Direct disassembly of α-syn preformed fibrils into α-syn monomers by an all-D-peptide.

A hallmark of Parkinson's disease (PD) is the progressive neurodegeneration associated with soluble oligomeric and fibrillar forms of misfolded α-synuclein (α-syn). In this study, all-D-enantiomeric peptide ligands are presented that bind monomeric α-syn with high affinity, stabilize its physiological monomeric status, prevent aggregation and dissolve existing aggregates. This "antiprionic" mode of action directly targets pathogenic aggregated particles. Using mirror-image phage display on D-enantiomeric full-length α-syn, SVD-1 and SVD-1a were identified, showing a delay of aggregation and reduction of aggregate formation in both de novo and seeded models. Picomolar KDs were confirmed by SPR, where a highly dynamic interaction mode was verified by PRE-NMR. SVD-1a also reduced the toxicity and intracellular seeding of α-syn fibrils in cell culture by disassembling them into monomers, as confirmed by atomic force microscopy and dynamic light scattering. These results support SVD-1a as a promising lead compound for the treatment of Parkinson's disease.