Decatenation of kinetoplast DNA by topoisomerases.

Reversible decatenation of kinetoplast DNA by a DNA topoisomerase from trypanosomatids.

DNA topoisomerase activity detected in cell extracts of the trypanosomatid Crithidia fasciculata interlocks kinetoplast DNA duplex minicircles into huge catenane forms resembling the natural kinetoplast DNA networks found in trypanosomes. Catenation of duplex DNA circles is reversible and equilibrium is affected by ionic strength, and by spermidine. The reaction requires magnesium, is ATP depen...

Binding of two DNA molecules by type II topoisomerases for decatenation

Topoisomerases (topos) maintain DNA topology and influence DNA transaction processes by catalysing relaxation, supercoiling and decatenation reactions. In the cellular milieu, division of labour between different topos ensures topological homeostasis and control of central processes. In Escherichia coli, DNA gyrase is the principal enzyme that carries out negative supercoiling, while topo IV ca...

Single-molecule analysis uncovers the difference between the kinetics of DNA decatenation by bacterial topoisomerases I and III

Escherichia coli topoisomerases I and III can decatenate double-stranded DNA (dsDNA) molecules containing single-stranded DNA regions or nicks as well as relax negatively supercoiled DNA. Although the proteins share a mechanism of action and have similar structures, they participate in different cellular processes. Whereas topoisomerase III is a more efficient decatenase than topoisomerase I, t...

DNA Topoisomerases

The double-helical nature of DNA and the anchoring of DNA to nuclear structures result in a number of topological problems during replication and transcription, mainly due to DNA-tracking polymerases and helicases. These activities cause the accumulation of positive supercoils ahead of the moving polymerase and negative supercoils behind it (Liu and Wang 1987; Brill and Sternglanz 1988; Giaever...

Sequence heterogeneity in kinetoplast minicircle DNA of Leishmania majer