Screening for Antifungal Peptides and Their Modes of Action in Aspergillus nidulans

Ref ID: 19343

Author:

Mania, D., Hilpert, K., Ruden, S., Fischer, R., Takeshita, N.

Author address:

Karlsruhe Institute of Technology, Institute for Applied Biosciences, Department of Microbiology, Hertzstrasse 16, D-76187 Karlsruhe,
Germany; Karlsruhe Institute of Technology, Institute of Functional Interfaces, P.O. Box 3640, D-76021 Karlsruhe, G

Full conference title:

Society for General Microbiology Autumn Conference 2013

Date: 19 August 2014

Abstract:

Many short cationic peptides have been identified as potent antimicrobial agents, but their modes of action
are not well understood. Peptide synthesis on cellulose membranes has resulted in the generation of peptide
libraries, while high-throughput assays have been developed to test their antibacterial activities. In this paper
a microtiter plate-based screening method for fungi has been developed and used to test nine antibacterial
peptides against the model fungus Aspergillus nidulans. Microscopical studies using sublethal peptide concentrations
caused defects in polarized growth, including increased branch formation and depolarized hyphae. We
characterized the mode of action for one of our target peptides, Sub5 (12 amino acids), which has already been
shown to possess pharmacological potential as an antibacterial agent and is able to interact with ATP and
ATP-dependent enzymes. The MIC for A. nidulans is 2 g/ml, which is in the same range as the MICs reported
for bacteria. Fluorescein isothiocyanate (FITC)-labeled Sub5 targeted the cytoplasmic membrane, particularly
hyphal tips, and entered the cytoplasm after prolonged exposure, independent of endocytosis. Interestingly,
Sub5 peptide treatment disturbed sterol-rich membrane domains, important for tip growth, at hyphal tips. A
very similar peptide, FITC-P7, also accumulated on the cell membrane but did not have antibacterial or
antifungal activity, suggesting that the cytoplasmic membrane is a first target for the Sub5 peptide; however,
the antifungal activity seems to be correlated with the ability to enter the cytoplasm, where the peptides might act on other targets.

Abstract Number: NULL

Conference Year: 2013

Link to conference website: NULL

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