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Title: Metal inhibition of human alkylpurine-DNA-N-glycosylase activityin base excision repair

Abstract

Cadmium (Cd{sup 2+}), nickel (Ni{sup 2+}) and cobalt (Co{sup 2+}) are human and/or animal carcinogens. Zinc (Zn{sup 2+}) is not categorized as a carcinogen, and rather an essential element to humans. Metals were recently shown to inhibit DNA repair proteins that use metals for their function and/or structure. Here we report that the divalent ions Cd{sup 2+}, Ni{sup 2+}, and Zn{sup 2+} can inhibit the activity of a recombinant human N-methylpurine-DNA glycosylase (MPG) toward a deoxyoligonucleotide with ethenoadenine (var epsilonA). MPG removes a variety of toxic/mutagenic alkylated bases and does not require metal for its catalytic activity or structural integrity. At concentrations starting from 50 to 1000 {micro}M, both Cd{sup 2+} and Zn{sup 2+} showed metal-dependent inhibition of the MPG catalytic activity. Ni{sup 2+} also inhibited MPG, but to a lesser extent. Such an effect can be reversed with EDTA addition. In contrast, Co{sup 2+} and Mg{sup 2+} did not inhibit the MPG activity in the same dose range. Experiments using HeLa cell-free extracts demonstrated similar patterns of inactivation of the var epsilonA excision activity by the same metals. Binding of MPG to the substrate was not significantly affected by Cd{sup 2+}, Zn{sup 2+}, and Ni{sup 2+} at concentrations thatmore » show strong inhibition of the catalytic function, suggesting that the reduced catalytic activity is not due to altered MPG binding affinity to the substrate. Molecular dynamics (MD) simulations with Zn{sup 2+} showed that the MPG active site has a potential binding site for Zn{sup 2+}, formed by several catalytically important and conserved residues. Metal binding to such a site is expected to interfere with the catalytic mechanism of this protein. These data suggest that inhibition of MPG activity may contribute to metal genotoxicity and depressed repair of alkylation damage by metals in vivo.« less

Authors:
; ;
Publication Date:
Research Org.:
Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
Sponsoring Org.:
USDOE Director, Office of Science; National Institutes ofHealth
OSTI Identifier:
919754
Report Number(s):
LBNL-59790
Journal ID: ISSN 0378-4274; TOLED5; R&D Project: 865B1C; BnR: 400412000; TRN: US200822%%518
DOE Contract Number:  
DE-AC02-05CH11231; NIHCA72079
Resource Type:
Journal Article
Resource Relation:
Journal Name: Toxicology Letters; Journal Volume: 166; Journal Issue: 3; Related Information: Journal Publication Date: 10/25/2006
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; DNA REPAIR; EXCISION REPAIR; IN VIVO; REPAIR; INHIBITION; CARCINOGENS; ALKYLATION; DAMAGE

Citation Formats

Wang, Ping, Guliaev, Anton B., and Hang, Bo. Metal inhibition of human alkylpurine-DNA-N-glycosylase activityin base excision repair. United States: N. p., 2006. Web. doi:10.1016/j.toxlet.2006.06.647.
Wang, Ping, Guliaev, Anton B., & Hang, Bo. Metal inhibition of human alkylpurine-DNA-N-glycosylase activityin base excision repair. United States. doi:10.1016/j.toxlet.2006.06.647.
Wang, Ping, Guliaev, Anton B., and Hang, Bo. Tue . "Metal inhibition of human alkylpurine-DNA-N-glycosylase activityin base excision repair". United States. doi:10.1016/j.toxlet.2006.06.647. https://www.osti.gov/servlets/purl/919754.
@article{osti_919754,
title = {Metal inhibition of human alkylpurine-DNA-N-glycosylase activityin base excision repair},
author = {Wang, Ping and Guliaev, Anton B. and Hang, Bo},
abstractNote = {Cadmium (Cd{sup 2+}), nickel (Ni{sup 2+}) and cobalt (Co{sup 2+}) are human and/or animal carcinogens. Zinc (Zn{sup 2+}) is not categorized as a carcinogen, and rather an essential element to humans. Metals were recently shown to inhibit DNA repair proteins that use metals for their function and/or structure. Here we report that the divalent ions Cd{sup 2+}, Ni{sup 2+}, and Zn{sup 2+} can inhibit the activity of a recombinant human N-methylpurine-DNA glycosylase (MPG) toward a deoxyoligonucleotide with ethenoadenine (var epsilonA). MPG removes a variety of toxic/mutagenic alkylated bases and does not require metal for its catalytic activity or structural integrity. At concentrations starting from 50 to 1000 {micro}M, both Cd{sup 2+} and Zn{sup 2+} showed metal-dependent inhibition of the MPG catalytic activity. Ni{sup 2+} also inhibited MPG, but to a lesser extent. Such an effect can be reversed with EDTA addition. In contrast, Co{sup 2+} and Mg{sup 2+} did not inhibit the MPG activity in the same dose range. Experiments using HeLa cell-free extracts demonstrated similar patterns of inactivation of the var epsilonA excision activity by the same metals. Binding of MPG to the substrate was not significantly affected by Cd{sup 2+}, Zn{sup 2+}, and Ni{sup 2+} at concentrations that show strong inhibition of the catalytic function, suggesting that the reduced catalytic activity is not due to altered MPG binding affinity to the substrate. Molecular dynamics (MD) simulations with Zn{sup 2+} showed that the MPG active site has a potential binding site for Zn{sup 2+}, formed by several catalytically important and conserved residues. Metal binding to such a site is expected to interfere with the catalytic mechanism of this protein. These data suggest that inhibition of MPG activity may contribute to metal genotoxicity and depressed repair of alkylation damage by metals in vivo.},
doi = {10.1016/j.toxlet.2006.06.647},
journal = {Toxicology Letters},
number = 3,
volume = 166,
place = {United States},
year = {Tue Feb 28 00:00:00 EST 2006},
month = {Tue Feb 28 00:00:00 EST 2006}
}