Mitochondrial DNA damage and mitochondrial function during acute oxidative stress induced by H2O2 in Saccharomyces cereviseae (550.4)

Base excision repair (BER) is the main repair mechanism responsible for the removal of mitochondrial DNA (mtDNA) damage, however, the relationship between mtDNA damage and mitochondrial function is not fully understood. We seek to determine the effect of mtDNA damage and mitochondrial function in yeast strains harboring mutations in BER genes after acute oxidative stress induced by H2O2. We observed that compared to a wild type (Wt) strain, mtDNA lesions after H2O2 treatment increased 4.3 fold in an ogg1∆ strain, 4.1 fold in an apn1∆ strain and 21.2 fold in a double mutant ogg1∆ apn1∆ strain. Similarly, mtDNA mutation rate increased in cells treated with H2O2 in the following manner: Wt strain, 7.7 fold; ogg1∆ strain, 11.9 fold; apn1∆ strain, 19.9 fold, and ogg1∆ apn1∆ strain, 30.6 fold. H2O2 treatment disrupted mitochondrial function as determined by mitochondrial membrane potential measurements: 15%, 15%, 10% and 24% decreased in Wt, ogg1∆, apn1∆, and ogg1∆ apn1∆, respectively. Finally, increased superoxide anion generation was observed after H2O2 treatment, particularly in the BER double mutant strain. We can conclude that an interaction between the OGG1 and APN1 genes is required for the maintenance of mitochondrial DNA integrity and function after an acute oxidative stress insult. Grant Funding Source : Supported by 5SC3GM08475902, R25GM068138 and G12RR03051