Prediction of a new SelD‐like family that may participate in sulfur metabolism in hyperthermophilic sulfur‐reducing archaea

Abstract

Selenium (Se) and sulfur (S) are closely related elements that exhibit similar chemical properties. Some genes related to S metabolism are also involved in Se utilization in many organisms. However, the evolutionary relationship between the two utilization traits is unclear. In this study, we conducted a comparative analysis of the selenophosphate synthetase (SelD) family, a key protein for all known Se utilization traits, in all sequenced archaea. Our search showed a very limited distribution of SelD and Se utilization in this kingdom. Interestingly, a SelD‐like protein was detected in two orders of Crenarchaeota: Sulfolobales and Thermoproteales. Genomic and phylogenetic analyses revealed that SelD‐like protein may share a common ancestor with SelD and might be involved in S metabolism in these S‐reducing organisms. Further genome‐wide analysis of patterns of genes occurrence in different thermoproteales suggested that several genes, including SirA‐like, Prx‐like and adenylylsulfate reductase, were strongly related to the SelD‐like protein. Finally, we proposed a simple model wherein the SelD‐like protein may play an important role in the biosynthesis of certain thiophosphate compound. Our data suggest novel genes involved in S metabolism in hyperthermophilic S‐reducing archaea, and may provide a new window for understanding the complex relationship between Se and S metabolism in archaea.