Author: Søe Kent Grosse Frank
Publisher: Oxford University Press
ISSN: 1362-4962
Source: Nucleic Acids Research, Vol.31, Iss.22, 2003-11, pp. : 6585-6592
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Abstract
The tumor suppressor protein p53 and the human DNA topoisomerase I (htopoI) interact with each other, which leads to a stimulation of the catalytic activity of htopoI. Moreover, p53 stimulates the topoisomerase I‐induced recombination repair (TIRR) reaction. However, little was known about how p53 stimulates this topoisomerase I activity. Here we demonstrate that monomeric p53 is sufficient for the stimulation of the topoisomerase I‐catalyzed relaxation activity, but the tetrameric form of p53 is required for the stimulation of TIRR. We also show that p53 stimulates topoisomerase I activity by increasing the dissociation of htopoI from DNA. Since htopoI forms a closed ring structure around the DNA, our results suggest that p53 induces a conformational change within htopoI that results in an opening of the clamp, and thereby releases htopoI from DNA.
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