Membrane interactions of the anuran antimicrobial peptide HSP1-NH2: Different aspects of the association to anionic and zwitterionic biomimetic systems

• Published in: Biochimica et biophysica acta. Biomembranes 2021-01, Vol.1863 (1), p.183449, Article 183449
• Main Authors: Gomes, Isabela P., Santos, Talita L., de Souza, Amanda N., Nunes, Lúcio O., Cardoso, Gabriele A., Matos, Carolina O., Costa, Lívia M.F., Lião, Luciano M., Resende, Jarbas M., Verly, Rodrigo M.
• Format: Article
• Language: English
• Subjects: Antimicrobial mechanism of action; Antimicrobial peptides; Biophysical prediction of peptide-membrane interactions; Conformational analysis of peptides; Membrane active peptides; Membrane-dependent composition; Peptide-membrane interaction
• ISSN: 0005-2736; 1879-2642
• DOI: 10.1016/j.bbamem.2020.183449

Studies have suggested that antimicrobial peptides act by different mechanisms, such as micellisation, self-assembly of nanostructures and pore formation on the membrane surface. This work presents an extensive investigation of the membrane interactions of the 14 amino-acid antimicrobial peptide hylaseptin P1-NH2 (HSP1-NH2), derived from the tree-frog Hyla punctata, which has stronger antifungal than antibacterial potential. Biophysical and structural analyses were performed and the correlated results were used to describe in detail the interactions of HSP1-NH2 with zwitterionic and anionic detergent micelles and phospholipid vesicles. HSP1-NH2 presents similar well-defined helical conformations in both zwitterionic and anionic micelles, although NMR spectroscopy revealed important structural differences in the peptide N-terminus. 2H exchange experiments of HSP1-NH2 indicated the insertion of the most N-terminal residues (1–3) in the DPC-d38 micelles. A higher enthalpic contribution was verified for the interaction of the peptide with anionic vesicles in comparison with zwitterionic vesicles. The pore formation ability of HSP1-NH2 (examined by dye release assays) and its effect on the size and surface charge as well as on the lipid acyl chain ordering (evaluated by Fourier-transform infrared spectroscopy) of anionic phospholipid vesicles showed membrane disruption even at low peptide-to-phospholipid ratios, and the effect increases proportionately to the peptide concentration. On the other hand, these biophysical investigations showed that a critical peptide-to-phospholipid ratio around 0.6 is essential for promoting disruption of zwitterionic membranes. In conclusion, this study demonstrates that the binding process of the antimicrobial HSP1-NH2 peptide depends on the membrane composition and peptide concentration. [Display omitted] •Structural and biophysical reports on HSP1-NH2 associated with zwitterionic and anionic media.•Different modes of interaction were observed for HSP1-NH2 in the presence of zwitterionic and anionic vesicles•The peptide disturbs zwitterionic membranes only over a critical concentration•The results contribute to a better understanding the differences regarding the antifungal and antibacterial activities.