Evaluation of Decoralin Peptide Identifies Activity Determinants and Synthetic Variants with In Vivo Activity

AMPs constitute promising alternatives to conventional antibiotics for the treatment of drug-resistant infections, which are rapidly emerging as a global health challenge. However, our understanding of the structure-function relationships of AMPs is limited, and we are just beginning to rationally engineer these molecules in order to develop them as therapeutics. Here, we leverage a physicochemical-guided screen to identify specific functional hotspots in the waspderived AMP decoralin and enable peptide design. Peptides were synthesized, and tested against fungi, Gram-negative and Gram-positive bacteria, and human kidney cells. Conformational analyses were performed by Circular Dichroism in ten different media. The scarification skin infection mouse model used involved inducing a P. aeruginosa abscess and treating mice with a single dose of the selected peptides at 8 μmol L-1. The Ala-scan screening was performed aiming to check the importance of amino acid side chains and hydrophilic/hydrophobic ratio of decoralin derivatives. After, we demonstrate that by tuning physicochemical parameters, such as net charge, helical fraction and hydrophobicity-related features, by substituting original residues by positively charged residues or symmetric aliphatic residues, it is possible to design synthetic peptides with enhanced nanomolar antimicrobial potency in vitro and anti-infective activity in vivo, and also low toxicity. We present a physicochemical-guided rational design strategy for identifying functional hotspots in a small cationic amphipathic natural peptide and for tuning structure-function to generate novel potent peptide antibiotics with low toxicity.