title: 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.
authors.affiliation: Yunnan Institute of Food Safety, Kunming University of Science and Technology, Kunming, Yunnan Province, China.
authors.forename: Lirong
authors.initials: L
authors.lastname: Li
authors.affiliation: Yunnan Institute of Food Safety, Kunming University of Science and Technology, Kunming, Yunnan Province, China.
authors.forename: Fengxia
authors.initials: F
authors.lastname: Song
authors.affiliation: Institute of Food Nutrition and Safety, School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu Province, China.
authors.forename: Jin
authors.initials: J
authors.lastname: Sun
authors.affiliation: Institute of Food Nutrition and Safety, School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu Province, China.
authors.forename: Xu
authors.initials: X
authors.lastname: Tian
authors.affiliation: Institute of Food Nutrition and Safety, School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu Province, China.
authors.forename: Shufang
authors.initials: S
authors.lastname: Xia
authors.affiliation: Institute of Food Nutrition and Safety, School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu Province, China.
authors.forename: Guowei
authors.initials: G
authors.lastname: Le
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology*; D001203:Ascomycota / Q000187:drug effects / Q000235:genetics; D001231:Aspergillus flavus / Q000187:drug effects / Q000235:genetics; D001234:Aspergillus niger / Q000187:drug effects / Q000235:genetics; D002176:Candida albicans / Q000187:drug effects* / Q000235:genetics; D002462:Cell Membrane / Q000187:drug effects*; D057846:Cell-Penetrating Peptides / Q000494:pharmacology*; D004271:DNA, Fungal / Q000187:drug effects*; D008564:Membrane Potentials / Q000187:drug effects; D009842:Oligopeptides / Q000737:chemistry
chemical_list: D000935:Antifungal Agents; D057846:Cell-Penetrating Peptides; D004271:DNA, Fungal; D009842:Oligopeptides; C465383:ppTG20 peptide
keywords: Candida albicans; DNA binding; antifungal activity; antimicrobial peptide; membrane damage