The Amyloid Fibril-Forming Properties of the Amphibian Antimicrobial Peptide Uperin3.5

Antonio N. Calabrese, Yanqin Liu, Tianfang Wang, Ian F. Musgrave, Tara L. Pukala, Rico F. Tabor, Lisandra L. Martin*, John A. Carver, John H. Bowie

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    40 Citations (Scopus)

    Abstract

    The amphibian skin is a vast resource for bioactive peptides, which form the basis of the animals' innate immune system. Key components of the secretions of the cutaneous glands are antimicrobial peptides (AMPs), which exert their cytotoxic effects often as a result of membrane disruption. It is becoming increasingly evident that there is a link between the mechanism of action of AMPs and amyloidogenic peptides and proteins. In this work, we demonstrate that the broad-spectrum amphibian AMP uperin3.5, which has a random-coil structure in solution but adopts an α-helical structure in membrane-like environments, forms amyloid fibrils rapidly in solution at neutral pH. These fibrils are cytotoxic to model neuronal cells in a similar fashion to those formed by the proteins implicated in neurodegenerative diseases. The addition of small quantities of 2,2,2-trifluoroethanol accelerates fibril formation by uperin3.5, and is correlated with a structural stabilisation induced by this co-solvent. Uperin3.5 fibril formation and the associated cellular toxicity are inhibited by the polyphenol (-)-epigallocatechin-3-gallate (EGCG). Furthermore, EGCG rapidly dissociates fully formed uperin3.5 fibrils. Ion mobility-mass spectrometry reveals that uperin3.5 adopts various oligomeric states in solution. Combined, these observations imply that the mechanism of membrane permeability by uperin3.5 is related to its fibril-forming properties.

    Original languageEnglish
    Pages (from-to)239-246
    Number of pages8
    JournalChemBioChem
    Volume17
    Issue number3
    DOIs
    Publication statusPublished - 2 Feb 2016

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