title: Site-specific DNA cleavage by Chlorella virus topoisomerase II.
abstract: The DNA cleavage reaction of topoisomerase II is central to the catalytic activity of the enzyme and is the target for a number of important anticancer drugs. Unfortunately, efforts to characterize this fundamental reaction have been limited by the low levels of DNA breaks normally generated by the enzyme. Recently, however, a type II topoisomerase with an extraordinarily high intrinsic DNA cleavage activity was isolated from Chlorella virus PBCV-1. To further our understanding of this enzyme, the present study characterized the site-specific DNA cleavage reaction of PBCV-1 topoisomerase II. Results indicate that the viral enzyme cleaves DNA at a limited number of sites. The DNA cleavage site utilization of PBCV-1 topoisomerase II is remarkably similar to that of human topoisomerase IIalpha, but the viral enzyme cleaves these sites to a far greater extent. Finally, PBCV-1 topoisomerase II displays a modest sensitivity to anticancer drugs and DNA damage in a site-specific manner. These findings suggest that PBCV-1 topoisomerase II represents a unique model with which to dissect the DNA cleavage reaction of eukaryotic type II topoisomerases.
authors.affiliation: Departments of Biochemistry and Medicine (Hematology/Oncology), Vanderbilt University School of Medicine, Nashville, TN 37232-0146, USA.
authors.forename: John M
authors.initials: JM
authors.lastname: Fortune
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: Dickey
authors.forename: Oleg V
authors.initials: OV
authors.lastname: Lavrukhin
authors.forename: James L
authors.initials: JL
authors.lastname: Van Etten
authors.forename: R Stephen
authors.initials: RS
authors.lastname: Lloyd
authors.forename: Neil
authors.initials: N
authors.lastname: Osheroff
mesh_terms: D000818:Animals; D000951:Antigens, Neoplasm; D002460:Cell Line; D002708:Chlorella / Q000821:virology*; D004249:DNA Damage; D004250:DNA Topoisomerases, Type II / Q000737:chemistry*; D004269:DNA, Bacterial / Q000737:chemistry; D004278:DNA, Superhelical / Q000737:chemistry; D004268:DNA-Binding Proteins; D004331:Drosophila melanogaster; D016503:Drug Delivery Systems; D004587:Electrophoresis, Agar Gel; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007527:Isoenzymes / Q000737:chemistry; D017862:Phycodnaviridae / Q000201:enzymology*; D013379:Substrate Specificity
chemical_list: D000951:Antigens, Neoplasm; D004269:DNA, Bacterial; D004278:DNA, Superhelical; D004268:DNA-Binding Proteins; D007527:Isoenzymes; D004250:DNA Topoisomerases, Type II