De Novo-designed antimicrobial peptides with broad-spectrum antimicrobial potency and rapid wound disinfection

Abstract

Antimicrobial peptides (AMPs) are widely regarded as a promising antibiotic alternative to current antibiotics in combating bacterial resistance. Cost-effective AMPs with outstanding antibacterial activity, fast killing kinetics, good biocompatibility, and strong stability are in urgent need. In this work, we took the short AMP G(IIKK)3I (denoted as G3-COOH, a de novo AMP) as template and mediated its physicochemical parameters by altering its hydrophobic and hydrophilic amino acid type, composition, amino acid sequence, and amino acid configuration to optimize its antibacterial performance and clarify the structure-bioactivity relationship. The results showed that AMPs with stronger hydrophobicity imposed stronger antibacterial activities, more rapid killing kinetics, but greater cytotoxicity and hemolytic activity as well. Among all the designed AMPs, Trp-substituting variants GW1 (G(WIKK)3W) and GW2 (G(IWKK)3W) showed the strongest antibacterial activity, good selectivity, and good salt and serum resistance. Particularly, GW1 presented very rapid bactericidal kinetics, which achieved 99.9% bacterial killing of all the tested strains in 0.25 min. Antibacterial mechanism investigations suggested that they destroyed membrane structure and eventually killed the bacteria. Furthermore, changing their chirality from L- to D-configuration (D-GW1 and D-GW2) had no obvious effects on their antibacterial activity, bactericidal kinetics, cytotoxicity, and hemolytic activity, but improved their biostability in serum. Subsequently, the excellent in vivo antibacterial performance of D-GW1 and its ability to effectively promote wound healing and re-epithelialization were confirmed in S. aureus-infected rat model. This work offers valuable insights into the structure-property-bioactivity relationship of AMPs and promote the development of AMP-based therapeutics.