Title: DNA-protein crosslinks are repaired via homologous recombination in mammalian mitochondria.
Authors: Chesner, Lisa N; Essawy, Maram; Warner, Cecilia; Campbell, Colin
Published In DNA Repair (Amst), (2021 01)
Abstract: While mammalian mitochondria are known to possess a robust base excision repair system, direct evidence for the existence of additional mitochondrial DNA repair pathways is elusive. Herein a PCR-based assay was employed to demonstrate that plasmids containing DNA-protein crosslinks are rapidly repaired following electroporation into isolated mammalian mitochondria. Several lines of evidence argue that this repair occurs via homologous recombination. First, DNA-protein crosslinks present on plasmid DNA homologous to the mitochondrial genome were efficiently repaired (21 % repair in three hours), whereas a DNA-protein crosslink present on DNA that lacked homology to the mitochondrial genome remained unrepaired. Second, DNA-protein crosslinks present on plasmid DNA lacking homology to the mitochondrial genome were repaired when they were co-electroporated into mitochondria with an undamaged, homologous plasmid DNA molecule. Third, no repair was observed when DNA-protein crosslink-containing plasmids were electroporated into mitochondria isolated from cells pre-treated with the Rad51 inhibitor B02. These findings suggest that mitochondria utilize homologous recombination to repair endogenous and xenobiotic-induced DNA-protein crosslinks. Consistent with this interpretation, cisplatin-induced mitochondrial DNA-protein crosslinks accumulated to higher levels in cells pre-treated with B02 than in control cisplatin-treated cells. These results represent the first evidence of how spontaneous and xenobiotic-induced DNA-protein crosslinks are removed from mitochondrial DNA.
PubMed ID: 33316746
MeSH Terms: Animals; Cell Line, Tumor; Cisplatin; Cricetulus/genetics; Cricetulus/metabolism; Cross-Linking Reagents; DNA Adducts*; DNA, Mitochondrial/metabolism*; HEK293 Cells; Humans; Mitochondria/genetics*; Mitochondria/metabolism; Rad51 Recombinase/metabolism*; Recombinational DNA Repair*