A radish seed antifungal peptide with a high amyloid fibril-forming propensity

• Published in: Biochimica et biophysica acta Vol. 1834; no. 8; pp. 1615 - 1623
• Main Authors: Garvey, Megan, Meehan, Sarah, Gras, Sally L., Schirra, Horst J., Craik, David J., Van der Weerden, Nicole L., Anderson, Marilyn A., Gerrard, Juliet A., Carver, John A.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.08.2013
• Subjects: amino acids; amyloid; Amyloid - chemistry; Amyloid - metabolism; Amyloid - ultrastructure; Amyloid fibril; Antifungal Agents - pharmacology; Antifungal peptide; antifungal properties; Antimicrobial peptide; antimicrobial peptides; atomic force microscopy; Benzothiazoles; Circular Dichroism; Defensins - metabolism; freezing; Fusarium - drug effects; Fusarium - growth & development; Microscopy, Atomic Force; Microscopy, Electron, Transmission; Nicotiana - chemistry; Peptide Fragments - pharmacology; Protein aggregation; Protein misfolding; Protein Structure, Secondary; radishes; Raphanus - chemistry; Raphanus - metabolism; Raphanus sativus; Seeds - chemistry; Seeds - metabolism; sequence analysis; thawing; Thiazoles - metabolism; transmission electron microscopy; X-radiation; X-Ray Diffraction; CSαβ; ThT; RsAFP; Antifungal peptide; Protein aggregation; Protein misfolding; NaD1; AFM; XRD; Amyloid fibril; TEM; Antimicrobial peptide
• ISSN: 1570-9639; 0006-3002; 1878-1454
• DOI: 10.1016/j.bbapap.2013.04.030

The amyloid fibril-forming ability of two closely related antifungal and antimicrobial peptides derived from plant defensin proteins has been investigated. As assessed by sequence analysis, thioflavin T binding, transmission electron microscopy, atomic force microscopy and X-ray fiber diffraction, a 19 amino acid fragment from the C-terminal region of Raphanus sativus antifungal protein, known as RsAFP-19, is highly amyloidogenic. Further, its fibrillar morphology can be altered by externally controlled conditions. Freezing and thawing led to amyloid fibril formation which was accompanied by loss of RsAFP-19 antifungal activity. A second, closely related antifungal peptide displayed no fibril-forming capacity. It is concluded that while fibril formation is not associated with the antifungal properties of these peptides, the peptide RsAFP-19 is of potential use as a controllable, highly amyloidogenic small peptide for investigating the structure of amyloid fibrils and their mechanism of formation. [Display omitted] •A 19-mer antifungal peptide from radish seeds (RsAFP-19) is highly amyloidogenic.•RsAFP-19 fibril formation is independent of, and inhibits, itsantifungal activity.•A propensity for amyloid fibril formation is not exhibited byrelated antifungal peptides.•RsAFP-19 has many properties which make it an ideal modelfibril-forming peptide.