Detailed illustration of conserved His interactions in Rad53-FHA1. (A) Overall FHA structure. Conserved His is in red; other residues around His that contribute to form a pThr binding pocket are in orange. The phosphopeptide and pThr are in cyan. (B) Cartoon representation of two loops held by His and the nearby residues. Red dashed lines indicate interactions between residues. (C) MD simulation snapshots with time. Atom pairs with electrostatic attractions are labeled with blue dashed lines.