Figure 7.
Effect of silencing mmpL3 expression on the membrane potential (ΔΨ) and electrochemical proton gradient (ΔpH) of Mtb. The ΔΨ (A) and inner bacterial pH (B) of wild-type (WT) Mtb and mmpL3 knock-down (MmpL3-DUC) cells grown in the presence of 0, 0.2, 1, 5, or 10 ng/mL anhydro-tetracycline were determined. The expression of mmpL3 was previously shown to be inhibited in an anhydro-tetracycline concentration-dependent manner in the MmpL3-DUC knock-down strain.3 The values represent the averages and standard deviations of measurements performed on three independent bacterial suspensions after exposure to CCCP (4× MIC; 25 μM) (gray bars) or the DMSO solvent (1%) solvent alone (green bars) for 30 min at 37 °C. Results are representative of two independent tests. Asterisks denote statistically significant differences between WT and DUC mutant cells pursuant to the Student’s t-test (P < 0.05).