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

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.
BBA - Proteins and Proteomics 2013 v.1834 pp. 1615-1623
Raphanus sativus, X-radiation, amino acids, amyloid, antifungal properties, antimicrobial peptides, atomic force microscopy, freezing, radishes, sequence analysis, thawing, transmission electron microscopy
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.