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Biasing the native ?-synuclein conformational ensemble towards compact states abolishes aggregation and neurotoxicity.

ABSTRACT: The aggregation of ?-synuclein (?-syn) into amyloid fibrils is a major pathological hallmark of Parkinson's disease (PD) and other synucleinopathies. The mechanisms underlying the structural transition of soluble and innocuous ?-syn to aggregated neurotoxic forms remains largely unknown. The disordered nature of ?-syn has hampered the use of structure-based protein engineering approaches to elucidate the molecular determinants of this transition. The recent 3D structure of a pathogenic ?-syn fibril provides a template for this kind of studies. The structure supports the NAC domain being a critical element in fibril formation, since it constitutes the core of the fibril, delineating a Greek-key motif. Here, we stapled the ends of this motif with a designed disulfide bond and evaluated its impact on the conformation, aggregation and toxicity of ?-syn in different environments. The new covalent link biases the native structural ensemble of ?-syn toward compact conformations, reducing the population of fully unfolded species. This conformational bias results in a strongly reduced fibril formation propensity both in the absence and in the presence of lipids and impedes the formation of neurotoxic oligomers. Our study does not support the Greek-key motif being already imprinted in early ?-syn assemblies, discarding it as a druggable interface to prevent the initiation of fibrillation. In contrast, it suggests the stabilization of native, compact ensembles as a potential therapeutic strategy to avoid the formation of toxic species and to target the early stages of PD.

SUBMITTER: Carija A

PROVIDER: S-EPMC6375061 | biostudies-literature | 2019 Apr

REPOSITORIES: biostudies-literature

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Biasing the native α-synuclein conformational ensemble towards compact states abolishes aggregation and neurotoxicity.

Carija Anita A Pinheiro Francisca F Pujols Jordi J Brás Inês C IC Lázaro Diana Fernandes DF Santambrogio Carlo C Grandori Rita R Outeiro Tiago F TF Navarro Susanna S Ventura Salvador S

Redox biology 20190205

The aggregation of α-synuclein (α-syn) into amyloid fibrils is a major pathological hallmark of Parkinson's disease (PD) and other synucleinopathies. The mechanisms underlying the structural transition of soluble and innocuous α-syn to aggregated neurotoxic forms remains largely unknown. The disordered nature of α-syn has hampered the use of structure-based protein engineering approaches to elucidate the molecular determinants of this transition. The recent 3D structure of a pathogenic α-syn fib ...[more]

PMID: 30769283

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Project description:Aggregation of ?-Synuclein (?S) protein to amyloid fibrils is a neuropathological hallmark of Parkinson's disease (PD). Growing evidence suggests that extracellular ?S aggregation plays a pivotal role in neurodegeneration found in PD in addition to the intracellular ?S aggregates in Lewy bodies (LB). Here, we identified and compared a diverse set of molecules capable of mitigating protein aggregation and exogenous toxicity of ?SA53T, a more aggregation-prone ?S mutant found in familial PD. For the first time, we investigated the ?S anti-amyloid activity of semi-synthetic flavonoid 2', 3', 4' trihydroxyflavone or 2-D08, which was compared with natural flavones myricetin and transilitin, as well as such structurally diverse polyphenols as honokiol and punicalagin. Additionally, two novel synthetic compounds with a dibenzyl imidazolidine scaffold, Compound 1 and Compound 2, were also investigated as they exhibited favorable binding with ?SA53T. All seven compounds inhibited ?SA53T aggregation as demonstrated by Thioflavin T fluorescence assays, with modified fibril morphology observed by transmission electron microscopy. Ion mobility-mass spectrometry (IM-MS) was used to monitor the structural conversion of native ?SA53T into amyloidogenic conformations and all seven compounds preserved the native unfolded conformations of ?SA53T following 48 h incubation. The presence of each test compound in a 1:2 molar ratio was also shown to inhibit the neurotoxicity of preincubated ?SA53T using phaeochromocytoma (PC12) cell viability assays. Among the seven tested compounds 2-D08, honokiol, and the synthetic Compound 2 demonstrated the highest inhibition of aggregation, coupled with neuroprotection from preincubated ?SA53T in vitro. Molecular docking predicted that all compounds bound near the lysine-rich region of the N-terminus of ?SA53T, where the flavonoids and honokiol predominantly interacted with Lys 23. Overall, these findings highlight that (i) restricted vicinal trihydroxylation in the flavone B-ring is more effective in stabilizing the native ?S conformations, thus blocking amyloidogenic aggregation, than dihydroxylation aggregation in both A and B-ring, and (ii) honokiol, punicalagin, and the synthetic imidazolidine Compound 2 also inhibit ?S amyloidogenic aggregation by stabilizing its native conformations. This diverse set of molecules acting on a singular pathological target with predicted binding to ?SA53T in the folding-prone N-terminal region may contribute toward novel drug-design for PD.

Dataset Information

Biasing the native ?-synuclein conformational ensemble towards compact states abolishes aggregation and neurotoxicity.

Publications

Biasing the native α-synuclein conformational ensemble towards compact states abolishes aggregation and neurotoxicity.

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