FIG 4.

Interactions of relebactam with active sites of class A β-lactamases. Close-up views of relebactam bound in the active sites of class A β-lactamases (colored as in Fig. 3). Hydrogen bonding interactions of relebactam with the protein main chain are shown as dashes with distances in Å. Water molecules are shown as red spheres; those that make conserved interactions are numbered. (A) CTX-M-15 (16-hour soak) showing relebactam bound in two conformations, (B) L2 (16-hour soak), and (C) KPC-4 (1-hour soak). Relebactam was modelled as both the imine (desulfated, acyl-98 as shown in Fig. 5A) and intact forms from 16-hour soaks of (D) KPC-2, (E) KPC-3, and (F) KPC-4 crystals.