DNA methylation influences the decatenation activity of topoisomerase II

Methylation of cytosine in CpG sequences of the DNA in mammalian cells is i nvolved in the regulation of events like gene expression, genomic imprintin g, transcription. and DNA replication. Changes in the DNA methylation patte rn influence the DNA conformation. Therefore. certain proteins are disturbe d in their interaction with DNA. In this paper, we investigate the influenc e on the decatenation activity of topoisomerase II, an essential enzyme tha t modulates DNA topology. We compare the decatenation activity of topoisome rase II for a mitochondrial parasite DNA, that we had methylated to differe nt degrees, and found the decatenation to be methylation dependent. Thus, c hanges in the methylation pattern are a mechanism for the disturbance of ce rtain topoisomerase II activities and may, therefore, be an el ent in topoi somerase II related mutagenicity and carcinogenicity. (C) 2001 Elsevier Sci ence B.V. All rights reserved.