Ensuring correct translation of the genetic code : interactions between aminoacyl-tRNA synthetases and their amino acid ligands

Aminoacyl-tRNA synthetases (aaRSs) are key enzymes in the process of protein biosynthesis, charging tRNA molecules with their corresponding amino acid. Whereas adenosine phosphate fixation is common to all aaRSs, recognition of the respective amino acid to ensure correct translation poses a complex task, which is still not understood to its full extent. Using all aaRS structures in the Protein Data Bank (PDB), this thesis reveals further details about the specificitydetermining interactions of each aaRS. Moreover, inspection of the similarities between these enzymes using the structure-derived interaction data reinforces the sequence-based evolutionary trace of aaRSs to a certain degree: The concurrent development of two distinct Classes of aaRS is apparent at functional level, and previously determined evolutionary subclasses coincide altogether with specific aminoacyl recognition in each aaRS Type. Still, discrimination of amino acids in aaRSs involves a multitude of further relevant mechanisms. Eventually, analysis of specificity-relevant binding site interactions sheds light on how aaRS evolved to distinguish different amino acids