Methionyl-tRNA synthetase

Methionyl-tRNA synthetase (MetRS) belongs to the family of 20 enzymes essen tial for protein biosynthesis. It links covalently methionine with its cogn ate tRNA. Crystal structures solved for bacterial MetRSs have given a numbe r of interesting insights into enzyme architecture and methionylation catal ysis. A comparison of sequences of MetRSs belonging to all kingdoms of life , as well as numerous biochemical and genetic studies have revealed the pre sence of various additional domains appended to the catalytic core of synth etase. They are responsible for interactions with tRNA and proteins. Tertia ry structure of C-terminal tRNA-binding appendices can be deduced from thos e determined for their homologues: tRNA binding protein 111 and endothelial monocyte-activating polypeptide II. Contacts between MetRS and other prote ins could be mediated not only by noncatalytic peptides but also by structu ral elements present in the catalytic core, e.g. Arg-Gly-Asp (RGD) motifs. Additional activities involve MetRS in the maintenance of translational fid elity and in coordination of ribosome biogenesis with protein synthesis.