Figure 5. Inhibition of the nsp14 and nsp16/nsp10 MTase activities.

Nsp14 (50 nM) and nsp16/nsp10 (200 nM/1.2 µM) were incubated with GpppAC₅ (in grey) and ^7MeGpppAC₅ (in black), respectively, in order to measure the methyl transfer to the RNA substrates by filter-binding assay (see Materials and Methods). Panel A: Methyl transfer was measured at a final concentration of 100 µM of each inhibitor candidate. The outcome of the control reaction in absence of inhibitor and at 5% of DMSO was set to 100%. The mean value of three independent experiments is given. 1: control, 2: AdoHcy, 3: sinefungin, 4: SIBA (5′-S-isobutylthio-5′-deoxyadenosine), 5: 3-deaza-adenosine, 6: MTA (5′-deoxy-5′-methylthio-adenosine), 7: 2′,3′,5′-tri-O-acetyl-adenosine, 8: S-5′-adenosyl-L-cysteine, 9: GTP, 10: ^7MeGTP, 11: ribavirin, 12: ribavirin-triphosphate, 13: EICAR-triphosphate, 14: GpppA, 15: ^7MeGpppA, 16: ATA, 17: adamantane-analog (N-({[3-(4-methylphenyl)-1-adamantyl]amino}carbonyl)phenylalanine). Panels B, C and D: Dose-response curves and IC₅₀ values of inhibitors AdoHcy, sinefungin and ATA, respectively. The results of three independent experiments are given. Standard deviations are shown for concentrations that were tested three times. IC₅₀ values were calculated as described in Materials and Methods.