Conserving energy with sulfate around 100 °C : structure and mechanism of key metal enzymes in hyperthermophilic Archaeoglobus fulgidus

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 SO₄^2- → H₂S reduction. This review summarizes recent advances in our understanding of the activation of sulfate to adenosine 5'-phosphosulfate, the following reductive cleavage to SO₃^2- and AMP, and the final six-electron reduction of SO₃^2- 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.