Chiral discrimination and writhe-dependent relaxation mechanism of human topoisomerase IIα

Abstract

Background: Human topoisomerase IIα unlinks catenated chromosomes and preferentially relaxes positive supercoils. Results: Supercoil chirality, twist density, and tension determine topoisomerase IIα relaxation rate and processivity. Conclusion: Strand passage rate is determined by the efficiency of transfer segment capture that is modulated by the topoisomerase C-terminal domains. Significance: Single-molecule measurements reveal the mechanism of chiral discrimination and tension dependence of supercoil relaxation by human topoisomerase IIα. Copyright © 2013 by The American Society for Biochemistry and Molecular Biology, Inc.