Dissimilatory sulfate reduction

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Overview of dissimilatory sulfate reduction performed by sulfate-reducing microorganisms.

Dissimilatory sulfate reduction is a form of

organosulfur compounds, even though hydrogen sulfide
may be an intermediate.

Dissimilatory sulfate reduction occurs in four steps:[1]

  1. Conversion (activation) of sulfate to adenosine 5’-phosphosulfate (APS) via sulfate adenylyltransferase
  2. Reduction of APS to sulfite via adenylyl-sulfate reductase
  3. Transfer of the sulfur atom of sulfite to the DsrC protein creating a trisulfide intermediate catalyzed by DsrAB
  4. Reduction of the trisulfide to sulfide and reduced DsrC via a membrane bound enzyme, DsrMKJOP

Which requires the consumption of a single ATP molecule and the input of 8 electrons (e−).[2][3]

The protein complexes responsible for these chemical conversions — Sat, Apr and Dsr — are found in all currently known organisms that perform dissimilatory sulfate reduction.

ATP sulfurylase (Sat), at the cost of a single ATP molecule. The APS-sulfite redox couple has a E0' of -60 mV, which allows APS to be reduced by either NADH or reduced ferrodoxin using the enzyme adenylyl-sulfate reductase (Apr), which requires the input of 2 electrons.[5] In the final step, sulfite is reduced by the dissimilatory sulfite reductase (Dsr) to form sulfide, requiring the input of 6 electrons.[3]

See also

References

  1. S2CID 206643054
    .
  2. PMID 25416397
    .
  3. ^
    PMID 22982583
    .
  4. PMID 21747791
    .
  5. ^
    S2CID 22775967
    .
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