Fig. 3: SAA inhibits LCMV CEN activity through competing substrate.

a The inhibitory effect of SAA on the cleavage of LCMV CEN on ssRNA substrate was examined at 5, 10, and 20 min via acrylamide-urea gel electrophoresis. Gray analysis of the corresponding strips was calculated for the inhibition rate, shown in the right panel. The divalent metal ion chelator, EDTA, was used as a positive control. The representative image was derived from three replicate experiments. b Dose-dependent inhibitory effect of SAA on LCMV CEN activity was detected using fluorescence resonance energy transfer (FRET), and an IC₅₀ was calculated based on the fluorescent signal value. Baloxavir (BXA) was used as a control. Data were from three independent experiments. c Enzymatic reaction rate was determined by adding different concentrations of LCMV CEN (left) to the reaction system while maintaining a constant substrate concentration, or adding different concentrations of substrate (right) to the reaction system in the presence of 1 µM of LCMV CEN. SAA was used as 5, 10, and 20 µM. Data were from three independent experiments. d Affinity of SAA to LCMV CEN was measured using surface plasmon resonance (SPR); K_D was calculated and is shown in the fitted curves. Data were from once representative experiment. e Interaction between SAA and LCMV CEN was analyzed by docking. SAA is shown in green, the blue sticks indicate amino acids interacting with SAA, and the Mn²⁺ is shown in purple. f Molecular dynamics simulations of SAA with LCMV CEN at 100 ns.