Structural characterization of the EmrAB-TolC efflux complex from E. coli

Gram-negative bacteria export a large variety of antimicrobial compounds by forming two-membrane spanning tripartite multidrug efflux systems composed an inner membrane transporter, outer channel and periplasmic adaptor protein. Here we present the co-expression, purification first electron microscopy insights Escherichia coli EmrAB–TolC Major Facilitator Superfamily (MSF) system as whole complex stabilized Amphipol polymer. The structure reveals 33 nm long delineated belt at both extremities. Comparison projection structures EmrAB-TolC AcrAB-TolC indicates that protein TolC linked to EmrA form extended canal. overall length is similar with probable tip-to-tip interaction between unveiling how connects EmrB embedded in membrane.