Key interactions in a tripartite multidrug efflux pump of pathogenic bacteria. (360G-Wellcome-093011_Z_10_Z)

Studying mechanisms of antibiotic resistance is essential to understand and counteract bacterial diseases, and also informs us about fundamental biological processes. We propose to continue our studies on the TolC-dependent machineries, or pumps, which effect efflux of antibacterial drugs by all Gram-negative bacteria. In these tripartite systems an outer membrane-anchored TolC protein presents a cell exit duct to diverse molecules bound by inner membrane transporters. The two apposed membrane c omponents are structurally and functionally linked by a periplasmic adaptor protein that is key to the recruitment and opening of the TolC exit channel. The assembled active pumps span the entire bacterial cell envelope of two membranes and intervening periplasmic space. We will continue to establish key details of the assembly and operation of the AcrA/AcrB/TolC RND type pump widespread among bacteria such as E.coli, Pseudomonas and Neisseria. Our work will advance understanding of this medic ally important system and will allow us to assess potential targets for future resistance inhibitors. It will also provide insights into the biogenesis and activity of complex membrane machineries.