Meropenem-inactivated LdtMt2Δ130. (a) Electron-density map (left) and a schematic diagram of interactions (right) of the covalently bound meropenem adduct with Cys354 in meropenem-complexed LdtMt2Δ130 (chain B). The OMIT mFo − DFc map (contoured at 2.5σ) for meropenem and the 2mFo − DFc map (contoured at 1.0σ) for Cys354 are coloured blue and yellow, respectively. Dotted lines denote interactions with LdtMt2Δ130 and the corresponding bond lengths are shown in Å. Variable regions (R1, R2 and R3) of carbapenems are shaded in green, blue and red, respectively. (b) Interactions of the bound meropenem with Tyr318 (left) and Tyr308 (right). Dotted lines and the electron-density map are presented as in (a). (c) Surface representation (left) and ribbon diagram (right) of the active site of LdtMt2Δ130 enclosing the meropenem adduct viewed along Path B. The β14–β15 loop, the β15–β16 loop and the active-site lid, which surround the bound meropenem, are coloured plum, orange and green, respectively. (d) Surface representation (left) and ribbon diagram (right) of the active site in the meropenem-complexed LdtMt2Δ130 viewed along Path A presented as in (c).