Figure 1.

Schematic of the tripartite multidrug efflux pump. The pumps comprise an exit duct (shown in orange; TolC in E. coli, OprM in P. aeruginosa) anchored in the outer membrane (OM), an integral inner membrane (IM) transporter (in blue; AcrB and MexB) and a periplasmic adaptor protein (in green; AcrA and MexA) linked to the inner membrane by a fatty acid (zigzagline). The adaptor binds the exit duct α-helical domain via it's α-hairpin (23) and thre transporter via it's α-hairpin (23) and the transporter via unknown interactions (indicated by ?). The adaptor linear multidomain structure is characterized by interdomain flexibility, but it is incompletye, missing the MP domain indicated by the dotted outline. Red dots indicate antibacterial drugs bound to putative pockets in the transporter, passing through TolC (arrowed), and out of the cell[9]