Fig. 6: Ion conductance is sensitive to lipid acyl chain disordering induced by WF AMPs and explains synergistic gain in potency.

Disordering of lipid acyl chains induced by WF AMPs in MD simulations is related to the lowest concentration at which ion conductance is detected by patch-clamp (a Pearson r = 0.7007, p = 0.0111). At these concentrations, only some WF AMPs trigger substantial membrane activity (f DPhPG; g DPhPE/DPhPG) and average MICs for Gram-positive or Gram-negative bacteria are unrelated to these threshold concentrations (b Pearson r = 0.4802; p = 0.1141; red dash = line of identity). At its threshold concentration (7.5 µM) WF2, d, g induces substantial ion conductance in DPhPE/DPhPG bilayers but this is slow (d, h) and precedes bilayer disruption. WF1a (15 µM) is largely inert (c, g). Combining WF2 (3.75 µM) and WF1a (5 µM) ensures substantial ion conductance is induced more rapidly and with less peptide (e, g, h). Time taken to onset of conductance (h) is the average and SE of five independent replicates. One-way ANOVA with Bonferroni’s multiple comparisons test: ***p < 0.001.