1
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Dear AJ, Thacker D, Wennmalm S, Ortigosa-Pascual L, Andrzejewska EA, Meisl G, Linse S, Knowles TPJ. Aβ Oligomer Dissociation Is Catalyzed by Fibril Surfaces. ACS Chem Neurosci 2024. [PMID: 38785363 DOI: 10.1021/acschemneuro.4c00127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2024] Open
Abstract
Oligomeric assemblies consisting of only a few protein subunits are key species in the cytotoxicity of neurodegenerative disorders, such as Alzheimer's and Parkinson's diseases. Their lifetime in solution and abundance, governed by the balance of their sources and sinks, are thus important determinants of disease. While significant advances have been made in elucidating the processes that govern oligomer production, the mechanisms behind their dissociation are still poorly understood. Here, we use chemical kinetic modeling to determine the fate of oligomers formed in vitro and discuss the implications for their abundance in vivo. We discover that oligomeric species formed predominantly on fibril surfaces, a broad class which includes the bulk of oligomers formed by the key Alzheimer's disease-associated Aβ peptides, also dissociate overwhelmingly on fibril surfaces, not in solution as had previously been assumed. We monitor this "secondary nucleation in reverse" by measuring the dissociation of Aβ42 oligomers in the presence and absence of fibrils via two distinct experimental methods. Our findings imply that drugs that bind fibril surfaces to inhibit oligomer formation may also inhibit their dissociation, with important implications for rational design of therapeutic strategies for Alzheimer's and other amyloid diseases.
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Affiliation(s)
- Alexander J Dear
- Biochemistry and Structural Biology, Lund University, Lund 221 00, Sweden
- Centre for Misfolding Diseases Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K
| | - Dev Thacker
- Biochemistry and Structural Biology, Lund University, Lund 221 00, Sweden
| | - Stefan Wennmalm
- Department of Applied Physics, Biophysics Group, SciLifeLab, Royal Institute of Technology-KTH, Solna 171 65, Sweden
| | | | - Ewa A Andrzejewska
- Centre for Misfolding Diseases Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K
| | - Georg Meisl
- Centre for Misfolding Diseases Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K
| | - Sara Linse
- Biochemistry and Structural Biology, Lund University, Lund 221 00, Sweden
| | - Tuomas P J Knowles
- Centre for Misfolding Diseases Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K
- Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE, U.K
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2
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Rinauro DJ, Chiti F, Vendruscolo M, Limbocker R. Misfolded protein oligomers: mechanisms of formation, cytotoxic effects, and pharmacological approaches against protein misfolding diseases. Mol Neurodegener 2024; 19:20. [PMID: 38378578 PMCID: PMC10877934 DOI: 10.1186/s13024-023-00651-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 08/17/2023] [Indexed: 02/22/2024] Open
Abstract
The conversion of native peptides and proteins into amyloid aggregates is a hallmark of over 50 human disorders, including Alzheimer's and Parkinson's diseases. Increasing evidence implicates misfolded protein oligomers produced during the amyloid formation process as the primary cytotoxic agents in many of these devastating conditions. In this review, we analyze the processes by which oligomers are formed, their structures, physicochemical properties, population dynamics, and the mechanisms of their cytotoxicity. We then focus on drug discovery strategies that target the formation of oligomers and their ability to disrupt cell physiology and trigger degenerative processes.
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Affiliation(s)
- Dillon J Rinauro
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, UK
| | - Fabrizio Chiti
- Section of Biochemistry, Department of Experimental and Clinical Biomedical Sciences, University of Florence, 50134, Florence, Italy
| | - Michele Vendruscolo
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, UK.
| | - Ryan Limbocker
- Department of Chemistry and Life Science, United States Military Academy, West Point, NY, 10996, USA.
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3
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Chen H, Chen TY. From Monomers to Hexamers: A Theoretical Probability of the Neighbor Density Approach to Dissect Protein Oligomerization in Cells. Anal Chem 2024; 96:895-903. [PMID: 38156958 PMCID: PMC10842889 DOI: 10.1021/acs.analchem.3c04728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2024]
Abstract
Deciphering the oligomeric state of proteins within cells is pivotal to understanding their role in intricate cellular processes. With the recent advances in single-molecule localization microscopy, previous efforts have harnessed protein location density approaches, coupled with simulations, to extract membrane protein oligomeric states in cells, highlighting the value of such techniques. However, a comprehensive theoretical approach that can be universally applied across different proteins (e.g., membrane and cytosolic proteins) remains elusive. Here, we introduce the theoretical probability of neighbor density (PND) as a robust tool to discern protein oligomeric states in cellular environments. Utilizing our approach, the theoretical PND was validated against simulated data for both membrane and cytosolic proteins, consistently aligning with experimental baselines for membrane proteins. This congruence was maintained even when adjusting for protein concentrations or exploring proteins of various oligomeric states. The strength of our method lies not only in its precision but also in its adaptability, accommodating diverse cellular protein scenarios without compromising the accuracy. The development and validation of the theoretical PND facilitate accurate protein oligomeric state determination and bolster our understanding of protein-mediated cellular functions.
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Affiliation(s)
- Huanhuan Chen
- Department of Chemistry, University of Houston, Houston, Texas 77204
| | - Tai-Yen Chen
- Department of Chemistry, University of Houston, Houston, Texas 77204
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4
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Pang KT, Yang YS, Zhang W, Ho YS, Sormanni P, Michaels TCT, Walsh I, Chia S. Understanding and controlling the molecular mechanisms of protein aggregation in mAb therapeutics. Biotechnol Adv 2023; 67:108192. [PMID: 37290583 DOI: 10.1016/j.biotechadv.2023.108192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 05/09/2023] [Accepted: 06/01/2023] [Indexed: 06/10/2023]
Abstract
In antibody development and manufacturing, protein aggregation is a common challenge that can lead to serious efficacy and safety issues. To mitigate this problem, it is important to investigate its molecular origins. This review discusses (1) our current molecular understanding and theoretical models of antibody aggregation, (2) how various stress conditions related to antibody upstream and downstream bioprocesses can trigger aggregation, and (3) current mitigation strategies employed towards inhibiting aggregation. We discuss the relevance of the aggregation phenomenon in the context of novel antibody modalities and highlight how in silico approaches can be exploited to mitigate it.
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Affiliation(s)
- Kuin Tian Pang
- Bioprocessing Technology Institute, Agency for Science, Technology and Research (A*STAR), Singapore; School of Chemistry, Chemical Engineering, and Biotechnology, Nanyang Technology University, Singapore
| | - Yuan Sheng Yang
- Bioprocessing Technology Institute, Agency for Science, Technology and Research (A*STAR), Singapore
| | - Wei Zhang
- Bioprocessing Technology Institute, Agency for Science, Technology and Research (A*STAR), Singapore
| | - Ying Swan Ho
- Bioprocessing Technology Institute, Agency for Science, Technology and Research (A*STAR), Singapore
| | - Pietro Sormanni
- Chemistry of Health, Yusuf Hamied Department of Chemistry, University of Cambridge, United Kingdom
| | - Thomas C T Michaels
- Department of Biology, Institute of Biochemistry, ETH Zurich, Otto-Stern-Weg 3, 8093 Zurich, Switzerland; Bringing Materials to Life Initiative, ETH Zurich, Switzerland
| | - Ian Walsh
- Bioprocessing Technology Institute, Agency for Science, Technology and Research (A*STAR), Singapore.
| | - Sean Chia
- Bioprocessing Technology Institute, Agency for Science, Technology and Research (A*STAR), Singapore.
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5
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Chu J, Romero A, Taulbee J, Aran K. Development of Single Molecule Techniques for Sensing and Manipulation of CRISPR and Polymerase Enzymes. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2300328. [PMID: 37226388 PMCID: PMC10524706 DOI: 10.1002/smll.202300328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 03/20/2023] [Indexed: 05/26/2023]
Abstract
Clustered regularly interspaced short palindromic repeats (CRISPR) and polymerases are powerful enzymes and their diverse applications in genomics, proteomics, and transcriptomics have revolutionized the biotechnology industry today. CRISPR has been widely adopted for genomic editing applications and Polymerases can efficiently amplify genomic transcripts via polymerase chain reaction (PCR). Further investigations into these enzymes can reveal specific details about their mechanisms that greatly expand their use. Single-molecule techniques are an effective way to probe enzymatic mechanisms because they may resolve intermediary conformations and states with greater detail than ensemble or bulk biosensing techniques. This review discusses various techniques for sensing and manipulation of single biomolecules that can help facilitate and expedite these discoveries. Each platform is categorized as optical, mechanical, or electronic. The methods, operating principles, outputs, and utility of each technique are briefly introduced, followed by a discussion of their applications to monitor and control CRISPR and Polymerases at the single molecule level, and closing with a brief overview of their limitations and future prospects.
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Affiliation(s)
- Josephine Chu
- Henry E. Riggs School of Applied Life Sciences, Keck Graduate Institute, Claremont, CA, 91711, USA
| | - Andres Romero
- Henry E. Riggs School of Applied Life Sciences, Keck Graduate Institute, Claremont, CA, 91711, USA
| | - Jeffrey Taulbee
- Henry E. Riggs School of Applied Life Sciences, Keck Graduate Institute, Claremont, CA, 91711, USA
| | - Kiana Aran
- Henry E. Riggs School of Applied Life Sciences, Keck Graduate Institute, Claremont, CA, 91711, USA
- Cardea, San Diego, CA, 92121, USA
- University of California Berkeley, Berkeley, CA, 94720, USA
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6
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Meng F, Kim JY, Gopich IV, Chung HS. Single-molecule FRET and molecular diffusion analysis characterize stable oligomers of amyloid-β 42 of extremely low population. PNAS NEXUS 2023; 2:pgad253. [PMID: 37564361 PMCID: PMC10411938 DOI: 10.1093/pnasnexus/pgad253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2023] [Revised: 07/12/2023] [Accepted: 07/21/2023] [Indexed: 08/12/2023]
Abstract
Soluble oligomers produced during protein aggregation have been thought to be toxic species causing various diseases. Characterization of these oligomers is difficult because oligomers are a heterogeneous mixture, which is not readily separable, and may appear transiently during aggregation. Single-molecule spectroscopy can provide valuable information by detecting individual oligomers, but there have been various problems in determining the size and concentration of oligomers. In this work, we develop and use a method that analyzes single-molecule fluorescence burst data of freely diffusing molecules in solution based on molecular diffusion theory and maximum likelihood method. We demonstrate that the photon count rate, diffusion time, population, and Förster resonance energy transfer (FRET) efficiency can be accurately determined from simulated data and the experimental data of a known oligomerization system, the tetramerization domain of p53. We used this method to characterize the oligomers of the 42-residue amyloid-β (Aβ42) peptide. Combining peptide incubation in a plate reader and single-molecule free-diffusion experiments allows for the detection of stable oligomers appearing at various stages of aggregation. We find that the average size of these oligomers is 70-mer and their overall population is very low, less than 1 nM, in the early and middle stages of aggregation of 1 µM Aβ42 peptide. Based on their average size and long diffusion time, we predict the oligomers have a highly elongated rod-like shape.
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Affiliation(s)
- Fanjie Meng
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0520, USA
| | - Jae-Yeol Kim
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0520, USA
| | - Irina V Gopich
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0520, USA
| | - Hoi Sung Chung
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0520, USA
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7
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Unravelling the microscopic characteristics of intrinsically disordered proteins upon liquid–liquid phase separation. Essays Biochem 2022; 66:891-900. [DOI: 10.1042/ebc20220148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 11/13/2022] [Accepted: 11/14/2022] [Indexed: 12/23/2022]
Abstract
Abstract
Biomolecular condensate formation via liquid–liquid phase separation (LLPS) has emerged as a ubiquitous mechanism underlying the spatiotemporal organization of biomolecules in the cell. These membraneless condensates form and disperse dynamically in response to environmental stimuli. Growing evidence indicates that the liquid-like condensates not only play functional physiological roles but are also implicated in a wide range of human diseases. As a major component of biomolecular condensates, intrinsically disordered proteins (IDPs) are intimately involved in the LLPS process. During the last decade, great efforts have been made on the macroscopic characterization of the physicochemical properties and biological functions of liquid condensates both in vitro and in the cellular context. However, characterization of the conformations and interactions at the molecular level within phase-separated condensates is still at an early stage. In the present review, we summarize recent biophysical studies investigating the intramolecular conformational changes of IDPs upon LLPS and the intermolecular clustering of proteins undergoing LLPS, with a particular focus on single-molecule fluorescence detection. We also discuss how these microscopic features are linked to the macroscopic phase transitions that are relevant to the physiological and pathological roles of the condensates.
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8
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Tahirbegi B, Magness AJ, Piersimoni ME, Teng X, Hooper J, Guo Y, Knöpfel T, Willison KR, Klug DR, Ying L. Toward high-throughput oligomer detection and classification for early-stage aggregation of amyloidogenic protein. Front Chem 2022; 10:967882. [PMID: 36110142 PMCID: PMC9468268 DOI: 10.3389/fchem.2022.967882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 07/28/2022] [Indexed: 12/01/2022] Open
Abstract
Aggregation kinetics of proteins and peptides have been studied extensively due to their significance in many human diseases, including neurodegenerative disorders, and the roles they play in some key physiological processes. However, most of these studies have been performed as bulk measurements using Thioflavin T or other fluorescence turn-on reagents as indicators of fibrillization. Such techniques are highly successful in making inferences about the nucleation and growth mechanism of fibrils, yet cannot directly measure assembly reactions at low protein concentrations which is the case for amyloid-β (Aβ) peptide under physiological conditions. In particular, the evolution from monomer to low-order oligomer in early stages of aggregation cannot be detected. Single-molecule methods allow direct access to such fundamental information. We developed a high-throughput protocol for single-molecule photobleaching experiments using an automated fluorescence microscope. Stepwise photobleaching analysis of the time profiles of individual foci allowed us to determine stoichiometry of protein oligomers and probe protein aggregation kinetics. Furthermore, we investigated the potential application of supervised machine learning with support vector machines (SVMs) as well as multilayer perceptron (MLP) artificial neural networks to classify bleaching traces into stoichiometric categories based on an ensemble of measurable quantities derivable from individual traces. Both SVM and MLP models achieved a comparable accuracy of more than 80% against simulated traces up to 19-mer, although MLP offered considerable speed advantages, thus making it suitable for application to high-throughput experimental data. We used our high-throughput method to study the aggregation of Aβ40 in the presence of metal ions and the aggregation of α-synuclein in the presence of gold nanoparticles.
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Affiliation(s)
- Bogachan Tahirbegi
- Department of Chemistry, Imperial College London, London, United Kingdom
| | - Alastair J. Magness
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | | | - Xiangyu Teng
- Department of Chemistry, Imperial College London, London, United Kingdom
| | - James Hooper
- School of Food Science and Nutrition and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Yuan Guo
- School of Food Science and Nutrition and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Thomas Knöpfel
- Department of Brain Sciences, Imperial College London, London, United Kingdom
| | - Keith R. Willison
- Department of Chemistry, Imperial College London, London, United Kingdom
| | - David R. Klug
- Department of Chemistry, Imperial College London, London, United Kingdom
| | - Liming Ying
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
- *Correspondence: Liming Ying,
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9
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Taylor AIP, Staniforth RA. General Principles Underpinning Amyloid Structure. Front Neurosci 2022; 16:878869. [PMID: 35720732 PMCID: PMC9201691 DOI: 10.3389/fnins.2022.878869] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Accepted: 05/11/2022] [Indexed: 12/14/2022] Open
Abstract
Amyloid fibrils are a pathologically and functionally relevant state of protein folding, which is generally accessible to polypeptide chains and differs fundamentally from the globular state in terms of molecular symmetry, long-range conformational order, and supramolecular scale. Although amyloid structures are challenging to study, recent developments in techniques such as cryo-EM, solid-state NMR, and AFM have led to an explosion of information about the molecular and supramolecular organization of these assemblies. With these rapid advances, it is now possible to assess the prevalence and significance of proposed general structural features in the context of a diverse body of high-resolution models, and develop a unified view of the principles that control amyloid formation and give rise to their unique properties. Here, we show that, despite system-specific differences, there is a remarkable degree of commonality in both the structural motifs that amyloids adopt and the underlying principles responsible for them. We argue that the inherent geometric differences between amyloids and globular proteins shift the balance of stabilizing forces, predisposing amyloids to distinct molecular interaction motifs with a particular tendency for massive, lattice-like networks of mutually supporting interactions. This general property unites previously characterized structural features such as steric and polar zippers, and contributes to the long-range molecular order that gives amyloids many of their unique properties. The shared features of amyloid structures support the existence of shared structure-activity principles that explain their self-assembly, function, and pathogenesis, and instill hope in efforts to develop broad-spectrum modifiers of amyloid function and pathology.
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10
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Michaels TCT, Dear AJ, Cohen SIA, Vendruscolo M, Knowles TPJ. Kinetic profiling of therapeutic strategies for inhibiting the formation of amyloid oligomers. J Chem Phys 2022; 156:164904. [PMID: 35490011 DOI: 10.1063/5.0077609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Protein self-assembly into amyloid fibrils underlies several neurodegenerative conditions, including Alzheimer's and Parkinson's diseases. It has become apparent that the small oligomers formed during this process constitute neurotoxic molecular species associated with amyloid aggregation. Targeting the formation of oligomers represents, therefore, a possible therapeutic avenue to combat these diseases. However, it remains challenging to establish which microscopic steps should be targeted to suppress most effectively the generation of oligomeric aggregates. Recently, we have developed a kinetic model of oligomer dynamics during amyloid aggregation. Here, we use this approach to derive explicit scaling relationships that reveal how key features of the time evolution of oligomers, including oligomer peak concentration and lifetime, are controlled by the different rate parameters. We discuss the therapeutic implications of our framework by predicting changes in oligomer concentrations when the rates of the individual microscopic events are varied. Our results identify the kinetic parameters that control most effectively the generation of oligomers, thus opening a new path for the systematic rational design of therapeutic strategies against amyloid-related diseases.
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Affiliation(s)
- Thomas C T Michaels
- Department of Physics and Astronomy, Institute for the Physics of Living Systems, University College London, London, United Kingdom
| | - Alexander J Dear
- Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Samuel I A Cohen
- Department of Physics and Astronomy, Institute for the Physics of Living Systems, University College London, London, United Kingdom
| | - Michele Vendruscolo
- Yusuf Hamied Department of Chemistry, Centre for Misfolding Diseases, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Tuomas P J Knowles
- Yusuf Hamied Department of Chemistry, Centre for Misfolding Diseases, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
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11
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Yao QQ, Wen J, Perrett S, Wu S. Distinct lipid membrane-mediated pathways of Tau assembly revealed by single-molecule analysis. NANOSCALE 2022; 14:4604-4613. [PMID: 35260870 DOI: 10.1039/d1nr05960b] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
The conversion of intrinsically disordered Tau to highly ordered amyloid aggregates is associated with a wide range of neurodegenerative diseases termed tauopathies. The presence of lipid bilayer membranes is a critical factor that accelerates the abnormal aggregation of Tau protein. However, the lipid membrane-induced conformational changes of Tau and the mechanism for the accelerated fibrillation remain elusive. In this study, single-molecule Förster resonance energy transfer (smFRET) and fluorescence correlation spectroscopy (FCS) were applied to detect the conformational changes and intermolecular interactions of full-length Tau in the presence of different concentrations of 1,2-dimyristoyl-sn-glycero-3-phosphatidylserine (DMPS) vesicles. The results show that the conformation of Tau becomes expanded with opening of the N-terminal and C-terminal domains of Tau upon binding to DMPS. At low DMPS concentrations, Tau forms oligomers with a partially extended conformation which facilitates the amyloid fibrillization process. At high DMPS concentrations, Tau monomer binds to lipid membranes in a fully expanded conformation at low density thus inhibiting intermolecular aggregation. Our study reveals the underlying mechanisms by which lipid membranes influence amyloid formation of Tau, providing a foundation for further understanding of the pathogenesis and physiology of the interplay between Tau protein and lipid membranes.
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Affiliation(s)
- Qiong-Qiong Yao
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, China.
- University of the Chinese Academy of Sciences, 19A Yuquan Road, Shijingshan District, Beijing 100049, China
| | - Jitao Wen
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, China.
- University of the Chinese Academy of Sciences, 19A Yuquan Road, Shijingshan District, Beijing 100049, China
| | - Sarah Perrett
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, China.
- University of the Chinese Academy of Sciences, 19A Yuquan Road, Shijingshan District, Beijing 100049, China
| | - Si Wu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, China.
- University of the Chinese Academy of Sciences, 19A Yuquan Road, Shijingshan District, Beijing 100049, China
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12
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Excitation energy migration to study protein oligomerization and amyloid formation. Biophys Chem 2021; 281:106719. [PMID: 34864229 DOI: 10.1016/j.bpc.2021.106719] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 11/08/2021] [Accepted: 11/10/2021] [Indexed: 11/22/2022]
Abstract
Excitation energy migration via homo-FRET (Förster resonance energy transfer) is a unique variant of traditional FRET that involves a non-radiative energy transfer between the dipoles of two or more chemical identical fluorophores in close proximity and with an overlap between its excitation and emission spectra. Such energy migrations between chemically identical fluorophores within the Förster distance having their dipoles oriented over a wide angular spread results in the depolarization of fluorescence anisotropy depending on the local density of the fluorophores. Therefore, this methodology can be employed to study protein oligomerization and amyloid fibril formation. The conceptual framework involves extracting structural information by identifying proximal and distal locations in supramolecular assemblies by monitoring the efficiency of homo-FRET between fluorophore-conjugated protein molecules within these supramolecular assemblies. This review highlights two such cases in which excitation energy migration via homo-FRET was used to characterize the formation of membrane-mediated β-sheet rich oligomers of the prion protein as well as to construct a site-specific 2D-proximity correlation map to probe inter-residue proximities within the highly organized amyloid fibrils of α-synuclein. Energy migration studies will find applications in studying a wide range of biomolecular assemblies such as lipid-protein complexes, oligomers, amyloids, and phase-separated condensates.
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13
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Fatafta H, Khaled M, Owen MC, Sayyed-Ahmad A, Strodel B. Amyloid-β peptide dimers undergo a random coil to β-sheet transition in the aqueous phase but not at the neuronal membrane. Proc Natl Acad Sci U S A 2021; 118:e2106210118. [PMID: 34544868 PMCID: PMC8488611 DOI: 10.1073/pnas.2106210118] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/16/2021] [Indexed: 11/21/2022] Open
Abstract
Mounting evidence suggests that the neuronal cell membrane is the main site of oligomer-mediated neuronal toxicity of amyloid-β peptides in Alzheimer's disease. To gain a detailed understanding of the mutual interference of amyloid-β oligomers and the neuronal membrane, we carried out microseconds of all-atom molecular dynamics (MD) simulations on the dimerization of amyloid-β (Aβ)42 in the aqueous phase and in the presence of a lipid bilayer mimicking the in vivo composition of neuronal membranes. The dimerization in solution is characterized by a random coil to β-sheet transition that seems on pathway to amyloid aggregation, while the interactions with the neuronal membrane decrease the order of the Aβ42 dimer by attenuating its propensity to form a β-sheet structure. The main lipid interaction partners of Aβ42 are the surface-exposed sugar groups of the gangliosides GM1. As the neurotoxic activity of amyloid oligomers increases with oligomer order, these results suggest that GM1 is neuroprotective against Aβ-mediated toxicity.
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Affiliation(s)
- Hebah Fatafta
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Mohammed Khaled
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Michael C Owen
- Central European Institute of Technology, Masaryk University, Brno 625 00, Czech Republic
- Institute of Chemistry, University of Miskolc, 3515 Miskolc-Egyetemváros, Hungary
| | | | - Birgit Strodel
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, 52425 Jülich, Germany;
- Institute of Theoretical and Computational Chemistry, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
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14
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Amyloid particles facilitate surface-catalyzed cross-seeding by acting as promiscuous nanoparticles. Proc Natl Acad Sci U S A 2021; 118:2104148118. [PMID: 34462352 PMCID: PMC8433567 DOI: 10.1073/pnas.2104148118] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Amyloid seeds are nanometer-sized protein particles that accelerate amyloid assembly as well as propagate and transmit the amyloid protein conformation associated with a wide range of protein misfolding diseases. However, seeded amyloid growth through templated elongation at fibril ends cannot explain the full range of molecular behaviors observed during cross-seeded formation of amyloid by heterologous seeds. Here, we demonstrate that amyloid seeds can accelerate amyloid formation via a surface catalysis mechanism without propagating the specific amyloid conformation associated with the seeds. This type of seeding mechanism is demonstrated through quantitative characterization of the cross-seeded assembly reactions involving two nonhomologous and unrelated proteins: the human Aβ42 peptide and the yeast prion-forming protein Sup35NM. Our results demonstrate experimental approaches to differentiate seeding by templated elongation from nontemplated amyloid seeding and rationalize the molecular mechanism of the cross-seeding phenomenon as a manifestation of the aberrant surface activities presented by amyloid seeds as nanoparticles.
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15
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Sharma S, Modi P, Sharma G, Deep S. Kinetics theories to understand the mechanism of aggregation of a protein and to design strategies for its inhibition. Biophys Chem 2021; 278:106665. [PMID: 34419715 DOI: 10.1016/j.bpc.2021.106665] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 08/05/2021] [Accepted: 08/06/2021] [Indexed: 12/14/2022]
Abstract
Protein aggregation phenomenon is closely related to the formation of amyloids which results in many neurodegenerative diseases like Alzheimer's, Parkinson's, Huntington's, and Amyotrophic Lateral Sclerosis. In order to prevent and treat these diseases, a clear understanding of the mechanism of misfolding and self-assembly of peptides and proteins is very crucial. The aggregation of a protein may involve various microscopic events. Multiple simulations utilizing the solutions of the master equation have given a better understanding of the kinetic profiles involved in the presence and absence of a particular microscopic event. This review focuses on understanding the contribution of these molecular events to protein aggregation based on the analysis of kinetic profiles of aggregation. We also discuss the effect of inhibitors, which target various species of aggregation pathways, on the kinetic profile of protein aggregation. At the end of this review, some strategies for the inhibition of aggregation that can be utilized by combining the chemical kinetics approach with thermodynamics are proposed.
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Affiliation(s)
- Shilpa Sharma
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Priya Modi
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Gargi Sharma
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Shashank Deep
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
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16
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Rice LJ, Ecroyd H, van Oijen AM. Illuminating amyloid fibrils: Fluorescence-based single-molecule approaches. Comput Struct Biotechnol J 2021; 19:4711-4724. [PMID: 34504664 PMCID: PMC8405898 DOI: 10.1016/j.csbj.2021.08.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 08/11/2021] [Accepted: 08/12/2021] [Indexed: 12/15/2022] Open
Abstract
The aggregation of proteins into insoluble filamentous amyloid fibrils is a pathological hallmark of neurodegenerative diseases that include Parkinson's disease and Alzheimer's disease. Since the identification of amyloid fibrils and their association with disease, there has been much work to describe the process by which fibrils form and interact with other proteins. However, due to the dynamic nature of fibril formation and the transient and heterogeneous nature of the intermediates produced, it can be challenging to examine these processes using techniques that rely on traditional ensemble-based measurements. Single-molecule approaches overcome these limitations as rare and short-lived species within a population can be individually studied. Fluorescence-based single-molecule methods have proven to be particularly useful for the study of amyloid fibril formation. In this review, we discuss the use of different experimental single-molecule fluorescence microscopy approaches to study amyloid fibrils and their interaction with other proteins, in particular molecular chaperones. We highlight the mechanistic insights these single-molecule techniques have already provided in our understanding of how fibrils form, and comment on their potential future use in studying amyloid fibrils and their intermediates.
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Affiliation(s)
- Lauren J. Rice
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia
- Illawarra Health & Medical Research Institute, Wollongong, NSW 2522, Australia
| | - Heath Ecroyd
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia
- Illawarra Health & Medical Research Institute, Wollongong, NSW 2522, Australia
| | - Antoine M. van Oijen
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia
- Illawarra Health & Medical Research Institute, Wollongong, NSW 2522, Australia
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17
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Gomes GN, Levine ZA. Defining the Neuropathological Aggresome across in Silico, in Vitro, and ex Vivo Experiments. J Phys Chem B 2021; 125:1974-1996. [PMID: 33464098 PMCID: PMC8362740 DOI: 10.1021/acs.jpcb.0c09193] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The loss of proteostasis over the life course is associated with a wide range of debilitating degenerative diseases and is a central hallmark of human aging. When left unchecked, proteins that are intrinsically disordered can pathologically aggregate into highly ordered fibrils, plaques, and tangles (termed amyloids), which are associated with countless disorders such as Alzheimer's disease, Parkinson's disease, type II diabetes, cancer, and even certain viral infections. However, despite significant advances in protein folding and solution biophysics techniques, determining the molecular cause of these conditions in humans has remained elusive. This has been due, in part, to recent discoveries showing that soluble protein oligomers, not insoluble fibrils or plaques, drive the majority of pathological processes. This has subsequently led researchers to focus instead on heterogeneous and often promiscuous protein oligomers. Unfortunately, significant gaps remain in how to prepare, model, experimentally corroborate, and extract amyloid oligomers relevant to human disease in a systematic manner. This Review will report on each of these techniques and their successes and shortcomings in an attempt to standardize comparisons between protein oligomers across disciplines, especially in the context of neurodegeneration. By standardizing multiple techniques and identifying their common overlap, a clearer picture of the soluble neuropathological aggresome can be constructed and used as a baseline for studying human disease and aging.
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Affiliation(s)
- Gregory-Neal Gomes
- Department of Pathology, Yale School of Medicine, New Haven, CT, 06520, USA
- Department of Molecular Biophysics & Biochemistry, Yale University, New Haven, CT 06511, USA
| | - Zachary A. Levine
- Department of Pathology, Yale School of Medicine, New Haven, CT, 06520, USA
- Department of Molecular Biophysics & Biochemistry, Yale University, New Haven, CT 06511, USA
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18
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Single Molecule Characterization of Amyloid Oligomers. Molecules 2021; 26:molecules26040948. [PMID: 33670093 PMCID: PMC7916856 DOI: 10.3390/molecules26040948] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 01/29/2021] [Accepted: 02/02/2021] [Indexed: 12/11/2022] Open
Abstract
The misfolding and aggregation of polypeptide chains into β-sheet-rich amyloid fibrils is associated with a wide range of neurodegenerative diseases. Growing evidence indicates that the oligomeric intermediates populated in the early stages of amyloid formation rather than the mature fibrils are responsible for the cytotoxicity and pathology and are potentially therapeutic targets. However, due to the low-populated, transient, and heterogeneous nature of amyloid oligomers, they are hard to characterize by conventional bulk methods. The development of single molecule approaches provides a powerful toolkit for investigating these oligomeric intermediates as well as the complex process of amyloid aggregation at molecular resolution. In this review, we present an overview of recent progress in characterizing the oligomerization of amyloid proteins by single molecule fluorescence techniques, including single-molecule Förster resonance energy transfer (smFRET), fluorescence correlation spectroscopy (FCS), single-molecule photobleaching and super-resolution optical imaging. We discuss how these techniques have been applied to investigate the different aspects of amyloid oligomers and facilitate understanding of the mechanism of amyloid aggregation.
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19
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Chen H, Xie X, Chen TY. Single-molecule microscopy for in-cell quantification of protein oligomeric stoichiometry. Curr Opin Struct Biol 2020; 66:112-118. [PMID: 33242727 DOI: 10.1016/j.sbi.2020.10.022] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 10/14/2020] [Accepted: 10/19/2020] [Indexed: 12/11/2022]
Abstract
Protein organization modification plays a vital role in initiating signaling pathways, transcriptional regulation, and cell apoptosis regulation. Simultaneous quantification of oligomeric state and cellular parameters in the same cell, even though challenging, is required to understand their correlation at the molecular level. Recent advances of fluorescence protein and single-molecule localization microscopy enables the determination of localizations and oligomeric states of target proteins in cells. We reviewed the fluorescence intensity-based, localization-based, and photophysical property-based approaches for in-cell quantification of protein oligomeric stoichiometry. We discussed their working principles, applications, advantages, and limitations. These results also imply the combination of methodologies targeting different biological parameters at the single-cell level is essential to uncover the structure-function relationship at the molecular level.
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Affiliation(s)
- Huanhuan Chen
- Department of Chemistry, University of Houston, Houston, TX 77204, United States
| | - Xihong Xie
- Department of Chemistry, University of Houston, Houston, TX 77204, United States
| | - Tai-Yen Chen
- Department of Chemistry, University of Houston, Houston, TX 77204, United States.
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20
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Cawood EE, Karamanos TK, Wilson AJ, Radford SE. Visualizing and trapping transient oligomers in amyloid assembly pathways. Biophys Chem 2020; 268:106505. [PMID: 33220582 PMCID: PMC8188297 DOI: 10.1016/j.bpc.2020.106505] [Citation(s) in RCA: 81] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2020] [Revised: 10/29/2020] [Accepted: 11/01/2020] [Indexed: 12/31/2022]
Abstract
Oligomers which form during amyloid fibril assembly are considered to be key contributors towards amyloid disease. However, understanding how such intermediates form, their structure, and mechanisms of toxicity presents significant challenges due to their transient and heterogeneous nature. Here, we discuss two different strategies for addressing these challenges: use of (1) methods capable of detecting lowly-populated species within complex mixtures, such as NMR, single particle methods (including fluorescence and force spectroscopy), and mass spectrometry; and (2) chemical and biological tools to bias the amyloid energy landscape towards specific oligomeric states. While the former methods are well suited to following the kinetics of amyloid assembly and obtaining low-resolution structural information, the latter are capable of producing oligomer samples for high-resolution structural studies and inferring structure-toxicity relationships. Together, these different approaches should enable a clearer picture to be gained of the nature and role of oligomeric intermediates in amyloid formation and disease. Methods to study structure, toxicity, and kinetics of transient amyloid oligomers. NMR and single particle methods can characterize lowly-populated oligomers. Chemical tools/antibodies stabilize oligomers for structural and toxicity studies A combination of methods is needed to fully characterize amyloid assembly pathways.
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Affiliation(s)
- Emma E Cawood
- Astbury Centre for Structural Molecular Biology, School of Chemistry, University of Leeds, LS2 9JT, UK; Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds, LS2 9JT, UK
| | - Theodoros K Karamanos
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds, LS2 9JT, UK; Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Andrew J Wilson
- Astbury Centre for Structural Molecular Biology, School of Chemistry, University of Leeds, LS2 9JT, UK.
| | - Sheena E Radford
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds, LS2 9JT, UK.
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21
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Yang J, Dear AJ, Yao QQ, Liu Z, Dobson CM, Knowles TPJ, Wu S, Perrett S. Amelioration of aggregate cytotoxicity by catalytic conversion of protein oligomers into amyloid fibrils. NANOSCALE 2020; 12:18663-18672. [PMID: 32794533 DOI: 10.1039/d0nr01481h] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The aggregation of peptides and proteins into amyloid fibrils is a molecular self-assembly phenomenon associated with both biological function and malfunction, notably in the context of neurodegenerative diseases. Oligomeric species formed early in the aggregation process are generally associated with cytotoxicity. Extrinsic molecules such as peptides have been found to influence amyloid formation kinetics and regulate this cellular process. Here, we use single-molecule FRET and bulk assays combined with global kinetic analysis to study quantitatively the effect of an 8-residue peptide (LQVNIGNR) on fibril formation by the yeast prion protein Ure2. This peptide, which is derived from a segment of the Ure2 prion domain, forms vesicular assemblies that accelerate fibril formation of Ure2 by promoting conformational conversion of oligomeric intermediates into fibrillar species in a catalytic manner. This reduces oligomer longevity and consequently ameliorates cytotoxicity. The LQVNIGNR peptide was found to accelerate fibril formation of unrelated proteins including Tau and α-Synuclein, suggesting a general ability to catalyse fibrillation. This study provides a general strategy for investigating the microscopic mechanism of extrinsic factors on amyloid aggregation. This approach can readily be applied to other amyloid systems and demonstrates that acceleration of oligomer conversion is a promising strategy to reduce amyloid toxicity.
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Affiliation(s)
- Jie Yang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, China.
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22
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Liu RN, Kang YM. Stochastic master equation for early protein aggregation in the transthyretin amyloid disease. Sci Rep 2020; 10:12437. [PMID: 32709875 PMCID: PMC7381670 DOI: 10.1038/s41598-020-69319-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 07/10/2020] [Indexed: 11/09/2022] Open
Abstract
It is significant to understand the earliest molecular events occurring in the nucleation of the amyloid aggregation cascade for the prevention of amyloid related diseases such as transthyretin amyloid disease. We develop chemical master equation for the aggregation of monomers into oligomers using reaction rate law in chemical kinetics. For this stochastic model, lognormal moment closure method is applied to track the evolution of relevant statistical moments and its high accuracy is confirmed by the results obtained from Gillespie's stochastic simulation algorithm. Our results show that the formation of oligomers is highly dependent on the number of monomers. Furthermore, the misfolding rate also has an important impact on the process of oligomers formation. The quantitative investigation should be helpful for shedding more light on the mechanism of amyloid fibril nucleation.
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Affiliation(s)
- Ruo-Nan Liu
- School of Mathematics and Statistics, Xi'an Jiaotong University, Xi'an, 710049, Shaanxi, China
| | - Yan-Mei Kang
- School of Mathematics and Statistics, Xi'an Jiaotong University, Xi'an, 710049, Shaanxi, China.
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23
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Ghosh DK, Ranjan A. The metastable states of proteins. Protein Sci 2020; 29:1559-1568. [PMID: 32223005 PMCID: PMC7314396 DOI: 10.1002/pro.3859] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 03/23/2020] [Accepted: 03/24/2020] [Indexed: 12/26/2022]
Abstract
The intriguing process of protein folding comprises discrete steps that stabilize the protein molecules in different conformations. The metastable state of protein is represented by specific conformational characteristics, which place the protein in a local free energy minimum state of the energy landscape. The native-to-metastable structural transitions are governed by transient or long-lived thermodynamic and kinetic fluctuations of the intrinsic interactions of the protein molecules. Depiction of the structural and functional properties of metastable proteins is not only required to understand the complexity of folding patterns but also to comprehend the mechanisms of anomalous aggregation of different proteins. In this article, we review the properties of metastable proteins in context of their stability and capability of undergoing atypical aggregation in physiological conditions.
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Affiliation(s)
- Debasish Kumar Ghosh
- Computational and Functional Genomics Group, Centre for DNA Fingerprinting and DiagnosticsUppal, HyderabadTelanganaIndia
| | - Akash Ranjan
- Computational and Functional Genomics Group, Centre for DNA Fingerprinting and DiagnosticsUppal, HyderabadTelanganaIndia
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24
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Dear AJ, Meisl G, Šarić A, Michaels TCT, Kjaergaard M, Linse S, Knowles TPJ. Identification of on- and off-pathway oligomers in amyloid fibril formation. Chem Sci 2020; 11:6236-6247. [PMID: 32953019 PMCID: PMC7480182 DOI: 10.1039/c9sc06501f] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 05/26/2020] [Indexed: 12/22/2022] Open
Abstract
A general non-binary definition for on- and off-pathway intermediates is developed, enabling comparison of amyloid oligomers' contributions to fibril formation.
The misfolding and aberrant aggregation of proteins into fibrillar structures is a key factor in some of the most prevalent human diseases, including diabetes and dementia. Low molecular weight oligomers are thought to be a central factor in the pathology of these diseases, as well as critical intermediates in the fibril formation process, and as such have received much recent attention. Moreover, on-pathway oligomeric intermediates are potential targets for therapeutic strategies aimed at interrupting the fibril formation process. However, a consistent framework for distinguishing on-pathway from off-pathway oligomers has hitherto been lacking and, in particular, no consensus definition of on- and off-pathway oligomers is available. In this paper, we argue that a non-binary definition of oligomers' contribution to fibril-forming pathways may be more informative and we suggest a quantitative framework, in which each oligomeric species is assigned a value between 0 and 1 describing its relative contribution to the formation of fibrils. First, we clarify the distinction between oligomers and fibrils, and then we use the formalism of reaction networks to develop a general definition for on-pathway oligomers, that yields meaningful classifications in the context of amyloid formation. By applying these concepts to Monte Carlo simulations of a minimal aggregating system, and by revisiting several previous studies of amyloid oligomers in light of our new framework, we demonstrate how to perform these classifications in practice. For each oligomeric species we obtain the degree to which it is on-pathway, highlighting the most effective pharmaceutical targets for the inhibition of amyloid fibril formation.
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Affiliation(s)
- Alexander J Dear
- Department of Chemistry , University of Cambridge , Lensfield Road , Cambridge CB2 1EW , UK.,Department of Biochemistry and Structural Biology , Lund Univerisity , SE22100 Lund , Sweden .
| | - Georg Meisl
- Department of Chemistry , University of Cambridge , Lensfield Road , Cambridge CB2 1EW , UK
| | - Anđela Šarić
- Department of Physics and Astronomy , Institute for the Physics of Living Systems , University College London , Gower Street , London WC1E 6BT , UK.,MRC Laboratory for Molecular Cell Biology , University College London , Gower St, WC1E 6BT , London , UK
| | - Thomas C T Michaels
- Department of Chemistry , University of Cambridge , Lensfield Road , Cambridge CB2 1EW , UK.,Paulson School of Engineering and Applied Sciences , Harvard University , Cambridge , MA 02138 , USA
| | - Magnus Kjaergaard
- Department of Molecular Biology and Genetics , Aarhus University , Høegh-Guldbergs Gade 6B , DK-8000 Aarhus C , Denmark
| | - Sara Linse
- Department of Biochemistry and Structural Biology , Lund Univerisity , SE22100 Lund , Sweden .
| | - Tuomas P J Knowles
- Department of Chemistry , University of Cambridge , Lensfield Road , Cambridge CB2 1EW , UK.,Cavendish Laboratory , Department of Physics , University of Cambridge , J J Thomson Avenue , Cambridge CB3 0HE , UK .
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25
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Abstract
The spontaneous assembly of proteins into amyloid fibrils is a phenomenon central to many increasingly common and currently incurable human disorders, including Alzheimer's and Parkinson's diseases. Oligomeric species form transiently during this process and not only act as essential intermediates in the assembly of new filaments but also represent major pathogenic agents in these diseases. While amyloid fibrils possess a common, defining set of physicochemical features, oligomers, by contrast, appear much more diverse, and their commonalities and differences have hitherto remained largely unexplored. Here, we use the framework of chemical kinetics to investigate their dynamical properties. By fitting experimental data for several unrelated amyloidogenic systems to newly derived mechanistic models, we find that oligomers present with a remarkably wide range of kinetic and thermodynamic stabilities but that they possess two properties that are generic: they are overwhelmingly nonfibrillar, and they predominantly dissociate back to monomers rather than maturing into fibrillar species. These discoveries change our understanding of the relationship between amyloid oligomers and amyloid fibrils and have important implications for the nature of their cellular toxicity.
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26
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Maity S, Lyubchenko YL. AFM Probing of Amyloid-Beta 42 Dimers and Trimers. Front Mol Biosci 2020; 7:69. [PMID: 32391380 PMCID: PMC7193107 DOI: 10.3389/fmolb.2020.00069] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 03/30/2020] [Indexed: 12/23/2022] Open
Abstract
Elucidating the molecular mechanisms in the development of such a devastating neurodegenerative disorder as Alzheimer's disease (AD) is currently one of the major challenges of molecular medicine. Evidence strongly suggests that the development of AD is due to the accumulation of amyloid β (Aβ) oligomers; therefore, understanding the molecular mechanisms defining the conversion of physiologically important monomers of Aβ proteins into neurotoxic oligomeric species is the key for the development of treatments and preventions of AD. However, these oligomers are unstable and unavailable for structural, physical, and chemical studies. We have recently developed a novel flexible nano array (FNA)-oligomer scaffold approach in which monomers tethered inside a flexible template can assemble spontaneously into oligomers with sizes defined by the number of tethered monomers. The FNA approach was tested on short decamer Aβ(14-23) peptides which were assembled into dimers and trimers. In this paper, we have extended our FNA technique for assembling full-length Aβ42 dimers. The FNA scaffold enabling the self-assembly of Aβ42 dimers from tethered monomeric species has been designed and the assembly of the dimers has been validated by AFM force spectroscopy experiments. Two major parameters of the force spectroscopy probing, the rupture forces and the rupture profiles, were obtained to prove the assembly of Aβ42 dimers. In addition, the FNA-Aβ42 dimers were used to probe Aβ42 trimers in the force spectroscopy experiments with the use of AFM tips functionalized with FNA-Aβ42 dimers and the surface with immobilized Aβ42 monomers. We found that the binding force for the Aβ42 trimer is higher than the dimer (75 ± 7 pN vs. 60 ± 3 pN) and the rupture pattern corresponds to a cooperative dissociation of the trimer. The rupture profiles for the dissociation of the Aβ42 dimers and trimers are proposed. Prospects for further extension of the FNA-based approach for probing of higher order oligomers of Aβ42 proteins are discussed.
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Affiliation(s)
| | - Yuri L. Lyubchenko
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, NE, United States
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27
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Abstract
Intrinsically disordered proteins (IDPs) are now widely recognized as playing critical roles in a broad range of cellular functions as well as being implicated in diverse diseases. Their lack of stable secondary structure and tertiary interactions, coupled with their sensitivity to measurement conditions, stymies many traditional structural biology approaches. Single-molecule Förster resonance energy transfer (smFRET) is now widely used to characterize the physicochemical properties of these proteins in isolation and is being increasingly applied to more complex assemblies and experimental environments. This review provides an overview of confocal diffusion-based smFRET as an experimental tool, including descriptions of instrumentation, data analysis, and protein labeling. Recent papers are discussed that illustrate the unique capability of smFRET to provide insight into aggregation-prone IDPs, protein–protein interactions involving IDPs, and IDPs in complex experimental milieus.
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Affiliation(s)
- Lauren Ann Metskas
- Department of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, USA
| | - Elizabeth Rhoades
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
- Biochemistry and Molecular Biophysics Graduate Group, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104, USA
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28
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Wang J, Park G, Lee YK, Nguyen M, San Fung T, Lin TY, Hsu F, Guo Z. Spin Label Scanning Reveals Likely Locations of β-Strands in the Amyloid Fibrils of the Ure2 Prion Domain. ACS OMEGA 2020; 5:5984-5993. [PMID: 32226879 PMCID: PMC7098000 DOI: 10.1021/acsomega.9b04358] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 02/28/2020] [Indexed: 06/10/2023]
Abstract
In yeast, the formation of Ure2 fibrils underlies the prion state [URE3], in which the yeast loses the ability to distinguish good nitrogen sources from bad ones. The Ure2 prion domain is both necessary and sufficient for the formation of amyloid fibrils. Understanding the structure of Ure2 fibrils is important for understanding the propagation not only of the [URE3] prion but also of other yeast prions whose prion domains share similar features, such as the enrichment of asparagine and glutamine residues. Here, we report a structural study of the amyloid fibrils formed by the Ure2 prion domain using site-directed spin labeling and electron paramagnetic resonance (EPR) spectroscopy. We completed a spin label scanning of all the residue positions between 2 and 80 of the Ure2 prion domain. The EPR data show that the Ure2 fibril core consists of residues 8-68 and adopts a parallel in-register β-sheet structure. Most of the residues show strong spin-exchange interactions, suggesting that there are only short turns and no long loops in the fibril core. Based on the strength of spin-exchange interactions, we determined the likely locations of the β-strands. EPR data also show that the C-terminal region of the Ure2 prion domain is more disordered than the N-terminal region. The roles of hydrophobic and charged residues are analyzed. Overall, the structure of Ure2 fibrils appears to involve a balance of stabilizing interactions, such as asparagine ladders, and destabilizing interactions, such as stacking of charged residues.
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29
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Manjrekar J, Shah H. Protein-based inheritance. Semin Cell Dev Biol 2019; 97:138-155. [PMID: 31344459 DOI: 10.1016/j.semcdb.2019.07.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Accepted: 07/08/2019] [Indexed: 01/17/2023]
Abstract
Epigenetic mechanisms of inheritance have come to occupy a prominent place in our understanding of living systems, primarily eukaryotes. There has been considerable and lively discussion of the possible evolutionary significance of transgenerational epigenetic inheritance. One particular type of epigenetic inheritance that has not figured much in general discussions is that based on conformational changes in proteins, where proteins with altered conformations can act as templates to propagate their own structure. An increasing number of such proteins - prions and prion-like - are being discovered. Phenotypes due to the structurally altered proteins are transmitted along with their structures. This review discusses the properties and implications of "classical" amyloid-forming prions, as well as the broader class of proteins with intrinsically disordered domains, which are proving to have fascinating properties that appear to play important roles in cell organisation and function, especially during stress responses.
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Affiliation(s)
- Johannes Manjrekar
- Microbiology Department and Biotechnology Centre, The Maharaja Sayajirao University of Baroda, Vadodara, 390002, India.
| | - Hiral Shah
- Microbiology Department and Biotechnology Centre, The Maharaja Sayajirao University of Baroda, Vadodara, 390002, India
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30
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Sengupta I, Udgaonkar J. Monitoring site-specific conformational changes in real-time reveals a misfolding mechanism of the prion protein. eLife 2019; 8:44698. [PMID: 31232689 PMCID: PMC6590988 DOI: 10.7554/elife.44698] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2018] [Accepted: 06/11/2019] [Indexed: 11/25/2022] Open
Abstract
During pathological aggregation, proteins undergo remarkable conformational re-arrangements to anomalously assemble into a heterogeneous collection of misfolded multimers, ranging from soluble oligomers to insoluble amyloid fibrils. Inspired by fluorescence resonance energy transfer (FRET) measurements of protein folding, an experimental strategy to study site-specific misfolding kinetics during aggregation, by effectively suppressing contributions from inter-molecular FRET, is described. Specifically, the kinetics of conformational changes across different secondary and tertiary structural segments of the mouse prion protein (moPrP) were monitored independently, after the monomeric units transformed into large oligomers OL, which subsequently disaggregated reversibly into small oligomers OS at pH 4. The sequence segments spanning helices α2 and α3 underwent a compaction during the formation of OL and elongation into β-sheets during the formation of OS. The β1-α1-β2 and α2-α3 subdomains were separated, and the helix α1 was unfolded to varying extents in both OL and OS.
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Affiliation(s)
- Ishita Sengupta
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru, India
| | - Jayant Udgaonkar
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru, India
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31
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Sang JC, Lee JE, Dear AJ, De S, Meisl G, Thackray AM, Bujdoso R, Knowles TPJ, Klenerman D. Direct observation of prion protein oligomer formation reveals an aggregation mechanism with multiple conformationally distinct species. Chem Sci 2019; 10:4588-4597. [PMID: 31123569 PMCID: PMC6492631 DOI: 10.1039/c8sc05627g] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 03/20/2019] [Indexed: 12/14/2022] Open
Abstract
The aggregation of the prion protein (PrP) plays a key role in the development of prion diseases. In the past decade, a similar process has been associated with other proteins, such as Aβ, tau, and α-synuclein, which participate in other neurodegenerative diseases. It is increasingly recognized that the small oligomeric species of aggregates can play an important role in the development of prion diseases. However, determining the nature of the oligomers formed during the aggregation process has been experimentally difficult due to the lack of suitable methods capable of the detection and characterization of the low level of oligomers that may form. To address this problem, we have utilized single-aggregate methods to study the early events associated with aggregation of recombinant murine PrP in vitro to approach the bona fide process in vivo. PrP aggregation resulted in the formation of thioflavin T (ThT)-inactive and ThT-active species of oligomers. The ThT-active oligomers undergo conversion from a Proteinase K (PK)-sensitive to PK-resistant conformer, from which mature fibrils can eventually emerge. Overall, our results show that single-aggregate methods can provide structural and mechanistic insights into PrP aggregation, identify the potential species that mediates cytotoxicity, and reveal that a range of distinct oligomeric species with different properties is formed during prion protein aggregation.
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Affiliation(s)
- Jason C Sang
- Department of Chemistry , University of Cambridge , Lensfield Road , Cambridge , CB2 1EW , UK .
| | - Ji-Eun Lee
- Department of Chemistry , University of Cambridge , Lensfield Road , Cambridge , CB2 1EW , UK .
| | - Alexander J Dear
- Department of Chemistry , University of Cambridge , Lensfield Road , Cambridge , CB2 1EW , UK .
| | - Suman De
- Department of Chemistry , University of Cambridge , Lensfield Road , Cambridge , CB2 1EW , UK .
| | - Georg Meisl
- Department of Chemistry , University of Cambridge , Lensfield Road , Cambridge , CB2 1EW , UK .
| | - Alana M Thackray
- Department of Veterinary Medicine , University of Cambridge , Madingley Road , Cambridge , CB3 0ES , UK
| | - Raymond Bujdoso
- Department of Veterinary Medicine , University of Cambridge , Madingley Road , Cambridge , CB3 0ES , UK
| | - Tuomas P J Knowles
- Department of Chemistry , University of Cambridge , Lensfield Road , Cambridge , CB2 1EW , UK .
| | - David Klenerman
- Department of Chemistry , University of Cambridge , Lensfield Road , Cambridge , CB2 1EW , UK .
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32
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Li X, Dong C, Hoffmann M, Garen CR, Cortez LM, Petersen NO, Woodside MT. Early stages of aggregation of engineered α-synuclein monomers and oligomers in solution. Sci Rep 2019; 9:1734. [PMID: 30741954 PMCID: PMC6370846 DOI: 10.1038/s41598-018-37584-6] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 12/10/2018] [Indexed: 12/15/2022] Open
Abstract
α-Synuclein is a protein that aggregates as amyloid fibrils in the brains of patients with Parkinson's disease and dementia with Lewy bodies. Small oligomers of α-synuclein are neurotoxic and are thought to be closely associated with disease. Whereas α-synuclein fibrillization and fibril morphologies have been studied extensively with various methods, the earliest stages of aggregation and the properties of oligomeric intermediates are less well understood because few methods are able to detect and characterize early-stage aggregates. We used fluorescence spectroscopy to investigate the early stages of aggregation by studying pairwise interactions between α-synuclein monomers, as well as between engineered tandem oligomers of various sizes (dimers, tetramers, and octamers). The hydrodynamic radii of these engineered α-synuclein species were first determined by fluorescence correlation spectroscopy and dynamic light scattering. The rate of pairwise aggregation between different species was then monitored using dual-color fluorescence cross-correlation spectroscopy, measuring the extent of association between species labelled with different dyes at various time points during the early aggregation process. The aggregation rate and extent increased with tandem oligomer size. Self-association of the tandem oligomers was found to be the preferred pathway to form larger aggregates: interactions between oligomers occurred faster and to a greater extent than interactions between oligomers and monomers, indicating that the oligomers were not as efficient in seeding further aggregation by addition of monomers. These results suggest that oligomer-oligomer interactions may play an important role in driving aggregation during its early stages.
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Affiliation(s)
- Xi Li
- Department of Chemistry, University of Alberta, Edmonton, AB, T6G 2G2, Canada.,Department of Physics, University of Alberta, Edmonton, AB, T6G 2E1, Canada
| | - Chunhua Dong
- Department of Chemistry, University of Alberta, Edmonton, AB, T6G 2G2, Canada.,Department of Physics, University of Alberta, Edmonton, AB, T6G 2E1, Canada
| | - Marion Hoffmann
- Department of Physics, University of Alberta, Edmonton, AB, T6G 2E1, Canada
| | - Craig R Garen
- Department of Physics, University of Alberta, Edmonton, AB, T6G 2E1, Canada
| | - Leonardo M Cortez
- Division of Neurology, Department of Medicine, Centre for Prions and Protein Folding Diseases, and Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, T6G 2M8, Canada
| | - Nils O Petersen
- Department of Chemistry, University of Alberta, Edmonton, AB, T6G 2G2, Canada.
| | - Michael T Woodside
- Department of Physics, University of Alberta, Edmonton, AB, T6G 2E1, Canada.
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33
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Imaging individual protein aggregates to follow aggregation and determine the role of aggregates in neurodegenerative disease. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2019; 1867:870-878. [PMID: 30611780 PMCID: PMC6676340 DOI: 10.1016/j.bbapap.2018.12.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 12/06/2018] [Accepted: 12/29/2018] [Indexed: 01/07/2023]
Abstract
Protein aggregates play a key role in the initiation and spreading of neurodegenerative disease but have been difficult to study due to their low abundance and heterogeneity, in both size and structure. Fluorescence based methods capable of detecting and characterising single aggregates have recently been developed and can be used to measure many important aggregate properties, and can be combined with sensitive assays to measure aggregate toxicity. Here we review these methods and discuss recent examples of their application to determine the molecular mechanism of aggregation and the detection of aggregates in cells and cerebrospinal fluid. The further development of these methods and their application to the aggregates present in humans has the potential to solve a major problem in the field and allow the identification of the key toxic species that should be targeted in therapies. Individual protein aggregates can be imaged using fluorescence imaging. Ultra-sensitive assays have been developed to measure aggregate toxicity. The aggregation mechanism of proteins can be determined. Experiments can be performed in cells or human cerebrospinal fluid. These methods can potentially identify the toxic aggregates that cause neurodegenerative disease.
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34
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Kjaergaard M, Dear AJ, Kundel F, Qamar S, Meisl G, Knowles TPJ, Klenerman D. Oligomer Diversity during the Aggregation of the Repeat Region of Tau. ACS Chem Neurosci 2018; 9:3060-3071. [PMID: 29953200 PMCID: PMC6302314 DOI: 10.1021/acschemneuro.8b00250] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
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The
molecular mechanism of protein aggregation is of both fundamental
and clinical importance as amyloid aggregates are linked to a number
of neurodegenerative disorders. Such protein aggregates include macroscopic
insoluble fibrils as well as small soluble oligomeric species. Time-dependent
resolution of these species is prerequisite for a detailed quantitative
understanding of protein aggregation; this remains challenging due
to the lack of methods for detecting and characterizing transient
and heterogeneous protein oligomers. Here we have used single molecule
fluorescence techniques combined with mechanistic modeling to study
the heparin-induced aggregation of the repeat region of tau, which
forms the core region of neurofibrillary tangles found in Alzheimer’s
disease. We distinguish several subpopulations of oligomers with different
stability and follow their evolution during aggregation reactions
as a function of temperature and concentration. Employment of techniques
from chemical kinetics reveals that the two largest populations are
structurally distinct from fibrils and are both kinetically and thermodynamically
unstable. The first population is in rapid exchange with monomers
and held together by electrostatic interactions; the second is kinetically
more stable, dominates at later times, and is probably off-pathway
to fibril formation. These more stable oligomers may contribute to
other oligomer induced effects in the cellular environment, for example,
by overloading protein quality control systems. We also show that
the shortest growing filaments remain suspended in aqueous buffer
and thus comprise a third, smaller population of transient oligomers
with cross-β structure. Overall our data show that a diverse
population of oligomers of different structures and half-lives are
formed during the aggregation reaction with the great majority of
oligomers formed not going on to form fibrils.
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Affiliation(s)
- Magnus Kjaergaard
- Department of Chemistry, Cambridge University, Lensfield Rd, Cambridge CB2 1EW, United Kingdom
- Aarhus Institute of Advanced Studies, Aarhus University, Høegh-Guldbergs Gade 6B, DK-8000 Aarhus C, Denmark
| | - Alexander J. Dear
- Department of Chemistry, Cambridge University, Lensfield Rd, Cambridge CB2 1EW, United Kingdom
| | - Franziska Kundel
- Department of Chemistry, Cambridge University, Lensfield Rd, Cambridge CB2 1EW, United Kingdom
| | - Seema Qamar
- Cambridge Institute for Medical Research, University of Cambridge, Hills Road, Cambridge CB2 0XY, United Kingdom
| | - Georg Meisl
- Department of Chemistry, Cambridge University, Lensfield Rd, Cambridge CB2 1EW, United Kingdom
| | - Tuomas P. J. Knowles
- Department of Chemistry, Cambridge University, Lensfield Rd, Cambridge CB2 1EW, United Kingdom
- Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge CB3 0HE, United Kingdom
| | - David Klenerman
- Department of Chemistry, Cambridge University, Lensfield Rd, Cambridge CB2 1EW, United Kingdom
- UK Dementia Research Institute, University of Cambridge, Cambridge CB2 0XY, United Kingdom
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35
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Sang J, Meisl G, Thackray AM, Hong L, Ponjavic A, Knowles TPJ, Bujdoso R, Klenerman D. Direct Observation of Murine Prion Protein Replication in Vitro. J Am Chem Soc 2018; 140:14789-14798. [PMID: 30351023 PMCID: PMC6225343 DOI: 10.1021/jacs.8b08311] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Prions are believed to propagate when an assembly of prion protein (PrP) enters a cell and replicates to produce two or more fibrils, leading to an exponential increase in PrP aggregate number with time. However, the molecular basis of this process has not yet been established in detail. Here, we use single-aggregate imaging to study fibril fragmentation and elongation of individual murine PrP aggregates from seeded aggregation in vitro. We found that PrP elongation occurs via a structural conversion from a PK-sensitive to PK-resistant conformer. Fibril fragmentation was found to be length-dependent and resulted in the formation of PK-sensitive fragments. Measurement of the rate constants for these processes also allowed us to predict a simple spreading model for aggregate propagation through the brain, assuming that doubling of the aggregate number is rate-limiting. In contrast, while α-synuclein aggregated by the same mechanism, it showed significantly slower elongation and fragmentation rate constants than PrP, leading to much slower replication rate. Overall, our study shows that fibril elongation with fragmentation are key molecular processes in PrP and α-synuclein aggregate replication, an important concept in prion biology, and also establishes a simple framework to start to determine the main factors that control the rate of prion and prion-like spreading in animals.
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Affiliation(s)
- Jason
C. Sang
- Department
of Chemistry, University of Cambridge, Cambridge, CB2 1EW, U.K.
| | - Georg Meisl
- Department
of Chemistry, University of Cambridge, Cambridge, CB2 1EW, U.K.
| | - Alana M. Thackray
- Department
of Veterinary Medicine, University of Cambridge, Cambridge, CB3 0ES, U.K.
| | - Liu Hong
- Department
of Chemistry, University of Cambridge, Cambridge, CB2 1EW, U.K.,Zhou
Pei-Yuan Center for Applied Mathematics, Tsinghua University, Beijing 100084, PR China
| | - Aleks Ponjavic
- Department
of Chemistry, University of Cambridge, Cambridge, CB2 1EW, U.K.
| | - Tuomas P. J. Knowles
- Department
of Chemistry, University of Cambridge, Cambridge, CB2 1EW, U.K.,Cavendish
Laboratory, University of Cambridge, Cambridge, CB3 0HE, U.K.
| | - Raymond Bujdoso
- Department
of Veterinary Medicine, University of Cambridge, Cambridge, CB3 0ES, U.K.
| | - David Klenerman
- Department
of Chemistry, University of Cambridge, Cambridge, CB2 1EW, U.K.,
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36
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Dear AJ, Šarić A, Michaels TCT, Dobson CM, Knowles TPJ. Statistical Mechanics of Globular Oligomer Formation by Protein Molecules. J Phys Chem B 2018; 122:11721-11730. [PMID: 30336667 DOI: 10.1021/acs.jpcb.8b07805] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The misfolding and aggregation of proteins into linear fibrils is widespread in human biology, for example, in connection with amyloid formation and the pathology of neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. The oligomeric species that are formed in the early stages of protein aggregation are of great interest, having been linked with the cellular toxicity associated with these conditions. However, these species are not characterized in any detail experimentally, and their properties are not well understood. Many of these species have been found to have approximately spherical morphology and to be held together by hydrophobic interactions. We present here an analytical statistical mechanical model of globular oligomer formation from simple idealized amphiphilic protein monomers and show that this correlates well with Monte Carlo simulations of oligomer formation. We identify the controlling parameters of the model, which are closely related to simple quantities that may be fitted directly from experiment. We predict that globular oligomers are unlikely to form at equilibrium in many polypeptide systems but instead form transiently in the early stages of amyloid formation. We contrast the globular model of oligomer formation to a well-established model of linear oligomer formation, highlighting how the differing ensemble properties of linear and globular oligomers offer a potential strategy for characterizing oligomers from experimental measurements.
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Affiliation(s)
- Alexander J Dear
- Centre for Misfolding Diseases, Department of Chemistry , University of Cambridge , Lensfield Road , Cambridge CB2 1EW , U.K
| | - Anđela Šarić
- Department of Physics and Astronomy, Institute for the Physics of Living Systems , University College London , Gower Street , London WC1E 6BT , U.K
| | - Thomas C T Michaels
- Centre for Misfolding Diseases, Department of Chemistry , University of Cambridge , Lensfield Road , Cambridge CB2 1EW , U.K.,Paulson School of Engineering and Applied Sciences , Harvard University , Cambridge , Massachusetts 02138 , United States
| | - Christopher M Dobson
- Centre for Misfolding Diseases, Department of Chemistry , University of Cambridge , Lensfield Road , Cambridge CB2 1EW , U.K
| | - Tuomas P J Knowles
- Centre for Misfolding Diseases, Department of Chemistry , University of Cambridge , Lensfield Road , Cambridge CB2 1EW , U.K.,Cavendish Laboratory, Department of Physics , University of Cambridge , JJ Thomson Avenue , Cambridge CB3 0HE , U.K
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37
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Törnquist M, Michaels TCT, Sanagavarapu K, Yang X, Meisl G, Cohen SIA, Knowles TPJ, Linse S. Secondary nucleation in amyloid formation. Chem Commun (Camb) 2018; 54:8667-8684. [PMID: 29978862 DOI: 10.1039/c8cc02204f] [Citation(s) in RCA: 263] [Impact Index Per Article: 43.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Nucleation of new peptide and protein aggregates on the surfaces of amyloid fibrils of the same peptide or protein has emerged in the past two decades as a major pathway for both the generation of molecular species responsible for cellular toxicity and for the autocatalytic proliferation of peptide and protein aggregates. A key question in current research is the molecular mechanism and driving forces governing such processes, known as secondary nucleation. In this context, the analogies with other self-assembling systems for which monomer-dependent secondary nucleation has been studied for more than a century provide a valuable source of inspiration. Here, we present a short overview of this background and then review recent results regarding secondary nucleation of amyloid-forming peptides and proteins, focusing in particular on the amyloid β peptide (Aβ) from Alzheimer's disease, with some examples regarding α-synuclein from Parkinson's disease. Monomer-dependent secondary nucleation of Aβ was discovered using a combination of kinetic experiments, global analysis, seeding experiments and selective isotope-enrichment, which pinpoint the monomer as the origin of new aggregates in a fibril-catalyzed reaction. Insights into driving forces are gained from variations of solution conditions, temperature and peptide sequence. Selective inhibition of secondary nucleation is explored as an effective means to limit oligomer production and toxicity. We also review experiments aimed at finding interaction partners of oligomers generated by secondary nucleation in an ongoing aggregation process. At the end of this feature article we bring forward outstanding questions and testable mechanistic hypotheses regarding monomer-dependent secondary nucleation in amyloid formation.
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Affiliation(s)
- Mattias Törnquist
- Lund University, Department of Biochemistry and Structural Biology, Chemical Centre, PO Box 124, SE221 00 Lund, Sweden.
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38
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Wagner AS, Politi AZ, Ast A, Bravo-Rodriguez K, Baum K, Buntru A, Strempel NU, Brusendorf L, Hänig C, Boeddrich A, Plassmann S, Klockmeier K, Ramirez-Anguita JM, Sanchez-Garcia E, Wolf J, Wanker EE. Self-assembly of Mutant Huntingtin Exon-1 Fragments into Large Complex Fibrillar Structures Involves Nucleated Branching. J Mol Biol 2018; 430:1725-1744. [PMID: 29601786 DOI: 10.1016/j.jmb.2018.03.017] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 03/14/2018] [Accepted: 03/19/2018] [Indexed: 11/18/2022]
Abstract
Huntingtin (HTT) fragments with extended polyglutamine tracts self-assemble into amyloid-like fibrillar aggregates. Elucidating the fibril formation mechanism is critical for understanding Huntington's disease pathology and for developing novel therapeutic strategies. Here, we performed systematic experimental and theoretical studies to examine the self-assembly of an aggregation-prone N-terminal HTT exon-1 fragment with 49 glutamines (Ex1Q49). Using high-resolution imaging techniques such as electron microscopy and atomic force microscopy, we show that Ex1Q49 fragments in cell-free assays spontaneously convert into large, highly complex bundles of amyloid fibrils with multiple ends and fibril branching points. Furthermore, we present experimental evidence that two nucleation mechanisms control spontaneous Ex1Q49 fibrillogenesis: (1) a relatively slow primary fibril-independent nucleation process, which involves the spontaneous formation of aggregation-competent fibrillary structures, and (2) a fast secondary fibril-dependent nucleation process, which involves nucleated branching and promotes the rapid assembly of highly complex fibril bundles with multiple ends. The proposed aggregation mechanism is supported by studies with the small molecule O4, which perturbs early events in the aggregation cascade and delays Ex1Q49 fibril assembly, comprehensive mathematical and computational modeling studies, and seeding experiments with small, preformed fibrillar Ex1Q49 aggregates that promote the assembly of amyloid fibrils. Together, our results suggest that nucleated branching in vitro plays a critical role in the formation of complex fibrillar HTT exon-1 aggregates with multiple ends.
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Affiliation(s)
- Anne S Wagner
- Neuroproteomics, Max Delbrueck Center for Molecular Medicine, Robert-Rössle-Straße 10, 13125 Berlin, Germany
| | - Antonio Z Politi
- Mathematical Modelling of Cellular Processes, Max Delbrueck Center for Molecular Medicine, Robert-Rössle-Straße 10, 13125 Berlin, Germany
| | - Anne Ast
- Neuroproteomics, Max Delbrueck Center for Molecular Medicine, Robert-Rössle-Straße 10, 13125 Berlin, Germany
| | - Kenny Bravo-Rodriguez
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 2, 45470 Mülheim an der Ruhr, Germany; Computational Biochemistry, University Duisburg-Essen, Universitätsstr. 2, 45141 Essen, Germany
| | - Katharina Baum
- Mathematical Modelling of Cellular Processes, Max Delbrueck Center for Molecular Medicine, Robert-Rössle-Straße 10, 13125 Berlin, Germany
| | - Alexander Buntru
- Neuroproteomics, Max Delbrueck Center for Molecular Medicine, Robert-Rössle-Straße 10, 13125 Berlin, Germany
| | - Nadine U Strempel
- Neuroproteomics, Max Delbrueck Center for Molecular Medicine, Robert-Rössle-Straße 10, 13125 Berlin, Germany
| | - Lydia Brusendorf
- Neuroproteomics, Max Delbrueck Center for Molecular Medicine, Robert-Rössle-Straße 10, 13125 Berlin, Germany
| | - Christian Hänig
- Neuroproteomics, Max Delbrueck Center for Molecular Medicine, Robert-Rössle-Straße 10, 13125 Berlin, Germany
| | - Annett Boeddrich
- Neuroproteomics, Max Delbrueck Center for Molecular Medicine, Robert-Rössle-Straße 10, 13125 Berlin, Germany
| | - Stephanie Plassmann
- Neuroproteomics, Max Delbrueck Center for Molecular Medicine, Robert-Rössle-Straße 10, 13125 Berlin, Germany
| | - Konrad Klockmeier
- Neuroproteomics, Max Delbrueck Center for Molecular Medicine, Robert-Rössle-Straße 10, 13125 Berlin, Germany
| | - Juan M Ramirez-Anguita
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 2, 45470 Mülheim an der Ruhr, Germany
| | - Elsa Sanchez-Garcia
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 2, 45470 Mülheim an der Ruhr, Germany; Computational Biochemistry, University Duisburg-Essen, Universitätsstr. 2, 45141 Essen, Germany
| | - Jana Wolf
- Mathematical Modelling of Cellular Processes, Max Delbrueck Center for Molecular Medicine, Robert-Rössle-Straße 10, 13125 Berlin, Germany.
| | - Erich E Wanker
- Neuroproteomics, Max Delbrueck Center for Molecular Medicine, Robert-Rössle-Straße 10, 13125 Berlin, Germany.
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