title: Reaching for the other side: generating sequence-dependent interstrand cross-links with 5-bromodeoxyuridine and gamma-rays.
abstract: Interstrand cross-links impede critical cellular processes such as transcription and replication and are thus considered to be one of the most toxic types of DNA damage. Although several studies now point to the existence of gamma-radiation-induced cross-links in cellular DNA, little is known about the characteristics required for their creation. Recently, we reported the formation of interstrand cross-links that were specific for mismatched nucleotides within 5-bromo-2'-deoxyuridine-substituted DNA. Given the structural specificity for interstrand cross-link formation, it is likely that open or mismatched regions of DNA in cells may be particularly favorable for cross-link production. Herein, we investigated the effect of the local DNA sequence on the formation of interstrand cross-links, using 5-bromo-2'-deoxyuridine to generate radicals in a mismatched region of DNA. We investigated a total of 12 variations of bases in the mismatched region. The oligonucleotides were irradiated with gamma-rays, and interstrand cross-link formation was analyzed by denaturing gel electrophoresis. We found that the efficiency of cross-link formation was highly dependent on the nature of mismatched bases and, on the basis of electrophoretic mobility, observed several distinctive cross-link structures with specific DNA sequences. This study provides new insights into the reactivity of mismatched DNA and the mechanisms leading to interstrand cross-link formation. The potential application of 5-bromo-2'-deoxyuridine-induced interstrand cross-links to the field of DNA repair is discussed.
authors.affiliation: Center for Research in Radiotherapy (CR2), Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences, Universite de Sherbrooke, Sherbrooke, Quebec, Canada J1H 5N4.
authors.forename: Marie-Eve
authors.initials: ME
authors.lastname: Dextraze
authors.forename: Sylvain
authors.initials: S
authors.lastname: Cecchini
authors.forename: François
authors.initials: F
authors.lastname: Bergeron
authors.forename: Sonia
authors.initials: S
authors.lastname: Girouard
authors.forename: Kathleen
authors.initials: K
authors.lastname: Turcotte
authors.forename: J Richard
authors.initials: JR
authors.lastname: Wagner
authors.forename: Darel J
authors.initials: DJ
authors.lastname: Hunting
mesh_terms: D020137:Base Pair Mismatch; D001483:Base Sequence; D001973:Bromodeoxyuridine / Q000737:chemistry*; D003432:Cross-Linking Reagents / Q000737:chemistry; D053960:DNA Breaks; D004249:DNA Damage; D004260:DNA Repair; D005720:Gamma Rays; D008957:Models, Genetic; D008958:Models, Molecular; D009690:Nucleic Acid Conformation / Q000528:radiation effects; D009841:Oligonucleotides / Q000737:chemistry* / Q000235:genetics; D014498:Uracil / Q000737:chemistry
chemical_list: D003432:Cross-Linking Reagents; D009841:Oligonucleotides; D014498:Uracil; D001973:Bromodeoxyuridine