Evolutionary Aspects of Selenium Binding Protein (SBP)

Selenium-binding proteins represent a ubiquitous protein family and recently SBP1 was described as a new stress response regulator in plants. SBP1 has been characterized as a methanethiol oxidase, however its exact role remains unclear. Moreover, in mammals, it is involved in the regulation of anti-carcinogenic growth and progression as well as reduction/oxidation modulation and detoxification. In this work, we delineate the functional potential of certain motifs of SBP in the context of evolutionary relationships. The phylogenetic profiling approach revealed the absence of SBP in the fungi phylum as well as in most non eukaryotic organisms. The phylogenetic tree also indicates the differentiation and evolution of characteristic SBP motifs. Main evolutionary events concern the CSSC motif for which Acidobacteria, Fungi and Archaea carry modifications. Moreover, the CC motif is harbored by some bacteria and remains conserved in Plants, while modified to CxxC in Animals. Thus, the characteristic sequence motifs of SBPs mainly appeared in Archaea and Bacteria and retained in Animals and Plants. Our results demonstrate the emergence of SBP from bacteria and most likely as a methanethiol oxidase.

Automated summary

Selenium-binding proteins (SBPs) are a widely distributed protein family, with SBP1 recently identified as a new stress response regulator in plants. Although SBP1 has been characterized as a methanethiol oxidase, its exact role is still unclear. In mammals, SBP1 is involved in anti-carcinogenic growth regulation, redox modulation, and detoxification. This study investigates the functional potential of specific motifs of SBPs in an evolutionary context. Phylogenetic analysis reveals the absence of SBP in fungi and most non-eukaryotic organisms. The phylogenetic tree also highlights the differentiation and evolution of characteristic SBP motifs, with modifications found in Acidobacteria, Fungi, and Archaea for the CSSC motif and a conserved CC motif in Plants modified to CxxC in Animals. These results suggest that SBPs likely emerged from bacteria as methanethiol oxidases.