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

Abstract

Acanthamoeba polyphaga mimivirus tyrosyl-tRNA synthetase (TyrRSapm) was the first reported aminoacyl-tRNA synthetase of viral origin. The previous crystal structure of TyrRSapm showed a non-canonical orientation of the dimer conformation and the CP1 domain, responsible for dimer formation, displays a major modification of a motif structurally conserved in other TyrRS structures. An earlier study reported that Bacillus stearothermophilus N-terminal TyrRS exists as a dimer under native conditions. N-terminal TyrRSapm (ΔTyrRSapm, 1–234 aa) was constructed to remove the C-terminal anticodon-binding domain. Here we show by Ferguson plot analysis and analytical ultracentrifugation that ΔTyrRSapm exists as a monomer and contains a disulfide-bridge. The ΔTyrRSapm loses the ability to bind tRNATyr, however it remains active in pyrophosphate exchange with similar ligand dissociation constants as the full-length enzyme. Structured summary of protein interactionsTyrRSapm and TyrRSapmbind by cosedimentation in solution (View interaction) TyrRSapmandTyrRSapmbindbyblue native page(View interaction)TyrRSapmandTyrRSapmbindbyfluorescence technology(View interaction)TyrRSapmandTyrRSapmbindbyfluorescence technology(View interaction)