Dual Peptide Modification via Isopeptide Bonding and Lipidation Boosts Antifungal Activity

Abstract The rapid rise in drug-resistant infectious diseases urgently demands new therapeutic strategies, particularly against fungi. Antimicrobial peptides (AMPs) are key effectors of innate immunity in all organisms, killing various microorganisms. Despite their potential, few AMPs effectively target pathogens without harming the host. Here, we incorporated isopeptide bonds and lipophilic acids into AMPs, forming lipo-isopeptides (LIIPs). LIIPs were active against diverse microorganisms, predominantly Candida albicans (C. albicans), and exhibited improved protease resistance. These modifications altered the secondary structure and oligomerization behavior, while enhancing membrane affinity. Consequently, by coating surfaces and cells, the non-toxic C8-Amp1EP reduces fungal adhesion and biofilm formation, and acts by disrupting and depolarizing the C. albicans membrane at both planktonic and biofilm stages. Importantly, under serial-passage conditions, C8-Amp1EP showed a lower propensity to induce resistance than conventional antifungal treatments. These findings identify LIIPs as promising, selective agents for combating infections, paving the way for future therapeutic development.