Biology subjects

Venclovaite, U.

Publications and source records attributed to Venclovaite, U..

2 recordsLinked to original sources

bioRxiv2025

Formation of Condition-Dependent Alpha-Synuclein Fibril Strain in Artificial Cerebrospinal Fluid

-Synuclein (aSyn) is an intrinsically disordered protein involved in neurotransmission and synaptic plasticity. The pathological aggregation of this protein is a hallmark of synucleinopathies such as Parkinsons disease (PD) or Multiple System Atrophy (MSA). Misfolded aSyn, which primarily originates in cell cytosol, transmits between neurons, promoting a prion-like propagation. However, the extracellular environments such as interstitial and cerebrospinal fluids (ISF & CSF) play a major role in its clearance and pathological transformation. The molecular components of CSF, including proteins, glycosaminoglycans, and metal ions may influence the aggregate morphology, structure and cytotoxicity to cells. To better understand how extracellular composition affects aggregates and their formation, we employed artificial cerebrospinal fluid (aCSF) to mimic potential aggregation processes occurring in CSF. We observed distinct aCSF-specific aSyn fibrils that exhibited low stability outside aCSF, and the removal of key CSF components led to its structural alterations. Cryo-electron microscopy revealed that these fibrils possess an electron density pocket coordinated with polar basic AAs (K43, K45, H50) that is also observed in aggregates obtained from MSA patients. Our findings illustrate the importance of physiologically relevant conditions in studying aSyn aggregation and may explain why disease-related fibril structure replication in vitro has not yet been successful.

biochemistry↗

bioRxiv2024

Phase Separation and Aggregation of α-Synuclein Diverge at Different Salt Conditions

The coacervation and structural rearrangement of the protein alpha-synuclein (Syn) into cytotoxic oligomers and amyloid fibrils are considered pathological hallmarks of Parkinsons disease. While aggregation is recognized as the key element of amyloid diseases, liquid-liquid phase separation (LLPS) and its interplay with aggregation have gained increasing interest. Previous work showed that factors promoting or inhibiting amyloid formation have similar effects on phase separation. Here, we provide a detailed scanning of a wide range of parameters including protein, salt and crowding concentrations at multiple pH values, revealing different salt dependencies of aggregation and phase separation. The influence of salt on aggregation under crowded conditions follows a non-monotonic pattern, showing increased effects at medium salt concentrations. This behavior can be elucidated through a combination of electrostatic screening and salting-out effects on the intramolecular interactions between the N-terminal and C-terminal regions of Syn. By contrast, we find a monotonic salt dependence of phase separation due to the intermolecular interaction. Furthermore, we observe the time evolution of the two distinct assembly states, with macroscopic fibrillar-like bundles initially forming at medium salt concentration but subsequently converting into droplets after prolonged incubation. The droplet state is therefore capable of inhibiting aggregation or even dissolving the aggregates through a variety of heterotypic interactions, thus preventing Syn from its dynamically arrested state.

biophysics↗