Figure 3.

Stabilization of cap-snatching endonucleases by a known endonuclease inhibitor and manganese binding. A, thermal stability of His+ and His− endonucleases in the presence of 2 mm MnCl₂ and 200 μm DPBA measured in a thermal shift assay (T_m, melting temperature). Thermal stabilization by DPBA is only observed in the presence of manganese ions. B, manganese binding to 160 μm CCHFV (left panel) or 140 μm LCMV (right panel) endonuclease protein was measured at 20 °C by isothermal titration calorimetry. The upper plot shows the binding isotherm, and the lower plot shows the integrated values. The dissociation constants from fitting a two-site sequential binding mode (K_d1 and K_d2) to one representative experiment are indicated.