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Reactions of glyceraldehyde 3-phosphate dehydrogenase sulfhydryl groups with bis-electrophiles produce DNA-protein cross-links but not mutations.
- Source :
-
Chemical research in toxicology [Chem Res Toxicol] 2008 Feb; Vol. 21 (2), pp. 453-8. Date of Electronic Publication: 2007 Dec 29. - Publication Year :
- 2008
-
Abstract
- The environmental contaminant 1,2-dibromoethane and diepoxybutane, an oxidation product of the important industrial chemical butadiene, are bis-functional electrophiles and are known to be mutagenic and carcinogenic. One mechanism by which bis-electrophiles can exert their toxic effects is through the induction of genotoxic and mutagenic DNA-peptide cross-links. This mechanism has been shown in systems overexpressing the DNA repair protein O6 -alkylguanine DNA-alkyltransferase (AGT) or glutathione S-transferase and involves reactions with nucleophilic cysteine residues. The hypothesis that DNA-protein cross-link formation is a more general mechanism for genotoxicity by bis-electrophiles was investigated by screening nuclear proteins for reactivity with model monofunctional electrophiles. Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) was identified as a candidate because of the nucleophilicity of two cysteine residues (Cys152 and Cys246) in reaction screens with model electrophiles (Dennehy, M. K. et al. (2006) Chem. Res. Toxicol. 19, 20-29). Incubation of GAPDH with bis-electrophiles resulted in inhibition of its catalytic activity, but only at high concentrations of diepoxybutane. In vitro assays indicated DNA-GAPDH cross-link formation in the presence of diepoxybutane, and bis-electrophile reactivity at Cys246 was confirmed using mass spectral analysis. In contrast to AGT, overexpression of human GAPDH in Escherichia coli did not enhance mutagenesis by diepoxybutane. We propose that the lack of mutational enhancement is in part due to the inherently lower reactivity of GAPDH toward bis-electrophiles as well as the reduced DNA binding ability relative to AGT, preventing the in vivo formation of DNA-protein cross-links and enhanced mutagenesis.
- Subjects :
- Cell Survival
Environmental Pollutants chemistry
Escherichia coli drug effects
Escherichia coli enzymology
Escherichia coli genetics
Glyceraldehyde-3-Phosphate Dehydrogenases genetics
Glyceraldehyde-3-Phosphate Dehydrogenases metabolism
Humans
Mutation
O(6)-Methylguanine-DNA Methyltransferase chemistry
O(6)-Methylguanine-DNA Methyltransferase metabolism
Recombinant Proteins chemistry
Sulfhydryl Compounds chemistry
Cross-Linking Reagents chemistry
DNA chemistry
Epoxy Compounds chemistry
Ethylene Dibromide chemistry
Glyceraldehyde-3-Phosphate Dehydrogenases chemistry
Mutagens chemistry
Subjects
Details
- Language :
- English
- ISSN :
- 0893-228X
- Volume :
- 21
- Issue :
- 2
- Database :
- MEDLINE
- Journal :
- Chemical research in toxicology
- Publication Type :
- Academic Journal
- Accession number :
- 18163542
- Full Text :
- https://doi.org/10.1021/tx7003618