MexAB-OprM efflux pump (MexAB-OprM)

The MexAB-OprM efflux pump is a major tripartite multidrug efflux complex in Pseudomonas aeruginosa, composed of three main proteins: MexA (a membrane fusion protein), MexB (a resistance–nodulation–division [RND] transporter in the inner membrane), and OprM (an outer membrane factor channel)[1][6][7]. These subunits span the inner and outer bacterial membranes and the periplasmic space, forming a conduit that actively transports a wide range of antibiotics and toxic compounds from the cytoplasm directly to the extracellular environment, bypassing the periplasm[1][4][7]. This efflux mechanism is powered by the proton motive force, enabling P. aeruginosa to resist treatment with various antibiotics, and is a key contributor to the organism’s notable multidrug resistance. The operon encoding these components is tightly regulated but can be upregulated in clinical settings, further complicating treatment of infections caused by this opportunistic pathogen[3][8].

Other names

MexAB-OprM multidrug efflux pumpMexAB-OprM pumpMexA–MexB–OprM complexMexA, MexB, OprM (refers to the subunits)

Efflux of structurally diverse drugs and toxic compounds from the bacterial cell, thereby reducing intracellular concentrations and conferring resistance[6][8][1].\nProton motive force-driven active export, using energy across the inner membrane[6][1].