title: Repair of oxidized abasic sites by exonuclease III, endonuclease IV, and endonuclease III.
abstract: 2-Deoxyribonolactone (L) and the C4'-oxidized abasic site (C4-AP) are produced by a variety of DNA-damaging agents. If not repaired, these lesions can be mutagenic. Exonuclease III and endonuclease IV are the major enzymes in E. coli responsible for 5'-incision of abasic sites (APs), the first steps in AP repair. Endonuclease III efficiently excises AP lesions via intermediate Schiff-base formation. Incision of L and C4-AP lesions by exonuclease III and endonuclease IV was determined under steady-state conditions using oligonucleotide duplexes containing the lesions at defined sites. An abasic lesion (AP) in an otherwise identical DNA sequence was incised by exonuclease III or endonuclease IV approximately 6-fold more efficiently than either of the oxidized abasic sites (L, C4-AP). Endonuclease IV incision efficiency of 2-deoxyribonolactone or C4-AP was independent of whether the lesion was opposite dA or dG. 2-Deoxyribonolactone is known to cross-link to endonuclease III (Hashimoto, M. (2001) J. Am. Chem. Soc. 123, 3161.). However, the C4-AP lesion is efficiently excised by endonuclease III. Oxidized abasic site repair by endonuclease IV and endonuclease III (C4-AP only) is approximately 100-fold less efficient than repair by exonuclease III. These results suggest that the first step of C4-AP and L oxidized abasic site repair will be the same as that of regular AP lesions in E. coli.
authors.affiliation: Department of Chemistry, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, USA. mgreenberg@jhu.edu
authors.forename: Marc M
authors.initials: MM
authors.lastname: Greenberg
authors.forename: Yvonne N
authors.initials: YN
authors.lastname: Weledji
authors.forename: Jaeseung
authors.initials: J
authors.lastname: Kim
authors.forename: Brian C
authors.initials: BC
authors.lastname: Bales
mesh_terms: D020029:Base Pairing; D001483:Base Sequence; D001665:Binding Sites; D004249:DNA Damage / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D004260:DNA Repair; D043223:Deoxyribonuclease IV (Phage T4-Induced) / Q000737:chemistry / Q000378:metabolism*; D004706:Endodeoxyribonucleases / Q000737:chemistry / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism; D005090:Exodeoxyribonucleases / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D015394:Molecular Structure; D009841:Oligonucleotides / Q000235:genetics; D010084:Oxidation-Reduction; D013379:Substrate Specificity; D013400:Sugar Acids / Q000737:chemistry / Q000378:metabolism / Q000528:radiation effects
chemical_list: D029968:Escherichia coli Proteins; D009841:Oligonucleotides; D013400:Sugar Acids; C056405:2,4,5-trihydroxypentanoic acid gamma-lactone; D004706:Endodeoxyribonucleases; D005090:Exodeoxyribonucleases; C020133:exodeoxyribonuclease III; D043223:Deoxyribonuclease IV (Phage T4-Induced)