Reaction: arsenate + glutathione + glutaredoxin = arsenite + a glutaredoxin-glutathione disulfide + H2O
For diagram of reaction click here
Other name(s): ArsC (ambiguous); arsenate:glutaredoxin oxidoreductase; arsenate reductase (glutaredoxin)
Systematic name: arsenate:glutathione/glutaredoxin oxidoreductase
Comments: The enzyme is part of a system for detoxifying arsenate. The substrate binds to a catalytic cysteine residue, forming a covalent thiolate—As(V) intermediate. A tertiary intermediate is then formed between the arsenic, the enzyme's cysteine, and a glutathione cysteine. This intermediate is reduced by glutaredoxin, which forms a dithiol with the glutathione, leading to the dissociation of arsenite. Thus reduction of As(V) is mediated by three cysteine residues: one in ArsC, one in glutathione, and one in glutaredoxin. Although the arsenite formed is more toxic than arsenate, it can be extruded from some bacteria by EC 7.3.2.7, arsenite-transporting ATPase; in other organisms, arsenite can be methylated by EC 2.1.1.137, arsenite methyltransferase, in a pathway that produces non-toxic organoarsenical compounds. cf. EC 1.20.4.4, arsenate reductase (thioredoxin).
Links to other databases: BRENDA, EAWAG-BBD, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 146907-46-2
References:
1. Gladysheva, T., Liu, J.Y. and Rosen, B.P. His-8 lowers the pKa of the essential Cys-12 residue of the ArsC arsenate reductase of plasmid R773. J. Biol. Chem. 271 (1996) 33256-33260. [PMID: 8969183]
2. Gladysheva, T.B., Oden, K.L. and Rosen, B.P. Properties of the arsenate reductase of plasmid R773. Biochemistry 33 (1994) 7288-7293. [PMID: 8003492]
3. Holmgren, A. and Aslund, F. Glutaredoxin. Methods Enzymol. 252 (1995) 283-292. [PMID: 7476363]
4. Krafft, T. and Macy, J.M. Purification and characterization of the respiratory arsenate reductase of Chrysiogenes arsenatis. Eur. J. Biochem. 255 (1998) 647-653. [PMID: 9738904]
5. Martin, J.L. Thioredoxin - a fold for all reasons. Structure 3 (1995) 245-250. [PMID: 7788290]
6. Radabaugh, T.R. and Aposhian, H.V. Enzymatic reduction of arsenic compounds in mammalian systems: reduction of arsenate to arsenite by human liver arsenate reductase. Chem. Res. Toxicol. 13 (2000) 26-30. [PMID: 10649963]
7. Sato, T. and Kobayashi, Y. The ars operon in the skin element of Bacillus subtilis confers resistance to arsenate and arsenite. J. Bacteriol. 180 (1998) 1655-1661. [PMID: 9537360]
8. Shi, J., Vlamis-Gardikas, V., Aslund, F., Holmgren, A. and Rosen, B.P. Reactivity of glutaredoxins 1, 2, and 3 from Escherichia coli shows that glutaredoxin 2 is the primary hydrogen donor to ArsC-catalyzed arsenate reduction. J. Biol. Chem. 274 (1999) 36039-36042. [PMID: 10593884]
9. Mukhopadhyay, R. and Rosen, B.P. Arsenate reductases in prokaryotes and eukaryotes. Environ Health Perspect 110 Suppl 5 (2002) 745-748. [PMID: 12426124]
10. Messens, J. and Silver, S. Arsenate reduction: thiol cascade chemistry with convergent evolution. J. Mol. Biol. 362 (2006) 1-17. [PMID: 16905151]