title: Distribution of topoisomerase II cleavage sites in simian virus 40 DNA and the effects of drugs.
abstract: The distributions of DNA cleavage sites induced by topoisomerase II in the presence or absence of specific drugs were mapped in the simian virus 40 genome. The drugs studied were 5-iminodaunorubicin, amsacrine (m-AMSA), teniposide (VM-26) and 2-methyl-9-hydroxyellipticinium; each produced a distinctive pattern of enhanced cleavage. Consistently intense cleavage, both in the presence and in the absence of drugs, occurred in the nuclear matrix-associated region. Since topoisomerase II is a major constituent of the nuclear matrix, and cleavage complexes include a covalent link between topoisomerase II and DNA, the findings suggest that topoisomerase II may function to attach DNA to the nuclear matrix. Cleavage usually occurred on both DNA strands with the expected four base-pair 5' stagger, and strong sites tended to occur within A/T runs such as have been associated with binding to the nuclear scaffold. Intense cleavage was present also in the replication termination region, but was absent from the vicinity of the replication origin. Cleavage intensities were found to change with time in a manner that depended both on the site and on the drug, suggesting that topoisomerase II can move along the DNA from a kinetically preferred site to a thermodynamically preferred site.
authors.affiliation: Laboratory of Molecular Pharmacology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892.
authors.forename: Y
authors.initials: Y
authors.lastname: Pommier
authors.forename: G
authors.initials: G
authors.lastname: Capranico
authors.forename: A
authors.initials: A
authors.lastname: Orr
authors.forename: K W
authors.initials: KW
authors.lastname: Kohn
mesh_terms: D000677:Amsacrine / Q000494:pharmacology*; D000818:Animals; D001483:Base Sequence; D004249:DNA Damage; D004261:DNA Replication; D004250:DNA Topoisomerases, Type II / Q000378:metabolism*; D004279:DNA, Viral / Q000187:drug effects / Q000378:metabolism*; D003630:Daunorubicin / Q000031:analogs & derivatives* / Q000494:pharmacology; D004611:Ellipticines / Q000494:pharmacology*; D016679:Genome, Viral; D007700:Kinetics; D007939:Leukemia L1210 / Q000201:enzymology; D051379:Mice; D008969:Molecular Sequence Data; D015183:Restriction Mapping; D013539:Simian virus 40 / Q000235:genetics*; D013379:Substrate Specificity; D013713:Teniposide / Q000494:pharmacology*
chemical_list: D004279:DNA, Viral; D004611:Ellipticines; D000677:Amsacrine; C027767:elliptinium; D013713:Teniposide; D004250:DNA Topoisomerases, Type II; C018979:5-iminodaunorubicin; D003630:Daunorubicin