Dissimilatory sulfite reductase

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dissimilatory sulfite reductase
Identifiers
EC no. 1.8.99.5
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BRENDA BRENDA entry
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MetaCyc metabolic pathway
PRIAM profile
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Dissimilatory sulfite reductase (EC 1.8.99.5) is an enzyme that participates in sulfur metabolism in dissimilatory sulfate reduction. [1]

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); while in sulfur oxidizers, it catalyses the opposite reaction (reaction 2). [2] The reaction involves the small protein DsrC, which is present in all the organisms that contain dissimilatory sulfite reductase. [3] During the process, an intramolecular trisulfide is formed between two L-cysteine residues of DsrC and the sulfur atom from sulfite. [4] This trisulfide can be reduced by a number of proteins including DsrK and TcmB. [5]

Reaction in organisms performing dissimilatory sulfate reduction:

1 (overall reaction)
SO2−3 + [DsrC]-(SH)2 + 2 acceptor red + 2H+ → H2S + [DsrC]-S2 + 2 acceptor ox + 3H2O
1a
SO2−3 + [DsrC]-(SH)2 + 2 acceptorred + 2H+ → [DsrC]-Cys-S-HS* + 2 acceptorox + 3H2O
1b
[DsrC]-Cys-S-HS* → H2S + [DsrC]-S2

Reaction in organisms performing sulfur oxidation:

2 (overall reaction)
[DsrC]-Cys-S-HS* + 3 acceptorox + 3H2O → SO2−3 + [DsrC]-S2 + 3 acceptorred + 2H+
2a
[DsrC]-Cys-S-HS* + 3 acceptorox + 3H2O → [DsrC]-Cys-S-SO3 + 3 acceptorred + H+
2b
[DsrC]-Cys-S-SO3 → SO2−3 + [DsrC]-S2 + H+

The systematic name of this enzyme class is hydrogen-sulfide:[DsrC sulfur-carrier protein],acceptor oxidoreductase.

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.

References

Creative Commons by small.svg  This article incorporates text available under the CC BY 4.0 license. BRENDA online database for enzymes: 1.8.99.5

  1. ↑ Parey K, Warkentin E, Kroneck PM, Ermler U (October 2010). "Reaction cycle of the dissimilatory sulfite reductase from Archaeoglobus fulgidus". Biochemistry. 49 (41): 8912–21. doi:10.1021/bi100781f. PMID   20822098.
  2. ↑ Schedel M, Vanselow M, Trüper HG (1979). "Siroheme sulfite reductase isolated from Chromatium vinosum. Purification and investigation of some of its molecular and catalytic properties". Archives of Microbiology. 121 (1): 29–36. Bibcode:1979ArMic.121...29S. doi:10.1007/BF00409202. S2CID   22126920.
  3. ↑ Oliveira TF, Vonrhein C, Matias PM, Venceslau SS, Pereira IA, Archer M (December 2008). "The crystal structure of Desulfovibrio vulgaris dissimilatory sulfite reductase bound to DsrC provides novel insights into the mechanism of sulfate respiration". The Journal of Biological Chemistry. 283 (49): 34141–9. doi: 10.1074/jbc.M805643200 . PMC   2662231 . PMID   18829451.
  4. ↑ Santos AA, Venceslau SS, Grein F, Leavitt WD, Dahl C, Johnston DT, Pereira IA (December 2015). "A protein trisulfide couples dissimilatory sulfate reduction to energy conservation". Science. 350 (6267): 1541–5. Bibcode:2015Sci...350.1541S. doi:10.1126/science.aad3558. PMID   26680199. S2CID   206643054.
  5. ↑ Venceslau SS, Stockdreher Y, Dahl C, Pereira IA (July 2014). "The "bacterial heterodisulfide" DsrC is a key protein in dissimilatory sulfur metabolism". Biochimica et Biophysica Acta (BBA) - Bioenergetics. 1837 (7): 1148–64. doi: 10.1016/j.bbabio.2014.03.007 . PMID   24662917.


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