Fig. 1: Newly acquired domains and motifs in ARSs during the evolutionary process.

During evolution, aminoacyl-tRNA synthetase have acquired new domains, allowing for an increase in the complexity of organisms in a particular phylogenetic group. Importantly, with the exception of MRS, these domains or motifs have been irreversibly retained by their respective tRNA synthetase until the evolution of humans. As a result, each aminoacyl-tRNA synthetase in humans has all of the newly acquired domains. Each of these domains imparts specific new functions that are more complex than simple aminoacylation, which was the original function of these enzymes. The model species used are: Homo sapiens, Danio rerio, Drosophila melanogaster, Caenorhabditis elegans, and Saccharomyces cerevisiae. LUCA last universal common ancestor, N-helix N-terminal amphiphilic helix, GST glutathione S-transferase (GST)-like domain, EMAPII endothelial monocyte-activating polypeptide II