Structural basis for the dissociation of α-synuclein fibrils triggered by pressure perturbation of the hydrophobic core

Abstract

Parkinson’s disease is a neurological disease in which aggregated forms of the α-synuclein (α-syn) protein are found. We used high hydrostatic pressure (HHP) coupled with NMR spectroscopy to study the dissociation of α-syn fibril into monomers and evaluate their structural and dynamic properties. Different dynamic properties in the non-amyloid-β component (NAC), which constitutes the Greek-key hydrophobic core, and in the acidic C-terminal region of the protein were identified by HHP NMR spectroscopy. In addition, solid-state NMR revealed subtle differences in the HHP-disturbed fibril core, providing clues to how these species contribute to seeding α-syn aggregation. These findings show how pressure can populate so far undetected α-syn species, and they lay out a roadmap for fibril dissociation via pathways not previously observed using other approaches. Pressure perturbs the cavity-prone hydrophobic core of the fibrils by pushing water inward, thereby inducing the dissociation into monomers. Our study offers the molecular details of how hydrophobic interaction and the formation of water-excluded cavities jointly contribute to the assembly and stabilization of the fibrils. Understanding the molecular forces behind the formation of pathogenic fibrils uncovered by pressure perturbation will aid in the development of new therapeutics against Parkinson’s disease.

Pressure effects on α-synuclein amyloid fibrils: An experimental investigation on their dissociation and reversible nature

“…Oliveira et al more recently studied the structural features of wild type aSN monomers resulting from high hydrostatic pressure-disturbed fibrils and investigated their capability to seed amyloid fibrils formation. Their findings support the hypothesis that the mechanism through which pressure triggers α-syn amyloid fibrils to be dissociated involves hydrophobic interaction and the released monomers present altered dynamics [20]. These studies confirmed that the high pressure dissociation of aSN fibrils could provide important information concerning undetected aSN species and help to trace the roadmap for fibril dissociation by exploring new approaches.…”

“…Both SAXS signals and FTIR curves can be succesfully fitted by a simple exponential decay. FTIR data could even be fitted by adopting a more complex model, in which two main time decays can be observed, in agreement with Oliveria results [20]. However, because it was not possible to achieve confident results by adopting bi-exponential fit for all the samples because experimental times did not always match the temporal characteristics of the kinetics, we chose to adopt the simplest single exponential decay.…”

Liquid‐liquid phase separation and fibrillation of the prion protein modulated by a high‐affinity DNA aptamer

“…29,31 In the presence of salt, Watson-Crick imino resonances were maintained ( Figure 2B). 26,32 Through the Guinier plot, we estimated a radius of gyration of 1.77 nm for A1. 1D 1 H NMR spectrum of A2 showed no evidence for paired imines ( Figure 2D), suggesting a single-stranded coil conformation with no secondary structure.…”

“…Kratky plots from SAXS data showed that A1 adopts a globular structure, while A2 is unfolded ( Figure 2E). 26,32 Through the Guinier plot, we estimated a radius of gyration of 1.77 nm for A1. The hydrodynamic radii of both aptamers were determined using dynamic light scattering (DLS), corresponding to 2.7 nm for A1 and 4.2 nm for A2.…”

Characterization of low-lying excited states of proteins by high-pressure NMR

“…Crystallography has shown the same result [17,56,59]. The same effect occurs with protein oligomers and amyloid: pressure inserts waters into cavities and leads to their dissociation [36,45,51,60].…”