicole A
authors.initials: NA
authors.lastname: Doudican
authors.forename: Binwei
authors.initials: B
authors.lastname: Song
authors.forename: Gerald S
authors.initials: GS
authors.lastname: Shadel
authors.forename: Paul W
authors.initials: PW
authors.lastname: Doetsch
mesh_terms: D000968:Antimycin A / Q000031:analogs & derivatives* / Q000494:pharmacology; D019069:Cell Respiration / Q000502:physiology*; D004249:DNA Damage; D004265:DNA Helicases / Q000235:genetics / Q000378:metabolism; D004260:DNA Repair; D004272:DNA, Mitochondrial / Q000378:metabolism*; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D042822:Genomic Instability; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008928:Mitochondria / Q000187:drug effects / Q000201:enzymology / Q000235:genetics; D009699:N-Glycosyl Hydrolases / Q000235:genetics / Q000378:metabolism; D016877:Oxidants / Q000494:pharmacology; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D017354:Point Mutation; D017382:Reactive Oxygen Species / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D000099156:Superoxide Dismutase 2
chemical_list: D000968:Antimycin A; D004265:DNA Helicases; D004272:DNA, Mitochondrial; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D006861:Hydrogen Peroxide; D009699:N-Glycosyl Hydrolases; D016877:Oxidants; D017382:Reactive Oxygen Species; D029701:Saccharomyces cerevisiae Proteins; D013482:Superoxide Dismutase; D000099156:Superoxide Dismutase 2; C032456:antimycin; C085463:PIF1 protein, S cerevisiae; C101825:NTG1 protein, S cerevisiae