Fig. 3: Effect of potentiators on membrane properties of the 2 reference strains PAO1 and PAO509 and 2 colistin-resistant clinical isolates PA2938 and PA307. | Communications Biology

Fig. 3: Effect of potentiators on membrane properties of the 2 reference strains PAO1 and PAO509 and 2 colistin-resistant clinical isolates PA2938 and PA307.

From: The membrane-active polyaminoisoprenyl compound NV716 re-sensitizes Pseudomonas aeruginosa to antibiotics and reduces bacterial virulence

Fig. 3

a Summary of the effect of potentiators at fixed concentrations (alexidine [ALE], 2.5 µM; polymyxin B nonapeptide [PMBN]: 30 μM; colistin [CST], 1 µM (MIC against PAO1); PAβN: 38 μM; NV716: 2.5 μM and 50 µM [MIC against PAO1]) on membrane properties of PAO1 (BC: Binding to LPS, assessed by measuring the displacement of BODIPY-cadaverine after incubation during 30 min; NPN: Effect on outer membrane permeability, assessed by measuring the rate of 1-N-phenylnaphthylamine (NPN) uptake at early-time points (0-4 seconds); PI: Effect on inner membrane permeability, assessed by measuring the fluorescence of propidium iodide (PI) after 1 h of incubation; DISC(3)5: Inner membrane depolarization, assessed by measuring the DiSC3(5) fluorescence after 15 min of incubation. Values are expressed in percentage of the effect of alexidine. Statistical analysis: one-way ANOVA with Tukey post-hoc test: ****p < 0.0001. b–e concentration-response for BC displacement (Imipenem: negative control). f–i NPN uptake (PAβN: 38 μM; polymyxin B nonapeptide [PMBN]: 30 μM; alexidine [ALE], colistin [CST], NV731, NV716: 2.5 μM), in the absence (open bars) or in the presence (closed bars) of 10 mM Mg2+. Statistical analysis: one-way ANOVA with Tukey post-hoc test comparing NPN uptake in all conditions: open bars with different letters are different from one another. One-way ANOVA with Dunnett’s post-hoc test for comparison between NPN uptake alone (as a control) or combined with each of the potentiator: ***p < 0.001; ****p < 0.0001. Two-tailed Student’s t test for comparison for each condition without and with Mg2+: p value indicated above each pair of columns. j–m concentration-response for PI fluorescence. The effect measured with 0.5 % SDS (w/v) after 1 h was taken as 100% (positive control). All data are means ± SEM (triplicates from 3 independent experiments). In panels b–e and j–m, the arrows point to the MIC of the corresponding compound (see Supplementary Table 1; when not shown, the MIC is higher than the highest concentration tested).

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