Fig. 5: Harmane induces proton flux through EmrE. | Nature Communications

Fig. 5: Harmane induces proton flux through EmrE.

From: Activating alternative transport modes in a multidrug resistance efflux pump to confer chemical susceptibility

Fig. 5

MeTPP+ (a, b) behaves as expected for an antiported substrate (see Fig. 3). The total transported charge reverses when the drug gradient is inverted, characteristic of coupled antiport. In contrast, the harmane transport signal (c, d) is the same regardless of the harmane gradient, matching the expected behavior for downhill proton transport (proton leak). The current is minimal in the absence of drug (b, c; gray) or for liposomes containing nonfunctional E14Q-EmrE (dashed lines), indicating that the observed charge transport is due to substrate-triggered EmrE activity. Data are presented as the mean value ± SD. Wild-type EmrE data were obtained from four independent sensors. E14Q-EmrE data were obtained from three independent sensors. These values are indicated on the corresponding bar graphs.

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