Molecular Basis of α-Synuclein Aggregation and Liquid-Liquid Phase Separation under Environmental Perturbations

Kernkonzepte

The aggregation of intrinsically disordered protein α-Synuclein is significantly influenced by environmental factors such as molecular crowding and ionic strength, leading to the formation of liquid-liquid phase separated droplets with distinct structural and thermodynamic properties.

Zusammenfassung

The study investigates the molecular basis of self-aggregation of the intrinsically disordered protein α-Synuclein and the underlying process of liquid-liquid phase separation (LLPS) under diverse environmental perturbations, including the presence of molecular crowders and salt.
Key highlights:

Simulations at different α-Synuclein concentrations reveal that the protein exhibits limited aggregation propensity in aqueous solution alone, suggesting a low inherent tendency for LLPS.
The addition of molecular crowders or salt significantly enhances α-Synuclein aggregation, leading to the formation of higher-order oligomers and LLPS-like droplets.
Analysis of the surface tension and excess free energy of transfer reveals that crowders and salt modulate LLPS through distinct thermodynamic mechanisms - crowders act via entropic effects, while salt increases surface tension and contributes enthalpically.
Conformational analysis shows that α-Synuclein chains within the droplets adopt extended conformations and orient perpendicular to each other to minimize electrostatic repulsions.
Graph-based analysis indicates that the protein chains within the droplets form small-world-like networks, exhibiting a consensus interaction pattern irrespective of the environmental conditions.
The study provides insights into the delicate balance between the protein's molecular grammar and environment-dependent aggregation behavior, which is crucial for understanding α-Synuclein's role in Parkinson's disease.

Statistiken

The concentration of α-Synuclein in the dilute phase is approximately two orders of magnitude lower than in the dense/droplet phase across all scenarios.

Zitate

"The addition of crowder or salt leads to a notable increase in the average number of proteins forming a cluster."
"The magnitude of surface tension is an estimate of the aggregation tendency of any liquid-liquid mixture. Since we find that γαS is much lower than γFUS, we assert that the propensity with which αS aggregates should be much lower than that of FUS."
"Crowders enhance aggregation primarily through excluded volume interactions, which are of an entropic nature. On the other hand, salt enhances aggregation by increasing the droplet's surface tension, thus contributing to the enthalpy of the system."

Wichtige Erkenntnisse aus

Modulation of α-Synuclein Aggregation Amid Diverse Environmental Perturbation

by Wasim,A., Me... um www.biorxiv.org 10-21-2023

https://www.biorxiv.org/content/10.1101/2023.10.19.563053v2

Tiefere Fragen

How do specific post-translational modifications of α-Synuclein influence its liquid-liquid phase separation and aggregation behavior

Specific post-translational modifications of α-Synuclein can have a significant impact on its liquid-liquid phase separation (LLPS) and aggregation behavior. For example, phosphorylation, ubiquitination, nitration, and acetylation are common modifications that can alter the structural and functional properties of α-Synuclein.
Phosphorylation, one of the most studied modifications, has been shown to influence α-Synuclein aggregation. Phosphorylation at specific residues can either promote or inhibit aggregation, depending on the site and extent of phosphorylation. For instance, phosphorylation at Ser129 has been linked to increased α-Synuclein aggregation and toxicity. This modification can enhance the propensity of α-Synuclein to undergo LLPS, leading to the formation of toxic aggregates.
Ubiquitination, another post-translational modification, can target α-Synuclein for degradation or alter its interactions with other proteins, affecting its aggregation behavior. Nitration and acetylation can also impact α-Synuclein aggregation by modifying its conformation and stability.
Understanding how these post-translational modifications influence α-Synuclein LLPS and aggregation can provide valuable insights into the pathogenesis of Parkinson's disease and may offer new therapeutic targets for intervention.

What are the potential therapeutic strategies that could target the disruption of α-Synuclein droplet stability and dissolution

Targeting the disruption of α-Synuclein droplet stability and promoting its dissolution could be a promising therapeutic strategy for Parkinson's disease. Several potential approaches could be explored:

Small Molecule Inhibitors: Developing small molecules that can interfere with the interactions driving α-Synuclein droplet formation and stability. These molecules could target specific residues or regions involved in the aggregation process, disrupting the droplet structure and promoting dissolution.

Chaperone Proteins: Utilizing chaperone proteins that can bind to α-Synuclein and prevent its aggregation into droplets. Chaperones can help maintain α-Synuclein in a soluble state, reducing the likelihood of droplet formation.

Enzyme Modulators: Modulating enzymes involved in post-translational modifications of α-Synuclein, such as kinases or phosphatases, to regulate its aggregation behavior. By controlling the modification status of α-Synuclein, it may be possible to prevent droplet formation and promote its dissolution.

Membrane Interactions: Targeting the interactions between α-Synuclein and cellular membranes, which play a crucial role in its aggregation and droplet formation. Disrupting these interactions could destabilize α-Synuclein droplets and facilitate their dissolution.

By exploring these therapeutic strategies and their effects on α-Synuclein droplet stability, researchers may uncover novel approaches for treating Parkinson's disease and related neurodegenerative disorders.

What insights can be gained by investigating the role of membrane interactions in modulating α-Synuclein liquid-liquid phase separation and its implications for Parkinson's disease pathogenesis

Investigating the role of membrane interactions in modulating α-Synuclein liquid-liquid phase separation (LLPS) can provide valuable insights into Parkinson's disease pathogenesis. Membrane interactions have been shown to influence α-Synuclein aggregation and toxicity, making them a key factor in disease progression.

Membrane Composition: Different types of cellular membranes can interact with α-Synuclein and modulate its aggregation behavior. Lipid composition, fluidity, and curvature of membranes can impact the propensity of α-Synuclein to undergo LLPS and form toxic aggregates.

Membrane Binding: α-Synuclein has a high affinity for lipid membranes, and this interaction can promote its aggregation and droplet formation. Understanding the specific membrane binding sites and mechanisms can shed light on how α-Synuclein transitions from a soluble state to forming droplets.

Toxicity Mechanisms: Membrane-bound α-Synuclein species have been implicated in cellular toxicity and neurodegeneration. Investigating how membrane interactions influence the toxicity of α-Synuclein droplets can provide insights into disease mechanisms and potential therapeutic targets.

Therapeutic Opportunities: Targeting the interactions between α-Synuclein and membranes could offer new therapeutic strategies for Parkinson's disease. By disrupting these interactions or stabilizing α-Synuclein in a non-toxic conformation, it may be possible to mitigate the pathological effects of α-Synuclein aggregation.

Overall, studying the interplay between α-Synuclein, membranes, and LLPS can deepen our understanding of Parkinson's disease etiology and guide the development of novel treatments targeting this critical pathway.