Competition between protons and substrate for binding to the major facilitator superfamily multidrug/H+ antiporter MdtM

Abstract Proton electrochemical gradient-driven multidrug efflux activity of representatives the major facilitator superfamily (MFS) secondary active transporters contributes to antimicrobial resistance pathogenic bacteria. Integral mechanism these is a proposed competition between substrate and protons for binding site protein. The current work investigated Escherichia coli MFS multidrug/H + antiporter MdtM by measuring quench intrinsic protein fluorescence upon titration tetraphenylphosphonium into solution purified over range pH values 8.8 5.9. results, which revealed that inhibit in competitive manner, are consistent with those reported study on related MdfA provide further evidence general feature efflux.