The Unusual Aggregation and Fusion Activity of the Antimicrobial Peptide W-BP100 in Anionic Vesicles

• Published in: Membranes (Basel) Vol. 13; no. 2; p. 138
• Main Authors: Ferreira, Ana Rita, Ferreira, Mariana, Nunes, Cláudia, Reis, Salette, Teixeira, Cátia, Gomes, Paula, Gameiro, Paula
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 21-01-2023; MDPI
• Subjects: Agglomeration; Antibacterial activity; Antibiotics; Antimicrobial agents; Antimicrobial peptides; Bacteria; Bacterial infections; bacterial membranes; Camps; Cationic antimicrobial peptides; Cecropin; Cell division; Circular dichroism; Confocal microscopy; Conformation; Dichroism; Drug resistance; Energy transfer; Fluorescence resonance energy transfer; Fluorescence spectroscopy; Förster resonance energy transfer; giant unilamellar vesicles; Gram-positive bacteria; large unilamellar vesicles; Lipids; membrane fusion; Membranes; Microscopy; Peptides; Pharmaceutical industry; Pore size; Ratios; Saturation; Sodium; Surface active agents; Surface charge; Vesicle fusion; Vesicles; United States; United Kingdom; Germany; United States > US; Förster resonance energy transfer; bacterial membranes; cationic antimicrobial peptides; confocal microscopy; giant unilamellar vesicles; large unilamellar vesicles; membrane fusion
• ISSN: 2077-0375; 2077-0375
• DOI: 10.3390/membranes13020138

Cationic antimicrobial peptides (CAMPs) offer a promising strategy to counteract bacterial resistance, mostly due to their membrane-targeting activity. W-BP100 is a potent broad-spectrum cecropin-melittin CAMP bearing a single N-terminal Trp, which was previously found to improve its antibacterial activity. W-BP100 has high affinity toward anionic membranes, inducing membrane saturation at low peptide-to-lipid (P/L) ratios and membrane permeabilization, with the unique property of promoting the aggregation of anionic vesicles only at specific P/L ratios. Herein, we aimed to investigate this unusual behavior of W-BP100 by studying its aggregation and fusion properties with negatively-charged large (LUVs) or giant (GUVs) unilamellar vesicles using biophysical tools. Circular dichroism (CD) showed that W-BP100 adopted an α-helical conformation in anionic LUVs, neutralizing its surface charge at the aggregation P/L ratio. Its fusion activity, assessed by Förster resonance energy transfer (FRET) using steady-state fluorescence spectroscopy, occurred mainly at the membrane saturation/aggregation P/L ratio. Confocal microscopy studies confirmed that W-BP100 displays aggregation and detergent-like effects at a critical P/L ratio, above which it induces the formation of new lipid aggregates. Our data suggest that W-BP100 promotes the aggregation and fusion of anionic vesicles at specific P/L ratios, being able to reshape the morphology of GUVs into new lipid structures.