Modulating α-synuclein misfolding and fibrillation in vitro by agrochemicals

Abstract

A combination of spectroscopic techniques including atomic force microscopy (AFM) and transmission electron microscopy (TEM), was used to analyze the effect of chemi- cally distinct agrochemicals (pesticides, herbicides, and fungicides) on the in vitro misfolding and aggregation of a presynaptic intrinsically disordered protein α-synuclein. Despite their differences in chemical properties, almost all the compounds screened affected the α-synuclein fibrillation in a concentration-dependent manner. The morphology of the aggregated α-synuclein was characterized by AFM and TEM techniques. In addition to typical fibrils abundantly found at the equilibrium phase, this analysis revealed the existence of a noticeable nonfibrillar fraction where α-synuclein was present as protofilaments, small oligomers, and large oligomeric spe- cies. The aggregated α-synuclein samples were separated into soluble and insoluble fractions by ultracentrifugation and subjected to structural and morphological characterization. Attenuated total reflectance Fourier transform infrared spectroscopic analysis showed that the insoluble α-synuclein fractions possessed a high content of ordered β-structure, whereas the β-structure content of the supernatant pool populated by oligomeric species was noticeably lower. This study provides evidence that chemically distinct agrochemicals can directly interact with α-synuclein to induce structural changes and affect the fibrillation process of this important protein. Keywords: