Ligand Profiling to Characterize Different Polymorphic Forms of α-Synuclein Aggregates

Chisholm, Timothy S.; Hunter, Christopher A.

doi:10.1021/jacs.3c10521

Cited by 3 publications

(3 citation statements)

References 51 publications

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“…We have previously shown that amyloid fibrils contain a collection of binding sites which are morphology-dependent . Different ligands and different binding assays report on different ligand binding sites. − These binding sites, and the fibril morphology, can therefore be characterized by ligand binding assays.…”

Section: Introductionmentioning

confidence: 99%

“…Here, the presence of morphology-dependent binding sites was used to distinguish eight different fibril morphologies of αSyn. Five αSyn fibrillar polymorphs were generated de novo. − ,,, These de novo polymorphs possess different chemical and biological properties that are distinct from the fibrils that we used previously to develop the approach, and therefore provide an independent test of the scope of the methodology. Three types of αSyn fibrils were derived from the brain homogenates of patients suffering from PD, MSA, and DLB using the PMCA process. ,, Although these fibrils are largely composed of recombinant αSyn, the morphologies of the PMCA fibrils have been shown to be determined by the seeding capabilities of the pathogenic αSyn aggregates present in the brain homogenates of the synucleinopathy patients.…”

Section: Introductionmentioning

confidence: 99%

“…Five αSyn fibrillar polymorphs were generated de novo. [34][35][36]39,54,55 These de novo polymorphs possess different chemical and biological properties that are distinct from the fibrils that we used previously to develop the approach, 40 and therefore provide an independent test of the scope of the methodology. Three types of αSyn fibrils were derived from the brain homogenates of patients suffering from PD, MSA, and DLB using the PMCA process.…”

Section: ■ Introductionmentioning

confidence: 99%

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Ligand Profiling as a Diagnostic Tool to Differentiate Patient-Derived α-Synuclein Polymorphs

Chisholm,

Melki,

Hunter

2024

ACS Chem. Neurosci.

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Amyloid fibrils are characteristic of many neurodegenerative diseases, including Alzheimer's and Parkinson's diseases. While different diseases may have fibrils formed of the same protein, the supramolecular morphology of these fibrils is diseasespecific. Here, a method is reported to distinguish eight morphologically distinct amyloid fibrils based on differences in ligand binding properties. Eight fibrillar polymorphs of α-synuclein (αSyn) were investigated: five generated de novo using recombinant αSyn and three generated using protein misfolding cyclic amplification (PMCA) of recombinant αSyn seeded with brain homogenates from deceased patients diagnosed with Parkinson's disease (PD), multiple system atrophy (MSA), and dementia with Lewy bodies (DLB). Fluorescence binding assays were carried out for each fibril using a toolkit of six different ligands. The fibril samples were separated into five categories based on a binary classification of whether they bound specific ligands or not. Quantitative binding measurements then allowed every fibrillar polymorph to be uniquely identified, and the PMCA fibrils derived from PD, MSA, and DLB patients could be unambiguously distinguished. This approach constitutes a novel and operationally simple method to differentiate amyloid fibril morphologies and to identify disease states using PMCA fibrils obtained by seeding with patient samples.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

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Ligand Profiling as a Diagnostic Tool to Differentiate Patient-Derived α-Synuclein Polymorphs

Chisholm,

Melki,

Hunter

2024

ACS Chem. Neurosci.

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Catalysis driven by an amyloid–substrate complex

Sawazaki,

Sasaki,

Sohma

2024

Proc. Natl. Acad. Sci. U.S.A.

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Amine modification through nucleophilic attack of the amine functionality is a very common chemical transformation. Under biorelevant conditions using acidic-to-neutral pH buffer, however, the nucleophilic reaction of alkyl amines (pKa ≈ 10) is not facile due to the generation of ammonium ions lacking nucleophilicity. Here, we disclose a unique molecular transformation system, c atalysis driven by a myloid– s ubstrate comp l ex (CASL), that promotes amine modifications in acidic buffer. Ammonium ions attached to molecules with amyloid-binding capability were activated through deprotonation due to the close proximity to the amyloid catalyst formed by Ac-Asn-Phe-Gly-Ala-Ile-Leu-NH 2 ( NL6 ), derived from islet amyloid polypeptide (IAPP). Under the CASL conditions, alkyl amines underwent various modifications, i.e., acylation, arylation, cyclization, and alkylation, in acidic buffer. Crystallographic analysis and chemical modification studies of the amyloid catalysts suggested that the carbonyl oxygen of the Phe–Gly amide bond of NL6 plays a key role in activating the substrate amine by forming a hydrogen bond. Using CASL, selective conversion of substrates possessing equivalently reactive amine functionalities was achieved in catalytic reactions using amyloids. CASL provides a unique method for applying nucleophilic conversion reactions of amines in diverse fields of chemistry and biology.

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Binding adaptability of chemical ligands to polymorphic α-synuclein amyloid fibrils

Liu,

Tao,

Zhao

et al. 2024

Proc. Natl. Acad. Sci. U.S.A.

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α-synuclein (α-syn) assembles into structurally distinct fibril polymorphs seen in different synucleinopathies, such as Parkinson’s disease and multiple system atrophy. Targeting these unique fibril structures using chemical ligands holds diagnostic significance for different disease subtypes. However, the molecular mechanisms governing small molecules interacting with different fibril polymorphs remain unclear. Here, we investigated the interactions of small molecules belonging to four distinct scaffolds, with different α-syn fibril polymorphs. Using cryo-electron microscopy, we determined the structures of these molecules when bound to the fibrils formed by E46K mutant α-syn and compared them to those bound with wild-type α-syn fibrils. Notably, we observed that these ligands exhibit remarkable binding adaptability, as they engage distinct binding sites across different fibril polymorphs. While the molecular scaffold primarily steered the binding locations and geometries on specific sites, the conjugated functional groups further refined this adaptable binding by fine-tuning the geometries and binding sites. Overall, our finding elucidates the adaptability of small molecules binding to different fibril structures, which sheds light on the diagnostic tracer and drug developments tailored to specific pathological fibril polymorphs.

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Ligand Profiling to Characterize Different Polymorphic Forms of α-Synuclein Aggregates

Cited by 3 publications

References 51 publications

Ligand Profiling as a Diagnostic Tool to Differentiate Patient-Derived α-Synuclein Polymorphs

Ligand Profiling as a Diagnostic Tool to Differentiate Patient-Derived α-Synuclein Polymorphs

Catalysis driven by an amyloid–substrate complex

Binding adaptability of chemical ligands to polymorphic α-synuclein amyloid fibrils

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