A nicking enzyme from trypanosomatids which specifically affects the topological linking of duplex DNA circles. Purification and characterization

J. Shlomai, M. Linial

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

Newly replicated duplex DNA minicircles of trypanosomal kinetoplast DNA are nicked in both their monomeric and catenated topological states, whereas mature ones are covalently sealed. The possibility that nicking may play a role during kinetoplast DNA replication by affecting the topological interconversions of monomeric DNA minicircles and catenane networks was studied here in vitro using Crithidia fasciculata DNA topoisomerase. An enzyme that catalyzes the nicking of duplex DNA circles has been purified to apparent homogeneity from C. fasciculata cell extracts. The native enzyme has a sedimentation coefficient of 6.8 S and was found to be a dimer with a protomer M(r) = 60,000. Nicking of kinetoplast DNA networks by the purified enzyme inhibits their decatenation by the Crithidia DNA topoisomerase but has no effect on the catenation of monomeric DNA minicircles into networks. This differential effect on decatenation versus catenation is specific to the purified nicking enzyme. Random nicking of interlocked DNA minicircles has no detectable effect on the reversibility of the topological reaction. The potential role of Crithidia nicking enzyme in the replication of kinetoplast DNA networks in trypanosomatids is discussed.

Original languageAmerican English
Pages (from-to)16219-16225
Number of pages7
JournalJournal of Biological Chemistry
Volume261
Issue number34
StatePublished - 1986

Fingerprint

Dive into the research topics of 'A nicking enzyme from trypanosomatids which specifically affects the topological linking of duplex DNA circles. Purification and characterization'. Together they form a unique fingerprint.

Cite this