Figure 1: MdfA confers resistance only against a unique class of symmetric dicationic compounds (LDC).
From: Export of a single drug molecule in two transport cycles by a multidrug efflux pump
(a) Structures of the tested dicationic drugs. Left: long dicationic compounds (LDCs): dequalinium (Dq), chlorhexidine (Chx) and pentamidine (Pent). Right: short dicationic compounds (SDCs): 4′,6-diamidino-2-phenylindole (DAPI), diminazene (Dmn) and methyl viologen (Met-Viol). (b) Growth of E. coli UTmdfA::kan expressing MdfA from a multicopy plasmid (or harboring empty vector) on solid media supplemented with the indicated drugs. Tenfold serial dilutions of cells were plated from left to right and grown overnight. The upper panels show controls of growth in the absence of drug or in the presence of previously known monocationic (TPP/ethidium bromide (EtBr)) or neutral (CAM) MdfA substrates. The experiments were repeated at least three times and the results shown are representative.
