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

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.