Structural perturbation of the mutation. (A) The RMSD of the interfacial residues and (B) the distance of the 25 water molecules in wild type interface to their nearest water in the mutant. The water molecules are sorted by their distance to the mutation sites. For water B2077, a water molecule in the mutant that is mutually the closest to it is observed with a distance larger than 1.0 Å (not reappear). For waters B2071 and A2075, no water that is mutually closest to them are observed, so a bar higher than 2.5 Å is shown for them. The remaining 22 waters reappear in the mutant.