Membrane damage as first and DNA as the secondary target for anti‐candidal activity of antimicrobial peptide P7 derived from cell‐penetrating peptide ppTG20 against Candida albicans

Abstract

P7, a peptide analogue derived from cell-penetrating peptide ppTG20, possesses antibacterial and antitumor activities without significant hemolytic activity. In this study, we investigated the antifungal effect of P7 and its anti-Candida acting mode in Candida albicans. P7 displayed antifungal activity against the reference C. albicans (MIC = 4 μM), Aspergilla niger (MIC = 32 μM), Aspergillus flavus (MIC = 8 μM), and Trichopyton rubrum (MIC = 16 μM). The effect of P7 on the C. albicans cell membrane was examined by investigating the calcein leakage from fungal membrane models made of egg yolk l-phosphatidylcholine/ergosterol (10 : 1, w/w) liposomes. P7 showed potent leakage effects against fungal liposomes similar to Melittin-treated cells. C. albicans protoplast regeneration assay demonstrated that P7 interacted with the C. albicans plasma membrane. Flow cytometry of the plasma membrane potential and integrity of C. albicans showed that P7 caused 60.9 ± 1.8% depolarization of the membrane potential of intact C. albicans cells and caused 58.1 ± 3.2% C. albicans cell membrane damage. Confocal laser scanning microscopy demonstrated that part of FITC-P7 accumulated in the cytoplasm. DNA retardation analysis was also performed, which showed that P7 interacted with C. albicans genomic DNA after penetrating the cell membrane, completely inhibiting the migration of genomic DNA above the weight ratio (peptide : DNA) of 6. Our results indicated that the plasma membrane was the primary target, and DNA was the secondary intracellular target of the mode of action of P7 against C. albicans. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.

In vitro and in vivo Activity of Phibilin Against Candida albicans

“…However, the scanning electron microscopy showed that Phibilin had no effect on the general morphology of C. albicans cells ( Figures 4B–D ). Due to the cationic property of most of the membrane-acting AMPs, they can interact with specific and vital anionic components in the microorganisms, especially nucleic acids, upon penetrating the membrane ( Phadke et al, 2003 ; Soman et al, 2009 ; Sousa et al, 2016 ; Wang et al, 2017 ), such as APP ( Li et al, 2016b ) and P7 ( Li et al, 2016a ). In addition to being a membrane-acting AMP, Phibilin is also a cationic antimicrobial peptide.…”

Emerging Landscape of Supercharged Proteins and Peptides for Drug Delivery

“…72 Later, based on the structure−activity relationship of CPPs and AMPs, scientists replaced Phe and Trp with Arg in ppTG20, resulting in a ppTG20 analogue (P7) proven to have a bactericidal effect on Salmonella typhimurium, 73 Escherichia coli ATCC25922, 74 and Candida albicans. 75 CPP-TP10, a transport protein analogue lacking 21 amino acids, inhibits the growth of Candida albicans and Staphylococcus aureus. pVEC, another cationic CPP, inhibits the growth of Mycobacterium avium at low micromolar concentrations without toxic effects on HeLa cells.…”

Characterization of the transcriptional response of Candida parapsilosis to the antifungal peptide MAF-1A

“…Whilst membrane damage is the canonical mechanism through which AMPs act, other mechanisms exist. AMPs have specific subcellular targets, including the inhibition of DNA synthesis, RNA synthesis, protein synthesis, and cell wall integrity ( Guilhelmelli et al, 2013 ; Li et al, 2016 ). However, their mechanism(s) of action at the molecular level remain unclear.…”