Bakshi, R and Galande, S and Muniyappa, K (2001) Substrate specificity plays an important role in uncoupling the catalytic and scaffolding activities of rat testis DNA topoisomerase IIalpha. In: Journal of Biomolecular Structure & Dynamics, 18 (5). pp. 749-760.
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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 IIalpha to the chromatin fraction. We used this observation to characterize DNA-binding specificity and catalytic properties of purified testis topo IIalpha. The results indicate that topo IIalpha 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 IIalpha displayed high-affinity and cooperativity in binding to the scaffold associated region. In contrast to the preferred site, however, high-affinity binding of topo IIalpha 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 IIalpha. These results implicate a dual role for topo IIalpha in vivo consistent with the notion that its sequestration to the chromatin might play a role in chromosome condensation and decondensation during spermatogenesis.
|Item Type:||Journal Article|
|Additional Information:||Copyright of this article belongs to Adenine Press.|
|Department/Centre:||Division of Biological Sciences > Biochemistry|
|Date Deposited:||22 Feb 2010 10:13|
|Last Modified:||04 Jul 2011 11:16|
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