Substrate specificity plays an important role in uncoupling the catalytic and scaffolding activities of rat testis DNA topoisomerase IIα

Rahul Bakshi, Sanjeev Galande, K. Muniyappa

Research output: Contribution to journalArticlepeer-review

Abstract

Topoisomerase II (topo II) is a dyadic enzyme found in all eukaryotic cells. Topo II is involved in a number of cellular processes related to DNA metabolism, including DNA replication, recombination and the maintenance of genomic stability. We discovered a correlation between the development of postnatal testis and increased binding of topo IIα to the chromatin fraction. We used this observation to characterize DNA-binding specificity and catalytic properties of purified testis topo IIα. The results indicate that topo IIα binds a substrate containing the preferred site with greater affinity and, consequently, catalyzes the conversion of form I to form IV DNA more efficiently in contrast to substrates lacking such a site. Interestingly, topo IIα displayed high-affinity and cooperativity in binding to the scaffold associated region. In contrast to the preferred site, however, high-affinity binding of topo IIα to the scaffold-associated region failed to result in enhanced catalytic activity. Intriguingly, competition assays involving scaffold-associated region revealed an additional DNA-binding site within the dyadic topo IIα. These results implicate a dual role for topo IIα in vivo consistent with the notion that its sequestration to the chromatin might play a role in chromosome condensation and decondensation during spermatogenesis.

Original languageEnglish (US)
Pages (from-to)749-760
Number of pages12
JournalJournal of Biomolecular Structure and Dynamics
Volume18
Issue number5
DOIs
StatePublished - 2001
Externally publishedYes

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology

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