Alteration of the Antifungal Action Mechanism Due to Structural Changes in the Antimicrobial Peptide, HnMc

The rapid induction of drug resistance is considered a fatal drawback of conventional antibiotics and requires the continuous development of new antibiotics. Accordingly, antibacterial peptides (AMPs) have attracted interest as next-generation antibiotics and many studies have been conducted. However, much remains unknown regarding the mechanism of AMPs and the effects of amino acid sequence changes. We compared the structures and antifungal effects of HnMc-W (F1W substitution, straight alpha-helical structure), HnMc-WP1 (S9P substitution, bending alpha-helical structure), and HnMc-WP2 (addition of the PXXP motif, helix-to-helix structure) to those of a parent hybrid AMP (HnMc) regarding their mechanism of action. The most active was HnMc-WP2, which exhibited an antifungal effect via membranolytic action on the fungal cell membrane. The others inhibited fungal growth by inducing apoptosis through reactive oxygen species production caused by mitochondrial damage. This study proposes the addition of the ‘PXXP’ motif in the design of AMPs acting on cell membranes.