FIG 5.

Stereoviews of the active site of the carbapenem complexes of the F110A/M221A OXA-23 mutant. (A) Superposition of the imipenem (PDB code 6N6U, yellow sticks) and meropenem (PDB code 6N6V, magenta sticks) structures at pH 4.6. The F110A/M221A OXA-23 mutant is shown as green ribbons and sticks for the imipenem complex only for clarity. (B) Superposition of the imipenem (PDB code 6N6X, yellow sticks) and meropenem (PDB code 6N6Y, magenta sticks) structures at pH 7.0. Only the F110A/M221A OXA-23 structure (green) for the imipenem complex is shown. (C) Superposition of the meropenem complexes of the F110A/M221A OXA-23 mutant (PDB code 6N6Y, pH 7.0, green ribbons and sticks) and wild-type OXA-23 (PDB code 4JF4, pH 4.1, pink ribbons and sticks). The meropenem Δ¹R tautomer in the mutant complex is shown as magenta sticks, and the meropenem Δ¹S tautomer in the wild-type complex is shown as cyan sticks.