FIGURE 3.

The dormant complex is catalytically competent but does not form with C115D MurA. A, upon incubation with UNAG, the dormant complex catalyzes a single turnover to yield EP-UNAG and free Cys-115 (VI). Shown as blue mesh is the 2 F_o − F_c electron density at 1.8 Å resolution, contoured at 1σ. Purified C115D mutant enzyme is free of ligands (D–VII) (B) and closes upon interaction with UNAG (D–VIII) (C). The conformation of the loop and positioning of the aspartate side chain in the closed state with UNAG (D) is similar to that of the wild-type enzyme (E).