A stereochemical switch in the aDrs model system, a candidate for a functional amyloid

• Published in: Archives of biochemistry and biophysics Vol. 522; no. 2; pp. 100 - 106
• Main Authors: Gößler-Schöfberger, Ruth, Hesser, Günter, Reif, Maria M., Friedmann, Jacqueline, Duscher, Bernadette, Toca-Herrera, José Luis, Oostenbrink, Chris, Jilek, Alexander
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15.06.2012; Academic Press
• Subjects: amino acids; Amphibian Proteins - chemistry; Amphibian Proteins - physiology; Amphibian skin; amyloid; Amyloid - chemistry; Amyloid - physiology; Antimicrobial Cationic Peptides - chemistry; Antimicrobial Cationic Peptides - physiology; Bioactive peptide; d-Amino acid; diastereomers; frogs; Functional amyloid; Kinetics; Microscopy, Atomic Force; Microscopy, Electron, Transmission; Models, Molecular; Molecular Dynamics Simulation; nanomaterials; Posttranslational modification; seeds; Self-assembly; Spectroscopy, Fourier Transform Infrared; stereochemistry; Stereoisomerism; Thermodynamics; Posttranslational modification; Bioactive peptide; Functional amyloid; Self-assembly; d-Amino acid; Amphibian skin
• ISSN: 0003-9861; 1096-0384
• DOI: 10.1016/j.abb.2012.04.006

► Residue 2 in frog skin peptide aDrs can be enzymatically converted to a d-amino acid. ► The d-amino acid does not affect the kinetic parameters of aggregation. ► The diastereomers assemble to amyloids with different superstructural architectures. ► pH-triggered, melting of the amyloid is markedly altered by the d-amino acid. Amyloid fibrils are commonly observed to adopt multiple distinct morphologies, which eventually can have significantly different neurotoxicities, as e.g. demonstrated in case of the Alzheimer peptide. The architecture of amyloid deposits is apparently also determined by the stereochemistry of amino acids. Post-translational changes of the chirality of certain residues may thus be a factor in controlling the formation of functional or disease-related amyloids. Anionic dermaseptin (aDrs), an unusual peptide from the skin secretions of the frog Pachymedusa dacnicolor, assembles to amyloid-like fibrils in a pH-dependent manner, which could play a functional role in defense. aDrs can be enzymatically converted into the diastereomer [d-Leu2]-aDrs by an l/d-isomerase. EM and AFM on fibrils formed by these isomers have shown that their predominant morphology is controlled by the stereochemistry of residue 2, whereas kinetic and thermodynamic parameters of aggregation are barely affected. When fibrils were grown from preformed seeds, backbone stereochemistry rather than templating-effects apparently dominated the superstructural organization of the isomers. Interestingly, MD indicated small differences in the conformational propensities between the isomers. Our results demonstrate how d-amino acid substitutions could take active part in the formation of functional or disease-related amyloid. Moreover, these findings contribute to the development of amyloid-based nanomaterials.