Long patch base excision repair in mammalian mitochondrial genomes

Bartosz Szczesny, Anne W. Tann, Matthew J. Longley, William C. Copeland, Sankar Mitra

Research output: Contribution to journalArticle

106 Citations (Scopus)

Abstract

The mitochondrial genome is highly susceptible to damage by reactive oxygen species (ROS) generated endogenously as a by-product of respiration. ROS-induced DNA lesions, including oxidized bases, abasic (AP) sites, and oxidized AP sites, cause DNA strand breaks and are repaired via the base excision repair (BER) pathway in both the nucleus and mitochondria. Repair of damaged bases and AP sites involving 1-nucleotide incorporation, named single nucleotide (SN)-BER, was observed with mitochondrial and nuclear extracts. During SN-BER, the 5′-phosphodeoxyribose (dRP) moiety, generated by AP-endonuclease (APE1), is removed by the lyase activity of DNA polymerase γ (pol γ) and polymerase β in the mitochondria and nucleus, respectively. However, the repair of oxidized deoxyribose fragments at the 5′ terminus after strand break would require 5′-exo/endonuclease activity that is provided by the flap endonuclease (FEN-1) in the nucleus, resulting in multinucleotide repair patch (long patch (LP)-BER). Here we show the presence of a 5′-exo/endonuclease in the mitochondrial extracts of mouse and human cells that is involved in the repair of a lyase-resistant AP site analog via multinucleotide incorporation, upstream and downstream to the lesion site. We conclude that LP-BER also occurs in the mitochondria requiring the 5′-exo/endonuclease and pol γ with 3′-exonuclease activity. Although a FEN-1 antibody cross-reacting species was detected in the mitochondria, it was absent in the LP-BER-proficient APE1 immunocomplex isolated from the mitochondrial extract that contains APE1, pol γ, and DNA ligase 3. The LP-BER activity was marginally affected in FEN-1-depleted mitochondrial extracts, further supporting the involvement of an unidentified 5′-exo/endonuclease in mitochondrial LP-BER.

Original languageEnglish (US)
Pages (from-to)26349-26356
Number of pages8
JournalJournal of Biological Chemistry
Volume283
Issue number39
DOIs
StatePublished - Sep 26 2008

Fingerprint

Mitochondrial Genome
DNA Repair
Repair
Genes
Flap Endonucleases
Endonucleases
Mitochondria
DNA-(Apurinic or Apyrimidinic Site) Lyase
spleen exonuclease
Lyases
Nucleotides
Reactive Oxygen Species
DNA Ligases
Deoxyribose
DNA Breaks
DNA-Directed DNA Polymerase
DNA
Respiration
Byproducts
Cells

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Molecular Biology

Cite this

Long patch base excision repair in mammalian mitochondrial genomes. / Szczesny, Bartosz; Tann, Anne W.; Longley, Matthew J.; Copeland, William C.; Mitra, Sankar.

In: Journal of Biological Chemistry, Vol. 283, No. 39, 26.09.2008, p. 26349-26356.

Research output: Contribution to journalArticle

Szczesny, Bartosz ; Tann, Anne W. ; Longley, Matthew J. ; Copeland, William C. ; Mitra, Sankar. / Long patch base excision repair in mammalian mitochondrial genomes. In: Journal of Biological Chemistry. 2008 ; Vol. 283, No. 39. pp. 26349-26356.
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AB - The mitochondrial genome is highly susceptible to damage by reactive oxygen species (ROS) generated endogenously as a by-product of respiration. ROS-induced DNA lesions, including oxidized bases, abasic (AP) sites, and oxidized AP sites, cause DNA strand breaks and are repaired via the base excision repair (BER) pathway in both the nucleus and mitochondria. Repair of damaged bases and AP sites involving 1-nucleotide incorporation, named single nucleotide (SN)-BER, was observed with mitochondrial and nuclear extracts. During SN-BER, the 5′-phosphodeoxyribose (dRP) moiety, generated by AP-endonuclease (APE1), is removed by the lyase activity of DNA polymerase γ (pol γ) and polymerase β in the mitochondria and nucleus, respectively. However, the repair of oxidized deoxyribose fragments at the 5′ terminus after strand break would require 5′-exo/endonuclease activity that is provided by the flap endonuclease (FEN-1) in the nucleus, resulting in multinucleotide repair patch (long patch (LP)-BER). Here we show the presence of a 5′-exo/endonuclease in the mitochondrial extracts of mouse and human cells that is involved in the repair of a lyase-resistant AP site analog via multinucleotide incorporation, upstream and downstream to the lesion site. We conclude that LP-BER also occurs in the mitochondria requiring the 5′-exo/endonuclease and pol γ with 3′-exonuclease activity. Although a FEN-1 antibody cross-reacting species was detected in the mitochondria, it was absent in the LP-BER-proficient APE1 immunocomplex isolated from the mitochondrial extract that contains APE1, pol γ, and DNA ligase 3. The LP-BER activity was marginally affected in FEN-1-depleted mitochondrial extracts, further supporting the involvement of an unidentified 5′-exo/endonuclease in mitochondrial LP-BER.

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