Kinetics of Amyloid Aggregation: A Study of the GNNQQNY Prion Sequence

AbstractAmyloid aggregation of the microtubule binding protein tau is a hallmark of Alzheimer’s disease and many other neurodegenerative diseases. Recently, tau has been found to undergo liquid-liquid phase separation (LLPS) near physiological conditions. Although LLPS and aggregation have been shown to simultaneously occur under certain common conditions, it remains to be seen whether tau LLPS promotes aggregation, or if they are two independent processes. In this study, we address this question by combining multiple biochemical and biophysical assays in vitro. We investigated the impacts of LLPS on tau aggregation at three stages: conformation of tau, kinetics of aggregation and fibril quantity. We showed that none of these properties are influenced directly by LLPS, while amyloid aggregation propensity of tau can be altered without affecting its LLPS behavior. LLPS and amyloid aggregation of tau occur under overlapping conditions of enhanced intermolecular interactions and localization, but are two independent processes.

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Effect of 1-Ethyl-3-methylimidazolium Tetrafluoroborate and Acetate Ionic Liquids on Stability and Amyloid Aggregation of Lysozyme

International Journal of Molecular Sciences ◽

10.3390/ijms23020783 ◽

2022 ◽

Vol 23 (2) ◽

pp. 783

Author(s):

Diana Fedunova ◽

Andrea Antosova ◽

Jozef Marek ◽

Vladimir Vanik ◽

Erna Demjen ◽

...

Keyword(s):

Ionic Liquids ◽

Amyloid Fibrils ◽

Cd Spectroscopy ◽

Dependent Manner ◽

Amyloid Aggregation ◽

Scanning Calorimetry ◽

Docking Calculations ◽

Fibril Morphology ◽

Time Frames ◽

Kinetics Of

Amyloid fibrils draw attention as potential novel biomaterials due to their high stability, strength, elasticity or resistance against degradation. Therefore, the controlled and fast fibrillization process is of great interest, which raises the demand for effective tools capable of regulating amyloid fibrillization. Ionic liquids (ILs) were identified as effective modulators of amyloid aggregation. The present work is focused on the study of the effect of 1-ethyl-3-methyl imidazolium-based ILs with kosmotropic anion acetate (EMIM-ac) and chaotropic cation tetrafluoroborate (EMIM-BF4) on the kinetics of lysozyme amyloid aggregation and morphology of formed fibrils using fluorescence and CD spectroscopy, differential scanning calorimetry, AFM with statistical image analysis and docking calculations. We have found that both ILs decrease the thermal stability of lysozyme and significantly accelerate amyloid fibrillization in a dose-dependent manner at concentrations of 0.5%, 1% and 5% (v/v) in conditions and time-frames when no fibrils are formed in ILs-free solvent. The effect of EMIM-BF4 is more prominent than EMIM-ac due to the different specific interactions of the anionic part with the protein surface. Although both ILs induced formation of amyloid fibrils with typical needle-like morphology, a higher variability of fibril morphology consisting of a different number of intertwining protofilaments was identified for EMIM-BF4.

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Kinetics of Inhibition of β-Amyloid Aggregation by Transthyretin†

Biochemistry ◽

10.1021/bi0618520 ◽

2006 ◽

Vol 45 (51) ◽

pp. 15702-15709 ◽

Cited By ~ 51

Author(s):

Lin Liu ◽

Regina M. Murphy

Keyword(s):

Amyloid Aggregation ◽

Β Amyloid ◽

Kinetics Of ◽

Kinetics Of Inhibition

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Exploring the potential of deep-blue autofluorescence for monitoring amyloid fibril formation and dissociation

PeerJ ◽

10.7717/peerj.7554 ◽

2019 ◽

Vol 7 ◽

pp. e7554

Author(s):

Mantas Ziaunys ◽

Tomas Sneideris ◽

Vytautas Smirnovas

Keyword(s):

Neurodegenerative Disorders ◽

Amyloid Fibrils ◽

Amyloid Fibril ◽

Fibril Formation ◽

Amyloid Formation ◽

Amyloid Aggregation ◽

Deep Blue ◽

Amyloid Fibril Formation ◽

Kinetics Of ◽

Kinetics Of Fibril Formation

Protein aggregation into amyloid fibrils has been linked to multiple neurodegenerative disorders. Determining the kinetics of fibril formation, as well as their structural stability are important for the mechanistic understanding of amyloid aggregation. Tracking both fibril association and dissociation is usually performed by measuring light scattering of the solution or fluorescence of amyloid specific dyes, such as thioflavin-T. A possible addition to these methods is the recently discovered deep-blue autofluorescence (dbAF), which is linked to amyloid formation. In this work we explore the potential of this phenomenon to monitor amyloid fibril formation and dissociation, as well as show its possible relation to fibril size rather than amyloid structure.

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The kinetics of islet amyloid polypeptide phase separated system and hydrogel formation are critically influenced by macromolecular crowding

Biochemical Journal ◽

10.1042/bcj20210384 ◽

2021 ◽

Author(s):

Lior Pytowski ◽

David Vaux ◽

Létitia Jean

Keyword(s):

Type Ii Diabetes ◽

Volume Fraction ◽

Biological Fluids ◽

Islet Amyloid Polypeptide ◽

Macromolecular Crowding ◽

Type Ii ◽

Amyloid Aggregation ◽

Islet Amyloid ◽

Kinetics Of

Many protein misfolding diseases (e.g. type II diabetes and Alzheimer’s disease) are characterised by amyloid deposition. Human islet amyloid polypeptide (hIAPP, involved in type II diabetes) spontaneously undergoes liquid-liquid phase separation (LLPS) and a kinetically complex hydrogelation, both catalysed by hydrophobic-hydrophilic interfaces (e.g. air-water interface and/or phospholipids-water interfaces). Gelation of hIAPP phase separated liquid droplets initiates amyloid aggregation and formation of clusters of interconnected aggregates, which grow and fuse to eventually percolate the whole system. Droplet maturation into irreversible hydrogels via amyloid aggregation is thought to be behind the pathology of several diseases. Biological fluids contain a high volume fraction of macromolecules, leading to macromolecular crowding. Despite crowding agent addition in in vitro studies playing a significant role in changing protein phase diagrams, the mechanism underlying enhanced LLPS, and the effect(s) on stages beyond LLPS remain poorly or not characterised.  We investigated the effect of macromolecular crowding and increased viscosity on the kinetics of hIAPP hydrogelation using rheology and the evolution of the system beyond LLPS by microscopy. We demonstrate that increased viscosity exacerbated the kinetic variability of hydrogelation and of the phase separated-aggregated system, whereas macromolecular crowding abolished heterogeneity. Increased viscosity also strengthened the gel meshwork and accelerated aggregate cluster fusion. In contrast, crowding either delayed cluster fusion onset (dextran) or promoted it (Ficoll). Our study highlights that an in vivo crowded environment would critically influence amyloid stages beyond LLPS and pathogenesis.

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Mechanisms and Kinetics of Amyloid Aggregation Investigated by a Phenomenological Coarse-Grained Model

Computational Modeling of Biological Systems - Biological and Medical Physics, Biomedical Engineering ◽

10.1007/978-1-4614-2146-7_8 ◽

2012 ◽

pp. 191-214 ◽

Cited By ~ 5

Author(s):

Andrea Magno ◽

Riccardo Pellarin ◽

Amedeo Caflisch

Keyword(s):

Coarse Grained ◽

Amyloid Aggregation ◽

Coarse Grained Model ◽

Kinetics Of

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Direct observations of radiation-enhanced transformations in glass

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100075543 ◽

1983 ◽

Vol 41 ◽

pp. 354-355

Author(s):

J. F. DeNatale ◽

D. G. Howitt

Keyword(s):

Glass Matrix ◽

Diffusion Mechanism ◽

Bubble Formation ◽

Silicate Glasses ◽

Phase Decomposition ◽

Direct Observations ◽

Thin Foils ◽

Oxygen Bubble ◽

Electron Energy Loss ◽

Kinetics Of

The electron irradiation of silicate glasses containing metal cations produces various types of phase separation and decomposition which includes oxygen bubble formation at intermediate temperatures figure I. The kinetics of bubble formation are too rapid to be accounted for by oxygen diffusion but the behavior is consistent with a cation diffusion mechanism if the amount of oxygen in the bubble is not significantly different from that in the same volume of silicate glass. The formation of oxygen bubbles is often accompanied by precipitation of crystalline phases and/or amorphous phase decomposition in the regions between the bubbles and the detection of differences in oxygen concentration between the bubble and matrix by electron energy loss spectroscopy cannot be discerned (figure 2) even when the bubble occupies the majority of the foil depth.The oxygen bubbles are stable, even in the thin foils, months after irradiation and if van der Waals behavior of the interior gas is assumed an oxygen pressure of about 4000 atmospheres must be sustained for a 100 bubble if the surface tension with the glass matrix is to balance against it at intermediate temperatures.

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