The N-terminal fragment of Acanthamoeba polyphaga mimivirus tyrosyl-tRNA synthetase (TyrRSapm) is a monomer in solution

► Tyrosyl-tRNA synthetase of mimivirus (TyrRSapm) forms weak dimers in solution. ► N-terminal TyrRSapm (ΔTyrRSapm) of mimivirus exists as a monomer in solution. ► The ligand-binding affinity for l-Tyr and ATP is not affected in ΔTyrRSapm, but is decreased 40-fold for tRNATyr.