Inhibition of short patch and long patch base excision repair by an oxidized abasic site.
5'-(2-Phosphoryl-1,4-dioxobutane) (DOB) is an oxidized abasic lesion that is produced by a variety of DNA damaging agents, including several antitumor antibiotics. DOB efficiently and irreversibly inhibits DNA polymerase β, an essential base excision repair enzyme in mammalian cells. The generality of this mode of inhibition by DOB is supported by the inactivation of DNA polymerase λ, which may serve as a possible backup for DNA polymerase β during abasic site repair. Protein digests suggest that Lys72 and Lys84, which are present in the lyase active site of DNA polymerase β, are modified by DOB. Monoaldehyde analogues of DOB substantiate the importance of the 1,4-dicarbonyl component of DOB for efficient inactivation of Pol β and the contribution of a freely diffusible electrophile liberated from the inhibitor by the enzyme. Inhibition of DNA polymerase β's lyase function is accompanied by inactivation of its DNA polymerase activity as well, which prevents long patch base excision repair of DOB. Overall, DOB is highly refractory to short patch and long patch base excision repair. Its recalcitrance to succumb to repair suggests that DOB is a significant source of the cytotoxicity of DNA damaging agents that produce it.
Guan
Lirui
L
Department of Chemistry, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States.
Bebenek
Katarzyna
K
Kunkel
Thomas A
TA
Greenberg
Marc M
MM
D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D020134:Catalytic Domain; D004249:DNA Damage; D019951:DNA Polymerase beta / Q000037:antagonists & inhibitors / Q000378:metabolism; D004260:DNA Repair / Q000187:drug effects; D004261:DNA Replication; D007700:Kinetics; D009841:Oligonucleotides / Q000138:chemical synthesis; D010084:Oxidation-Reduction; D010766:Phosphorylation
D000903:Antibiotics, Antineoplastic; D009841:Oligonucleotides; D019951:DNA Polymerase beta