Mass spectrometric based detection of protein nucleotidylation in the RNA polymerase of SARS-CoV-2

Nidovirus RNA synthesis machineries catalyze nucleotide transfer, but characterization of this activity is limited using existing methods. Here the nucleotidyl transferase activity of SARSCoV-2 replicase proteins is characterized by mass spectrometry of GMP and UMP protein adducts, allowing identification of nucleotidylation sites in vitro.