Designed Amyloid Fibers with Emergent Melanosomal Functions

Short peptides designed to self-associate into amyloidfibers with metal ion-binding ability have been used to catalyzevarious types of chemical reactions. This manuscript demonstrates that one of these short-peptidefibers coordinated with CuIIcanexhibit melanosomal functions. The coordinated CuIIand the amyloid structure itself are differentially functional in acceleratingoxidative self-association of dopamine into melanin-like species and in regulating their material properties (e.g., water dispersion,morphology, and the density of unpaired electrons). The results have implications for the role of functional amyloids in melaninbiosynthesis and for designing peptide-based supramolecular structures with various emergent functions.