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The Drosophila orthologue of progeroid human WRN exonuclease, DmWRNexo, cleaves replication substrates but is inhibited by uracil or abasic sites

Mason, Penelope A.; Boubriak, Ivan; Robbins, Timothy; Lasala, Ralph; Saunders, Robert and Cox, Lynne S. (2013). The Drosophila orthologue of progeroid human WRN exonuclease, DmWRNexo, cleaves replication substrates but is inhibited by uracil or abasic sites. AGE - The Journal of the American Aging Association, 35(3) pp. 793–806.

DOI (Digital Object Identifier) Link: https://doi.org/10.1007/s11357-012-9411-0
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Abstract

Werner syndrome (WS) is a rare late-onset premature ageing disease showing many of the phenotypes associated with normal ageing, and provides one of the best models for investigating cellular pathways that lead to normal ageing. WS is caused by mutation of WRN, which encodes a multifunctional DNA replication and repair helicase/exonuclease. To investigate the role of WRN protein’s unique exonuclease domain, we have recently identified DmWRNexo, the fly orthologue of the exonuclease domain of human WRN. Here, we fully characterise DmWRNexo exonuclease activity in vitro, confirming 3′–5′ polarity, demonstrating a requirement for Mg2+, inhibition by ATP, and an ability to degrade both single-stranded DNA and duplex DNA substrates with 3′ or 5′ overhangs, or bubble structures, but with no activity on blunt ended DNA duplexes. We report a novel active site mutation that ablates enzyme activity. Lesional substrates containing uracil are partially cleaved by DmWRNexo, but the enzyme pauses on such substrates and is inhibited by abasic sites. These strong biochemical similarities to human WRN suggest that Drosophila can provide a valuable experimental system for analysing the importance of WRN exonuclease in cell and organismal ageing.

Item Type: Journal Item
Copyright Holders: 2012 The Author(s)
ISSN: 1574-4647
Keywords: WRN; Werner syndrome; Exonuclease; ageing; RecQ; DmWRNexo; progeroid syndromes; DNA replication; DNA repair; DNA recombination
Academic Unit/School: Faculty of Science, Technology, Engineering and Mathematics (STEM) > Life, Health and Chemical Sciences
Faculty of Science, Technology, Engineering and Mathematics (STEM)
Item ID: 36781
Depositing User: Robert Saunders
Date Deposited: 06 Mar 2013 14:45
Last Modified: 07 Dec 2018 10:14
URI: http://oro.open.ac.uk/id/eprint/36781
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