Antimicrobial Spectrum of Activity and Mechanism of Action of Linear Alpha-Helical Peptides Inspired by Shrimp Anti-Lipopolysaccharide Factors
Gabriel Machado Matos, Beatriz Garcia-Teodoro, Camila Pimentel Martins, Paulina Schmitt, Fanny Guzmán, Ana Claudia Oliveira de Freitas, Patrícia Hermes Stoco, Fabienne Antunes Ferreira, Marciel J. Stadnik, Diogo Robl, Luciane Maria Perazzolo, Rafael Diego Rosa
Abstract
Shrimp antilipopolysaccharide factors (ALFs) form a multifunctional and diverse family of antimicrobial host defense peptides (AMPs) composed of seven members (groups A to G), which differ in terms of their primary structure and biochemical properties. They are amphipathic peptides with two conserved cysteine residues stabilizing a central β-hairpin that is understood to be the core region for their biological activities. In this study, we synthetized three linear (cysteine-free) peptides based on the amino acid sequence of the central β-hairpin of the newly identified shrimp (Litopenaeus vannamei) ALFs from groups E to G. Unlike whole mature ALFs, the ALF-derived peptides exhibited an α-helix secondary structure. In vitro assays revealed that the synthetic peptides display a broad spectrum of activity against both Gram-positive and Gram-negative bacteria and fungi but not against the protozoan parasites Trypanosoma cruzi and Leishmania (L.) infantum. Remarkably, they displayed synergistic effects and showed the ability to permeabilize bacterial membranes, a mechanism of action of classical AMPs. Having shown low cytotoxicity to THP-1 human cells and being active against clinical multiresistant bacterial isolates, these nature-inspired peptides represent an interesting class of bioactive molecules with biotechnological potential for the development of novel therapeutics in medical sciences.