Figure 1.

Baloxavir acid (BXA) chelates divalent metal ions at the active site of the Influenza B cap-snatching endonuclease subunit (PA).A, model depicting baloxavir acid (BXA, top) binding to the Influenza B PA active site (PDB:6FS8) (21). Selected residues are depicted as sticks. E81, D109, and E120 coordinate metal ions (purple balls), which bind to the anchor domain of baloxavir. I38 forms part of the hydrophobic interface that interacts with the specificity domain of BXA. B, schematic diagram of baloxavir acid (BXA) highlighting anchor and specificity domains. Me²⁺ represents either Mg²⁺ or Mn²⁺.