Structural characterization and biological activity of Crabrolin peptide isoforms with different positive charge

• Published in: Biochimica et biophysica acta. Biomembranes 2020-02, Vol.1862 (2), p.183055-183055, Article 183055
• Main Authors: Aschi, M., Perini, N., Bouchemal, N., Luzi, C., Savarin, P., Migliore, L., Bozzi, A., Sette, M.
• Format: Article
• Language: English
• Subjects: Anti-Bacterial Agents - chemistry; Anti-Bacterial Agents - pharmacology; Antimicrobial Cationic Peptides - chemistry; Antimicrobial Cationic Peptides - pharmacology; Antimicrobial peptides; Binding Sites; Biochemistry, Molecular Biology; Circular dichroism; Crabrolin; Gram-Negative Bacteria - drug effects; Gram-Positive Bacteria - drug effects; Ions - chemistry; Life Sciences; Lipopolysaccharides; Molecular dynamics; Molecular Structure; Nuclear magnetic resonance; Protein Engineering - methods; Protein Isoforms - chemistry; Structural Biology; Wasp Venoms - chemistry; Wasp Venoms - pharmacology
• ISSN: 0005-2736; 1879-2642
• DOI: 10.1016/j.bbamem.2019.183055

The search of antimicrobial peptides (AMP) as candidates for the development of antibiotics is an active research field. In this paper we investigated the role of charged residues in antimicrobial activity by using as a template the previously characterized crabrolin peptide. Mutant peptides in which the charge was diminished (Crabrolin Minus) or increased (Crabrolin Plus) were assayed for their ability to inhibit bacterial growth and to bind model bacterial membranes or lipopolysaccharide (LPS). Structural analysis of both peptides by means of CD, NMR and Molecular Dynamics was also performed and correlated to the biological data. Although native Crabrolin (WT) displays smaller efficacy than other antibacterial peptides with similar length, Crabrolin Plus displays a significant antimicrobial activity while Crabrolin Minus is not active, thus confirming the key role of the positive charge for interacting with the bacterial membrane. Moreover, our results show that charge position has no effect on the helical propensity of the peptides but drastically affects their antimicrobial activity. Antimicrobial activity versus Gram-positive and Gram-negative bacteria, as well as specific interaction with LPS, suggest multiple binding modes for the active peptide. [Display omitted] •Crabrolin peptide mutant show modified antimicrobial activity on Gram +/- bacteria and membrane-permeabilizing ability on synthetic membranes•Despite mutations, spectroscopic and computational methods show that the peptides adopt the same alpha-elical structure•Differences in antimicrobial activity are related to charge distribution along the peptide’s structure•LPS may be the binding site of active peptide during the interaction with Gram- bacteria