title: Trypanosoma seryl-tRNA synthetase is a metazoan-like enzyme with high affinity for tRNASec.
abstract: Trypanosomatids are important human pathogens that form a basal branch of eukaryotes. Their evolutionary history is still unclear as are many aspects of their molecular biology. Here we characterize essential components required for the incorporation of serine and selenocysteine into the proteome of Trypanosoma. First, the biological function of a putative Trypanosoma seryl-tRNA synthetase was characterized in vivo. Secondly, the molecular recognition by Trypanosoma seryl-tRNA synthetase of its cognate tRNAs was dissected in vitro. The cellular distribution of tRNA(Sec) was studied, and the catalytic constants of its aminoacylation were determined. These were found to be markedly different from those reported in other organisms, indicating that this reaction is particularly efficient in trypanosomatids. Our functional data were analyzed in the context of a new phylogenetic analysis of eukaryotic seryl-tRNA synthetases that includes Trypanosoma and Leishmania sequences. Our results show that trypanosomatid seryl-tRNA synthetases are functionally and evolutionarily more closely related to their metazoan homologous enzymes than to other eukaryotic enzymes. This conclusion is supported by sequence synapomorphies that clearly connect metazoan and trypanosomatid seryl-tRNA synthetases.
authors.affiliation: Institució Catalana de Recerca i Estudis Avançats (ICREA) and Institute for Research in Biomedicine, Barcelona, Barcelona Science Park, C/Samitier 1-5, Barcelona 08015, Catalonia, Spain.
authors.forename: Renaud
authors.initials: R
authors.lastname: Geslain
authors.forename: Eric
authors.initials: E
authors.lastname: Aeby
authors.forename: Tanit
authors.initials: T
authors.lastname: Guitart
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Jones
authors.forename: Manuel
authors.initials: M
authors.lastname: Castro de Moura
authors.forename: Fabien
authors.initials: F
authors.lastname: Charrière
authors.forename: André
authors.initials: A
authors.lastname: Schneider
authors.forename: Lluís
authors.initials: L
authors.lastname: Ribas de Pouplana
mesh_terms: D000215:Acylation; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002384:Catalysis; D003001:Cloning, Molecular; D017931:DNA Primers; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D012343:RNA, Transfer / Q000737:chemistry / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D012714:Serine-tRNA Ligase / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D013379:Substrate Specificity; D014345:Trypanosoma / Q000201:enzymology*
chemical_list: D017931:DNA Primers; D012343:RNA, Transfer; D012714:Serine-tRNA Ligase