Abstract
The synthetic, linear peptide, D4E1, demonstrates antimicrobial activity against a broad spectrum of organisms including the toxigenic filamentous Ascomycete, Aspergillus flavus with a minimal lethal concentration of 12.5 µM against germinating conidia. However, the mechanism associated with the antimicrobial properties of D4E1 has not been studied in detail. Here we demonstrate that D4E1 permeabilizes mycelial membranes through monitoring cellular infiltration of SYTOX Green dye, a nucleic acid intercalating agent that can only enter cells through compromised membranes. The membrane lesions resulting from treatment with D4E1 allowed translocation into cells of 3000 Da dextran-fluorescein conjugates but not 10,000 Da conjugates. In addition to permeabilizing membranes, treatment with D4E1 at concentrations as low as 1 µM induced the accumulation of reactive oxygen species (ROS) in germinating A. flavus conidia. ROS accumulation is associated with stress response and initiation of apoptosis. Thus, the antimicrobial activity of D4E1 likely results from membrane permeabilization and accumulation of ROS which induces apoptotic events.
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Acknowledgements
This study was supported by a cooperative research agreement between the United States Department of Agriculture (Agreement No. 58-6435-8-300) and the University of Louisiana at Lafayette (Dr. Caryl Chlan, PI).
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Moore, J., Rajasekaran, K., Cary, J.W. et al. Mode of Action of the Antimicrobial Peptide D4E1 on Aspergillus flavus. Int J Pept Res Ther 25, 1135–1145 (2019). https://doi.org/10.1007/s10989-018-9762-1
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DOI: https://doi.org/10.1007/s10989-018-9762-1