Figure 5.

Structural variation of VvOxyR2 His-205 at the H₂O₂ and water binding sites near the peroxidatic cysteine residue. The putative chloride ion in VvOxyR2 (A) and the H₂O₂ molecule in P. aeruginosa OxyR (B; PDB code 4X6G) are bound near the peroxidatic cysteine (C206) or the mutated aspartic acid (C199D) residue. The polar interactions involved in binding the chloride ion (gray ball) or H₂O₂ (red ball and stick) are indicated by dotted lines. The bound water molecules (W1 and W2) are indicated by red balls. The 2F_o − F_c (blue mesh) and F_o − F_c (green mesh) omit maps of chloride ion and water molecules are contoured at 1.0 σ and 3.0 σ, respectively. C, two orthogonal views of the SO₄-free high-resolution structure of VvOxyR2 E204G variant. The alternative residues are presented by yellow or orange ball-and-stick representations. The difference points in dual conformation are indicated by red dihedral arrows. t and n letters in red indicate the typical conformation observed in the most OxyR proteins and the noncanonical conformation only observed in the wild-type VvOxyR2, respectively. *, carbonyl atom between Glu-204 (or Gly-204) and His-205.