A gene fusion event in the evolution of aminoacyl-tRNA synthetases.
The genes of glutamyl- and prolyl-tRNA synthetases (GluRS and ProRS) are organized differently in the three kingdoms of the tree of life. In bacteria and archaea, distinct genes encode the two proteins. In several organisms from the eukaryotic phylum of coelomate metazoans, the two polypeptides are carried by a single polypeptide chain to form a bifunctional protein. The linker region is made of imperfectly repeated units also recovered as singular or plural elements connected as N-terminal or C-terminal polypeptide extensions in various eukaryotic aminoacyl-tRNA synthetases. Phylogenetic analysis points to the monophyletic origin of this polypeptide motif appended to six different members of the synthetase family, belonging to either of the two classes of aminoacyl-tRNA synthetases. In particular, the monospecific GluRS and ProRS from Caenorhabditis elegans, an acoelomate metazoan, exhibit this recurrent motif as a C-terminal or N-terminal appendage, respectively. Our analysis of the extant motifs suggests a possible series of events responsible for a gene fusion that gave rise to the bifunctional glutamyl-prolyl-tRNA synthetase through recombination between genomic sequences encoding the repeated units.
Berthonneau
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Laboratoire d'Enzymologie et Biochimie Structurales, C.N.R.S., 1 Avenue de la Terrasse, 91190, Gif-sur-Yvette, France.
Mirande
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D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000604:Amino Acyl-tRNA Synthetases / Q000737:chemistry* / Q000145:classification / Q000235:genetics*; D000818:Animals; D017360:Arabidopsis; D017173:Caenorhabditis elegans / Q000201:enzymology / Q000235:genetics; D003001:Cloning, Molecular; D006224:Cricetinae; D003434:Crossing Over, Genetic / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D019143:Evolution, Molecular; D005975:Glutamate-tRNA Ligase / Q000737:chemistry / Q000145:classification / Q000235:genetics; D006801:Humans; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D011995:Recombination, Genetic / Q000235:genetics*; D020449:Repetitive Sequences, Amino Acid / Q000235:genetics; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D015003:Yeasts
D018076:DNA, Complementary; D000604:Amino Acyl-tRNA Synthetases; C100134:prolyl T RNA synthetase; D005975:Glutamate-tRNA Ligase