Previous proteomic analyses have shown that aminoacyl-tRNA synthetases (aaRSs) in many organisms can be modified by acetylation of lysine (Lys). In this present study, leucyl-tRNA synthetase and arginyl-tRNA synthetase from Escherichia coli (EcLeuRS and EcArgRS) were overexpressed and purified, and found to be acetylated on Lys residues by mass spectrometry (MS). Glutamine (Gln) scanning mutage...