title: Plasmid linking number change induced by topoisomerase I-mediated DNA damage.
abstract: The state of cellular chromatin in response to DNA damage has been examined by monitoring the change in the linking number of circular episomes. COS cells transfected with an SV40-based vector were treated with camptothecin (CPT), a eukaryotic DNA topoisomerase I (TOP1) poison which induces TOP1-mediated DNA damage. Within minutes, a large increase in the linking number (over 10 linking number) of a small fraction (5-15%) of the episomal DNA was observed. A similar CPT-induced increase in plasmid DNA linking number was observed in Saccharomyces cerevisae expressing human DNA TOP1. In this case, the majority of the plasmid DNA can undergo rapid relaxation. The large increase in the plasmid linking number suggests major chromatin structural reorganization in response to TOP I-mediated DNA damage.
authors.affiliation: Department of Pharmacology, UMDNJ-Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, NJ 08854, USA.
authors.forename: P
authors.initials: P
authors.lastname: Duann
authors.forename: M
authors.initials: M
authors.lastname: Sun
authors.forename: C T
authors.initials: CT
authors.lastname: Lin
authors.forename: H
authors.initials: H
authors.lastname: Zhang
authors.forename: L F
authors.initials: LF
authors.lastname: Liu
mesh_terms: D000818:Animals; D019556:COS Cells; D002166:Camptothecin / Q000494:pharmacology; D002460:Cell Line; D002738:Chloroquine / Q000494:pharmacology; D002843:Chromatin / Q000737:chemistry / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D004249:DNA Damage / Q000187:drug effects / Q000528:radiation effects; D004264:DNA Topoisomerases, Type I / Q000235:genetics / Q000378:metabolism*; D004278:DNA, Superhelical / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005656:Fungal Proteins / Q000235:genetics / Q000502:physiology; D006801:Humans; D008836:Micrococcal Nuclease / Q000378:metabolism; D008957:Models, Genetic; D009690:Nucleic Acid Conformation / Q000187:drug effects / Q000528:radiation effects; D010957:Plasmids / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D013539:Simian virus 40 / Q000235:genetics; D013997:Time Factors; D059004:Topoisomerase I Inhibitors; D014162:Transfection; D014466:Ultraviolet Rays; D015003:Yeasts / Q000187:drug effects / Q000235:genetics
chemical_list: D002843:Chromatin; D004278:DNA, Superhelical; D004791:Enzyme Inhibitors; D005656:Fungal Proteins; D059004:Topoisomerase I Inhibitors; D002738:Chloroquine; D008836:Micrococcal Nuclease; D004264:DNA Topoisomerases, Type I; D002166:Camptothecin