Singly-linked catenation and knotting of cisplatin-DNA adduct by DNA topoisomerase I.

We studied the topological interaction between topoisomerase I (topo I) and cisplatin-DNA adduct. The topoisomers of the cisplatinized DNA formed by topo I are different in none-, low- and high-cisplatin concentrations to bind to DNA. Two unique topologically distinct invariants, singly-linked catenane and torefoiled knot DNA generated from cisplatin adduct, by topological reaction but not from none cisplatinized DNA. The results are discussed in relation with a possible recombinational role of cisplatin on the topological reaction with DNA.