Integrating cationic backbone with hydrophobic core: a structure-function approach to self-assembling antimicrobial peptides with superior activity

Combating problematic nosocomial pathogens such as Carbapenem-resistant Klebsiella pneumoniae and methicillin-resistant Staphylococcus aureus (MRSA) requires innovative antimicrobial strategies. Here, we present a structure-function approach to antimicrobial peptide (AMP) design through the strategic integration of a cationic backbone with a hydrophobic core architecture. This dual-domain integration leverages hydrophobic and electrostatic interactions to facilitate self-assembly and superior antimicrobial performance through enhanced membrane interaction and penetration capabilities. Our lead peptide, Tryptolycin (TRPY), self-assembled into stable monodisperse nanoparticles. TRPY exhibited broad-spectrum efficacy against multiple strains of MRSA and K. pneumoniae (minimum inhibitory concentrations ≤ 1 µM) with minimal cytotoxicity toward mammalian cells. Notably, TRPY rapidly killed bacteria, eradicating 99.9% of both planktonic and persister cells within minutes. Mechanistically, TRPY exerted its bacteriolytic activity through membrane permeabilization, generation of reactive oxygen species (ROS), and inhibition of biofilm formation. In murine infection, TRPY effectively eradicated established infections, reducing bacterial load in organs by 3- to 5-fold without significant cytotoxicity at therapeutic concentrations. Collectively, these findings position Tryptolycin as a promising therapeutic agent for further development into a versatile tool for combating recalcitrant pathogens.