Supramolecular Regulation of Polydopamine Formation by Amyloid Fibers

Polydopamine (PD) and melanin species are chemically complex systems whose formation and properties are incompletely understood. Inspired by the role of functional amyloids in melanin biosynthesis, this paper examines influences of amyloid supramolecular structures on oxidation polymerization of dopamine. Kinetic analyses on the formation of PD species in the presence of Hen Egg White Lysozyme (HEWL) fibers or soluble HEWL revealed that the both forms gave rise to the total quantity of PD species, but the rate of their formation could be accelerated only by the amyloid form. PD species formed with HEWL fibers showed a morphology of bundled fibers, whereas those with soluble HEWL had a mesh-like structure. Amyloid fibers of recombinant Pmel17 had a similar property with HEWL fibers in modulating PD formation. The results presented here suggests a way how nature designs functionality with an amyloid structure and would help understand or engineer chemistries of other functional amyloids.