Spatiotemporal modulations in heterotypic condensates of prion and \u03b1-synuclein control phase transitions and amyloid conversion

Aishwarya Agarwal,Samrat Mukhopadhyay,Sandeep K Rai,Anamika Avni,Lisha Arora

doi:10.1038/s41467-022-28797-5

Aishwarya Agarwal, Samrat Mukhopadhyay + Show 3 more

Open Access

https://doi.org/10.1038/s41467-022-28797-5

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Abstract

Biomolecular condensation via liquid-liquid phase separation of proteins and nucleic acids is associated with a range of critical cellular functions and neurodegenerative diseases. Here, we demonstrate that complex coacervation of the prion protein and α-synuclein within narrow stoichiometry results in the formation of highly dynamic, reversible, thermo-responsive liquid droplets via domain-specific electrostatic interactions between the positively-charged intrinsically disordered N-terminal segment of prion and the acidic C-terminal tail of α-synuclein. The addition of RNA to these coacervates yields multiphasic, vesicle-like, hollow condensates. Picosecond time-resolved measurements revealed the presence of transient electrostatic nanoclusters that are stable on the nanosecond timescale and can undergo breaking-and-making of interactions on slower timescales giving rise to a liquid-like behavior in the mesoscopic regime. The liquid-to-solid transition drives a rapid conversion of complex coacervates into heterotypic amyloids. Our results suggest that synergistic prion-α-synuclein interactions within condensates provide mechanistic underpinnings of their physiological role and overlapping neuropathological features.

Highlights

Biomolecular condensation via liquid-liquid phase separation of proteins and nucleic acids is associated with a range of critical cellular functions and neurodegenerative diseases
Abnormal deposits of α-Syn in the form of Lewy bodies have been found in patients with sporadic or genetic prion diseases such as Creutzfeldt-Jakob disease (CJD), which is linked to the misfolding of the prion protein (PrP)[42]
The linear net charge per residue (NCPR) plots generated using Classification of Intrinsically Disordered Ensemble Regions (CIDER)[51] showed clustering of positive charges at the N-terminal part of PrP and negative charges preferentially located at the C-terminal part of α-Syn (Fig. S1c, d)

Summary

Introduction

Biomolecular condensation via liquid-liquid phase separation of proteins and nucleic acids is associated with a range of critical cellular functions and neurodegenerative diseases. The physical origin of these condensates is dictated by the sequence architecture and composition of the scaffolds These assemblies often comprise putative RNA-binding proteins such as Fused in Sarcoma (FUS) and FUS family proteins, which have been linked to various neurodegenerative diseases[29]. Α-Syn contains three distinct regions namely, an amphipathic lysine-rich amino terminus (residues 1–60) with a highly conserved lipid-binding region, a central hydrophobic region known as the non-amyloid-βcomponent (NAC; residues 61–95) essential for aggregation, and an acidic carboxy-tail (residues 96–140) that interacts with metal ions and other proteins (Fig. 1a, b)[48]. We demonstrate that phase separation via a complex coacervation of α-Syn and PrP yields highly dynamic heterotypic condensates comprising ephemeral electrostatic nanoclusters within the liquid-like mesoscopic organization. Domain-specific interactions and charge anisotropies provide spatiotemporal modulations of these highly tunable and thermo-responsive condensates that eventually undergo maturation into highly ordered, heterotypic, solidlike amyloid fibrils

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