DNA-protein crosslinks are repaired via homologous recombination in mammalian mitochondria

Lisa N. Chesner, Maram Essawy, Cecilia Warner, Colin Campbell

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


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.

Original languageEnglish (US)
Article number103026
JournalDNA Repair
StatePublished - Jan 1 2021

Bibliographical note

Funding Information:
This work was funded by the National Institutes of Health ( ES023350 ). Lisa N. Chesner and Maram Essawy were supported by Training Grant 5T32HL007741 . Funding for open access charge: National Institutes of Health.

Publisher Copyright:
© 2020 The Authors

Copyright 2020 Elsevier B.V., All rights reserved.


  • Cisplatin
  • DNA repair
  • DNA-protein crosslinks
  • Homologous recombination
  • Mitochondria
  • Rad51


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