title: Differential poisoning of topoisomerases by menogaril and nogalamycin dictated by the minor groove-binding nogalose sugar.
abstract: The effect of DNA binding on poisoning of human DNA TOP1 has been studied using a pair of related anthracyclines which differ only by a nogalose sugar ring. We show that the nogalose sugar ring of nogalamycin, which binds to the minor groove of DNA, plays an important role in affecting topoisomerase-specific poisoning. Using purified mammalian topoisomerases, menogaril is shown to poison topoisomerase II but not topoisomerase I. By contrast, nogalamycin poisons topoisomerase I but not topoisomerase II. Consistent with the biochemical studies, CEM/VM-1 cells which express drug-resistant TOP2alpha are cross-resistant to menogaril but not nogalamycin. The mechanism by which nogalamycin poisons topoisomerase I has been studied by analyzing a major topoisomerase I-mediated DNA cleavage site induced by nogalamycin. This site is mapped to a sequence embedded in an AT-rich region with four scattered GC base pairs (bps) (at -10, -6, +2, and +12 positions). GC bps embedded in AT-rich regions are known to be essential for nogalamycin binding. Surprisingly, DNase I footprinting analysis of nogalamycin-DNA complexes has revealed a drug-free region from -2 to +9 encompassing the major cleavage site. Our results suggest that nogalamycin, in contrast to camptothecin, may stimulate TOP1 cleavage by binding to a site(s) distal to the site of cleavage.
authors.affiliation: Department of Pharmacology, UMDNJ-Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA.
authors.forename: S P
authors.initials: SP
authors.lastname: Sim
authors.forename: B
authors.initials: B
authors.lastname: Gatto
authors.forename: C
authors.initials: C
authors.lastname: Yu
authors.forename: A A
authors.initials: AA
authors.lastname: Liu
authors.forename: T K
authors.initials: TK
authors.lastname: Li
authors.forename: D S
authors.initials: DS
authors.lastname: Pilch
authors.forename: E J
authors.initials: EJ
authors.lastname: LaVoie
authors.forename: L F
authors.initials: LF
authors.lastname: Liu
mesh_terms: D000900:Anti-Bacterial Agents / Q000633:toxicity; D001483:Base Sequence / Q000187:drug effects; D004247:DNA / Q000187:drug effects* / Q000378:metabolism*; D004249:DNA Damage / Q000187:drug effects; D018983:DNA Footprinting; D004264:DNA Topoisomerases, Type I / Q000187:drug effects* / Q000502:physiology; D004250:DNA Topoisomerases, Type II / Q000378:metabolism; D003850:Deoxyribonuclease I; D004795:Enzyme Stability / Q000187:drug effects; D017290:Menogaril / Q000633:toxicity*; D008766:Methylmannosides / Q000737:chemistry / Q000378:metabolism*; D009621:Nogalamycin / Q000737:chemistry / Q000633:toxicity*; D013754:Tetracyclines
chemical_list: D000900:Anti-Bacterial Agents; D008766:Methylmannosides; D013754:Tetracyclines; C055919:nogalose; D017290:Menogaril; D004247:DNA; D003850:Deoxyribonuclease I; D004264:DNA Topoisomerases, Type I; D004250:DNA Topoisomerases, Type II; D009621:Nogalamycin