TY - JOUR
T1 - Long patch base excision repair in mammalian mitochondrial genomes
AU - Szczesny, Bartosz
AU - Tann, Anne W.
AU - Longley, Matthew J.
AU - Copeland, William C.
AU - Mitra, Sankar
PY - 2008/9/26
Y1 - 2008/9/26
N2 - 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.
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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U2 - 10.1074/jbc.M803491200
DO - 10.1074/jbc.M803491200
M3 - Article
C2 - 18635552
AN - SCOPUS:55049124777
SN - 0021-9258
VL - 283
SP - 26349
EP - 26356
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 39
ER -