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Abstract

Sulfate-reducing bacteria and archaea are important players in the biogeochemical sulfur cycle. ATP sulfurylase, adenosine 5′-phosphosulfate reductase and dissimilatory sulfite reductase are the key enzymes in the energy conserving process of SO₄²⁻ → H₂S reduction. This review summarizes recent advances in our understanding of the activation of sulfate to adenosine 5′-phosphosulfate, the following reductive cleavage to SO₃²⁻ and AMP, and the final six-electron reduction of SO₃²⁻ to H₂S in the hyperthermophilic archaeon Archaeoglobus fulgidus. Structure based mechanisms will be discussed for these three enzymes which host unique metal centers at their catalytic sites.