2015/12/17 by André A. Santos, Sofia S. Venceslau, Fabian Grein +4 · 1 voice · 1 citation
Biochemistry, Genetics and Molecular Biology · Environmental Science · #Microbial Community Ecology and Physiology #Nitrogen and Sulfur Effects on Brassica #Sulfur Compounds in Biology
paper · doi:10.1126/science.aad3558
openalex publication_date 2015/12/17 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Microbial sulfate reduction has governed Earth's biogeochemical sulfur cycle for at least 2.5 billion years. However, the enzymatic mechanisms behind this pathway are incompletely understood, particularly for the reduction of sulfite-a key intermediate in the pathway. This critical reaction is performed by DsrAB, a widespread enzyme also involved in other dissimilatory sulfur metabolisms. Using in vitro assays with an archaeal DsrAB, supported with genetic experiments in a bacterial system, we show that the product of sulfite reduction by DsrAB is a protein-based trisulfide, in which a sulfite-derived sulfur is bridging two conserved cysteines of DsrC. Physiological studies also reveal that sulfate reduction rates are determined by cellular levels of DsrC. Dissimilatory sulfate reduction couples the four-electron reduction of the DsrC trisulfide to energy conservation.