Using a stable protein scaffold to display peptides that bind to alpha-synuclein fibrils.

Amyloid fibrils are ordered aggregates that are a pathological hallmark of many neurodegenerative disorders including Alzheimer's disease and Parkinson's disease. The process of amyloid formation involves a complex cascade by which soluble monomeric protein converts to insoluble, ordered aggregates (amyloid fibrils). Although inhibiting the aggregation pathway is a key target for therapeutic development, the heterogeneous collection of aggregation-prone species formed in this process, including oligomers, protofibrils, and fibrils, represents other targets for modifying disease pathology. Developing molecules that can bind to amyloid fibrils and potentially disrupt the harmful interactions between the fibrils and the cellular components would be advantageous. Designing peptide modulators for α-synuclein aggregation is of great interest; however, effective inhibitory peptides are often hydrophobic and hence difficult to handle. Therefore, developing strategies to display these peptides in a soluble scaffold would be very beneficial. Here we demonstrate that the ultra-stable consensus-designed tetratricopeptide repeat (CTPR) protein scaffold can be grafted with "KLVFF" derived peptides previously identified to inhibit protein aggregation and interact with amyloid fibrils to produce proteins that bind along the surface of α-synuclein fibrils with micromolar affinity. Given the ability to insert hydrophobic peptides to produce soluble, CTPR-based binders, this method may prove beneficial in screening for peptide modulators of protein aggregation.