FIG 2.

Overall cryo-EM structure of the A. baumannii AdeB multidrug efflux pump. (A) Ribbon diagram of the structure of the AdeB trimer viewed in the membrane plane. Each subunit of AdeB is labeled with a different color. Subdomains DN, DC, PN2, PC1, and PC2 are labeled on the front protomer. PN1 is located behind PN2, PC1, and PC2 and is therefore not labeled in this view. No channel is formed in the periplasmic domain of each protomer. The bound PE lipids are depicted as spheres (gray, carbon; blue, nitrogen; orange, phosphorus; red, oxygen). (B) The PE binding site at the interior wall of the central cavity of an AdeB protomer. The EM density of the bound PE is in blue mesh and shown at 5 σ. The secondary structural elements of the AdeB protomer involved in binding this lipid molecule are colored pink. (C) The PE binding site at the interface between two AdeB protomers. The EM density of the bound PE is in blue mesh and shown at 5 σ. The secondary structural elements of the two AdeB protomers that form the protein-protein interface are colored pink and gray.