Extended Data Fig. 4. Characterization of NiRAN RNAylation activity.

a. Intact mass LC/MS spectra (overlayed) of unmodified nsp9 (cyan) or nsp9 after incubation with 5′-pppRNA^LS10 and WT nsp12 (pink). The theoretical and observed masses are shown in the insets. The Δmass of 3233.17 Da corresponds to monophosphorylated RNA^LS10 (5′-pRNA^LS10). b. Incorporation of RNA into nsp9 by nsp12 (0–4 µM) in the presence of Mg²⁺ or Mn²⁺. Reaction products were analysed as in Fig. 2b. c. Incorporation of RNA with the indicated 5′ ends into nsp9 by nsp12. Reaction products were analysed as in Fig. 2b. d. Time-dependent incorporation of 5′-pRNA^LS10 into nsp9 or the nsp9 N1A mutant. Reaction products were analysed as in Fig. 2b.

Source data