Antifungal Mechanism of an Antimicrobial Peptide, HP (2–20), Derived from N-Terminus of Helicobacter pylori Ribosomal Protein L1 against Candida albicans

Abstract

The antifungal activity and mechanism of HP (2–20), a peptide derived from the N-terminus sequence of Helicobacter pylori Ribosomal Protein L1 were investigated. HP (2–20) displayed a strong antifungal activity against various fungi, and the antifungal activity was inhibited by Ca 2+ and Mg 2+ ions. In order to investigate the antifungal mechanism(s) of HP (2–20), fluorescence activated flow cytometry was performed. As determined by propidium iodide staining, Candida albicans treated with HP (2–20) showed a higher fluorescence intensity than untreated cells and was similar to melittin-treated cells. The effect on fungal cell membranes was examined by investigating the change in membrane dynamics of C. albicans using 1,6-diphenyl-1,3,5-hexatriene as a membrane probe and by testing the membrane disrupting activity using liposome (PC/PS; 3:1, w/w) and by treating protoplasts of C. albicans with the peptide. The action of peptide against fungal cell membrane was further examined by the potassium-release test, and HP (2–20) was able to increase the amount of K + released from the cells. The result suggests that HP (2–20) may exert its antifungal activity by disrupting the structure of cell membrane via pore formation or directly interacts with the lipid bilayers in a salt-dependent manner.