Action of mitochondrial endonuclease G on DNA damaged by L-ascorbic acid, peplomycin, and cis-diamminedichloroplatinum (II).
Mitochondrial DNA (mtDNA) suffers extensive damage from the environment, however, the enzymes involved in the repair of mtDNA are still unknown. Here, we partially purified mitochondrial endonuclease G (Endo G) from the bovine heart, and examined the action of Endo G on damaged DNA. Treatment of DNA with L-ascorbic acid or peplomycin, that introduces single-strand breaks through active oxygen radicals, greatly enhanced the susceptibility to nucleolytic attacks from Endo G. The enzyme cleaved at or near sites where single-strand breaks were present in the opposite strand. Cisplatin-mediated DNA damage, which causes intrastrand crosslinks between adjacent guanine residues, also facilitated Endo G digestion, indicating that the enzyme can recognize local distortions in the duplex DNA introduced by adducts. These nucleolytic properties of Endo G in vitro suggest its possible involvement in the maintenance of mtDNA by eliminating defective genomes from the multicopy pool.
Ikeda
S
S
Department of Biochemistry, Faculty of Science, Okayama University of Science, Ridai-cho, Japan. ikeda@dbc.ous.ac.jp
Ozaki
K
K
D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology; D001205:Ascorbic Acid / Q000494:pharmacology; D002417:Cattle; D002945:Cisplatin / Q000494:pharmacology; D004247:DNA / Q000378:metabolism; D004249:DNA Damage; D004260:DNA Repair; D004272:DNA, Mitochondrial / Q000187:drug effects / Q000378:metabolism*; D015246:Deoxyribonuclease EcoRI / Q000378:metabolism; D004587:Electrophoresis, Agar Gel; D004591:Electrophoresis, Polyacrylamide Gel; D004706:Endodeoxyribonucleases / Q000302:isolation & purification / Q000378:metabolism*; D008929:Mitochondria, Heart / Q000201:enzymology*; D017663:Peplomycin / Q000494:pharmacology; D010957:Plasmids / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D013379:Substrate Specificity
D000903:Antibiotics, Antineoplastic; D000970:Antineoplastic Agents; D004272:DNA, Mitochondrial; D017382:Reactive Oxygen Species; D017663:Peplomycin; D004247:DNA; D004706:Endodeoxyribonucleases; D015246:Deoxyribonuclease EcoRI; C052391:endonuclease G; D001205:Ascorbic Acid; D002945:Cisplatin