Cisplatin was shown to strongly inhibit the decatenation and relaxation activity of isolated human DNA topoisomerase IIalpha. This inhibition was not accompanied by stabilization of a covalent topoisomerase IIalpha-DNA intermediate. Pretreatment of kinetoplast plasmid DNA (kDNA) or pBR322 DNA with submicromolar concentrations of cisplatin quickly rendered these substrates incompetent in the top...

Candida albicans topoisomerase II, encoded by the TOP2 gene, mediates chromosome segregation by a double-strand DNA break mechanism and is a potential target for anti-fungal therapy. In this paper, we report the characterization of the C. albicans TOP2 gene and its use to develop a yeast system that allows the identification and study of anti-fungal topoisomerase II inhibitors in vivo. The gene...

BACKGROUND Type II DNA topoisomerases are essential, ubiquitous enzymes that act to relieve topological problems arising in DNA from normal cellular activity. Their mechanism of action involves the ATP-dependent transport of one DNA duplex through a transient break in a second DNA duplex; metal ions are essential for strand passage. Humans have two isoforms, topoisomerase IIα and topoisomerase ...

Several naturally occurring dietary polyphenols with chemopreventive or anticancer properties are topoisomerase II poisons. To identify additional phytochemicals that enhance topoisomerase II-mediated DNA cleavage, a library of 341 Mediterranean plant extracts was screened for activity against human topoisomerase IIα. An extract from Phillyrea latifolia L., a member of the olive tree family, di...

Regulating the topological state of DNA is a vital function of the enzyme DNA topoisomerase I. However, when acting on damaged DNA, topoisomerase I may get trapped in a covalent complex with nicked DNA (stalled topoisomerase I), that, if unrepaired, may lead to genomic instability or cell death. Here we show that ADP-ribose polymers target specific domains of topoisomerase I and reprogram the e...

The human DNA replication origin, located in the lamin B2 gene, interacts with the DNA topoisomerases I and II in a cell cycle-modulated manner. The topoisomerases interact in vivo and in vitro with precise bonds ahead of the start sites of bidirectional replication, within the pre-replicative complex region; topoisomerase I is bound in M, early G1 and G1/S border and topoisomerase II in M and ...

We have used an antibody probe to measure the levels of topoisomerase II in several transformed and developmentally regulated normal cell types. Transformed cells contain roughly 1 X 10(6) copies of the enzyme. During erythropoiesis in chicken embryos the enzyme level drops from 7.8 X 10(4) copies per erythroblast to less than 300 copies per erythrocyte concomitant with the cessation of mitosis...

DNA topoisomerases are highly exploited targets for antimicrobial drugs. The spread of antibiotic resistance represents a significant threat to public health and necessitates the discovery of inhibitors that target topoisomerases in novel ways. However, the traditional assays for topoisomerase activity are not suitable for the high-throughput approaches necessary for drug discovery. In this stu...

Yeast temperature-sensitive mutants of DNA topoisomerase II are incapable of chromosome condensation and anaphase chromatid segregation. In mammalian cells, topoisomerase II inhibitors such as etoposide (VP-16-123) have similar effects. Unfortunately, conclusions drawn from work with mammalian cells have been limited by the fact that the standard inhibitors of topoisomerase II also generate DNA...

Topoisomerase I was phosphorylated in vitro by protein kinase C (PKC) purified from rat brain with high affinity (Km about 0.1 microM). Tryptic phosphopeptide mapping indicated that two major topoisomerase I peptides phosphorylated in vivo were comigrating with minor peptides phosphorylated by PKC in vitro. Topoisomerase I phosphorylation was stimulated 3-fold in HL-60 cells exposed to the tumo...