The case for an error minimizing set of coding amino acids

The fidelity of the translation machinery largely depends on the accuracy by which the tRNAs within the living cells are charged. Aminoacyl-tRNA synthetases (aaRSs) attach amino acids to their cognate tRNAs ensuring the fidelity of translation in coding sequences. Based on the sequence analysis and catalytic domain structure, these enzymes are classified into two major groups of 10 enzymes each. In this study, we have generally tackled the role of aaRSs in decreasing the effects of mistranslations and consequently the evolution of the translation machinery. To this end, a fitness function was introduced in order to measure the accuracy by which each tRNA is charged with its cognate amino acid. Our results suggest that the aaRSs are very well optimized in “load minimization” based on their classes and their mechanisms in distinguishing the correct amino acids. Besides, our results support the idea that from an evolutionary point, a selectional pressure on the translational fidelity seems to be responsible in the occurrence of the 20 coding amino acids.