Decatenation of kinetoplast DNA by an ATP-dependent DNA topoisomerase from the kinetoplast hemoflagellate Leishmania donovani.

An enzyme from Leishmania donovani that decatenates kinetoplast DNA networks into covalently closed monomeric circles has been isolated and characterized. The enzyme also relaxes supercoiled plasmid pBR322. The decatenation and relaxation reactions both require ATP and Mg2+. In both reactions the formation of topological isomers of unique linking numbers suggests that the enzyme is a type II DNA topoisomerase. Both the relaxation and decatenating activities are inhibited by novobiocin at a very high concentration.