Arsenate Reductases in Prokaryotes and Eukaryotes

• Published in: Environmental health perspectives Vol. 110; no. suppl 5; pp. 745 - 748
• Main Authors: Mukhopadhyay, Rita, Rosen, Barry P.
• Format: Journal Article
• Language: English
• Published: United States National Institute of Environmental Health Sciences. National Institutes of Health. Department of Health, Education and Welfare 01.10.2002
• Subjects: Active sites; Arsenate Reductases; Arsenates; Arsenates - pharmacology; Arsenic; Arsenic - metabolism; Arsenic Carcinogenesis; Arsenite Transporting ATPases; Biochemistry; Drug Resistance; Environmental agencies; Enzymes; Escherichia coli - enzymology; Ion Pumps - pharmacology; Multienzyme Complexes - pharmacology; Oxidation-Reduction; Phosphatases; Plasmids; Proteins; Saccharomyces cerevisiae - enzymology; Saccharomyces cerevisiae Proteins; Yeasts
• ISSN: 0091-6765; 1552-9924
• DOI: 10.1289/ehp.02110s5745

The ubiquity of arsenic in the environment has led to the evolution of enzymes for arsenic detoxification. An initial step in arsenic metabolism is the enzymatic reduction of arsenate [As(V)] to arsenite [As(III)]. At least three families of arsenate reductase enzymes have arisen, apparently by convergent evolution. The properties of two of these are described here. The first is the prokaryotic ArsC arsenate reductase of Escherichia coli. The second, Acr2p of Saccharomyces cerevisiae, is the only identified eukaryotic arsenate reductase. Although unrelated to each other, both enzymes receive their reducing equivalents from glutaredoxin and reduced glutathione. The structure of the bacterial ArsC has been solved at 1.65 Å. As predicted from its biochemical properties, ArsC structures with covalent enzyme-arsenic intermediates that include either As(V) or As(III) were observed. The yeast Acr2p has an active site motif HC( X)5R that is conserved in protein phosphotyrosine phosphatases and rhodanases, suggesting that these three groups of enzymes may have evolved from an ancestral oxyanion-binding protein.