CONICET | Buscador de Institutos y Recursos Humanos

Parkinsons disease (PD) is a movement disorder characterized by the presence in the mid-brain of amyloid deposits of the protein a-synuclein (AS). Three familial mutants, A53T, A30P and E46K, are linked with early onset PD. Compared to the WT, the mutants exhibit faster aggregation in vitro and subtle differences in ultrastructural features. Using the extrinsic dual-color emission probe 4-diethylamino-3-hydroxyflavone (FE) we demonstrate that amyloid fibrils formed by WT and mutant AS differ in their supramolecular fibrillar organization. The environment-sensitive FE probe exhibits two intensive well-separated emission bands reflecting excited state redistributions. Its ratiometric response constitutes a sensitive and tunable reporter of microenvironmental properties such as polarity and hydrogen-bonding. The FE probe bound to the four AS variants exhibits distinctive fluorescence spectral signatures. Two-dimensional deconvolution of the excitation-emission spectra reveals binding site heterogeneity characterized by different dielectric constants and extents of hydration. The sensitivity of this probe to structural alterations induced by point mutations is unprecedented and will contribute to the understanding of various phenomena associated with amyloid fibrils and their prefibrillar intermediates: plasticity, polymorphism, and structure-function relationships underlying toxicity.