Author:
Mariotti Marco,Santesmasses Didac,Capella-Gutierrez Salvador,Mateo Andrea,Arnan Carme,Johnson Rory,D'Aniello Salvatore,Yim Sun Hee,Gladyshev Vadim N.,Serras Florenci,Corominas Montserrat,Gabaldón Toni,Guigó Roderic
Abstract
Selenoproteins are proteins that incorporate selenocysteine (Sec), a nonstandard amino acid encoded by UGA, normally a stop codon. Sec synthesis requires the enzyme Selenophosphate synthetase (SPS or SelD), conserved in all prokaryotic and eukaryotic genomes encoding selenoproteins. Here, we study the evolutionary history of SPS genes, providing a map of selenoprotein function spanning the whole tree of life. SPS is itself a selenoprotein in many species, although functionally equivalent homologs that replace the Sec site with cysteine (Cys) are common. Many metazoans, however, possess SPS genes with substitutions other than Sec or Cys (collectively referred to as SPS1). Using complementation assays in fly mutants, we show that these genes share a common function, which appears to be distinct from the synthesis of selenophosphate carried out by the Sec- and Cys- SPS genes (termed SPS2), and unrelated to Sec synthesis. We show here that SPS1 genes originated through a number of independent gene duplications from an ancestral metazoan selenoprotein SPS2 gene that most likely already carried the SPS1 function. Thus, in SPS genes, parallel duplications and subsequent convergent subfunctionalization have resulted in the segregation to different loci of functions initially carried by a single gene. This evolutionary history constitutes a remarkable example of emergence and evolution of gene function, which we have been able to trace thanks to the singular features of SPS genes, wherein the amino acid at a single site determines unequivocally protein function and is intertwined to the evolutionary fate of the entire selenoproteome.
Funder
Spanish Ministry of Science
Catalan Government
Spanish Ministry of Education
Spanish Ministry of Economy and Competitiveness
Qatar National Research Fund
European Research Council
National Institutes of Health
Publisher
Cold Spring Harbor Laboratory
Subject
Genetics(clinical),Genetics
Cited by
45 articles.
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