dissimilatory sulfite reductase alpha subunit [EC:1.8.99.5]

PMID:9695921

Pott AS, 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 144 ( Pt 7):1881-94 (1998)
DOI:10.1099/00221287-144-7-1881

[alv:Alvin_1251]

dissimilatory sulfite reductase beta subunit [EC:1.8.99.5]

PMID:9695921

Pott AS, 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 144 ( Pt 7):1881-94 (1998)
DOI:10.1099/00221287-144-7-1881

[alv:Alvin_1252]

Oxidoreductases;
Acting on a sulfur group of donors;
With unknown physiological acceptors

hydrogen-sulfide:[DsrC sulfur-carrier protein],acceptor oxidoreductase

(1) hydrogen sulfide + a [DsrC protein]-disulfide + 2 acceptor + 3 H2O = sulfite + a [DsrC protein]-dithiol + 2 reduced acceptor + 2 H+ (overall reaction);
(1a) hydrogen sulfide + a [DsrC protein]-disulfide = a [DsrC protein]-S-sulfanyl-L-cysteine;
(1b) a [DsrC protein]-S-sulfanyl-L-cysteine + 2 acceptor + 3 H2O = sulfite + a [DsrC protein]-dithiol + 2 reduced acceptor + 2 H+;
(2) a [DsrC protein]-S-sulfanyl-L-cysteine + 3 acceptor + 3 H2O = sulfite + a [DsrC protein]-disulfide + 3 reduced acceptor + 2 H+ (overall reaction);
(2a) a [DsrC protein]-S-sulfanyl-L-cysteine + 3 acceptor + 3 H2O = a [DsrC]-S-sulfo-L-cysteine + 3 reduced acceptor + H+;
(2b) a [DsrC]-S-sulfo-L-cysteine = sulfite + a [DsrC protein]-disulfide

(other) R00295 R00861 R08035

hydrogen sulfide [CPD:C00283];
[DsrC protein]-disulfide;
acceptor [CPD:C00028];
H2O [CPD:C00001];
[DsrC protein]-S-sulfanyl-L-cysteine;
[DsrC]-S-sulfo-L-cysteine

Contain siroheme. The enzyme is essential in prokaryotic sulfur-based energy metabolism, including sulfate/sulfite reducing organisms, sulfur-oxidizing bacteria, and organosulfonate reducers. In sulfur reducers it catalyses the reduction of sulfite to sulfide (reaction 1 in the right to left direction), while in sulfur oxidizers it catalyses the opposite reaction (reaction 2 in the left to right direction) [1]. The reaction involves the small protein DsrC, which is present in all the organisms that contain dissimilatory sulfite reductase. During the process an intramolecular disulfide bond is formed between two L-cysteine residues of DsrC. This disulfide can be reduced by a number of proteins including DsrK and TcmB [5]. This enzyme is different from EC 1.8.1.2, assimilatory sulfite reductase (NADPH), and EC 1.8.7.1, assimilatory sulfite reductase (ferredoxin), which are involved in sulfate assimilation.

EC 1.8.99.5 created 2015

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.

2  [PMID:7338517]

Seki Y, Sogawa N, Ishimoto M

Siroheme as an active catalyst in sulfite reduction.

J. Biochem. 90 (1981) 1487-92.

3  [PMID:9695921]

Pott AS, 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. 144 ( Pt 7) (1998) 1881-94.

[alv:Alvin_1251 Alvin_1252]

4  [PMID:18829451]

Oliveira TF, Vonrhein C, Matias PM, Venceslau SS, Pereira IA, 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) 34141-9.

5  [PMID:24662917]

Venceslau SS, Stockdreher Y, Dahl C, Pereira IA

The "bacterial heterodisulfide" DsrC is a key protein in dissimilatory sulfur metabolism.

Biochim. Biophys. Acta. 1837 (2014) 1148-64.