Hybrids of Membrane-Translocating Antimicrobial Peptides Show Enhanced Activity through Membrane Permeabilization

Antimicrobial peptides (AMPs) hold promise as useful tools to combat bacterial infection. Hybrid peptides, made by linking two independent AMPs together through peptide bonds, have the potential for enhancing antimicrobial activity. Here we explore hybrids created by combining two histone-derived antimicrobial peptides (HDAPs), BF2 and DesHDAP1, that each translocate across bacterial membranes. Our work represents the first systematic approach considering the activity and mechanism of hybrids made from two translocating AMPs. BF2/DesHDAP1 hybrids showed increased antimicrobial activity against both Gram-positive and Gram-negative bacteria compared with the parent peptides and no cytotoxicity against eukaryotic cells. Introducing amino acid linkers between the parent peptides did not further enhance the antibacterial activity. The increased antimicrobial activity comes from a mechanistic shift, as hybrid peptides show decreased translocation across bacterial cell membranes but increased membrane permeabilization compared to BF2 and DesHDAP1. These observations lay the groundwork for the further design of hybrid AMPs made from translocating peptides.