α-Synucleins from Animal Species Show Low Fibrillation Propensities and Weak Oligomer Membrane Disruption

Abstract

The intrinsically disordered protein α-synuclein (aSN) forms insoluble aggregates in the brains of Parkinson's disease (PD) patients. Cytotoxicity is attributed to a soluble aSN oligomeric species that permeabilizes membranes significantly more than monomers and fibrils. In humans, the A53T mutation induces early onset PD and increases the level of aSN oligomerization and fibrillation propensity, but Thr53 occurs naturally in aSNs of most animals. We compared aSNs from elephant, bowhead whale, and pig with human aSN. While all three animal aSNs showed significantly weakened fibrillation, elephant aSN formed much more oligomer, and pig aSN much less, than human aSN did. However, all animal aSN oligomers showed weakened permeabilization toward anionic lipid vesicles, indicative of decreased cytotoxicity. These animal aSNs share three substitutions compared to human aSN: A53T, G68E, and V95G. We analyzed aggregation and membrane binding of all eight mutants combining these three mutations. While the G68E mutation is particularly important in weakening fibrillation and possible toxicity, the strongest effect is seen when all three mutations are present. Thus, a small number of mutations can significantly decrease aSN toxicity.

Plant Polyphenols Inhibit Functional Amyloid and Biofilm Formation in Pseudomonas Strains by Directing Monomers to Off-Pathway Oligomers

“…The main feature between 0 and 20 nm indicated that the PGG, EGCG, and baicalein oligomers all had a somewhat compact structure and a radius of gyration ( R g ) for the whole oligomer (core and shell) of 10.1 ± 0.2, 7.2 ± 0.1, and 10.0 ± 0.2 nm, respectively (Table 1). We were able to fit to the data with a model developed for α-synuclein oligomers [45], in which a compact prolate ellipsoidal core is surrounded by a shell of flexible protein (Figure 8E). This model could describe all three oligomers and gave short axis diameters of 27.2 ± 0.5, 25.6 ± 0.3, and 25.8 ± 0.4 nm and similar aggregations numbers ( N agg ) of 7.6 ± 0.2, 6.7 ± 0.1, and 6.7 ± 0.1 for PGG, EGCG, and baicalein, respectively.…”

“…The mass can be converted into an aggregation number of the protein ( N agg ) by dividing by the mass of the monomeric protein. To model the oligomers, we used a core-shell model with a compact core surrounded by a shell of flexible protein as described [45]. Modelling was done on an absolute scale to obtain N agg .…”

The interactome of stabilized α‐synuclein oligomers and neuronal proteins

“…WT human αSN was recombinantly expressed in Escherichia coli and purified as described . Unmodified αSOs and fibrils were prepared and stored in PBS buffer as described . Briefly, 12 mg·mL −1 αSN monomers were shaken at 900 r.p.m.…”

Scratching the surface: native mass spectrometry of peripheral membrane protein complexes

“…Notably, one of these proteins, α-synuclein, is a peripheral membrane protein that shares sequence features with apolipoproteins and associates with synaptic vesicles in vivo and negatively charged phospholipids in vitro [16]. Several naturally occurring mutations have been found to alter lipid-binding preferences of α-synuclein, potentially influencing its propensity to form toxic aggregates on or off the membrane [16][17][18]. Interestingly, the role of lipids in the aggregation of these proteins shares similarities with membrane interactions found in antimicrobial peptides (AMPs) [19].…”