Repair activity of base and nucleotide excision repair enzymes for guanine lesions induced by nitrosative stress.
Nitric oxide (NO) induces deamination of guanine, yielding xanthine and oxanine (Oxa). Furthermore, Oxa reacts with polyamines and DNA binding proteins to form cross-link adducts. Thus, it is of interest how these lesions are processed by DNA repair enzymes in view of the genotoxic mechanism of NO. In the present study, we have examined the repair capacity for Oxa and Oxa-spermine cross-link adducts (Oxa-Sp) of enzymes involved in base excision repair (BER) and nucleotide excision repair (NER) to delineate the repair mechanism of nitrosative damage to guanine. Oligonucleotide substrates containing Oxa and Oxa-Sp were incubated with purified BER and NER enzymes or cell-free extracts (CFEs), and the damage-excising or DNA-incising activity was compared with that for control (physiological) substrates. The Oxa-excising activities of Escherichia coli and human DNA glycosylases and HeLa CFEs were 0.2-9% relative to control substrates, implying poor processing of Oxa by BER. In contrast, DNA containing Oxa-Sp was incised efficiently by UvrABC nuclease and SOS-induced E.coli CFEs, suggesting a role of NER in ameliorating genotoxic effects associated with nitrosative stress. Analyses of the activity of CFEs from NER-proficient and NER-deficient human cells on Oxa-Sp DNA confirmed further the involvement of NER in the repair of nitrosative DNA damage.
Nakano
Toshiaki
T
Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University Higashi-Hiroshima 739-8526, Japan.
Katafuchi
Atsushi
A
Shimizu
Ryoko
R
Terato
Hiroaki
H
Suzuki
Toshinori
T
Tauchi
Hiroshi
H
Makino
Keisuke
K
Skorvaga
Milan
M
Van Houten
Bennett
B
Ide
Hiroshi
H
D001483:Base Sequence; D002457:Cell Extracts; D018736:DNA Adducts / Q000378:metabolism; D004249:DNA Damage; D045647:DNA Glycosylases / Q000378:metabolism; D004260:DNA Repair; D045643:DNA Repair Enzymes / Q000378:metabolism*; D004706:Endodeoxyribonucleases / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology; D029968:Escherichia coli Proteins / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D009569:Nitric Oxide / Q000633:toxicity*; D009841:Oligonucleotides / Q000737:chemistry / Q000378:metabolism; D011684:Purine Nucleosides / Q000378:metabolism*; D013096:Spermine / Q000378:metabolism*
D002457:Cell Extracts; D018736:DNA Adducts; D029968:Escherichia coli Proteins; D009841:Oligonucleotides; D011684:Purine Nucleosides; C468766:oxanine; D013096:Spermine; D009569:Nitric Oxide; D004706:Endodeoxyribonucleases; C036385:endodeoxyribonuclease uvrABC; D045647:DNA Glycosylases; D045643:DNA Repair Enzymes