ExplorEnz: EC 1.8.1.22

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1.8.1.22

Accepted name:

dissimilatory sulfite reductase system

Reaction:

a [DsrC protein]-trisulfide + NAD⁺ + 3 H₂O = a [DsrC protein]-dithiol + sulfite + NADH + H⁺

Other name(s):

siroheme sulfite reductase; DsrABL; hydrogen-sulfide:(acceptor) oxidoreductase (incorrect)

Systematic name:

[DsrC protein]-trisulfide,NAD⁺ oxidoreductase (sulfite-forming)

Comments:

Contains siroheme. The enzyme is essential in prokaryotic sulfur-based energy metabolism, including sulfate/sulfite reducing organisms, sulfur-oxidizing bacteria, and organosulfonate reducers. The system comprises the DsrAB reductase and the DsrL protein, which form a tight complex. The reaction involves the small protein DsrC, which is present in all the organisms that contain dissimilatory sulfite reductase. In sulfite reducers the DsrL component transfers two electrons from NADH to the DsrAB component, which then reduces the sulfur in sulfite to an S(II) intermediate that forms (together with two cysteine residues of DsrC) a trisulfide. In sulfur oxidizers the enzyme catalyses the opposite reaction [1].

Links to other databases:

BRENDA, EXPASY, KEGG, MetaCyc

References:

1.	Schedel, M., Vanselow, M. and Trueper, H. G. Siroheme sulfite reductase from Chromatium vinosum. Purification and investigation of some of its molecular and catalytic properties. Arch. Microbiol. 121 (1979) 29–36. [DOI]
2.	Seki, Y., Sogawa, N. and Ishimoto, M. Siroheme as an active catalyst in sulfite reduction. J. Biochem. 90 (1981) 1487–1492. [DOI] [PMID: 7338517]
3.	Pott, A.S. and Dahl, C. Sirohaem sulfite reductase and other proteins encoded by genes at the dsr locus of Chromatium vinosum are involved in the oxidation of intracellular sulfur. Microbiology (Reading) 144 (1998) 1881–1894. [DOI] [PMID: 9695921]
4.	Oliveira, T.F., Vonrhein, C., Matias, P.M., Venceslau, S.S., Pereira, I.A. and Archer, M. The crystal structure of Desulfovibrio vulgaris dissimilatory sulfite reductase bound to DsrC provides novel insights into the mechanism of sulfate respiration. J. Biol. Chem. 283 (2008) 34141–34149. [DOI] [PMID: 18829451]
5.	Venceslau, S.S., Stockdreher, Y., Dahl, C. and Pereira, I.A. The "bacterial heterodisulfide" DsrC is a key protein in dissimilatory sulfur metabolism. Biochim. Biophys. Acta 1837 (2014) 1148–1164. [DOI] [PMID: 24662917]
6.	Loffler, M., Feldhues, J., Venceslau, S.S., Kammler, L., Grein, F., Pereira, I.AC. and Dahl, C. DsrL mediates electron transfer between NADH and rDsrAB in Allochromatium vinosum. Environ. Microbiol. 22 (2020) 783–795. [DOI] [PMID: 31854015]

[EC 1.8.1.22 created 2015 as EC 1.8.99.5, transferred 2023 to EC 1.8.1.22 ]