Catenation of DNA by eucaryotic topoisomerase II associated with simian virus 40 minichromosomes.

After incubation of purified SV40 minichromosomes with superhelical DNA molecules either of SV40 or plasmid origin, a catenation of monomeric DNA via dimers and multimers to large networks was observed. The catenation reaction was stimulated by the DNA condensing agent spermidine with ATP as an energy donor and was dependent on the presence of magnesium ions. The reaction could be blocked by inhibitors of topoisomerase II such as novobiocin and nalidixic acid. Relaxed covalently closed circular DNA was catenated to networks in the presence of ATP as the energy donor.