251
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Noda K, Tachi Y, Okamoto Y. Structural Characteristics of Monomeric Aβ42 on Fibril in the Early Stage of Secondary Nucleation Process. ACS Chem Neurosci 2020; 11:2989-2998. [PMID: 32794732 DOI: 10.1021/acschemneuro.0c00163] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Amyloid-β (Aβ) aggregates are believed to be one of the main causes of Alzheimer's disease. Aβ peptides form fibrils having cross β-sheet structures mainly through primary nucleation, secondary nucleation, and elongation. In particular, self-catalyzed secondary nucleation is of great interest. Here, we investigate the adsorption of Aβ42 peptides to the Aβ42 fibril to reveal a role of adsorption as a part of secondary nucleation. We performed extensive molecular dynamics simulations based on replica exchange with solute tempering 2 (REST2) to two systems: a monomeric Aβ42 in solution and a complex of an Aβ42 peptide and Aβ42 fibril. Results of our simulations show that the Aβ42 monomer is extended on the fibril. Furthermore, we find that the hairpin structure of the Aβ42 monomer decreases but the helix structure increases by adsorption to the fibril surface. These structural changes are preferable for forming fibril-like aggregates, suggesting that the fibril surface serves as a catalyst in the secondary nucleation process. In addition, the stabilization of the helix structure of the Aβ42 monomer on the fibril indicates that the strategy of a secondary nucleation inhibitor design for Aβ40 can also be used for Aβ42.
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Affiliation(s)
- Kohei Noda
- Department of Physics, Graduate School of Science, Nagoya University, Nagoya, Aichi 464-8602, Japan
| | - Yuhei Tachi
- Department of Physics, Graduate School of Science, Nagoya University, Nagoya, Aichi 464-8602, Japan
| | - Yuko Okamoto
- Department of Physics, Graduate School of Science, Nagoya University, Nagoya, Aichi 464-8602, Japan
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252
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Murakami K, Yamaguchi T, Izuo N, Kume T, Hara H, Irie K. Synthetic and Biophysical Studies on the Toxic Conformer in Amyloid β with the E22Δ Mutation in Alzheimer Pathology. ACS Chem Neurosci 2020; 11:3017-3024. [PMID: 32790274 DOI: 10.1021/acschemneuro.0c00331] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The toxic conformer of the 40- or 42-mer-amyloid β-proteins (Aβ) (Aβ40, Aβ42) with a turn at positions 22 and 23 plays a role in oligomer formation, leading to neurotoxicity as part of the pathogenesis of Alzheimer's disease (AD). A deletion mutant at Glu22 (E22Δ) of Aβ, known as an Osaka mutation, accelerates oligomerization. Although E22Δ-Aβ has not been found to be toxic to cultured neuronal cells and is instead synaptotoxic in long-term potentiation, there is no information on the toxic conformer of E22Δ-Aβ in AD. The site-directed spin labeling study of E22Δ-Aβ40 by continuous wave-electron spin resonance (CW-ESR) spectroscopy in part showed the spatial proximity between positions 10 and 35, which are characteristic of the toxic conformation of Aβ, indicating the existence of a toxic conformer of Aβ with the E22Δ mutation. To obtain structural insight, E22Δ-Aβ42 substitutes with proline (F20P, A21P, D23P, and V24P), in which proline is known as a turn inducer but is a β-sheet breaker, were synthesized. An enzyme immunoassay using the 24B3 antibody recognizing toxic conformer of Aβ was carried out. 24B3 reacted with these substitutes of E22Δ-Aβ42 as well as E22Δ-Aβ42 in a similar manner to WT-Aβ42. Notably, only A21P-E22Δ-Aβ42 exhibited strong neurotoxicity in rat primary neurons after 8 days of incubation, with potent high-order oligomerization compared with E22Δ-Aβ42. These results suggest that E22Δ-Aβ42 could enhance neurotoxicity by generating a toxic oligomer conformation with a turn near position 21.
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Affiliation(s)
- Kazuma Murakami
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan
| | - Tomomi Yamaguchi
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan
| | - Naotaka Izuo
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
| | - Toshiaki Kume
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
| | - Hideyuki Hara
- BioSpin Division, Bruker Japan K. K., Yokohama 221-0022, Japan
| | - Kazuhiro Irie
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan
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253
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Azizyan RA, Wang W, Anikeenko A, Radkova Z, Bakulina A, Garro A, Charlier L, Dumas C, Ventura S, Kajava AV. Amyloidogenicity as a driving force for the formation of functional oligomers. J Struct Biol 2020; 212:107604. [PMID: 32805411 DOI: 10.1016/j.jsb.2020.107604] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 08/11/2020] [Accepted: 08/12/2020] [Indexed: 11/28/2022]
Abstract
Insoluble amyloid fibrils formed by self-assembly of amyloidogenic regions of proteins have a cross-β-structure. In this work, by using targeted molecular dynamics and rigid body simulation, we demonstrate that if a protein consists of an amyloidogenic region and a globular domain(s) and if the linker between them is short enough, such molecules cannot assemble into amyloid fibrils, instead, they form oligomers with a defined and limited number of β-strands in the cross-β core. We show that this blockage of the amyloid growth is due to the steric repulsion of the globular structures linked to amyloidogenic regions. Furthermore, we establish a relationship between the linker length and the number of monomers in such nanoparticles. We hypothesise that such oligomerisation can be a yet unrecognised way to form natural protein complexes involved in biological processes. Our results can also be used in protein engineering for designing soluble nanoparticles carrying different functional domains.
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Affiliation(s)
- Rafayel A Azizyan
- Centre de Recherche en Biologie cellulaire de Montpellier, UMR 5237, CNRS, Université Montpellier, Montpellier, France; Institut de Biologie Computationnelle, Université Montpellier, Montpellier, France
| | - Weiqiang Wang
- Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, 08193-Bellaterra, Spain
| | | | | | | | - Adriana Garro
- Universidad Nacional de San Luis IMASL-CONICET, San Luis, Argentina
| | - Landry Charlier
- Institut des Biomolécules Max Mousseron, Montpellier, France
| | - Christian Dumas
- Centre de Biochimie Structurale, CNRS, UMR5048, INSERM, U1054, Université de Montpellier, Montpellier, France
| | - Salvador Ventura
- Institut de Biotecnologia i Biomedicina and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, 08193-Bellaterra, Spain
| | - Andrey V Kajava
- Centre de Recherche en Biologie cellulaire de Montpellier, UMR 5237, CNRS, Université Montpellier, Montpellier, France; Institut de Biologie Computationnelle, Université Montpellier, Montpellier, France.
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254
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The role of fibril structure and surface hydrophobicity in secondary nucleation of amyloid fibrils. Proc Natl Acad Sci U S A 2020; 117:25272-25283. [PMID: 33004626 PMCID: PMC7568274 DOI: 10.1073/pnas.2002956117] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Alzheimer’s disease affects a rapidly growing number of individuals worldwide. Key unresolved questions relate to the onset and propagation of the disease, linked to the self-assembly of amyloid β peptide into fibrillar and smaller aggregates. This study investigates the propagation of aggregates of amyloid β peptide and asks whether hydrophobic molecular features observed on the fibril surface correlate with its ability to catalyze the formation of new aggregates. This question is motivated by the associated formation of intermediate forms that are toxic to neuronal cells. The results imply that surface catalysis is independent of surface details but requires that the monomers that form the new aggregate can adopt the structure of the parent aggregate without steric clashes. Crystals, nanoparticles, and fibrils catalyze the generation of new aggregates on their surface from the same type of monomeric building blocks as the parent assemblies. This secondary nucleation process can be many orders of magnitude faster than primary nucleation. In the case of amyloid fibrils associated with Alzheimer’s disease, this process leads to the multiplication and propagation of aggregates, whereby short-lived oligomeric intermediates cause neurotoxicity. Understanding the catalytic activity is a fundamental goal in elucidating the molecular mechanisms of Alzheimer’s and associated diseases. Here we explore the role of fibril structure and hydrophobicity by asking whether the V18, A21, V40, and A42 side chains which are exposed on the Aβ42 fibril surface as continuous hydrophobic patches play a role in secondary nucleation. Single, double, and quadruple serine substitutions were made. Kinetic analyses of aggregation data at multiple monomer concentrations reveal that all seven mutants retain the dominance of secondary nucleation as the main mechanism of fibril proliferation. This finding highlights the generality of secondary nucleation and its independence of the detailed molecular structure. Cryo-electron micrographs reveal that the V18S substitution causes fibrils to adopt a distinct morphology with longer twist distance than variants lacking this substitution. Self- and cross-seeding data show that surface catalysis is only efficient between peptides of identical morphology, indicating a templating role of secondary nucleation with structural conversion at the fibril surface. Our findings thus provide clear evidence that the propagation of amyloid fibril strains is possible even in systems dominated by secondary nucleation rather than fragmentation.
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255
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Wiegand T, Malär AA, Cadalbert R, Ernst M, Böckmann A, Meier BH. Asparagine and Glutamine Side-Chains and Ladders in HET-s(218-289) Amyloid Fibrils Studied by Fast Magic-Angle Spinning NMR. Front Mol Biosci 2020; 7:582033. [PMID: 33195425 PMCID: PMC7556116 DOI: 10.3389/fmolb.2020.582033] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 08/28/2020] [Indexed: 12/11/2022] Open
Abstract
Asparagine and glutamine side-chains can form hydrogen-bonded ladders which contribute significantly to the stability of amyloid fibrils. We show, using the example of HET-s(218–289) fibrils, that the primary amide side-chain proton resonances can be detected in cross-polarization based solid-state NMR spectra at fast magic-angle spinning (MAS). J-coupling based experiments offer the possibility to distinguish them from backbone amide groups if the spin-echo lifetimes are long enough, which turned out to be the case for the glutamine side-chains, but not for the asparagine side-chains forming asparagine ladders. We explore the sensitivity of NMR observables to asparagine ladder formation. One of the two possible asparagine ladders in HET-s(218–289), the one comprising N226 and N262, is assigned by proton-detected 3D experiments at fast MAS and significant de-shielding of one of the NH2 proton resonances indicative of hydrogen-bond formation is observed. Small rotating-frame 15N relaxation-rate constants point to rigidified asparagine side-chains in this ladder. The proton resonances are homogeneously broadened which could indicate chemical exchange, but is presently not fully understood. The second asparagine ladder (N243 and N279) in contrast remains more flexible.
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Affiliation(s)
- Thomas Wiegand
- Physical Chemistry, Eidgenössische Technische Hochschule (ETH) Zurich, Zurich, Switzerland
| | - Alexander A Malär
- Physical Chemistry, Eidgenössische Technische Hochschule (ETH) Zurich, Zurich, Switzerland
| | - Riccardo Cadalbert
- Physical Chemistry, Eidgenössische Technische Hochschule (ETH) Zurich, Zurich, Switzerland
| | - Matthias Ernst
- Physical Chemistry, Eidgenössische Technische Hochschule (ETH) Zurich, Zurich, Switzerland
| | - Anja Böckmann
- Molecular Microbiology and Structural Biochemistry, UMR 5086 CNRS/Université de Lyon, Labex Ecofect, Lyon, France
| | - Beat H Meier
- Physical Chemistry, Eidgenössische Technische Hochschule (ETH) Zurich, Zurich, Switzerland
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256
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Kinetic fingerprints differentiate the mechanisms of action of anti-Aβ antibodies. Nat Struct Mol Biol 2020; 27:1125-1133. [PMID: 32989305 DOI: 10.1038/s41594-020-0505-6] [Citation(s) in RCA: 116] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 08/13/2020] [Indexed: 12/28/2022]
Abstract
The amyloid cascade hypothesis, according to which the self-assembly of amyloid-β peptide (Aβ) is a causative process in Alzheimer's disease, has driven many therapeutic efforts for the past 20 years. Failures of clinical trials investigating Aβ-targeted therapies have been interpreted as evidence against this hypothesis, irrespective of the characteristics and mechanisms of action of the therapeutic agents, which are highly challenging to assess. Here, we combine kinetic analyses with quantitative binding measurements to address the mechanism of action of four clinical stage anti-Aβ antibodies, aducanumab, gantenerumab, bapineuzumab and solanezumab. We quantify the influence of these antibodies on the aggregation kinetics and on the production of oligomeric aggregates and link these effects to the affinity and stoichiometry of each antibody for monomeric and fibrillar forms of Aβ. Our results reveal that, uniquely among these four antibodies, aducanumab dramatically reduces the flux of Aβ oligomers.
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257
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Yu Y, Grazioli G, Unhelkar MH, Martin RW, Butts CT. Network Hamiltonian models reveal pathways to amyloid fibril formation. Sci Rep 2020; 10:15668. [PMID: 32973286 PMCID: PMC7515878 DOI: 10.1038/s41598-020-72260-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 08/27/2020] [Indexed: 12/26/2022] Open
Abstract
Amyloid fibril formation is central to the etiology of a wide range of serious human diseases, such as Alzheimer's disease and prion diseases. Despite an ever growing collection of amyloid fibril structures found in the Protein Data Bank (PDB) and numerous clinical trials, therapeutic strategies remain elusive. One contributing factor to the lack of progress on this challenging problem is incomplete understanding of the mechanisms by which these locally ordered protein aggregates self-assemble in solution. Many current models of amyloid deposition diseases posit that the most toxic species are oligomers that form either along the pathway to forming fibrils or in competition with their formation, making it even more critical to understand the kinetics of fibrillization. A recently introduced topological model for aggregation based on network Hamiltonians is capable of recapitulating the entire process of amyloid fibril formation, beginning with thousands of free monomers and ending with kinetically accessible and thermodynamically stable amyloid fibril structures. The model can be parameterized to match the five topological classes encompassing all amyloid fibril structures so far discovered in the PDB. This paper introduces a set of network statistical and topological metrics for quantitative analysis and characterization of the fibrillization mechanisms predicted by the network Hamiltonian model. The results not only provide insight into different mechanisms leading to similar fibril structures, but also offer targets for future experimental exploration into the mechanisms by which fibrils form.
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Affiliation(s)
- Yue Yu
- Department of Computer Science, University of California, Irvine, CA, 92697, USA
| | - Gianmarc Grazioli
- Department of Chemistry, San José State University, San Jose, CA, 95192, USA
| | - Megha H Unhelkar
- Department of Chemistry, University of California, Irvine, CA, 92697, USA
| | - Rachel W Martin
- Department of Chemistry, University of California, Irvine, CA, 92697, USA.,Department of Molecular Biology and Biochemistry, University of California, Irvine, CA, 92697, USA
| | - Carter T Butts
- Department of Computer Science, University of California, Irvine, CA, 92697, USA. .,California Institute for Telecommunications and Information Technology, University of California, Irvine, CA, 92697, USA. .,Departments of Sociology, Statistics, and EECS, University of California, Irvine, CA, 92697, USA.
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258
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Ikenoue T, Aprile FA, Sormanni P, Ruggeri FS, Perni M, Heller GT, Haas CP, Middel C, Limbocker R, Mannini B, Michaels TCT, Knowles TPJ, Dobson CM, Vendruscolo M. A rationally designed bicyclic peptide remodels Aβ42 aggregation in vitro and reduces its toxicity in a worm model of Alzheimer's disease. Sci Rep 2020; 10:15280. [PMID: 32943652 PMCID: PMC7498612 DOI: 10.1038/s41598-020-69626-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 06/26/2020] [Indexed: 01/01/2023] Open
Abstract
Bicyclic peptides have great therapeutic potential since they can bridge the gap between small molecules and antibodies by combining a low molecular weight of about 2 kDa with an antibody-like binding specificity. Here we apply a recently developed in silico rational design strategy to produce a bicyclic peptide to target the C-terminal region (residues 31–42) of the 42-residue form of the amyloid β peptide (Aβ42), a protein fragment whose aggregation into amyloid plaques is linked with Alzheimer’s disease. We show that this bicyclic peptide is able to remodel the aggregation process of Aβ42 in vitro and to reduce its associated toxicity in vivo in a C. elegans worm model expressing Aβ42. These results provide an initial example of a computational approach to design bicyclic peptides to target specific epitopes on disordered proteins.
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Affiliation(s)
- Tatsuya Ikenoue
- Centre for Misfolding Diseases, Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, UK.,Department of Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Francesco A Aprile
- Centre for Misfolding Diseases, Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, UK.,Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, London, W12 0BZ, UK
| | - Pietro Sormanni
- Centre for Misfolding Diseases, Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, UK
| | - Francesco S Ruggeri
- Centre for Misfolding Diseases, Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, UK
| | - Michele Perni
- Centre for Misfolding Diseases, Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, UK
| | - Gabriella T Heller
- Centre for Misfolding Diseases, Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, UK
| | - Christian P Haas
- Centre for Misfolding Diseases, Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, UK
| | - Christoph Middel
- Centre for Misfolding Diseases, Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, UK
| | - Ryan Limbocker
- Centre for Misfolding Diseases, Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, UK.,Department of Chemistry and Life Science, United States Military Academy, West Point, NY, 10996, USA
| | - Benedetta Mannini
- Centre for Misfolding Diseases, Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, UK
| | - Thomas C T Michaels
- Centre for Misfolding Diseases, Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, UK
| | - Tuomas P J Knowles
- Centre for Misfolding Diseases, Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, UK
| | - Christopher M Dobson
- Centre for Misfolding Diseases, Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, UK
| | - Michele Vendruscolo
- Centre for Misfolding Diseases, Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, UK.
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259
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Fibril structures of diabetes-related amylin variants reveal a basis for surface-templated assembly. Nat Struct Mol Biol 2020; 27:1048-1056. [PMID: 32929282 DOI: 10.1038/s41594-020-0496-3] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 08/04/2020] [Indexed: 12/19/2022]
Abstract
Aggregation of the peptide hormone amylin into amyloid deposits is a pathological hallmark of type-2 diabetes (T2D). While no causal link between T2D and amyloid has been established, the S20G mutation in amylin is associated with early-onset T2D. Here we report cryo-EM structures of amyloid fibrils of wild-type human amylin and its S20G variant. The wild-type fibril structure, solved to 3.6-Å resolution, contains two protofilaments, each built from S-shaped subunits. S20G fibrils, by contrast, contain two major polymorphs. Their structures, solved at 3.9-Å and 4.0-Å resolution, respectively, share a common two-protofilament core that is distinct from the wild-type structure. Remarkably, one polymorph contains a third subunit with another, distinct, cross-β conformation. The presence of two different backbone conformations within the same fibril may explain the increased aggregation propensity of S20G, and illustrates a potential structural basis for surface-templated fibril assembly.
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260
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Vadukul DM, Maina M, Franklin H, Nardecchia A, Serpell LC, Marshall KE. Internalisation and toxicity of amyloid-β 1-42 are influenced by its conformation and assembly state rather than size. FEBS Lett 2020; 594:3490-3503. [PMID: 32871611 DOI: 10.1002/1873-3468.13919] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 07/30/2020] [Accepted: 08/19/2020] [Indexed: 01/18/2023]
Abstract
Amyloid fibrils found in plaques in Alzheimer's disease (AD) brains are composed of amyloid-β peptides. Oligomeric amyloid-β 1-42 (Aβ42) is thought to play a critical role in neurodegeneration in AD. Here, we determine how size and conformation affect neurotoxicity and internalisation of Aβ42 assemblies using biophysical methods, immunoblotting, toxicity assays and live-cell imaging. We report significant cytotoxicity of Aβ42 oligomers and their internalisation into neurons. In contrast, Aβ42 fibrils show reduced internalisation and no toxicity. Sonicating Aβ42 fibrils generates species similar in size to oligomers but remains nontoxic. The results suggest that Aβ42 oligomers have unique properties that underlie their neurotoxic potential. Furthermore, we show that incubating cells with Aβ42 oligomers for 24 h is sufficient to trigger irreversible neurotoxicity.
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Affiliation(s)
- Devkee M Vadukul
- Dementia Research group, Sussex Neuroscience, School of Life Sciences, University of Sussex, Falmer, E Sussex, UK.,CEMO-Alzheimer Dementia group, Institute of Neuroscience, Université catholique de Louvain, Brussels, Belgium
| | - Mahmoud Maina
- Dementia Research group, Sussex Neuroscience, School of Life Sciences, University of Sussex, Falmer, E Sussex, UK.,College of Medical Sciences, Yobe State University, Nigeria
| | - Hannah Franklin
- Dementia Research group, Sussex Neuroscience, School of Life Sciences, University of Sussex, Falmer, E Sussex, UK
| | - Astrid Nardecchia
- Dementia Research group, Sussex Neuroscience, School of Life Sciences, University of Sussex, Falmer, E Sussex, UK
| | - Louise C Serpell
- Dementia Research group, Sussex Neuroscience, School of Life Sciences, University of Sussex, Falmer, E Sussex, UK
| | - Karen E Marshall
- Dementia Research group, Sussex Neuroscience, School of Life Sciences, University of Sussex, Falmer, E Sussex, UK
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261
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Schledorn M, Malär AA, Torosyan A, Penzel S, Klose D, Oss A, Org M, Wang S, Lecoq L, Cadalbert R, Samoson A, Böckmann A, Meier BH. Protein NMR Spectroscopy at 150 kHz Magic-Angle Spinning Continues To Improve Resolution and Mass Sensitivity. Chembiochem 2020; 21:2540-2548. [PMID: 32501630 PMCID: PMC7497035 DOI: 10.1002/cbic.202000341] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Indexed: 12/21/2022]
Abstract
Spectral resolution is the key to unleashing the structural and dynamic information contained in NMR spectra. Fast magic-angle spinning (MAS) has recently revolutionized the spectroscopy of biomolecular solids. Herein, we report a further remarkable improvement in the resolution of the spectra of four fully protonated proteins and a small drug molecule by pushing the MAS rotation frequency higher (150 kHz) than the more routinely used 100 kHz. We observed a reduction in the average homogeneous linewidth by a factor of 1.5 and a decrease in the observed linewidth by a factor 1.25. We conclude that even faster MAS is highly attractive and increases mass sensitivity at a moderate price in overall sensitivity.
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Affiliation(s)
| | | | | | | | - Daniel Klose
- Physical ChemistryETH Zürich8093ZürichSwitzerland
| | - Andres Oss
- Institute of Health TechnologiesTallinn University of TechnologyAkadeemia tee 15a12618TallinnEstonia
| | - Mai‐Liis Org
- Institute of Health TechnologiesTallinn University of TechnologyAkadeemia tee 15a12618TallinnEstonia
| | - Shishan Wang
- Institut de Biologie et Chimie des Protéines MMSB UMR 5086 CNRS/Université de Lyon, Labex Ecofect7 passage du Vercors69367LyonFrance
| | - Lauriane Lecoq
- Institut de Biologie et Chimie des Protéines MMSB UMR 5086 CNRS/Université de Lyon, Labex Ecofect7 passage du Vercors69367LyonFrance
| | | | - Ago Samoson
- Institute of Health TechnologiesTallinn University of TechnologyAkadeemia tee 15a12618TallinnEstonia
| | - Anja Böckmann
- Institut de Biologie et Chimie des Protéines MMSB UMR 5086 CNRS/Université de Lyon, Labex Ecofect7 passage du Vercors69367LyonFrance
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262
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Foley AR, Raskatov JA. Assessing Reproducibility in Amyloid β Research: Impact of Aβ Sources on Experimental Outcomes. Chembiochem 2020; 21:2425-2430. [PMID: 32249510 PMCID: PMC7647053 DOI: 10.1002/cbic.202000125] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 04/04/2020] [Indexed: 12/16/2022]
Abstract
The difficulty of synthesizing and purifying the amyloid β (Aβ) peptide, combined with its high aggregation propensity and low solubility under physiological conditions, leads to a wide variety of experimental results from kinetic assays to biological activity. Thus, it becomes challenging to reproduce outcomes, and this limits our ability to rely on reported results as the foundation for new research. This article examines variability of the Aβ peptide from different sources, comparing purity, and oligomer and fibril formation propensity side by side. The results highlight the importance of performing rigorous controls so that meaningful biophysical, biochemical, and neurobiological results can be obtained to improve our understanding on Aβ.
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Affiliation(s)
- Alejandro R Foley
- Department of Chemistry and Biochemistry, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA, 95064, USA
| | - Jevgenij A Raskatov
- Department of Chemistry and Biochemistry, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA, 95064, USA
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263
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Niu Z, Sarkar R, Aichler M, Wester H, Yousefi BH, Reif B. Mapping the Binding Interface of PET Tracer Molecules and Alzheimer Disease Aβ Fibrils by Using MAS Solid-State NMR Spectroscopy. Chembiochem 2020; 21:2495-2502. [PMID: 32291951 PMCID: PMC7496087 DOI: 10.1002/cbic.202000143] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 04/10/2020] [Indexed: 12/13/2022]
Abstract
Positron emission tomography (PET) tracer molecules like thioflavin T specifically recognize amyloid deposition in brain tissue by selective binding to hydrophobic or aromatic surface grooves on the β-sheet surface along the fibril axis. The molecular basis of this interaction is, however, not well understood. We have employed magic angle spinning (MAS) solid-state NMR spectroscopy to characterize Aβ-PET tracer complexes at atomic resolution. We established a titration protocol by using bovine serum albumin as a carrier to transfer hydrophobic small molecules to Aβ(1-40) fibrillar aggregates. The same Aβ(1-40) amyloid fibril sample was employed in subsequent titrations to minimize systematic errors that potentially arise from sample preparation. In the experiments, the small molecules 13 C-methylated Pittsburgh compound B (PiB) as well as a novel Aβ tracer based on a diarylbithiazole (DABTA) scaffold were employed. Classical 13 C-detected as well as proton-detected spectra of protonated and perdeuterated samples with back-substituted protons, respectively, were acquired and analyzed. After titration of the tracers, chemical-shift perturbations were observed in the loop region involving residues Gly25-Lys28 and Ile32-Gly33, thus suggesting that the PET tracer molecules interact with the loop region connecting β-sheets β1 and β2 in Aβ fibrils. We found that titration of the PiB derivatives suppressed fibril polymorphism and stabilized the amyloid fibril structure.
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Affiliation(s)
- Zheng Niu
- Munich Center for Integrated Protein Science (CIPS−M) Department ChemieTechnische Universität MünchenLichtenbergstrasse 485747GarchingGermany
- Helmholtz-Zentrum MünchenInstitute of Structural Biology (STB)Ingolstädter Landstrasse 185764NeuherbergGermany
| | - Riddhiman Sarkar
- Munich Center for Integrated Protein Science (CIPS−M) Department ChemieTechnische Universität MünchenLichtenbergstrasse 485747GarchingGermany
- Helmholtz-Zentrum MünchenInstitute of Structural Biology (STB)Ingolstädter Landstrasse 185764NeuherbergGermany
| | - Michaela Aichler
- Helmholtz Zentrum MünchenResearch Unit Analytical Pathology (AAP)Ingolstädter Landstrasse 185764NeuherbergGermany
| | - Hans‐Jürgen Wester
- Technische Universität MünchenDepartment of Pharmaceutical RadiochemistryWalther-Meißner-Strasse 385748GarchingGermany
| | - Behrooz Hooshyar Yousefi
- Technische Universität MünchenDepartment of Pharmaceutical RadiochemistryWalther-Meißner-Strasse 385748GarchingGermany
- Philipps University of MarburgDepartment of Nuclear MedicineBaldingerstrasse. 135043MarburgGermany
| | - Bernd Reif
- Munich Center for Integrated Protein Science (CIPS−M) Department ChemieTechnische Universität MünchenLichtenbergstrasse 485747GarchingGermany
- Helmholtz-Zentrum MünchenInstitute of Structural Biology (STB)Ingolstädter Landstrasse 185764NeuherbergGermany
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264
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Gelenter MD, Dregni AJ, Hong M. Pulsed Third-Spin-Assisted Recoupling NMR for Obtaining Long-Range 13C- 13C and 15N- 13C Distance Restraints. J Phys Chem B 2020; 124:7138-7151. [PMID: 32700540 PMCID: PMC8324326 DOI: 10.1021/acs.jpcb.0c04574] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
We present a class of pulsed third-spin-assisted recoupling (P-TSAR) magic-angle-spinning solid-state NMR techniques that achieve efficient polarization transfer over long distances to provide important restraints for structure determination. These experiments utilize second-order cross terms between strong 1H-13C and 1H-15N dipolar couplings to achieve 13C-13C and 15N-13C polarization transfer, similar to the principle of continuous-wave (CW) TSAR experiments. However, in contrast to the CW-TSAR experiments, these P-TSAR experiments require much less radiofrequency (rf) energy and allow a much simpler routine for optimizing the rf field strength. We call the technique PULSAR (pulsed proton-assisted recoupling) for homonuclear spin pairs. For heteronuclear spin pairs, we improve the recently introduced PERSPIRATIONCP (proton-enhanced rotor-echo short pulse irradiation cross-polarization) experiment by shifting the pulse positions and removing the z-filters, which significantly broaden the bandwidth and increase the efficiency of polarization transfer. We demonstrate the PULSAR and PERSPIRATIONCP techniques on the model protein GB1 and found cross peaks for distances as long as 10 and 8 Å for 13C-13C and 15N-13C spin pairs, respectively. We then apply these methods to the amyloid fibrils formed by the peptide hormone glucagon and show that long-range correlation peaks are readily observed to constrain intermolecular packing in this cross-β fibril. We provide an analytical model for the PULSAR and PERSPIRATIONCP experiments to explain the measured and simulated chemical shift dependence and pulse flip angle dependence of polarization transfer. These two techniques are useful for measuring long-range distance restraints to determine the three-dimensional structures of proteins and other biological macromolecules.
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Affiliation(s)
- Martin D. Gelenter
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139
| | - Aurelio J. Dregni
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139
| | - Mei Hong
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139
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265
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Lu J, Cao Q, Hughes MP, Sawaya MR, Boyer DR, Cascio D, Eisenberg DS. CryoEM structure of the low-complexity domain of hnRNPA2 and its conversion to pathogenic amyloid. Nat Commun 2020; 11:4090. [PMID: 32796831 PMCID: PMC7427792 DOI: 10.1038/s41467-020-17905-y] [Citation(s) in RCA: 66] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 07/14/2020] [Indexed: 01/02/2023] Open
Abstract
hnRNPA2 is a human ribonucleoprotein (RNP) involved in RNA metabolism. It forms fibrils both under cellular stress and in mutated form in neurodegenerative conditions. Previous work established that the C-terminal low-complexity domain (LCD) of hnRNPA2 fibrillizes under stress, and missense mutations in this domain are found in the disease multisystem proteinopathy (MSP). However, little is known at the atomic level about the hnRNPA2 LCD structure that is involved in those processes and how disease mutations cause structural change. Here we present the cryo-electron microscopy (cryoEM) structure of the hnRNPA2 LCD fibril core and demonstrate its capability to form a reversible hydrogel in vitro containing amyloid-like fibrils. Whereas these fibrils, like pathogenic amyloid, are formed from protein chains stacked into β-sheets by backbone hydrogen bonds, they display distinct structural differences: the chains are kinked, enabling non-covalent cross-linking of fibrils and disfavoring formation of pathogenic steric zippers. Both reversibility and energetic calculations suggest these fibrils are less stable than pathogenic amyloid. Moreover, the crystal structure of the disease-mutation-containing segment (D290V) of hnRNPA2 suggests that the replacement fundamentally alters the fibril structure to a more stable energetic state. These findings illuminate how molecular interactions promote protein fibril networks and how mutation can transform fibril structure from functional to a pathogenic form. hnRNPA2 is involved in RNA metabolism and can form both functional amyloid-like fibrils in membraneless organelles, and pathogenic fibrils in neurodegenerative conditions. Here, the authors present the cryo-EM fibril structure of the wild-type hnRNPA2 low-complexity domain (LCD) and the crystal structure of a LCD segment with the disease causing D290V variant and discuss how mutations can transform fibril structure from a functional to a pathogenic form.
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Affiliation(s)
- Jiahui Lu
- Departments of Chemistry and Biochemistry and Biological Chemistry, University of California, Los Angeles, Los Angeles, CA, USA.,UCLA-DOE Institute, Molecular Biology Institute, Howard Hughes Medical Institute, Los Angeles, CA, USA
| | - Qin Cao
- Departments of Chemistry and Biochemistry and Biological Chemistry, University of California, Los Angeles, Los Angeles, CA, USA.,UCLA-DOE Institute, Molecular Biology Institute, Howard Hughes Medical Institute, Los Angeles, CA, USA
| | - Michael P Hughes
- Departments of Chemistry and Biochemistry and Biological Chemistry, University of California, Los Angeles, Los Angeles, CA, USA.,UCLA-DOE Institute, Molecular Biology Institute, Howard Hughes Medical Institute, Los Angeles, CA, USA.,Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Michael R Sawaya
- Departments of Chemistry and Biochemistry and Biological Chemistry, University of California, Los Angeles, Los Angeles, CA, USA.,UCLA-DOE Institute, Molecular Biology Institute, Howard Hughes Medical Institute, Los Angeles, CA, USA
| | - David R Boyer
- Departments of Chemistry and Biochemistry and Biological Chemistry, University of California, Los Angeles, Los Angeles, CA, USA.,UCLA-DOE Institute, Molecular Biology Institute, Howard Hughes Medical Institute, Los Angeles, CA, USA
| | - Duilio Cascio
- Departments of Chemistry and Biochemistry and Biological Chemistry, University of California, Los Angeles, Los Angeles, CA, USA.,UCLA-DOE Institute, Molecular Biology Institute, Howard Hughes Medical Institute, Los Angeles, CA, USA
| | - David S Eisenberg
- Departments of Chemistry and Biochemistry and Biological Chemistry, University of California, Los Angeles, Los Angeles, CA, USA. .,UCLA-DOE Institute, Molecular Biology Institute, Howard Hughes Medical Institute, Los Angeles, CA, USA.
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266
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Ke PC, Zhou R, Serpell LC, Riek R, Knowles TPJ, Lashuel HA, Gazit E, Hamley IW, Davis TP, Fändrich M, Otzen DE, Chapman MR, Dobson CM, Eisenberg DS, Mezzenga R. Half a century of amyloids: past, present and future. Chem Soc Rev 2020; 49:5473-5509. [PMID: 32632432 PMCID: PMC7445747 DOI: 10.1039/c9cs00199a] [Citation(s) in RCA: 304] [Impact Index Per Article: 76.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Amyloid diseases are global epidemics with profound health, social and economic implications and yet remain without a cure. This dire situation calls for research into the origin and pathological manifestations of amyloidosis to stimulate continued development of new therapeutics. In basic science and engineering, the cross-β architecture has been a constant thread underlying the structural characteristics of pathological and functional amyloids, and realizing that amyloid structures can be both pathological and functional in nature has fuelled innovations in artificial amyloids, whose use today ranges from water purification to 3D printing. At the conclusion of a half century since Eanes and Glenner's seminal study of amyloids in humans, this review commemorates the occasion by documenting the major milestones in amyloid research to date, from the perspectives of structural biology, biophysics, medicine, microbiology, engineering and nanotechnology. We also discuss new challenges and opportunities to drive this interdisciplinary field moving forward.
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Affiliation(s)
- Pu Chun Ke
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
- Zhongshan Hospital, Fudan University, 111 Yixueyuan Rd, Xuhui District, Shanghai, China
| | - Ruhong Zhou
- Institute of Quantitative Biology, Zhejiang University, Hangzhou 310058, China; Department of Chemistry, Columbia University, New York, New York, 10027, USA
| | - Louise C. Serpell
- School of Life Sciences, University of Sussex, Falmer, East Sussex BN1 9QG, UK
| | - Roland Riek
- Laboratory of Physical Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich, Wolfgang-Pauli-Str. 10, 8093 Zurich, Switzerland
| | - Tuomas P. J. Knowles
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
- Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, CB3 0HE, Cambridge, UK
| | - Hilal A. Lashuel
- Laboratory of Molecular Neurobiology and Neuroproteomics, Brain Mind Institute, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Ehud Gazit
- Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences; Department of Materials Science and Engineering, Iby and Aladar Fleischman Faculty of Engineering, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Ian W. Hamley
- School of Chemistry, Food Biosciences and Pharmacy, University of Reading, Whiteknights, Reading RG6 6AD, UK
| | - Thomas P. Davis
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane Qld 4072, Australia
| | - Marcus Fändrich
- Institute of Protein Biochemistry, Ulm University, 89081, Ulm, Germany
| | - Daniel Erik Otzen
- Department of Molecular Biology, Center for Insoluble Protein Structures (inSPIN), Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark
| | - Matthew R. Chapman
- Department of Molecular, Cellular and Developmental Biology, Centre for Microbial Research, University of Michigan, Ann Arbor, MI 48109-1048, USA
| | - Christopher M. Dobson
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - David S. Eisenberg
- Departments of Chemistry and Biochemistry and Biological Chemistry, UCLA-DOE Institute and Howard Hughes Medical Institute, UCLA, Los Angeles, CA, USA
| | - Raffaele Mezzenga
- Department of Health Science & Technology, ETH Zurich, Schmelzbergstrasse 9, LFO, E23, 8092 Zurich, Switzerland
- Department of Materials, ETH Zurich, Wolfgang Pauli Strasse 10, 8093 Zurich, Switzerland
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267
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Anomalous Salt Dependence Reveals an Interplay of Attractive and Repulsive Electrostatic Interactions in α-synuclein Fibril Formation. QRB DISCOVERY 2020. [PMID: 37528959 PMCID: PMC10392692 DOI: 10.1017/qrd.2020.7] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Abstractα-Synuclein (α-syn) is an intrinsically disordered protein with a highly asymmetric charge distribution, whose aggregation is linked to Parkinson’s disease. The effect of ionic strength was investigated at mildly acidic pH (5.5) in the presence of catalytic surfaces in the form of α-syn seeds or anionic lipid vesicles using thioflavin T fluorescence measurements. Similar trends were observed with both surfaces: increasing ionic strength reduced the rate of α-syn aggregation although the surfaces as well as α-syn have a net negative charge at pH 5.5. This anomalous salt dependence implies that short-range attractive electrostatic interactions are critical for secondary nucleation as well as heterogeneous primary nucleation. Such interactions were confirmed in Monte Carlo simulations of α-syn monomers interacting with surface-grafted C-terminal tails, and found to be weakened in the presence of salt. Thus, nucleation of α-syn aggregation depends critically on an attractive electrostatic component that is screened by salt to the extent that it outweighs the screening of the long-range repulsion between negatively charged monomers and negative surfaces. Interactions between the positively charged N-termini of α-syn monomers on the one hand, and the negatively C-termini of α-syn on fibrils or vesicles surfaces on the other hand, are thus critical for nucleation.
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268
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Proteotoxicity and Neurodegenerative Diseases. Int J Mol Sci 2020; 21:ijms21165646. [PMID: 32781742 PMCID: PMC7460676 DOI: 10.3390/ijms21165646] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Revised: 08/01/2020] [Accepted: 08/04/2020] [Indexed: 02/07/2023] Open
Abstract
Neurodegenerative diseases are a major burden for our society, affecting millions of people worldwide. A main goal of past and current research is to enhance our understanding of the mechanisms underlying proteotoxicity, a common theme among these incurable and debilitating conditions. Cell proteome alteration is considered to be one of the main driving forces that triggers neurodegeneration, and unraveling the biological complexity behind the affected molecular pathways constitutes a daunting challenge. This review summarizes the current state on key processes that lead to cellular proteotoxicity in Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis, providing a comprehensive landscape of recent literature. A foundational understanding of how proteotoxicity affects disease etiology and progression may provide essential insight towards potential targets amenable of therapeutic intervention.
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269
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Kreutzer AG, Samdin TD, Guaglianone G, Spencer RK, Nowick JS. X-ray Crystallography Reveals Parallel and Antiparallel β-Sheet Dimers of a β-Hairpin Derived from Aβ 16-36 that Assemble to Form Different Tetramers. ACS Chem Neurosci 2020; 11:2340-2347. [PMID: 32584538 DOI: 10.1021/acschemneuro.0c00290] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
High-resolution structures of oligomers formed by the β-amyloid peptide, Aβ, are important for understanding the molecular basis of Alzheimer's disease. Dimers of Aβ are linked to the pathogenesis and progression of Alzheimer's disease, and tetramers of Aβ are neurotoxic. This paper reports the X-ray crystallographic structures of dimers and tetramers, as well as an octamer, formed by a peptide derived from the central and C-terminal regions of Aβ. In the crystal lattice, the peptide assembles to form two different dimers-an antiparallel β-sheet dimer and a parallel β-sheet dimer-that each further self-assemble to form two different tetramers-a sandwich-like tetramer and a twisted β-sheet tetramer. The structures of these dimers and tetramers derived from Aβ serve as potential models for dimers and tetramers of full-length Aβ that form in vitro and in Alzheimer's disease-afflicted brains.
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270
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Roy R, Pradhan K, Khan J, Das G, Mukherjee N, Das D, Ghosh S. Human Serum Albumin-Inspired Glycopeptide-Based Multifunctional Inhibitor of Amyloid-β Toxicity. ACS OMEGA 2020; 5:18628-18641. [PMID: 32775865 PMCID: PMC7407538 DOI: 10.1021/acsomega.0c01028] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 05/19/2020] [Indexed: 05/07/2023]
Abstract
In Alzheimer's disease (AD), insoluble Aβ42 peptide fragments self-aggregate and form oligomers and fibrils in the brain, causing neurotoxicity. Further, the presence of redox-active metal ions such as Cu2+ enhances the aggregation process through chelation with these Aβ42 aggregates as well as generation of Aβ42-mediated reactive oxygen species (ROS). Herein, we have adopted a bioinspired strategy to design and develop a multifunctional glycopeptide hybrid molecule (Glupep), which can serve as a potential AD therapeutic. This molecule consists of a natural metal-chelating tetrapeptide motif of human serum albumin (HSA), a β-sheet breaker peptide, and a sugar moiety for better bioavailability. We performed different biophysical and docking experiments, which revealed that Glupep not only associates with Aβ42 but also prevents its self-aggregation to form toxic oligomers and fibrils. Moreover, Glupep was also shown to sequester out Cu2+ from the Aβ-Cu2+ complex, reducing the ROS formation and toxicity. Besides, this study also revealed that Glupep could protect PC12-derived neurons from Aβ-Cu2+-mediated toxicity by reducing intracellular ROS generation and stabilizing the mitochondrial membrane potential. All these exciting features show Glupep to be a potent inhibitor of Aβ42-mediated multifaceted toxicity and a prospective therapeutic lead for AD.
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Affiliation(s)
- Rajsekhar Roy
- Department
of Bioscience & Bioengineering, Indian
Institute of Technology Jodhpur, NH 65, Surpura Bypass Road, Karwar, Rajasthan 342037, India
| | - Krishnangsu Pradhan
- Organic
and Medicinal Chemistry and Structural Biology and Bioinformatics
Division, CSIR-Indian Institute of Chemical
Biology, 4, Raja S. C. Mullick Road, Jadavpur, Kolkata 700 032, WB, India
| | - Juhee Khan
- Organic
and Medicinal Chemistry and Structural Biology and Bioinformatics
Division, CSIR-Indian Institute of Chemical
Biology, 4, Raja S. C. Mullick Road, Jadavpur, Kolkata 700 032, WB, India
| | - Gaurav Das
- Organic
and Medicinal Chemistry and Structural Biology and Bioinformatics
Division, CSIR-Indian Institute of Chemical
Biology, 4, Raja S. C. Mullick Road, Jadavpur, Kolkata 700 032, WB, India
| | - Nabanita Mukherjee
- Department
of Bioscience & Bioengineering, Indian
Institute of Technology Jodhpur, NH 65, Surpura Bypass Road, Karwar, Rajasthan 342037, India
| | - Durba Das
- Department
of Bioscience & Bioengineering, Indian
Institute of Technology Jodhpur, NH 65, Surpura Bypass Road, Karwar, Rajasthan 342037, India
| | - Surajit Ghosh
- Organic
and Medicinal Chemistry and Structural Biology and Bioinformatics
Division, CSIR-Indian Institute of Chemical
Biology, 4, Raja S. C. Mullick Road, Jadavpur, Kolkata 700 032, WB, India
- Department
of Bioscience & Bioengineering, Indian
Institute of Technology Jodhpur, NH 65, Surpura Bypass Road, Karwar, Rajasthan 342037, India
- Academy
of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
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271
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Okamura E, Aki K. Real-time in-situ 1H NMR of reactions in peptide solution: preaggregation of amyloid-β fragments prior to fibril formation. PURE APPL CHEM 2020. [DOI: 10.1515/pac-2019-1201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Abstract
In-situ analytical methods are essential for the reliable observation of peptide reactions without perturbation of the system. In this work, a real-time in-situ NMR analysis was performed to gain insight into the initial stage of the aggregation of amyloid-beta (Aβ) 8–25 monomers, S8GY10EVHHQKLVFF20AEDVG25, in solution prior to the fibril formation. NMR chemical shift and intensity changes in combination with the CD spectra revealed no changes in Aβ secondary structure, but the presence of soluble, oligomeric intermediates followed by the appearance of insoluble and non-structured aggregates before β-fibril formation. Molecular views of intermediates and aggregation mechanisms were proposed in comparison with NMR spectral changes in wild-type Aβ 8–25 and its two mutants, A21G and E22G. The mutation of just one amino acid modified the aggregation properties of Aβ 8–25; it slowed or accelerated the fibril formation by controlling the progress of conversion from monomer to aggregate via a soluble, small oligomer.
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Affiliation(s)
- Emiko Okamura
- Faculty of Pharmaceutical Sciences , Himeji Dokkyo University , 7-2-1, Kamiohno , Himeji 670-8524, Japan
| | - Kenzo Aki
- Faculty of Pharmaceutical Sciences , Himeji Dokkyo University , 7-2-1, Kamiohno , Himeji 670-8524, Japan
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272
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Differences in the free energies between the excited states of A β40 and A β42 monomers encode their aggregation propensities. Proc Natl Acad Sci U S A 2020; 117:19926-19937. [PMID: 32732434 DOI: 10.1073/pnas.2002570117] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The early events in the aggregation of the intrinsically disordered peptide, amyloid-β (Aβ), involve transitions from the disordered free energy ground state to assembly-competent states. Are the fingerprints of order found in the amyloid fibrils encoded in the conformations that the monomers access at equilibrium? If so, could the enhanced aggregation rate of Aβ42 compared to Aβ40 be rationalized from the sparsely populated high free energy states of the monomers? Here, we answer these questions in the affirmative using coarse-grained simulations of the self-organized polymer-intrinsically disordered protein (SOP-IDP) model of Aβ40 and Aβ42. Although both the peptides have practically identical ensemble-averaged properties, characteristic of random coils (RCs), the conformational ensembles of the two monomers exhibit sequence-specific heterogeneity. Hierarchical clustering of conformations reveals that both the peptides populate high free energy aggregation-prone ([Formula: see text]) states, which resemble the monomers in the fibril structure. The free energy gap between the ground (RC) and the [Formula: see text] states of Aβ42 peptide is smaller than that for Aβ40. By relating the populations of excited states of the two peptides to the fibril formation time scales using an empirical formula, we explain nearly quantitatively the faster aggregation rate of Aβ42 relative to Aβ40. The [Formula: see text] concept accounts for fibril polymorphs, leading to the prediction that the less stable [Formula: see text] state of Aβ42, encoding for the U-bend fibril, should form earlier than the structure with the S-bend topology, which is in accord with Ostwald's rule rationalizing crystal polymorph formation.
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273
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Röder C, Kupreichyk T, Gremer L, Schäfer LU, Pothula KR, Ravelli RBG, Willbold D, Hoyer W, Schröder GF. Cryo-EM structure of islet amyloid polypeptide fibrils reveals similarities with amyloid-β fibrils. Nat Struct Mol Biol 2020; 27:660-667. [PMID: 32541895 DOI: 10.1101/2020.02.11.944546] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 04/30/2020] [Indexed: 05/18/2023]
Abstract
Amyloid deposits consisting of fibrillar islet amyloid polypeptide (IAPP) in pancreatic islets are associated with beta-cell loss and have been implicated in type 2 diabetes (T2D). Here, we applied cryo-EM to reconstruct densities of three dominant IAPP fibril polymorphs, formed in vitro from synthetic human IAPP. An atomic model of the main polymorph, built from a density map of 4.2-Å resolution, reveals two S-shaped, intertwined protofilaments. The segment 21-NNFGAIL-27, essential for IAPP amyloidogenicity, forms the protofilament interface together with Tyr37 and the amidated C terminus. The S-fold resembles polymorphs of Alzheimer's disease (AD)-associated amyloid-β (Aβ) fibrils, which might account for the epidemiological link between T2D and AD and reports on IAPP-Aβ cross-seeding in vivo. The results structurally link the early-onset T2D IAPP genetic polymorphism (encoding Ser20Gly) with the AD Arctic mutation (Glu22Gly) of Aβ and support the design of inhibitors and imaging probes for IAPP fibrils.
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Affiliation(s)
- Christine Röder
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, Jülich, Germany
- Jülich Centre for Structural Biology (JuStruct), Forschungszentrum Jülich, Jülich, Germany
- Institut für Physikalische Biologie, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Tatsiana Kupreichyk
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, Jülich, Germany
- Jülich Centre for Structural Biology (JuStruct), Forschungszentrum Jülich, Jülich, Germany
- Institut für Physikalische Biologie, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Lothar Gremer
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, Jülich, Germany
- Jülich Centre for Structural Biology (JuStruct), Forschungszentrum Jülich, Jülich, Germany
- Institut für Physikalische Biologie, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Luisa U Schäfer
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, Jülich, Germany
- Jülich Centre for Structural Biology (JuStruct), Forschungszentrum Jülich, Jülich, Germany
| | - Karunakar R Pothula
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, Jülich, Germany
- Jülich Centre for Structural Biology (JuStruct), Forschungszentrum Jülich, Jülich, Germany
| | - Raimond B G Ravelli
- The Multimodal Molecular Imaging Institute, Maastricht University, Maastricht, the Netherlands
| | - Dieter Willbold
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, Jülich, Germany
- Jülich Centre for Structural Biology (JuStruct), Forschungszentrum Jülich, Jülich, Germany
- Institut für Physikalische Biologie, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Wolfgang Hoyer
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, Jülich, Germany.
- Jülich Centre for Structural Biology (JuStruct), Forschungszentrum Jülich, Jülich, Germany.
- Institut für Physikalische Biologie, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.
| | - Gunnar F Schröder
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Forschungszentrum Jülich, Jülich, Germany.
- Jülich Centre for Structural Biology (JuStruct), Forschungszentrum Jülich, Jülich, Germany.
- Physics Department, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.
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274
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Cao Q, Boyer DR, Sawaya MR, Ge P, Eisenberg DS. Cryo-EM structure and inhibitor design of human IAPP (amylin) fibrils. Nat Struct Mol Biol 2020; 27:653-659. [PMID: 32541896 PMCID: PMC8579859 DOI: 10.1038/s41594-020-0435-3] [Citation(s) in RCA: 89] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 04/13/2020] [Indexed: 12/21/2022]
Abstract
Human islet amyloid polypeptide (hIAPP) functions as a glucose-regulating hormone but deposits as amyloid fibrils in more than 90% of patients with type II diabetes (T2D). Here we report the cryo-EM structure of recombinant full-length hIAPP fibrils. The fibril is composed of two symmetrically related protofilaments with ordered residues 14-37. Our hIAPP fibril structure (i) supports the previous hypothesis that residues 20-29 constitute the core of the hIAPP amyloid; (ii) suggests a molecular mechanism for the action of the hIAPP hereditary mutation S20G; (iii) explains why the six residue substitutions in rodent IAPP prevent aggregation; and (iv) suggests regions responsible for the observed hIAPP cross-seeding with β-amyloid. Furthermore, we performed structure-based inhibitor design to generate potential hIAPP aggregation inhibitors. Four of the designed peptides delay hIAPP aggregation in vitro, providing a starting point for the development of T2D therapeutics and proof of concept that the capping strategy can be used on full-length cryo-EM fibril structures.
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Affiliation(s)
- Qin Cao
- Department of Chemistry and Biochemistry and Biological Chemistry, UCLA-DOE Institute, Molecular Biology Institute, and Howard Hughes Medical Institute, University of California, Los Angeles, Los Angeles, CA, USA
| | - David R Boyer
- Department of Chemistry and Biochemistry and Biological Chemistry, UCLA-DOE Institute, Molecular Biology Institute, and Howard Hughes Medical Institute, University of California, Los Angeles, Los Angeles, CA, USA
| | - Michael R Sawaya
- Department of Chemistry and Biochemistry and Biological Chemistry, UCLA-DOE Institute, Molecular Biology Institute, and Howard Hughes Medical Institute, University of California, Los Angeles, Los Angeles, CA, USA
| | - Peng Ge
- California NanoSystem Institute, University of California, Los Angeles, Los Angeles, CA, USA
| | - David S Eisenberg
- Department of Chemistry and Biochemistry and Biological Chemistry, UCLA-DOE Institute, Molecular Biology Institute, and Howard Hughes Medical Institute, University of California, Los Angeles, Los Angeles, CA, USA.
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275
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Haya K, Makino Y, Kikuchi-Kinoshita A, Kawamura I, Naito A. 31P and 13C solid-state NMR analysis of morphological changes of phospholipid bilayers containing glucagon during fibril formation of glucagon under neutral condition. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183290. [DOI: 10.1016/j.bbamem.2020.183290] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 02/25/2020] [Accepted: 03/23/2020] [Indexed: 02/07/2023]
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276
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The Structure of Amyloid Versus the Structure of Globular Proteins. Int J Mol Sci 2020; 21:ijms21134683. [PMID: 32630137 PMCID: PMC7370054 DOI: 10.3390/ijms21134683] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 06/21/2020] [Accepted: 06/27/2020] [Indexed: 12/19/2022] Open
Abstract
The issue of changing the structure of globular proteins into an amyloid form is in the focus of researchers' attention. Numerous experimental studies are carried out, and mathematical models to define the essence of amyloid transformation are sought. The present work focuses on the issue of the hydrophobic core structure in amyloids. The form of ordering the hydrophobic core in globular proteins is described by a 3D Gaussian distribution analog to the distribution of hydrophobicity in a spherical micelle. Amyloid fibril is a ribbon-like micelle made up of numerous individual chains, each representing a flat structure. The distribution of hydrophobicity within a single chain included in the fibril describes the 2D Gaussian distribution. Such a description expresses the location of polar residues on a circle with a center with a high level of hydrophobicity. The presence of this type of order in the amyloid forms available in Preotin Data Bank (PDB) (both in proto- and superfibrils) is demonstrated in the present work. In this system, it can be assumed that the amyloid transformation is a chain transition from 3D Gauss ordering to 2D Gauss ordering. This means changing the globular structure to a ribbon-like structure. This observation can provide a simple mathematical model for simulating the amyloid transformation of proteins.
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277
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Abstract
The epididymal lumen contains a complex cystatin-rich nonpathological amyloid matrix with putative roles in sperm maturation and sperm protection. Given our growing understanding for the biological function of this and other functional amyloids, the problem still remains: how functional amyloids assemble including their initial transition to early oligomeric forms. To examine this, we developed a protocol for the purification of nondenatured mouse CRES, a component of the epididymal amyloid matrix, allowing us to examine its assembly to amyloid under conditions that may mimic those in vivo. Herein we use X-ray crystallography, solution-state NMR, and solid-state NMR to follow at the atomic level the assembly of the CRES amyloidogenic precursor as it progressed from monomeric folded protein to an advanced amyloid. We show the CRES monomer has a typical cystatin fold that assembles into highly branched amyloid matrices, comparable to those in vivo, by forming β-sheet assemblies that our data suggest occur via two distinct mechanisms: a unique conformational switch of a highly flexible disulfide-anchored loop to a rigid β-strand and by traditional cystatin domain swapping. Our results provide key insight into our understanding of functional amyloid assembly by revealing the earliest structural transitions from monomer to oligomer and by showing that some functional amyloid structures may be built by multiple and distinctive assembly mechanisms.
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278
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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] [Grants] [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
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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279
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Boatz JC, Piretra T, Lasorsa A, Matlahov I, Conway JF, van der Wel PCA. Protofilament Structure and Supramolecular Polymorphism of Aggregated Mutant Huntingtin Exon 1. J Mol Biol 2020; 432:4722-4744. [PMID: 32598938 DOI: 10.1016/j.jmb.2020.06.021] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Revised: 06/01/2020] [Accepted: 06/18/2020] [Indexed: 12/11/2022]
Abstract
Huntington's disease is a progressive neurodegenerative disease caused by expansion of the polyglutamine domain in the first exon of huntingtin (HttEx1). The extent of expansion correlates with disease progression and formation of amyloid-like protein deposits within the brain. The latter display polymorphism at the microscopic level, both in cerebral tissue and in vitro. Such polymorphism can dramatically influence cytotoxicity, leading to much interest in the conditions and mechanisms that dictate the formation of polymorphs. We examine conditions that govern HttEx1 polymorphism in vitro, including concentration and the role of the non-polyglutamine flanking domains. Using electron microscopy, we observe polymorphs that differ in width and tendency for higher-order bundling. Strikingly, aggregation yields different polymorphs at low and high concentrations. Narrow filaments dominate at low concentrations that may be more relevant in vivo. We dissect the role of N- and C-terminal flanking domains using protein with the former (httNT or N17) largely removed. The truncated protein is generated by trypsin cleavage of soluble HttEx1 fusion protein, which we analyze in some detail. Dye binding and solid-state NMR studies reveal changes in fibril surface characteristics and flanking domain mobility. Higher-order interactions appear facilitated by the C-terminal tail, while the polyglutamine forms an amyloid core resembling those of other polyglutamine deposits. Fibril-surface-mediated branching, previously attributed to secondary nucleation, is reduced in absence of httNT. A new model for the architecture of the HttEx1 filaments is presented and discussed in context of the assembly mechanism and biological activity.
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Affiliation(s)
- Jennifer C Boatz
- Department of Structural Biology, School of Medicine, University of Pittsburgh, 3501 5th Ave, Biomedical Science Tower 3, Pittsburgh, PA 15213, USA.
| | - Talia Piretra
- Department of Structural Biology, School of Medicine, University of Pittsburgh, 3501 5th Ave, Biomedical Science Tower 3, Pittsburgh, PA 15213, USA.
| | - Alessia Lasorsa
- Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747, AG, Groningen, the Netherlands.
| | - Irina Matlahov
- Department of Structural Biology, School of Medicine, University of Pittsburgh, 3501 5th Ave, Biomedical Science Tower 3, Pittsburgh, PA 15213, USA; Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747, AG, Groningen, the Netherlands.
| | - James F Conway
- Department of Structural Biology, School of Medicine, University of Pittsburgh, 3501 5th Ave, Biomedical Science Tower 3, Pittsburgh, PA 15213, USA.
| | - Patrick C A van der Wel
- Department of Structural Biology, School of Medicine, University of Pittsburgh, 3501 5th Ave, Biomedical Science Tower 3, Pittsburgh, PA 15213, USA; Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747, AG, Groningen, the Netherlands.
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280
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Raskatov JA. Conformational Selection as the Driving Force of Amyloid β Chiral Inactivation. Chembiochem 2020; 21:2945-2949. [PMID: 32424959 DOI: 10.1002/cbic.202000237] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Revised: 05/17/2020] [Indexed: 12/19/2022]
Abstract
We recently introduced amyloid β chiral inactivation (Aβ-CI) as a molecular approach that uses mirror-image peptides to chaperone the natural Aβ stereoisomer into a less toxic state. The oligomer-to-fibril conversion mechanism remains the subject of active research. Perhaps the most striking feature of Aβ-CI is the virtual obliteration of the incubation/induction phase that is so characteristic of Aβ fibril formation kinetics. This qualitative change is indicative of the distinct mechanistic pathway Aβ-CI operates through. The current working model of Aβ-CI invokes the formation of "rippled" cross-β sheets, in which alternating l- and d-peptide strands form periodic networks. However, the assumption of rippled cross-β sheets does not per se explain the dramatic changes in reaction kinetics upon mixing of Aβ enantiomers. Herein, it is shown by DFT computational methods that the individual peptide strands in rippled cross-β networks are less conformationally strained than their pleated counterparts. This means that the adoption of fibril-seeding conformations is more probable for rippled cross-β. Conformational selection is thus suggested as the mechanistic rationale for the acceleration of fibril formation upon Aβ-CI.
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Affiliation(s)
- Jevgenij A Raskatov
- Department of Chemistry and Biochemistry, University of California Santa Cruz Physical Science Building 356, 1156 High Street, Santa Cruz, CA 95064, USA
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281
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Sasanian N, Bernson D, Horvath I, Wittung-Stafshede P, Esbjörner EK. Redox-Dependent Copper Ion Modulation of Amyloid-β (1-42) Aggregation In Vitro. Biomolecules 2020; 10:E924. [PMID: 32570820 PMCID: PMC7355640 DOI: 10.3390/biom10060924] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 06/12/2020] [Accepted: 06/16/2020] [Indexed: 12/20/2022] Open
Abstract
Plaque deposits composed of amyloid-β (Aβ) fibrils are pathological hallmarks of Alzheimer's disease (AD). Although copper ion dyshomeostasis is apparent in AD brains and copper ions are found co-deposited with Aβ peptides in patients' plaques, the molecular effects of copper ion interactions and redox-state dependence on Aβ aggregation remain elusive. By combining biophysical and theoretical approaches, we here show that Cu2+ (oxidized) and Cu+ (reduced) ions have opposite effects on the assembly kinetics of recombinant Aβ(1-42) into amyloid fibrils in vitro. Cu2+ inhibits both the unseeded and seeded aggregation of Aβ(1-42) at pH 8.0. Using mathematical models to fit the kinetic data, we find that Cu2+ prevents fibril elongation. The Cu2+-mediated inhibition of Aβ aggregation shows the largest effect around pH 6.0 but is lost at pH 5.0, which corresponds to the pH in lysosomes. In contrast to Cu2+, Cu+ ion binding mildly catalyzes the Aβ(1-42) aggregation via a mechanism that accelerates primary nucleation, possibly via the formation of Cu+-bridged Aβ(1-42) dimers. Taken together, our study emphasizes redox-dependent copper ion effects on Aβ(1-42) aggregation and thereby provides further knowledge of putative copper-dependent mechanisms resulting in AD.
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Affiliation(s)
| | | | | | | | - Elin K. Esbjörner
- Department of Biology and Biological Engineering, Chalmers University of Technology, 412 96 Gothenburg, Sweden; (N.S.); (D.B.); (I.H.); (P.W.-S.)
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282
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Zhan C, Chen Y, Tang Y, Wei G. Green Tea Extracts EGCG and EGC Display Distinct Mechanisms in Disrupting Aβ 42 Protofibril. ACS Chem Neurosci 2020; 11:1841-1851. [PMID: 32441920 DOI: 10.1021/acschemneuro.0c00277] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The amyloid beta (Aβ) fibrillar aggregate is the hallmark of Alzheimer's disease (AD). Disassembling preformed fibril or inhibiting Aβ aggregation is considered as a therapeutic strategy for AD. Increasing evidence shows that green tea extracts, epigallocatechin-3-gallate (EGCG, containing an extra gallic acid ester group compared to EGC) and epigallocatechin (EGC), can disassociate Aβ fibrils and attenuate Aβ toxicity. However, the underlying molecular mechanism is poorly understood. Herein, we performed microsecond all-atom molecular dynamics (MD) simulations to investigate the influences of EGCG/EGC on the newly cryo-EM resolved LS-shaped Aβ42 protofibrils and their detailed interactions. MD simulations demonstrate that both EGCG and EGC can disrupt Aβ42 protofibril and EGCG displays a higher disruptive capacity than EGC. EGCG alters the L-shape of Aβ42 protofibril by breaking the hydrogen bond between H6 and E11 through π-π interactions with residues H14/Y10 and hydrogen-bonding interactions with E11, while EGC remodels the L-shape by inserting into the hydrophobic core formed by A2, F4, L34, and V36 and via aromatics interaction with H6/Y10. EGCG disrupts the salt bridges between the K28 side chain and A42 COO- through hydrogen-bonding interaction with A42 and cation-π interaction between its gallic acid ester group and K28, while EGC damages the salt bridges through hydrophobic interactions with V39 and I41 as well as with I32, M35, and V40 located in the C-terminal hydrophobic core. This study demonstrates the pivotal role of the gallic acid ester group of EGCG in disrupting Aβ42 protofibril and provides atomic-level insights into the distinct mechanism by which EGCG and EGC disrupt Aβ protofibril, which could be useful for designing amyloid inhibitors.
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Affiliation(s)
- Chendi Zhan
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Multiscale Research Institute of Complex Systems, Fudan University, Shanghai 200438, People’s Republic of China
| | - Yujie Chen
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Multiscale Research Institute of Complex Systems, Fudan University, Shanghai 200438, People’s Republic of China
| | - Yiming Tang
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Multiscale Research Institute of Complex Systems, Fudan University, Shanghai 200438, People’s Republic of China
| | - Guanghong Wei
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Multiscale Research Institute of Complex Systems, Fudan University, Shanghai 200438, People’s Republic of China
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283
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Cryo-EM structure of islet amyloid polypeptide fibrils reveals similarities with amyloid-β fibrils. Nat Struct Mol Biol 2020; 27:660-667. [PMID: 32541895 DOI: 10.1038/s41594-020-0442-4] [Citation(s) in RCA: 110] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 04/30/2020] [Indexed: 01/09/2023]
Abstract
Amyloid deposits consisting of fibrillar islet amyloid polypeptide (IAPP) in pancreatic islets are associated with beta-cell loss and have been implicated in type 2 diabetes (T2D). Here, we applied cryo-EM to reconstruct densities of three dominant IAPP fibril polymorphs, formed in vitro from synthetic human IAPP. An atomic model of the main polymorph, built from a density map of 4.2-Å resolution, reveals two S-shaped, intertwined protofilaments. The segment 21-NNFGAIL-27, essential for IAPP amyloidogenicity, forms the protofilament interface together with Tyr37 and the amidated C terminus. The S-fold resembles polymorphs of Alzheimer's disease (AD)-associated amyloid-β (Aβ) fibrils, which might account for the epidemiological link between T2D and AD and reports on IAPP-Aβ cross-seeding in vivo. The results structurally link the early-onset T2D IAPP genetic polymorphism (encoding Ser20Gly) with the AD Arctic mutation (Glu22Gly) of Aβ and support the design of inhibitors and imaging probes for IAPP fibrils.
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284
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Ciudad S, Puig E, Botzanowski T, Meigooni M, Arango AS, Do J, Mayzel M, Bayoumi M, Chaignepain S, Maglia G, Cianferani S, Orekhov V, Tajkhorshid E, Bardiaux B, Carulla N. Aβ(1-42) tetramer and octamer structures reveal edge conductivity pores as a mechanism for membrane damage. Nat Commun 2020; 11:3014. [PMID: 32541820 PMCID: PMC7296003 DOI: 10.1038/s41467-020-16566-1] [Citation(s) in RCA: 147] [Impact Index Per Article: 36.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Accepted: 05/01/2020] [Indexed: 12/20/2022] Open
Abstract
Formation of amyloid-beta (Aβ) oligomer pores in the membrane of neurons has been proposed to explain neurotoxicity in Alzheimer's disease (AD). Here, we present the three-dimensional structure of an Aβ oligomer formed in a membrane mimicking environment, namely an Aβ(1-42) tetramer, which comprises a six stranded β-sheet core. The two faces of the β-sheet core are hydrophobic and surrounded by the membrane-mimicking environment while the edges are hydrophilic and solvent-exposed. By increasing the concentration of Aβ(1-42) in the sample, Aβ(1-42) octamers are also formed, made by two Aβ(1-42) tetramers facing each other forming a β-sandwich structure. Notably, Aβ(1-42) tetramers and octamers inserted into lipid bilayers as well-defined pores. To establish oligomer structure-membrane activity relationships, molecular dynamics simulations were carried out. These studies revealed a mechanism of membrane disruption in which water permeation occurred through lipid-stabilized pores mediated by the hydrophilic residues located on the core β-sheets edges of the oligomers.
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Affiliation(s)
- Sonia Ciudad
- University of Bordeaux, CBMN (UMR 5248)-CNRS-IPB, Institut Européen de Chimie et Biologie, 2 rue Escarpit, 33600, Pessac, France
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Baldiri Reixac 10, 08028, Barcelona, Spain
| | - Eduard Puig
- University of Bordeaux, CBMN (UMR 5248)-CNRS-IPB, Institut Européen de Chimie et Biologie, 2 rue Escarpit, 33600, Pessac, France
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Baldiri Reixac 10, 08028, Barcelona, Spain
- Departament de Química Inorgànica i Orgànica, Universitat de Barcelona, Martí i Franqués 1, 08028, Barcelona, Spain
| | - Thomas Botzanowski
- Laboratoire de Spectrométrie de Masse BioOrganique, Université de Strasbourg, CNRS UMR7178, IPHC, Strasbourg, France
| | - Moeen Meigooni
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Center for Biophysics and Quantitative Biology and Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Andres S Arango
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Center for Biophysics and Quantitative Biology and Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Jimmy Do
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Center for Biophysics and Quantitative Biology and Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Maxim Mayzel
- Swedish NMR Centre, University of Gothenburg, Box 465, 405 30, Gothenburg, Sweden
| | - Mariam Bayoumi
- Biochemistry, Molecular and Structural Biology Section, University of Leuven, Celestijnenlaan 200G, 3001, Leuven, Belgium
| | - Stéphane Chaignepain
- University of Bordeaux, CBMN (UMR 5248)-CNRS-IPB, Institut Européen de Chimie et Biologie, 2 rue Escarpit, 33600, Pessac, France
| | - Giovanni Maglia
- Groningen Biomolecular Sciences & Biotechnology Institute, University of Groningen, 9747 AG, Groningen, The Netherlands
| | - Sarah Cianferani
- Laboratoire de Spectrométrie de Masse BioOrganique, Université de Strasbourg, CNRS UMR7178, IPHC, Strasbourg, France
| | - Vladislav Orekhov
- Swedish NMR Centre, University of Gothenburg, Box 465, 405 30, Gothenburg, Sweden
- Department of Chemistry and Molecular Biology, University of Gothenburg, Box 465, 405 30, Gothenburg, Sweden
| | - Emad Tajkhorshid
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Center for Biophysics and Quantitative Biology and Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Benjamin Bardiaux
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry, C3BI, Institut Pasteur; CNRS UMR3528; CNRS USR3756, Paris, France
| | - Natàlia Carulla
- University of Bordeaux, CBMN (UMR 5248)-CNRS-IPB, Institut Européen de Chimie et Biologie, 2 rue Escarpit, 33600, Pessac, France.
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Baldiri Reixac 10, 08028, Barcelona, Spain.
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285
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Boopathi S, Dinh Quoc Huy P, Gonzalez W, Theodorakis PE, Li MS. Zinc binding promotes greater hydrophobicity inAlzheimer's Aβ42peptide than copper binding: Molecular dynamics and solvation thermodynamics studies. Proteins 2020; 88:1285-1302. [DOI: 10.1002/prot.25901] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 05/04/2020] [Accepted: 05/13/2020] [Indexed: 12/29/2022]
Affiliation(s)
- Subramanian Boopathi
- Centro de Bioinformática y Simulación Molecular (CBSM), Facultad de IngenieríaUniversidad de Talca Talca Chile
| | | | - Wendy Gonzalez
- Centro de Bioinformática y Simulación Molecular (CBSM), Facultad de IngenieríaUniversidad de Talca Talca Chile
- Millennium Nucleus of Ion Channels‐Associated Diseases (MiNICAD)Universidad de Talca Talca Chile
| | | | - Mai Suan Li
- Institute of PhysicsPolish Academy of Sciences Warsaw Poland
- Institute for Computational Science and Technology, Quang Trung Software City Tan Chanh Hiep Ward Ho Chi Minh City Vietnam
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286
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Vugmeyster L, Au DF, Ostrovsky D, Rickertsen DRL, Reed SM. Dynamics of Serine-8 Side-Chain in Amyloid-β Fibrils and Fluorenylmethyloxycarbonyl Serine Amino Acid, Investigated by Solid-State Deuteron NMR. J Phys Chem B 2020; 124:4723-4731. [PMID: 32396356 DOI: 10.1021/acs.jpcb.0c02490] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Serine side-chains are strategic sites of post-translational modifications, and it is important to establish benchmarks of their internal dynamics. In this work, we compare the dynamics of serine side-chains in several biologically important systems: serine-8 in the disordered domain of Aβ1-40 fibrils in the hydrated and dry states and fluorenylmethyloxycarbonyl (Fmoc) serine with the bulky group that mimics the hydrophobicity of the fibril contacts yet lacks the complexity of the protein system. Using deuterium solid-state NMR static line shape and longitudinal relaxation techniques in the 310 to 180 K temperature range, we compare the main features of the dynamics in these systems. The main motional modes in the fibrils are large-scale fluctuations in the hydrated state of the fibrils as well as local motions such as 3-site jumps of the Cβ deuterons at high temperatures and small-angle fluctuations of the Cα-Cβ axis at low temperatures. In the hydrated fibrils, two distinct states are present with vastly different extents of large-scale diffusive motions and 3-site-jump rate constants. The hydrated state at the physiological conditions is dominated by the "free" state undergoing large-scale diffusive motions and very fast local 3-site jumps, while in the "bound" state, these large-scale motions are quenched due to transient inter- and intramolecular interactions. Additionally, in the bound state, the 3-site-jump motions are orders of magnitude slower. Details of the dynamics in the serine side-chain are dependent on fine structural features and hydration levels of the systems.
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Affiliation(s)
- Liliya Vugmeyster
- Department of Chemistry, University of Colorado Denver, Denver, Colorado 80204, United States
| | - Dan Fai Au
- Department of Chemistry, University of Colorado Denver, Denver, Colorado 80204, United States
| | - Dmitry Ostrovsky
- Department of Mathematics, University of Colorado Denver, Denver, Colorado 80204, United States
| | | | - Scott M Reed
- Department of Chemistry, University of Colorado Denver, Denver, Colorado 80204, United States
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287
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Frieg B, Gremer L, Heise H, Willbold D, Gohlke H. Binding modes of thioflavin T and Congo red to the fibril structure of amyloid-β(1-42). Chem Commun (Camb) 2020; 56:7589-7592. [PMID: 32510059 DOI: 10.1039/d0cc01161d] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Binding modes for the amyloid-β(1-42) fibril fluorescent dyes thioflavin T and Congo red were predicted by molecular dynamics simulations and binding free energy calculations. Both probes bind on the fibril surface to primarily hydrophobic grooves, with their long axis oriented almost parallel to the fibril axis. The computed binding affinities are in agreement with experimental values. The binding modes also explain observables from previous structural studies and, thus, provide a starting point for the systematic search and design of novel molecules, which may improve in vitro diagnostics for Alzheimer's disease.
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Affiliation(s)
- Benedikt Frieg
- John von Neumann Institute for Computing (NIC), Jülich Supercomputing Centre (JSC), Forschungszentrum Jülich GmbH, Jülich, Germany
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288
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Biophysical studies of protein misfolding and aggregation in in vivo models of Alzheimer's and Parkinson's diseases. Q Rev Biophys 2020; 49:e22. [PMID: 32493529 DOI: 10.1017/s0033583520000025] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Neurodegenerative disorders, including Alzheimer's (AD) and Parkinson's diseases (PD), are characterised by the formation of aberrant assemblies of misfolded proteins. The discovery of disease-modifying drugs for these disorders is challenging, in part because we still have a limited understanding of their molecular origins. In this review, we discuss how biophysical approaches can help explain the formation of the aberrant conformational states of proteins whose neurotoxic effects underlie these diseases. We discuss in particular models based on the transgenic expression of amyloid-β (Aβ) and tau in AD, and α-synuclein in PD. Because biophysical methods have enabled an accurate quantification and a detailed understanding of the molecular mechanisms underlying protein misfolding and aggregation in vitro, we expect that the further development of these methods to probe directly the corresponding mechanisms in vivo will open effective routes for diagnostic and therapeutic interventions.
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289
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Rational design of a conformation-specific antibody for the quantification of Aβ oligomers. Proc Natl Acad Sci U S A 2020; 117:13509-13518. [PMID: 32493749 PMCID: PMC7306997 DOI: 10.1073/pnas.1919464117] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The accurate quantification of the amounts of small oligomeric assemblies formed by the amyloid β (Aβ) peptide represents a major challenge in the Alzheimer’s field. There is therefore great interest in the development of methods to specifically detect these oligomers by distinguishing them from larger aggregates. The availability of these methods will enable the development of effective diagnostic and therapeutic interventions for this and other diseases related to protein misfolding and aggregation. We describe here a single-domain antibody able to selectively quantify oligomers of the Aβ peptide in isolation and in complex protein mixtures from animal models of disease. Protein misfolding and aggregation is the hallmark of numerous human disorders, including Alzheimer’s disease. This process involves the formation of transient and heterogeneous soluble oligomers, some of which are highly cytotoxic. A major challenge for the development of effective diagnostic and therapeutic tools is thus the detection and quantification of these elusive oligomers. Here, to address this problem, we develop a two-step rational design method for the discovery of oligomer-specific antibodies. The first step consists of an “antigen scanning” phase in which an initial panel of antibodies is designed to bind different epitopes covering the entire sequence of a target protein. This procedure enables the determination through in vitro assays of the regions exposed in the oligomers but not in the fibrillar deposits. The second step involves an “epitope mining” phase, in which a second panel of antibodies is designed to specifically target the regions identified during the scanning step. We illustrate this method in the case of the amyloid β (Aβ) peptide, whose oligomers are associated with Alzheimer’s disease. Our results show that this approach enables the accurate detection and quantification of Aβ oligomers in vitro, and in Caenorhabditis elegans and mouse hippocampal tissues.
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290
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Metal complexes that bind to the amyloid-β peptide of relevance to Alzheimer’s disease. Coord Chem Rev 2020. [DOI: 10.1016/j.ccr.2020.213255
expr 886172045 + 931245952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023]
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291
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Gomes LM, Bataglioli JC, Storr T. Metal complexes that bind to the amyloid-β peptide of relevance to Alzheimer’s disease. Coord Chem Rev 2020. [DOI: 10.1016/j.ccr.2020.213255] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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292
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Khorvash M, Blinov N, Ladner-Keay C, Lu J, Silverman JM, Gibbs E, Wang YT, Kovalenko A, Wishart D, Cashman NR. Molecular interactions between monoclonal oligomer-specific antibody 5E3 and its amyloid beta cognates. PLoS One 2020; 15:e0232266. [PMID: 32469918 PMCID: PMC7259632 DOI: 10.1371/journal.pone.0232266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 04/12/2020] [Indexed: 11/30/2022] Open
Abstract
Oligomeric amyloid β (Aβ) is currently considered the most neurotoxic form of the Aβ peptide implicated in Alzheimer’s disease (AD). The molecular structures of the oligomers have remained mostly unknown due to their transient nature. As a result, the molecular mechanisms of interactions between conformation-specific antibodies and their Aβ oligomer (AβO) cognates are not well understood. A monoclonal conformation-specific antibody, m5E3, was raised against a structural epitope of Aβ oligomers. m5E3 binds to AβOs with high affinity, but not to Aβ monomers or fibrils. In this study, a computational model of the variable fragment (Fv) of the m5E3 antibody (Fv5E3) is introduced. We further employ docking and molecular dynamics simulations to determine the molecular details of the antibody-oligomer interactions, and to classify the AβOs as Fv5E3-positives and negatives, and to provide a rationale for the low affinity of Fv5E3 for fibrils. This information will help us to perform site-directed mutagenesis on the m5E3 antibody to improve its specificity and affinity toward oligomeric Aβ species. We also provide evidence for the possible capability of the m5E3 antibody to disaggregate AβOs and to fragment protofilaments.
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Affiliation(s)
- Massih Khorvash
- Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
- University of British Columbia, Djavad Mowafaghian Centre for Brain Health, Vancouver, British Columbia, Canada
| | - Nick Blinov
- Department of Mechanical Engineering, Edmonton, Alberta, Canada
- National Research Council of Canada, Edmonton, Alberta, Canada
| | - Carol Ladner-Keay
- National Research Council of Canada, Edmonton, Alberta, Canada
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Jie Lu
- University of British Columbia, Djavad Mowafaghian Centre for Brain Health, Vancouver, British Columbia, Canada
| | - Judith M. Silverman
- University of British Columbia, Djavad Mowafaghian Centre for Brain Health, Vancouver, British Columbia, Canada
| | - Ebrima Gibbs
- University of British Columbia, Djavad Mowafaghian Centre for Brain Health, Vancouver, British Columbia, Canada
| | - Yu Tian Wang
- University of British Columbia, Djavad Mowafaghian Centre for Brain Health, Vancouver, British Columbia, Canada
| | - Andriy Kovalenko
- Department of Mechanical Engineering, Edmonton, Alberta, Canada
- National Research Council of Canada, Edmonton, Alberta, Canada
| | - David Wishart
- National Research Council of Canada, Edmonton, Alberta, Canada
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
- Department of Computing Science, University of Alberta, Edmonton, Alberta, Canada
| | - Neil R. Cashman
- Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
- University of British Columbia, Djavad Mowafaghian Centre for Brain Health, Vancouver, British Columbia, Canada
- * E-mail:
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293
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Gao Y, Guo C, Watzlawik JO, Randolph PS, Lee EJ, Huang D, Stagg SM, Zhou HX, Rosenberry TL, Paravastu AK. Out-of-Register Parallel β-Sheets and Antiparallel β-Sheets Coexist in 150-kDa Oligomers Formed by Amyloid-β(1-42). J Mol Biol 2020; 432:4388-4407. [PMID: 32470558 DOI: 10.1016/j.jmb.2020.05.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 05/17/2020] [Accepted: 05/18/2020] [Indexed: 12/15/2022]
Abstract
We present solid-state NMR measurements of β-strand secondary structure and inter-strand organization within a 150-kDa oligomeric aggregate of the 42-residue variant of the Alzheimer's amyloid-β peptide (Aβ(1-42)). We build upon our previous report of a β-strand spanned by residues 30-42, which arranges into an antiparallel β-sheet. New results presented here indicate that there is a second β-strand formed by residues 11-24. Contrary to expectations, NMR data indicate that this second β-strand is organized into a parallel β-sheet despite the co-existence of an antiparallel β-sheet in the same structure. In addition, the in-register parallel β-sheet commonly observed for amyloid fibril structure does not apply to residues 11-24 in the 150-kDa oligomer. Rather, we present evidence for an inter-strand registry shift of three residues that likely alternate in direction between adjacent molecules along the β-sheet. We corroborated this unexpected scheme for β-strand organization using multiple two-dimensional NMR and 13C-13C dipolar recoupling experiments. Our findings indicate a previously unknown assembly pathway and inspire a suggestion as to why this aggregate does not grow to larger sizes.
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Affiliation(s)
- Yuan Gao
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive NW, Atlanta, GA 30332, USA
| | - Cong Guo
- Department of Physics and International Centre for Quantum and Molecular Structures, Shanghai University, 99 Shangda Road, Shanghai, China
| | - Jens O Watzlawik
- Departments of Neuroscience and Pharmacology, Mayo Clinic College of Medicine, 4500 San Pablo Road, Jacksonville, FL 32224, USA
| | - Peter S Randolph
- Institute of Molecular Biophysics, Florida State University, Tallahasse, FL 32306, USA
| | - Elizabeth J Lee
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive NW, Atlanta, GA 30332, USA
| | - Danting Huang
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive NW, Atlanta, GA 30332, USA
| | - Scott M Stagg
- Institute of Molecular Biophysics, Florida State University, Tallahasse, FL 32306, USA; Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, USA
| | - Huan-Xiang Zhou
- Department of Chemistry and Physics, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Terrone L Rosenberry
- Departments of Neuroscience and Pharmacology, Mayo Clinic College of Medicine, 4500 San Pablo Road, Jacksonville, FL 32224, USA
| | - Anant K Paravastu
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive NW, Atlanta, GA 30332, USA.
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294
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Saranya V, Mary PV, Vijayakumar S, Shankar R. The hazardous effects of the environmental toxic gases on amyloid beta-peptide aggregation: A theoretical perspective. Biophys Chem 2020; 263:106394. [PMID: 32480019 DOI: 10.1016/j.bpc.2020.106394] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 05/12/2020] [Accepted: 05/12/2020] [Indexed: 12/13/2022]
Abstract
Alzheimer's disease (AD) is one of the leading causes of dementia in elderly people. It has been well documented that the exposure to environmental toxins such as CO, CO2, SO2 and NO2 that are present in the air is considered as a hallmark for the progression of Alzheimer's disease. However, their actual mechanism by which environmental toxin triggers the aggregation of Aβ42 peptide at the molecular and atomic levels remain unknown. In this study, molecular dynamics simulation was carried out to study the aggregation mechanism of the Aβ42 peptide due to its interaction of toxic gas (CO, CO2, SO2 and NO2). During the 400 ns simulation, all the Aβ42 interacted toxic gas (CO, CO2, SO2, and NO2) complexes have smaller Root Mean Square Deviation values when compared to the Aβ42 peptide, which shows that the interaction of toxic gases (CO, CO2, SO2, and NO2) would increase the Aβ42 peptide structural stability. The radius of gyration analysis also supports that Aβ42 interacted CO2 and SO2 complexes have the minimum value in the range of 0.95 nm and 1.5 nm. It is accounted that the Aβ42 interacted CO2 and SO2 complexes have a greater compact structure in comparison to Aβ42 interacted CO and NO2 complexes. Furthermore, all the Aβ42 interacted toxic gas (CO, CO2, SO2, and NO2) complexes exhibited an enhanced secondary structural probability for coil and turn regions with a reduced α-helix probability, which indicates that the interaction of toxic gases may enhance the toxicity and aggregation of Aβ42.
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Affiliation(s)
- Vasudevan Saranya
- Molecular Simulation Laboratory, Department of Physics, Bharathiar University, Coimbatore 641 046, India
| | - Pitchumani Violet Mary
- Department of Physics, Sri Shakthi Institute of Engineering and Technology, Coimbatore 641 062, India
| | | | - Ramasamy Shankar
- Molecular Simulation Laboratory, Department of Physics, Bharathiar University, Coimbatore 641 046, India.
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295
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Ultrastructural evidence for self-replication of Alzheimer-associated Aβ42 amyloid along the sides of fibrils. Proc Natl Acad Sci U S A 2020; 117:11265-11273. [PMID: 32439711 PMCID: PMC7260961 DOI: 10.1073/pnas.1918481117] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Two unresolved problems in Alzheimer’s disease (AD) are its onset and propagation, linked to Aβ peptide aggregation. Fibrils of Aβ42 may grow by monomer addition at their ends. Additionally, through so-called secondary nucleation, fibrils can catalyse the formation of new aggregates from monomer on their surface, thereby generating oligomeric species that are toxic to brain tissue. Insights into the structural transitions occurring during secondary nucleation will facilitate the design of therapies to limit the neurotoxicity in AD, but such information is currently lacking. This study identifies conditions that allow the capture of reaction intermediates of secondary nucleation for the purpose of ultrastructural characterization. These reaction intermediates are morphologically distinct from mature fibrils and cover the sides of fibrils during an on-going aggregation reaction. The nucleation of Alzheimer-associated Aβ peptide monomers can be catalyzed by preexisting Aβ fibrils. This leads to autocatalytic amplification of aggregate mass and underlies self-replication and generation of toxic oligomers associated with several neurodegenerative diseases. However, the nature of the interactions between the monomeric species and the fibrils during this key process, and indeed the ultrastructural localization of the interaction sites have remained elusive. Here we used NMR and optical spectroscopy to identify conditions that enable the capture of transient species during the aggregation and secondary nucleation of the Aβ42 peptide. Cryo-electron microscopy (cryo-EM) images show that new aggregates protrude from the entire length of the progenitor fibril. These protrusions are morphologically distinct from the well-ordered fibrils dominating at the end of the aggregation process. The data provide direct evidence that self-replication through secondary nucleation occurs along the sides of fibrils, which become heavily decorated under the current solution conditions (14 µM Aβ42, 20 mM sodium phosphate, 200 µM EDTA, pH 6.8).
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296
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Murakami K, Kato H, Hanaki M, Monobe Y, Akagi KI, Kawase T, Hirose K, Irie K. Synthetic and biochemical studies on the effect of persulfidation on disulfide dimer models of amyloid β42 at position 35 in Alzheimer's etiology. RSC Adv 2020; 10:19506-19512. [PMID: 35515472 PMCID: PMC9054097 DOI: 10.1039/d0ra03429k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 05/08/2020] [Indexed: 11/21/2022] Open
Abstract
Protein persulfidation plays a role in redox signaling as an anti-oxidant. Dimers of amyloid β42 (Aβ42), which induces oxidative stress-associated neurotoxicity as a causative agent of Alzheimer's disease (AD), are minimum units of oligomers in AD pathology. Met35 can be susceptible to persulfidation through its substitution to homoCys residue under the condition of oxidative stress. In order to verify whether persulfidation has an effect in AD, herein we report a chemical approach by synthesizing disulfide dimers of Aβ42 and their evaluation of biochemical properties. A homoCys-disulfide dimer model at position 35 of Aβ42 formed a partial β-sheet structure, but its neurotoxicity was much weaker than that of the corresponding monomer. In contrast, the congener with an alkyl linker generated β-sheet-rich 8–16-mer oligomers with potent neurotoxicity. The length of protofibrils generated from the homoCys-disulfide dimer model was shorter than that of its congener with an alkyl linker. Therefore, the current data do not support the involvement of Aβ42 persulfidation in Alzheimer's disease. Our data do not support the Aβ42 persulfidation hypothesis in Alzheimer's etiology because the neurotoxicity of the homoCys-disulfide-Aβ42 dimer was very weak.![]()
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Affiliation(s)
- Kazuma Murakami
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University Kyoto 606-8502 Japan
| | - Haruka Kato
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University Kyoto 606-8502 Japan
| | - Mizuho Hanaki
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University Kyoto 606-8502 Japan
| | - Yoko Monobe
- National Institute of Biomedical Innovation, Health and Nutrition Osaka 567-0085 Japan
| | - Ken-Ichi Akagi
- National Institute of Biomedical Innovation, Health and Nutrition Osaka 567-0085 Japan
| | | | | | - Kazuhiro Irie
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University Kyoto 606-8502 Japan
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297
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Peters C, Bascuñán D, Burgos CF, Bobadilla C, González-Sanmiguel J, Boopathi S, Riffo N, Fernández-Pérez EJ, Tarnok ME, Aguilar LF, Gonzalez W, Aguayo LG. Characterization of a new molecule capable of inhibiting several steps of the amyloid cascade in Alzheimer's disease. Neurobiol Dis 2020; 141:104938. [PMID: 32434047 DOI: 10.1016/j.nbd.2020.104938] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 05/04/2020] [Indexed: 11/16/2022] Open
Abstract
INTRODUCTION Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder in elderly people. Existent therapies are directed at alleviating some symptoms, but are not effective in altering the course of the disease. METHODS Based on our previous study that showed that an Aβ-interacting small peptide protected against the toxic effects of amyloid-beta peptide (Aβ), we carried out an array of in silico, in vitro, and in vivo assays to identify a molecule having neuroprotective properties. RESULTS In silico studies showed that the molecule, referred to as M30 (2-Octahydroisoquinolin-2(1H)-ylethanamine), was able to interact with the Aβ peptide. Additionally, in vitro assays showed that M30 blocked Aβ aggregation, association to the plasma membrane, synaptotoxicity, intracellular calcium, and cellular toxicity, while in vivo experiments demonstrated that M30 induced a neuroprotective effect by decreasing the toxicity of Aβ in the dentate gyrus of the hippocampus and improving the alteration in spatial memory in behavior assays. DISCUSSION Therefore, we propose that this new small molecule could be a useful candidate for the additional development of a treatment against AD since it appears to block multiple steps in the amyloid cascade. Overall, since there are no drugs that effectively block the progression of AD, this approach represents an innovative strategy. SIGNIFICANCE Currently, there is no effective treatment for AD and the expectations to develop an effective therapy are low. Using in silico, in vitro, and in vivo experiments, we identified a new compound that is able to inhibit Aβ-induced neurotoxicity, specifically aggregation, association to neurons, synaptic toxicity, calcium dyshomeostasis and memory impairment induced by Aβ. Because Aβ toxicity is central to AD progression, the inhibition mediated by this new molecule might be useful as a therapeutic tool.
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Affiliation(s)
- Christian Peters
- Laboratory of Neurophysiology, Department of Physiology, Universidad de Concepción, Concepción, Chile
| | - Denisse Bascuñán
- Laboratory of Neurophysiology, Department of Physiology, Universidad de Concepción, Concepción, Chile
| | - Carlos F Burgos
- Laboratory of Neurophysiology, Department of Physiology, Universidad de Concepción, Concepción, Chile
| | - Catalina Bobadilla
- Laboratory of Neurophysiology, Department of Physiology, Universidad de Concepción, Concepción, Chile
| | | | - Subramanian Boopathi
- The Center for Bioinformatics and Molecular Simulations (CBSM), Universidad de Talca, Talca, Chile
| | - Nicolás Riffo
- Laboratory of Neurophysiology, Department of Physiology, Universidad de Concepción, Concepción, Chile
| | - Eduardo J Fernández-Pérez
- Laboratory of Neurophysiology, Department of Physiology, Universidad de Concepción, Concepción, Chile
| | - María Elena Tarnok
- Laboratory of Photophysics and Molecular Spectroscopy, Chemistry, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile
| | - Luis Felipe Aguilar
- Laboratory of Photophysics and Molecular Spectroscopy, Chemistry, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile
| | - Wendy Gonzalez
- The Center for Bioinformatics and Molecular Simulations (CBSM), Universidad de Talca, Talca, Chile; Millennium Nucleus of Ion Channels-Associated Diseases (MiNICAD), Universidad de Talca, Talca, Chile
| | - Luis G Aguayo
- Laboratory of Neurophysiology, Department of Physiology, Universidad de Concepción, Concepción, Chile.
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298
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Kundu D, Prerna K, Chaurasia R, Bharty MK, Dubey VK. Advances in protein misfolding, amyloidosis and its correlation with human diseases. 3 Biotech 2020; 10:193. [PMID: 32269898 PMCID: PMC7128022 DOI: 10.1007/s13205-020-2166-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 03/11/2020] [Indexed: 12/24/2022] Open
Abstract
Protein aggregation, their mechanisms and trends in the field of neurodegenerative diseases is still far from completely being decoded. It is mainly attributed to the complexity surrounding the interaction between proteins which includes various regulatory mechanisms involved with the presentation of abnormal conditions. Although most proteins are functional in their soluble form, they have also been reported to convert themselves into insoluble aggregates under certain conditions naturally. Misfolded protein forms aggregates which are mostly unwanted by the cellular system and are mostly involved in various pathophysiologies including Alzheimer's, Type II Diabetes mellitus, Kurus's etc. Challenges lie in understanding the complex mechanism of protein misfolding and its correlation with clinical evidence. It is often understood that due to the slowness of the process and its association with ageing, timely intervention with drugs or preventive measures will play an essential role in lowering the rate of dementia causing diseases and associated ailments in the future. Today approximately more than 35 proteins have been identified capable of forming amyloids under defined conditions, and nearly all of them have been associated with disease outcomes. This review incorporates a major understanding from the history of diseases associated with protein misfolding, to the current state of neurodegenerative diseases globally, highlighting challenges in drug development and current state of research in a comprehensive manner in the field of protein misfolding diseases. There is increasing clinical association of protein misfolding with regards to amyloids compelling us to thread questions solved and further helping us design possible solutions by generating a pathway-based research on which future work in this field could be driven.
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Affiliation(s)
- Debanjan Kundu
- School of Biochemical Engineering, Indian Institute of Technology (BHU), Varanasi, UP 221005 India
| | - Kumari Prerna
- School of Biochemical Engineering, Indian Institute of Technology (BHU), Varanasi, UP 221005 India
| | - Rahul Chaurasia
- Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi, UP 221005 India
| | - Manoj Kumar Bharty
- Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi, UP 221005 India
| | - Vikash Kumar Dubey
- School of Biochemical Engineering, Indian Institute of Technology (BHU), Varanasi, UP 221005 India
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299
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Das A, Gupta A, Hong Y, Carver JA, Maiti S. A Spectroscopic Marker for Structural Transitions Associated with Amyloid-β Aggregation. Biochemistry 2020; 59:1813-1822. [PMID: 32329604 DOI: 10.1021/acs.biochem.0c00113] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
An amyloid aggregate evolves through a series of intermediates that have different secondary structures and intra- and intermolecular contacts. The structural parameters of these intermediates are important determinants of their toxicity. For example, the early oligomeric species of the amyloid-β (Aβ) peptide have been implicated as the most cytotoxic species in Alzheimer's disease but are difficult to identify because of their dynamic and transitory nature. Conventional aggregation monitors such as the fluorescent dye thioflavin T report on only the overall transition of the soluble species to the final amyloid fibrillar aggregated state. Here, we show that the fluorescent dye bis(triphenylphosphonium) tetraphenylethene (TPE-TPP) identifies at least three distinct aggregation intermediates of Aβ. Some atomic-level features of these intermediates are known from solid state nuclear magnetic resonance spectroscopy. Hence, the TPE-TPP fluorescence data may be interpreted in terms of these Aβ structural transitions. Steady state fluorescence and lifetime characteristics of TPE-TPP distinguish between the small oligomeric species (emission wavelength maximum, λmax = 465 nm; average fluorescence lifetime, τFl measured at 420 nm = 3.58 ± 0.04 ns), the intermediate species (λmax = 452 nm; τFl = 3.00 ± 0.03 ns), and the fibrils (λmax = 406 nm; τFl = 5.19 ± 0.08 ns). Thus, TPE-TPP provides a ready diagnostic for differentiating between the various, including the toxic, Aβ aggregates and potentially can be utilized to screen for amyloid aggregation inhibitors.
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Affiliation(s)
- Anirban Das
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India
| | - Ankur Gupta
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India
| | - Yuning Hong
- Department of Chemistry and Physics, La Trobe Institute for Molecular Science, La Trobe University, Bundoora, VIC 3086, Australia
| | - John A Carver
- Research School of Chemistry, The Australian National University, Acton, ACT 2601, Australia
| | - Sudipta Maiti
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India
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300
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Sahoo BR, Cox SJ, Ramamoorthy A. High-resolution probing of early events in amyloid-β aggregation related to Alzheimer's disease. Chem Commun (Camb) 2020; 56:4627-4639. [PMID: 32300761 PMCID: PMC7254607 DOI: 10.1039/d0cc01551b] [Citation(s) in RCA: 66] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
In Alzheimer's disease (AD), soluble oligomers of amyloid-β (Aβ) are emerging as a crucial entity in driving disease progression as compared to insoluble amyloid deposits. The lacuna in establishing the structure to function relationship for Aβ oligomers prevents the development of an effective treatment for AD. While the transient and heterogeneous properties of Aβ oligomers impose many challenges for structural investigation, an effective use of a combination of NMR techniques has successfully identified and characterized them at atomic-resolution. Here, we review the successful utilization of solution and solid-state NMR techniques to probe the aggregation and structures of small and large oligomers of Aβ. Biophysical studies utilizing the commonly used solution and 19F based NMR experiments to identify the formation of small size early intermediates and to obtain their structures, and dock-lock mechanism of fiber growth at atomic-resolution are discussed. In addition, the use of proton-detected magic angle spinning (MAS) solid-state NMR experiments to obtain high-resolution insights into the aggregation pathways and structures of large oligomers and other aggregates is also presented. We expect these NMR based studies to be valuable for real-time monitoring of the depletion of monomers and the formation of toxic oligomers and high-order aggregates under a variety of conditions, and to solve the high-resolution structures of small and large size oligomers for most amyloid proteins, and therefore to develop inhibitors and drugs.
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Affiliation(s)
- Bikash R Sahoo
- Biophysics Program, Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA.
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