Faculty Opinions recommendation of Amyloid fibril formation of alpha-synuclein is accelerated by preformed amyloid seeds of other proteins: implications for the mechanism of transmissible conformational diseases.

Ion mobility-mass spectrometry (IM-MS) is emerging as an important biophysical technique for the structural analysis of proteins and their assemblies, in particular for structurally heterogeneous systems such as those on the protein misfolding and aggregation pathway. Using IM-MS we have monitored amyloid fibril formation of A53T α-synuclein, a mutant synuclein protein associated with Parkinson’s disease, and identified that a conformational change towards a more compact structure occurs during the initial stages of aggregation. Binding of A53T α-synuclein to a flavenoid based amyloid fibril inhibitor, (–)-epigallocatechin-3-gallate, has been observed with a 1:1 stoichiometry. By analysis of ion collision cross-sections, we show epigallocatechin gallate binding prevents protein conformational change, and in turn decreases the formation of fibrillar aggregates.

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Acceleration of amyloid fibril formation by multichannel sonochemical reactor

Japanese Journal of Applied Physics ◽

10.35848/1347-4065/ac4142 ◽

2021 ◽

Author(s):

Kentaro Noi ◽

Kichitaro Nakajima ◽

Keiichi Yamaguchi ◽

Masatomo So ◽

Kensuke Ikenaka ◽

...

Keyword(s):

Amyloid Fibrils ◽

Amyloid Fibril ◽

Ultrasonic Transducer ◽

Reaction System ◽

Ultrasound Irradiation ◽

Alpha Synuclein ◽

Fibril Formation ◽

Driving Voltage ◽

Amyloid Fibril Formation ◽

Beta 2 Microglobulin

Abstract Formation of amyloid fibrils of various amyloidogenic proteins is dramatically enhanced by ultrasound irradiation. For applying this phenomenon to the study of protein aggregation science and diagnosis of neurodegenerative diseases, a multichannel ultrasound irradiation system with individually adjustable ultrasound-irradiation conditions is necessary. Here, we develop a sonochemical reaction system, where an ultrasonic transducer is placed in each well of a 96-well microplate to perform ultrasonic irradiation of sample solutions under various conditions with high reproducibility, and applied it for studying amyloid-fibril formation of amyloid $\beta$, $\alpha$-synuclein, $\beta$2-microglobulin, and lysozyme. The results clearly show that our instrument is superior to conventional shaking method in terms of degree of acceleration and reproducibility of fibril formation reaction. The acceleration degree is controllable by controlling the driving voltage applied to each transducer. We have thus succeeded in developing a useful tool for the study of amyloid fibril formation in various proteins.

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Conformational distortion in a fibril-forming oligomer arrests alpha-Synuclein fibrillation and minimizes its toxic effects

Communications Biology ◽

10.1038/s42003-021-02026-z ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Ritobrita Chakraborty ◽

Sandip Dey ◽

Pallabi Sil ◽

Simanta Sarani Paul ◽

Dipita Bhattacharyya ◽

...

Keyword(s):

Small Molecule ◽

Solid State Nmr ◽

Amyloid Fibril ◽

Alpha Synuclein ◽

Fibril Formation ◽

Stoichiometric Ratio ◽

Oligomeric State ◽

C Terminus ◽

Amyloid Fibril Formation ◽

Oligomeric Forms

AbstractThe fibrillation pathway of alpha-Synuclein, the causative protein of Parkinson’s disease, encompasses transient, heterogeneous oligomeric forms whose structural understanding and link to toxicity are not yet understood. We report that the addition of the physiologically-available small molecule heme at a sub-stoichiometric ratio to either monomeric or aggregated α-Syn, targets a His50 residue critical for fibril-formation and stabilizes the structurally-heterogeneous populations of aggregates into a minimally-toxic oligomeric state. Cryo-EM 3D reconstruction revealed a ‘mace’-shaped structure of this monodisperse population of oligomers, which is comparable to a solid-state NMR Greek key-like motif (where the core residues are arranged in parallel in-register sheets with a Greek key topology at the C terminus) that forms the fundamental unit/kernel of protofilaments. Further structural analyses suggest that heme binding induces a distortion in the Greek key-like architecture of the mace oligomers, which impairs their further appending into protofilaments and fibrils. Additionally, our study reports a novel mechanism of prevention as well as reclamation of amyloid fibril formation by blocking an inter-protofilament His50 residue using a small molecule.

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Natural Alkaloid Compounds as Inhibitors for Alpha-Synuclein Seeded Fibril Formation and Toxicity

Molecules ◽

10.3390/molecules26123736 ◽

2021 ◽

Vol 26 (12) ◽

pp. 3736

Author(s):

Simona S. Ghanem ◽

Hend S. Fayed ◽

Qi Zhu ◽

Jia-Hong Lu ◽

Nishant N. Vaikath ◽

...

Keyword(s):

Cell Viability ◽

Therapeutic Strategy ◽

Amyloid Fibril ◽

Lewy Bodies ◽

Alpha Synuclein ◽

Fibril Formation ◽

Amyloid Fibril Formation ◽

Dependent Cell ◽

Natural Alkaloid

The accumulation and aggregation of α-synuclein (α-syn) is the main pathologic event in Parkinson’s disease (PD), dementia with Lewy bodies, and multiple system atrophy. α-Syn-seeded fibril formation and its induced toxicity occupy a major role in PD pathogenesis. Thus, assessing compounds that inhibit this seeding process is considered a key towards the therapeutics of synucleinopathies. Using biophysical and biochemical techniques and seeding-dependent cell viability assays, we screened a total of nine natural compounds of alkaloid origin extracted from Chinese medicinal herbs. Of these compounds, synephrine, trigonelline, cytisine, harmine, koumine, peimisine, and hupehenine exhibited in vitro inhibition of α-syn-seeded fibril formation. Furthermore, using cell viability assays, six of these compounds inhibited α-syn-seeding-dependent toxicity. These six potent inhibitors of amyloid fibril formation and toxicity caused by the seeding process represent a promising therapeutic strategy for the treatment of PD and other synucleinopathies.

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The Aggregation Conditions Define Whether EGCG Is an Inhibitor or Enhancer of α-Synuclein Amyloid Fibril Formation

10.20944/preprints202002.0018.v1 ◽

2020 ◽

Author(s):

Rebecca Sternke-Hoffmann ◽

Alessia Peduzzo ◽

Najoua Bolakhrif ◽

Rainer Haas ◽

Alexander K. Buell

Keyword(s):

Amyloid Fibrils ◽

Amyloid Fibril ◽

Epigallocatechin Gallate ◽

Small Region ◽

Alpha Synuclein ◽

Fibril Formation ◽

Relevant Parameter ◽

Experimental Conditions ◽

Amyloid Fibril Formation ◽

Complex Picture

The amyloid fibril formation by $\alpha$-synuclein is a hallmark of various neurodegenerative disorders, most notably Parkinson's disease. Epigallocatechin gallate (EGCG) has been reported to be an efficient aggregation inhibitor of numerous proteins, among them $\alpha$-synuclein. Here we show that this applies only to a small region of relevant parameter space and that under some conditions, EGCG can even accelerate α-synuclein amyloid fibril formation through facilitating its heterogeneous primary nucleation. Furthermore, we show through quantitative seeding experiments that contrary to previous reports, EGCG is not able to re-model α-synuclein amyloid fibrils into seeding-incompetent structures. Taken together, our results paint a complex picture of EGCG as a compound that can under some conditions inhibit the amyloid fibril formation of α-synuclein, but the inhibitory action is not robust against various relevant changes in experimental conditions. Our results are important for the development of strategies to identify and characterise promising amyloid inhibitors.

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Immunocytochemical Localization of Amyloid Protein AA in the “Dense Fibrillar Inclusions” of the Reticuloendothelical Cells

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100079632 ◽

1977 ◽

Vol 35 ◽

pp. 438-439

Author(s):

T. Shirahama ◽

M. Skinner ◽

A.S. Cohen

Keyword(s):

Amyloid Fibril ◽

Close Association ◽

Gel Filtration ◽

Fibril Formation ◽

Amyloid Protein ◽

Electron Microscopic ◽

Amyloid Deposits ◽

Amyloid Fibril Formation ◽

Electron Microscopic Technique ◽

Lysosomal System

A1thought the mechanisms of amyloidogenesis have not been entirely clarified, proteolysis of the parent proteins may be one of the important steps in the amyloid fibril formation. Recently, we reported that "dense fibrillar inclusions" (DFI), which had the characteristics of lysosomes and contained organized fibrillar profiles as well, were observed in the reticuloendothelial cells in close association with the foci of new amyloid deposits. We considered the findings as evidence for the involvement of lysosomal system in amyloid fibril formation (l). In the present study, we attempted to determine the identity of the contents of the DFI by the use of antisera against the amyloid protein (AA) and an immuno-electron microscopic technique.Amyloidosis was induced in CBA/J mice by daily injections of casein (l). AA was isolated from amyloid-laden spleens by gel filtration and antibody to it was produced in rabbits (2). For immunocytochemistry, the unlabeled antibody enzyme method (3) was employed.

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