title: Nucleotide excision repair of a DNA interstrand cross-link produces single- and double-strand breaks.
abstract: The DNA radical resulting from formal abstraction of a hydrogen atom from the thymidine methyl group, 5-(2'-deoxyuridinyl)methyl radical, forms interstrand cross-links with the opposing 2'-deoxyadenosine. This is the first chemically characterized, radical-mediated cross-link between two opposing nucleotides. In addition, cross-linking between opposing bases in the duplex is less common than between those separated by one or two nucleotides. The first step in cross-link repair was investigated using the UvrABC bacterial nucleotide excision repair system. UvrABC incised both strands of the cross-linked DNA, although the strand containing the cross-linked purine was preferred by the enzyme in two different duplexes. The incision sites in one strand were spaced 11-14 nucleotides apart, as is typical for UvrABC incision. The majority of incisions occur at the third phosphate from the 3'-side of the cross-link and eighth or ninth phosphate on the 5'-side. In addition, cleavage was found to occur on both strands, producing double-strand breaks in approximately 25-29% of the incision events. This is the first example of double-strand cleavage during nucleotide excision repair of cross-linked DNA that does not already contain a strand break in the vicinity of the cross-link.
authors.affiliation: Department of Chemistry, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, USA.
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Peng
authors.forename: Avik K
authors.initials: AK
authors.lastname: Ghosh
authors.forename: Bennett
authors.initials: B
authors.lastname: Van Houten
authors.forename: Marc M
authors.initials: MM
authors.lastname: Greenberg
mesh_terms: D001483:Base Sequence; D003432:Cross-Linking Reagents / Q000737:chemistry; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D053903:DNA Breaks, Double-Stranded; D053904:DNA Breaks, Single-Stranded; D004260:DNA Repair; D003857:Deoxyuridine / Q000031:analogs & derivatives / Q000737:chemistry; D004706:Endodeoxyribonucleases / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009841:Oligonucleotides / Q000737:chemistry / Q000378:metabolism
chemical_list: C510308:5-(2'-deoxyuridinyl)methyl; D003432:Cross-Linking Reagents; D029968:Escherichia coli Proteins; D009841:Oligonucleotides; D004247:DNA; D004706:Endodeoxyribonucleases; C036385:endodeoxyribonuclease uvrABC; D003857:Deoxyuridine