Activation of topoisomerase I by poly [ADP-ribose] polymerase.

  • Authors: P I Bauer, K G Buki, J A Comstock, E Kun
  • View Affiliations

  • Published online on: Monday, May 1, 2000
  • Pages: 533-573
  • DOI: 10.3892/ijmm.5.5.533

Abstract

Poly(ADP-ribose) polymerase (PARP I) and Topoisomerase I (Topo I) were reisolated from calf thymus to eliminate cross contamination as tested by immunotransblots. The specific activity of Topo I was greatly increased by added PARP I, following saturation kinetics. Recombinant PARP I and isolated PARP I at final purity were indistinguishable in terms of their activation of Topo I. There was a coincidence of experimentally obtained binding constants and computer generated values based on the kinetic model, indicating that the association of PARP I and Topo I is rate limiting in the catalytic activation of Topo I by PARP I. Polypeptide domains of PARP I that are required for protein-protein binding and protein-DNA binding also activate Topo I. Fluorescence resonance energy transfer between fluorophor-labeled PARP I and Topo I was demonstrated. The binding of Topo I to circular SV40 DNA, assayed either by the formation of a) the sum of non-covalently and covalently attached Topo I to DNA or b) by the covalently bound transient intermediate in the presence of camptothecin, was augmented when PARP I protein was bound to SV40 DNA. These binding experiments provide a molecular basis for the kinetic activation of Topo I by PARP I inasmuch as the increased superhelicity of SV40 DNA induced by PARP I may facilitate the formation of a more <tight fisted> Topo I-DNA complex that increases the rate of the DNA breakage-reunion cycle of Topo I catalysis.
Journal Cover

May 2000
Volume 5 Issue 5

Print ISSN: 1107-3756
Online ISSN:1791-244X

2012 Impact Factor: 1.957
Ranked #26/121 Medicine Research and Experimental
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APA
Bauer, P., Buki, K., Comstock, J., & Kun, E. (2000). Activation of topoisomerase I by poly [ADP-ribose] polymerase.. International Journal of Molecular Medicine, 5(5), 533-573.
MLA
Bauer, Buki, Comstock, and E Kun. "Activation of topoisomerase I by poly [ADP-ribose] polymerase.." International Journal of Molecular Medicine International Journal of Molecular Medicine 5.5 (2000): 533-573.
Chicago
Bauer, Buki, Comstock, and E Kun. "Activation of topoisomerase I by poly [ADP-ribose] polymerase.." International Journal of Molecular Medicine International Journal of Molecular Medicine 5 no. 5 (2000): 533-573.