XRCC1 stimulates polynucleotide kinase by enhancing its damage discrimination and displacement from DNA repair intermediates

Mani, Rajam S, Fanta, Mesfin, Karimi-Busheri, Feridoun, Silver, Elizabeth, Virgen, César A, Caldecott, Keith W, Cass, Carol E and Weinfeld, Michael (2007) XRCC1 stimulates polynucleotide kinase by enhancing its damage discrimination and displacement from DNA repair intermediates. Journal of Biological Chemistry, 282 (38). pp. 28004-28013. ISSN 0021-9258

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Abstract

Human polynucleotide kinase (hPNK) is required for processing and rejoining DNA strand break termini. The 5'-DNA kinase and 3'-phosphatase activities of hPNK can be stimulated by the ¿scaffold¿ protein XRCC1, but the mechanism remains to be fully elucidated. Using a variety of fluorescence techniques, we examined the interaction of hPNK with XRCC1 and substrates that model DNA single-strand breaks. hPNK binding to substrates with 5'-OH termini was only ~5-fold tighter than that to identical DNA molecules with 5'-phosphate termini, suggesting that hPNK remains bound to the product of its enzymatic activity. The presence of XRCC1 did not influence the binding of hPNK to substrates with 5'-OH termini, but sharply reduced the interaction of hPNK with DNA bearing a 5'-phosphate terminus. These data, together with kinetic data obtained at limiting enzyme concentration, indicate a dual function for the interaction of XRCC1 with hPNK. First, XRCC1 enhances the capacity of hPNK to discriminate between strand breaks with 5'-OH termini and those with 5'-phosphate termini; and second, XRCC1 stimulates hPNK activity by displacing hPNK from the phosphorylated DNA product.

Item Type: Article
Schools and Departments: School of Life Sciences > Sussex Centre for Genome Damage and Stability
Depositing User: Keith Caldecott
Date Deposited: 06 Feb 2012 18:41
Last Modified: 29 Mar 2012 13:31
URI: http://sro.sussex.ac.uk/id/eprint/17798
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