title: The Amyloid Fibril-Forming Properties of the Amphibian Antimicrobial Peptide Uperin 3.5.
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 uperin 3.5, 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 uperin 3.5, and is correlated with a structural stabilisation induced by this co-solvent. Uperin 3.5 fibril formation and the associated cellular toxicity are inhibited by the polyphenol (-)-epigallocatechin-3-gallate (EGCG). Furthermore, EGCG rapidly dissociates fully formed uperin 3.5 fibrils. Ion mobility-mass spectrometry reveals that uperin 3.5 adopts various oligomeric states in solution. Combined, these observations imply that the mechanism of membrane permeability by uperin 3.5 is related to its fibril-forming properties.
authors.affiliation: School of Physical Sciences or School of Medical Sciences, The University of Adelaide, Adelaide, 5005, South Australia, Australia.
authors.forename: Antonio N
authors.initials: AN
authors.lastname: Calabrese
authors.affiliation: School of Physical Sciences or School of Medical Sciences, The University of Adelaide, Adelaide, 5005, South Australia, Australia.|School of Technology, Hebei Agricultural University, Cangzhou, Hebei, 061100, China.
authors.forename: Yanqin
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Sippy Downs, 4556, Queensland, Australia.
authors.forename: Tianfang
authors.initials: T
authors.lastname: Wang
authors.affiliation: School of Physical Sciences or School of Medical Sciences, The University of Adelaide, Adelaide, 5005, South Australia, Australia.
authors.forename: Ian F
authors.initials: IF
authors.lastname: Musgrave
authors.affiliation: School of Physical Sciences or School of Medical Sciences, The University of Adelaide, Adelaide, 5005, South Australia, Australia.
authors.forename: Tara L
authors.initials: TL
authors.lastname: Pukala
authors.affiliation: School of Chemistry, Monash University, Clayton, 3800, Victoria, Australia.
authors.forename: Rico F
authors.initials: RF
authors.lastname: Tabor
authors.affiliation: School of Chemistry, Monash University, Clayton, 3800, Victoria, Australia. lisa.martin@monash.edu.
authors.forename: Lisandra L
authors.initials: LL
authors.lastname: Martin
authors.affiliation: Research School of Chemistry, The Australian National University, Acton, 2601, Australian Capital Territory, Australia. john.carver@anu.edu.au.
authors.forename: John A
authors.initials: JA
authors.lastname: Carver
authors.affiliation: School of Physical Sciences or School of Medical Sciences, The University of Adelaide, Adelaide, 5005, South Australia, Australia.
authors.forename: John H
authors.initials: JH
authors.lastname: Bowie
mesh_terms: D000595:Amino Acid Sequence; D000663:Amphibians / Q000378:metabolism*; D000682:Amyloid / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D002392:Catechin / Q000031:analogs & derivatives / Q000737:chemistry; D002470:Cell Survival / Q000187:drug effects; D002942:Circular Dichroism; D016716:PC12 Cells; D017433:Protein Structure, Secondary; D051381:Rats; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D000682:Amyloid; D023181:Antimicrobial Cationic Peptides; D002392:Catechin; C045651:epigallocatechin gallate
keywords: aggregation; amyloid; antimicrobial peptides; mass spectrometry; uperin