Historically, amyloid fibrils have been considered as pathogenic entities, being related to more than 30 diseases in humans such as Parkinson’s, Alzheimer’s and Huntington’s Disease. However, the presence of biologically active amyloid structures has been recently described, ranging from bacteria to humans, with diverse roles including mediation of host interactions, pigment biosynthesis and hormone storage. Molecular chaperones are a diverse group of proteins playing a key role in cellular proteostasis, typically with regards to protein folding and misfolding. However, recent research suggests that chaperones can actively participate in both the formation of amyloids or in their disassembly. This makes them a novel target for drug development in amyloid-related pathologies.
Using a cell-free expression system and single molecule spectroscopy techniques, we aim to determine the binding selectivity of different families of molecular chaperones and co-chaperones to distinct amyloid species. After the screening of a molecular chaperone library against α-synuclein (human pathological amyloid), M45 (viral amyloid), and RIPK3 (human functional amyloid), two-colour coincidence experiments have revealed a clear preference for association to the viral M45 fibril, with a reduced preference towards α-synuclein, and a very low association with RIPK3. In addition, some of the tested chaperones can recognise and bind to a hybrid M45-RIPK3 fibril with higher affinity than to RIPK3 alone, but to a lower extent than to M45 alone. Overall, these results demonstrate the ability of cells to discriminate between functional and pathological amyloids. Our data can give us an opportunity to build an amyloid binding map of different chaperone families and this classification can feed into drug discovery and drug development. Specific chaperones can be used for amyloid detection and can be developed as markers for disease-related amyloids.