Figure 2.

Baloxavir bound to the PA_N endonuclease. (A) Wild type PA_N. (B) I38T PA_N. (C) E119D PA_N. In each figure, baloxavir is represented as sticks with black carbon atoms, the PA_N cartoon and key residues are colored cyan, the active site Mn²⁺ ions are large yellow spheres and the water molecules are small red spheres. Note in B that the side chain of the Thr38 point mutant is oriented such that the hydroxyl group can make hydrogen bond interactions with the main chain carbonyl oxygens of Lys34 and Phe35 (dotted black lines) while the methyl group optimizes its apolar interaction with baloxavir.