Aminoacyl-tRNA synthetases catalyze a fundamental reaction for the flow of genetic information from RNA to protein. Their presence in all organisms known today highlights their important role in the early evolution of life. We investigated the evolutionary history of aminoacyl-tRNA synthetases on the basis of sequence data from more than 200 Archaea, Bacteria, and Eukaryota. Phylogenetic profiles are in agreement with previous observations that many genes for aminoacyl-tRNA synthetases were transferred horizontally between species from all domains of life. We extended these findings by a detailed analysis of the history of leucyl-tRNA synthetases. Thereby, we identified a previously undetected case of horizontal gene transfer from Bacteria to Archaea based on phylogenetic profiles, trees, and networks. This means that, finally, the last subfamily of aminoacyl-tRNA synthetases has lost its exceptional position as the sole subfamily that is devoid of horizontal gene transfer. Furthermore, the leucyl-tRNA synthetase phylogenetic tree suggests a dichotomy of the archaeal/eukaryotic-cytosolic and bacterial/eukaryotic-mitochondrial proteins. We argue that the traditional division of life into Prokaryota (non-chimeric) and Eukaryota (chimeric) is favorable compared to Woese's trichotomy into Archaea/Bacteria/Eukaryota.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Annotation Extension||Reference|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Assay||Construct||Conditions||Strain Background||Reference|