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Dey P, Biswas P. Effect of caffeine on the aggregation of amyloid-β-A 3D RISM study. J Chem Phys 2024; 160:125101. [PMID: 38516974 DOI: 10.1063/5.0202636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Accepted: 03/10/2024] [Indexed: 03/23/2024] Open
Abstract
Alzheimer's disease is a detrimental neurological disorder caused by the formation of amyloid fibrils due to the aggregation of amyloid-β peptide. The primary therapeutic approaches for treating Alzheimer's disease are targeted to prevent this amyloid fibril formation using potential inhibitor molecules. The discovery of such inhibitor molecules poses a formidable challenge to the design of anti-amyloid drugs. This study investigates the effect of caffeine on dimer formation of the full-length amyloid-β using a combined approach of all-atom, explicit water molecular dynamics simulations and the three-dimensional reference interaction site model theory. The change in the hydration free energy of amyloid-β dimer, with and without the inhibitor molecules, is calculated with respect to the monomeric amyloid-β, where the hydration free energy is decomposed into energetic and entropic components, respectively. Dimerization is accompanied by a positive change in the partial molar volume. Dimer formation is spontaneous, which implies a decrease in the hydration free energy. However, a reverse trend is observed for the dimer with inhibitor molecules. It is observed that the negatively charged residues primarily contribute for the formation of the amyloid-β dimer. A residue-wise decomposition reveals that hydration/dehydration of the side-chain atoms of the charged amino acid residues primarily contribute to dimerization.
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Affiliation(s)
- Priya Dey
- Department of Chemistry, University of Delhi, Delhi 110007, India
| | - Parbati Biswas
- Department of Chemistry, University of Delhi, Delhi 110007, India
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2
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Zahraee H, Arab SS, Khoshbin Z, Bozorgmehr MR. A comprehensive computer simulation insight into inhibitory mechanisms of EGCG and NQTrp ligands on amyloid-beta assemblies as the Alzheimer's disease insignia. J Biomol Struct Dyn 2023; 41:10830-10839. [PMID: 36576270 DOI: 10.1080/07391102.2022.2158939] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Accepted: 12/10/2022] [Indexed: 12/29/2022]
Abstract
Amyloid-β peptide with predominant presence in the senile plaques is the most common agent for Alzheimer's disease (AD) incidence. Assembly of the amyloid-β(1-42) (Aβ1-42) isoform is known as the main reason for the AD appearance. Epigallocatechin gallate (EGCG) and 1,4-naphthoquinone-2-yl-L-tryptophan (NQTrp) are two small molecules that inhibit the formation of the Aβ1-42 fibrils. The present study provides molecular insight to clarify the inhibitory mechanisms of the EGCG and NQTrp ligands on the Aβ1-42 assemblies by using molecular dynamics (MD) simulation. Hence, nine different Aβ1-42-containing systems including the monomer, dimer, and hexamer of Aβ1-42 considering each of them in a media with no ligands, in the presence of one EGCG ligand, and in the presence of one EGCG ligand were studied with a simulation time of 1 µs for each system. The precise investigation of the peptide-ligand distance, conformational factor (Pi), solvent accessible surface area (SASA), dictionary of secondary structure (DSSP), and Lys28-Ala42 salt bridge analyses confirmed that the hydroxyl-rich structure of the EGCG ligand applied its inhibitory effect on the aggregation of the peptides indirectly by involving water molecules. While the hydroxyl-free structure of the NQTrp ligand exposed its inhibitory effect through a direct interaction with the Aβ1-42 peptides. Besides, reduced density gradient (RDG) analysis clarified the hydrogen bonding interactions as the dominant ones for the peptide-EGCG systems, and also, steric and van der Waals interactions for the peptide-NQTrp systems.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Hamed Zahraee
- Targeted Drug Delivery Research Center, Pharmaceutical Technology Institute, Mashhad University of Medical Sciences, Mashhad, Iran
- Department of Medicinal Chemistry, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran
- Pharmaceutical Research Center, Pharmaceutical Technology Institute, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Seyed Shahriar Arab
- Department of Biophysics, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran
| | - Zahra Khoshbin
- Targeted Drug Delivery Research Center, Pharmaceutical Technology Institute, Mashhad University of Medical Sciences, Mashhad, Iran
- Department of Medicinal Chemistry, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran
- Pharmaceutical Research Center, Pharmaceutical Technology Institute, Mashhad University of Medical Sciences, Mashhad, Iran
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3
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Maiuolo J, Costanzo P, Masullo M, D’Errico A, Nasso R, Bonacci S, Mollace V, Oliverio M, Arcone R. Hydroxytyrosol-Donepezil Hybrids Play a Protective Role in an In Vitro Induced Alzheimer's Disease Model and in Neuronal Differentiated Human SH-SY5Y Neuroblastoma Cells. Int J Mol Sci 2023; 24:13461. [PMID: 37686262 PMCID: PMC10488223 DOI: 10.3390/ijms241713461] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 08/24/2023] [Accepted: 08/28/2023] [Indexed: 09/10/2023] Open
Abstract
Alzheimer's disease (AD) is the most common neurodegenerative pathology among progressive dementias, and it is characterized by the accumulation in the brain of extracellular aggregates of beta-amyloid proteins and neurofibrillary intracellular tangles consisting of τ-hyperphosphorylated proteins. Under normal conditions, beta-amyloid peptides exert important trophic and antioxidant roles, while their massive presence leads to a cascade of events culminating in the onset of AD. The fibrils of beta-amyloid proteins are formed by the process of fibrillogenesis that, starting from individual monomers of beta-amyloid, can generate polymers of this protein, constituting the hypothesis of the "amyloid cascade". To date, due to the lack of pharmacological treatment for AD without toxic side effects, chemical research is directed towards the realization of hybrid compounds that can act as an adjuvant in the treatment of this neurodegenerative pathology. The hybrid compounds used in this work include moieties of a hydroxytyrosol, a nitrohydroxytyrosol, a tyrosol, and a homovanillyl alcohol bound to the N-benzylpiperidine moiety of donepezil, the main drug used in AD. Previous experiments have shown different properties of these hybrids, including low toxicity and antioxidant and chelating activities. The purpose of this work was to test the effects of hybrid compounds mixed with Aβ1-40 to induce fibrillogenesis and mimic AD pathogenesis. This condition has been studied both in test tubes and by an in vitro model of neuronal differentiated human SH-SY5Y neuroblastoma cells. The results obtained from test tube experiments showed that some hybrids inhibit the activity of the enzymes AChE, BuChE, and BACE-1. Cell experiments suggested that hybrids could inhibit fibrillogenesis, negatively modulating caspase-3. They were also shown to exert antioxidant effects, and the acetylated hybrids were found to be more functional and efficient than nonacetylated forms.
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Affiliation(s)
- Jessica Maiuolo
- Department of Health Science, Institute of Research for Food Safety & Health (IRC-FSH), University Magna Græcia of Catanzaro, Viale Europa, 88100 Catanzaro, Italy
| | - Paola Costanzo
- Department of Chemistry and Chemical Technologies, University of Calabria, Via P. Bucci, Cubo 12C, 87036 Rende, Italy
| | - Mariorosario Masullo
- Department of Movement Science and Well-Being, University “Parthenope” of Naples, Via Medina, 40, 80133 Napoli, Italy; (M.M.); (R.A.)
| | - Antonio D’Errico
- Department of Movement Science and Well-Being, University “Parthenope” of Naples, Via Medina, 40, 80133 Napoli, Italy; (M.M.); (R.A.)
| | - Rosarita Nasso
- Department of Movement Science and Well-Being, University “Parthenope” of Naples, Via Medina, 40, 80133 Napoli, Italy; (M.M.); (R.A.)
| | - Sonia Bonacci
- Department of Health Sciences, University Magna Græcia of Catanzaro, Viale Europa, 88100 Catanzaro, Italy (M.O.)
| | - Vincenzo Mollace
- Department of Health Science, Institute of Research for Food Safety & Health (IRC-FSH), University Magna Græcia of Catanzaro, Viale Europa, 88100 Catanzaro, Italy
| | - Manuela Oliverio
- Department of Health Sciences, University Magna Græcia of Catanzaro, Viale Europa, 88100 Catanzaro, Italy (M.O.)
| | - Rosaria Arcone
- Department of Movement Science and Well-Being, University “Parthenope” of Naples, Via Medina, 40, 80133 Napoli, Italy; (M.M.); (R.A.)
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Zahraee H, Mohammadi F, Parvaee E, Khoshbin Z, Arab SS. Reducing the assemblies of amyloid-beta multimers by sodium dodecyl sulfate surfactant at concentrations lower than critical micelle concentration: molecular dynamics simulation exploration. J Biomol Struct Dyn 2023:1-15. [PMID: 37599504 DOI: 10.1080/07391102.2023.2247086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Accepted: 08/05/2023] [Indexed: 08/22/2023]
Abstract
Amyloid-β peptide, the predominant proteinaceous component of senile plaques, is responsible for the incidence of Alzheimer's disease (AD), an age-associated neurodegenerative disorder. Specifically, the amyloid-β(1-42) (Aβ1-42) isoform, known for its high toxicity, is the predominant biomarker for the preliminary diagnosis of AD. The aggregation of the Aβ1-42 peptides can be affected by the components of the cellular medium through changing their structures and molecular interactions. In this study, we investigated the effect of sodium dodecyl sulfate (SDS) at much lower concentrations than the critical micelle concentration (CMC) on Aβ1-42 aggregation. For this purpose, we studied mono-, di-, tri- and tetramers of Aβ1-42 peptide in two different concentrations of SDS molecules (10 and 40 molecules) using a 300 ns molecular dynamics simulation for each system. The distance between the center of mass (COM) of Aβ1-42 peptides confirms that an increase in the number of SDS molecules decreases their aggregation probability due to greater interaction with SDS molecules. Besides, the less compactness parameter reveals the reduced aggregation probability of Aβ1-42 peptides. Based on the energetic FEL landscapes, SDS molecules with the concentration closer to the CMC are an effective inhibitory agent to prevent the formation of Aβ1-42 fibrils. Also, the aggregation direction of the peptide pairs can be predicted by determining the direction of the accumulation-deterrent forces.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Hamed Zahraee
- Targeted Drug Delivery Research Center, Pharmaceutical Technology Institute, Mashhad University of Medical Sciences, Mashhad, Iran
- Pharmaceutical Research Center, Pharmaceutical Technology Institute, Mashhad University of Medical Sciences, Mashhad, Iran
- Department of Medicinal Chemistry, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Fatemeh Mohammadi
- Targeted Drug Delivery Research Center, Pharmaceutical Technology Institute, Mashhad University of Medical Sciences, Mashhad, Iran
- Pharmaceutical Research Center, Pharmaceutical Technology Institute, Mashhad University of Medical Sciences, Mashhad, Iran
- Department of Medicinal Chemistry, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Elahe Parvaee
- Department of Chemistry, Mashhad Branch, Islamic Azad University, Mashhad, Iran
| | - Zahra Khoshbin
- Targeted Drug Delivery Research Center, Pharmaceutical Technology Institute, Mashhad University of Medical Sciences, Mashhad, Iran
- Pharmaceutical Research Center, Pharmaceutical Technology Institute, Mashhad University of Medical Sciences, Mashhad, Iran
- Department of Medicinal Chemistry, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Seyed Shahriar Arab
- Department of Biophysics, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran
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5
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Dey P, Biswas P. Exploring the aggregation of amyloid-β 42 through Monte Carlo simulations. Biophys Chem 2023; 297:107011. [PMID: 37037120 DOI: 10.1016/j.bpc.2023.107011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 03/25/2023] [Accepted: 03/26/2023] [Indexed: 04/09/2023]
Abstract
Coarse-grained Monte Carlo simulations are performed for a disordered protein, amyloid-β 42 to identify the interactions and understand the mechanism of its aggregation. A statistical potential is developed from a selected dataset of intrinsically disordered proteins, which accounts for the respective contributions of the bonded and non-bonded potentials. While, the bonded potential comprises the bond, bend, and dihedral constraints, the nonbonded interactions include van der Waals interactions, hydrogen bonds, and the two-body potential. The two-body potential captures the features of both hydrophobic and electrostatic interactions that brings the chains at a contact distance, while the repulsive van der Waals interactions prevent them from a collapse. Increased two-body hydrophobic interactions facilitate the formation of amorphous aggregates rather than the fibrillar ones. The formation of aggregates is validated from the interchain distances, and the total energy of the system. The aggregate is structurally characterized by the root-mean-square deviation, root-mean-square fluctuation and the radius of gyration. The aggregates are characterized by a decrease in SASA, an increase in the non-local interactions and a distinct free energy minimum relative to that of the monomeric state of amyloid-β 42. The hydrophobic residues help in nucleation, while the charged residues help in oligomerization and aggregation.
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Andrews B, Ruggiero T, Urbanc B. How do salt and lipids affect conformational dynamics of Aβ42 monomers in water? Phys Chem Chem Phys 2023; 25:2566-2583. [PMID: 36602150 DOI: 10.1039/d2cp05044g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
It is well established that amyloid β-protein (Aβ) self-assembly is involved in triggering of Alzheimer's disease. On the other hand, evidence of physiological function of Aβ interacting with lipids has only begun to emerge. Details of Aβ-lipid interactions, which may underlie physiological and pathological activities of Aβ, are not well understood. Here, the effects of salt and 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) lipids on conformational dynamics of Aβ42 monomer in water are examined by all-atom molecular dynamics (MD). We acquired six sets of 250 ns long MD trajectories for each of the three lipid concentrations (0, 27, and 109 mM) in the absence and presence of 150 mM salt. Ten replica trajectories per set are used to enhance sampling of Aβ42 conformational space. We show that salt facilitates long-range tertiary contacts in Aβ42, resulting in more compact Aβ42 conformations. By contrast, addition of lipids results in lipid-concentration dependent Aβ42 unfolding concomitant with enhanced stability of the turn in the A21-A30 region. At the high lipid concentration, salt enables the N-terminal region of Aβ42 to form long-range tertiary contacts and interact with lipids, which results in formation of a parallel β-strand. Aβ42 forms stable lipid-protein complexes whereby the protein is adhered to the lipid cluster rather than embedded into it. We propose that the inability of Aβ42 monomer to get embedded into the lipid cluster may be important for facilitating repair of leaks in the blood-brain barrier without penetrating and damaging cellular membranes.
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Affiliation(s)
- Brian Andrews
- Department of Physics, Drexel University, Philadelphia, Pennsylvania, USA.
| | - Thomas Ruggiero
- Department of Physics, Drexel University, Philadelphia, Pennsylvania, USA.
| | - Brigita Urbanc
- Department of Physics, Drexel University, Philadelphia, Pennsylvania, USA.
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Chatterjee S, Nam Y, Salimi A, Lee JY. Monitoring early-stage β-amyloid dimer aggregation by histidine site-specific two-dimensional infrared spectroscopy in a simulation study. Phys Chem Chem Phys 2022; 24:18691-18702. [PMID: 35899740 DOI: 10.1039/d2cp02479a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Monitoring early-stage β-amyloid (Aβ) dimerization is a formidable challenge for understanding neurological diseases. We compared β-sheet formation and histidine site-specific two-dimensional infrared (2D IR) spectroscopic signatures of Aβ dimers with different histidine states (δ; Nδ1-H, ε; Nε2-H, or π; both protonated). Molecular dynamics (MD) simulations revealed that β-sheet formation is favored for the δδδ:δδδ and πππ:πππ tautomeric isomers showing strong couplings and frequent contacts between the central hydrophobic core and C-terminus compared with the εεε:εεε isomer. Characteristic blue-shifts in the 2D IR central bands were observed upon monomer-dimer transformation. The εεε:εεε dimer exhibited larger frequency shifts than δδδ:δδδ and πππ:πππ implying that the red-shift may have a correlation with Nδ1-H(δ) protonation. Our results support the tautomerization/protonation hypothesis that attributes Aβ misfolding to histidine tautomers as a possible primary initiator for Aβ aggregation and facilitates the application of histidine site-specific 2D IR spectroscopy for studying early-stage Aβ self-assembly.
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Affiliation(s)
| | - Yeonsig Nam
- Department of Chemistry, Sungkyunkwan University, Suwon 440-746, Korea. .,Department of Chemistry, University of California, Irvine, California 92697-2025, USA
| | - Abbas Salimi
- Department of Chemistry, Sungkyunkwan University, Suwon 440-746, Korea.
| | - Jin Yong Lee
- Department of Chemistry, Sungkyunkwan University, Suwon 440-746, Korea.
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Constructing conformational library for amyloid-β42 dimers as the smallest toxic oligomers using two CHARMM force fields. J Mol Graph Model 2022; 115:108207. [DOI: 10.1016/j.jmgm.2022.108207] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Revised: 04/21/2022] [Accepted: 04/23/2022] [Indexed: 11/19/2022]
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9
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Tagad A, Singh RK, Patwari GN. Binary Matrix Method to Enumerate, Hierarchically Order, and Structurally Classify Peptide Aggregation. J Chem Inf Model 2022; 62:1585-1594. [PMID: 35232014 DOI: 10.1021/acs.jcim.2c00069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Protein aggregation is a common and complex phenomenon in biological processes, yet a robust analysis of this aggregation process remains elusive. The commonly used methods such as center-of-mass to center-of-mass (COM-COM) distance, the radius of gyration (Rg), hydrogen bonding (HB), and solvent accessible surface area do not quantify the aggregation accurately. Herein, a new and robust method that uses an aggregation matrix (AM) approach to investigate peptide aggregation in a MD simulation trajectory is presented. An nxn two-dimensional AM is created by using the interpeptide Cα-Cα cutoff distances, which are binarily encoded (0 or 1). These aggregation matrices are analyzed to enumerate, hierarchically order, and structurally classify the aggregates. Comparison of the present AM method suggests that it is superior to the HB method since it can incorporate nonspecific interactions and the Rg and COM-COM methods since the cutoff distance is independent of the length of the peptide. More importantly, the present method can structurally classify the peptide aggregates, which the conventional Rg, COM-COM, and HB methods fail to do. The unique selling point of this method is its ability to structurally classify peptide aggregates using two-dimensional matrices.
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Affiliation(s)
- Amol Tagad
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Reman Kumar Singh
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - G Naresh Patwari
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
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Mrdenovic D, Pieta IS, Nowakowski R, Kutner W, Lipkowski J, Pieta P. Amyloid β interaction with model cell membranes – What are the toxicity-defining properties of amyloid β? Int J Biol Macromol 2022; 200:520-531. [DOI: 10.1016/j.ijbiomac.2022.01.117] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 01/10/2022] [Accepted: 01/18/2022] [Indexed: 01/26/2023]
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Molecular insight into the early stage of amyloid-β(1-42) Homodimers aggregation influenced by histidine tautomerism. Int J Biol Macromol 2021; 184:887-897. [PMID: 34153362 DOI: 10.1016/j.ijbiomac.2021.06.078] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 05/23/2021] [Accepted: 06/10/2021] [Indexed: 11/20/2022]
Abstract
Aggregated amyloid β-peptide (Aβ) in small oligomeric forms inside the brain causes synaptic function disruption and the development of Alzheimer's disease (AD). Histidine is an important amino acid that may lead to structural changes. Aβ42 monomer chain includes 3 histidine residues that considering two ε and δ tautomers 8 isomers, including (εεε) and (εδδ) could be formed. Molecular dynamics simulation on homodimerization of (εεε) (the most common type of tautomers) and (εδδ) tautomers with different initial configurations using monomer chains from our previous work were performed to uncover the tautomeric behavior of histidine on Aβ42 aggregation in a physiological pH which is still largely unknown and impossible to observe experimentally. We found a higher propensity of forming β-sheet in (εδδ) homodimers and specifically in a greater amount from Aβ42 than from Aβ40. A smaller amount of β-sheet formation was observed for (εεε) homodimers compared with (εδδ). Additionally, interactions in (εδδ) homodimers may indicate the importance of the hydrophobic core and C-/N-terminals during oligomerization. Our findings indicate the important role of the tautomeric effect of histidine and (εδδ) homodimers at the early stage of Aβ aggregation.
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12
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Li X, Lao Z, Zou Y, Dong X, Li L, Wei G. Mechanistic Insights into the Co-Aggregation of Aβ and hIAPP: An All-Atom Molecular Dynamic Study. J Phys Chem B 2021; 125:2050-2060. [PMID: 33616398 DOI: 10.1021/acs.jpcb.0c11132] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Patients with Alzheimer's disease (AD) have a high risk of developing Type II diabetes (T2D). The co-aggregation of the two disease-related proteins, Aβ and hIAPP, has been proposed as a potential molecular mechanism. However, the detailed Aβ-hIAPP interactions and structural characteristics of co-aggregates are mostly unknown at atomic level. Here, we explore the conformational ensembles of the Aβ-hIAPP heterodimer and Aβ or hIAPP homodimer by performing all-atom explicit-solvent replica exchange molecular dynamic simulations. Our simulations show that the interaction propensity of Aβ-hIAPP in the heterodimer is comparable with that of Aβ-Aβ/hIAPP-hIAPP in the homodimer. Similar hot spot residues of Aβ/hIAPP in the homodimer and heterodimer are identified, indicating that both Aβ and hIAPP have similar molecular recognition sites for self-aggregation and co-aggregation. Aβ in the heterodimer possesses three high β-sheet probability regions: the N-terminal region E3-H6, the central hydrophobic core region K16-E22, and the C-terminal hydrophobic region I31-A41, which is highly similar to Aβ in the homodimer. More importantly, in the heterodimer, the regions E3-H6, F19-E22, and I31-M35 of Aβ and the amyloid core region N20-T30 of hIAPP display higher β-sheet probability than they do in homodimer, implying their crucial roles in the formation of β-sheet-rich co-aggregates. Our study sheds light on the co-aggregation of Aβ and hIAPP at an atomic level, which will be helpful for an in-depth understanding of the molecular mechanism for epidemiological correlation of AD and T2D.
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Affiliation(s)
- Xuhua Li
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, 2005 Songhu Road, Shanghai 200438, China.,MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Physics, Xi'an Jiaotong University, Xi'an 710049, China
| | - Zenghui Lao
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, 2005 Songhu Road, Shanghai 200438, China
| | - Yu Zou
- Department of Sport and Exercise Science, College of Education, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310007 Zhejiang, China
| | - Xuewei Dong
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, 2005 Songhu Road, Shanghai 200438, China
| | - Le Li
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, 2005 Songhu Road, Shanghai 200438, China
| | - Guanghong Wei
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, 2005 Songhu Road, Shanghai 200438, China
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13
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Barz B, Buell AK, Nath S. Compact fibril-like structure of amyloid β-peptide (1-42) monomers. Chem Commun (Camb) 2021; 57:947-950. [PMID: 33399148 DOI: 10.1039/d0cc06607a] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Amyloid β (Aβ) monomers are the smallest assembly units, and play an important role in most of the individual processes involved in amyloid fibril formation. An important question is whether the monomer can adopt transient fibril-like conformations in solution. Here we use enhanced sampling simulations to study the Aβ42 monomer structural flexibility. We show that the monomer frequently adopts conformations with the N-terminus region structured very similarly to the conformation it adopts inside the fibril. This intrinsic propensity of monomeric Aβ to adopt fibril-like conformations could explain the low free energy barrier for Aβ42 fibril elongation.
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Affiliation(s)
- Bogdan Barz
- Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany and Institute of Biological Information Processing - Structural Biochemistry (IBI-7), Research Centre Jülich, Jülich, Germany.
| | - Alexander K Buell
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Lyngby, Denmark
| | - Soumav Nath
- Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany and Institute of Biological Information Processing - Structural Biochemistry (IBI-7), Research Centre Jülich, Jülich, Germany.
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14
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Urbanc B. Cross-Linked Amyloid β-Protein Oligomers: A Missing Link in Alzheimer's Disease Pathology? J Phys Chem B 2021; 125:1307-1316. [PMID: 33440940 DOI: 10.1021/acs.jpcb.0c07716] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Amyloid β-protein (Aβ) oligomers are broadly viewed as the proximate mediators of toxicity in Alzheimer's disease (AD). Recent studies, however, provide substantial evidence that Aβ is involved in protection and repair of the central nervous system whereby Aβ oligomer and subsequent fibril formation are integral to its normal antimicrobial and antiviral function. These developments raise a question of what exactly makes Aβ oligomers toxic in the context of AD. This Perspective describes a paradigm shift in the search for toxic Aβ oligomer species that involves oxidative-stress-induced stabilization of Aβ oligomers via cross-linking and reviews most recent research elucidating structural aspects of cross-linked Aβ oligomers and potential inhibition of their toxicity.
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Affiliation(s)
- Brigita Urbanc
- Department of Physics, Drexel University, Philadelphia, Pennsylvania 19104, United States
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Press-Sandler O, Miller Y. Distinct Primary Nucleation of Polymorphic Aβ Dimers Yields to Distinguished Fibrillation Pathways. ACS Chem Neurosci 2019; 10:4407-4413. [PMID: 31532176 DOI: 10.1021/acschemneuro.9b00437] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Polymorphic Aβ dimers are the smallest toxic species that play a role in the pathology of Alzheimer's disease. There is great interest in understanding the malfunctions that yield to these toxic species and in providing insights into the molecular mechanisms of the primary nucleation. Herein, we present a first work that demonstrates two distant edges states of Aβ dimers. The first is the so-called "random coil" state dimer that mimics the primary seeding/nucleation that is far from a fibrillation state. The second is the "fibril-like" state dimer that is structurally in close proximity to the fibril, a well-organized state into a fibril-like structure. We show for the first time that a conformational change of one monomer within the dimer impedes primary nucleation, while less fluctuations and relatively large number of interactions in nucleation domains induce the primary nucleation to produce toxic stable species. Overall, the current study exhibits a diversity of primary nucleation in each dimer state, suggesting distinct molecular mechanisms of fibril formation. The conformations of the early stage Aβ dimers that were achieved may provide crucial data for designing inhibitors to impede the primary nucleation.
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Affiliation(s)
- Olga Press-Sandler
- Department of Chemistry, Ben-Gurion University of the Negev, Be’er Sheva 84105, Israel
- The Ilse Katz Institute for Nanoscale Science & Technology, Ben-Gurion University of the Negev, Be’er Sheva 84105, Israel
| | - Yifat Miller
- Department of Chemistry, Ben-Gurion University of the Negev, Be’er Sheva 84105, Israel
- The Ilse Katz Institute for Nanoscale Science & Technology, Ben-Gurion University of the Negev, Be’er Sheva 84105, Israel
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16
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Nguyen HL, Krupa P, Hai NM, Linh HQ, Li MS. Structure and Physicochemical Properties of the Aβ42 Tetramer: Multiscale Molecular Dynamics Simulations. J Phys Chem B 2019; 123:7253-7269. [DOI: 10.1021/acs.jpcb.9b04208] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Hoang Linh Nguyen
- Institute for Computational Science and Technology, SBI Building, Quang Trung Software
City, Tan Chanh Hiep Ward, District 12, Ho Chi Minh City 700000, Vietnam
- Biomedical Engineering Department, Ho Chi Minh City University of Technology-VNU HCM, 268 Ly Thuong Kiet Street, Distr. 10, Ho Chi Minh City 700000, Vietnam
| | - Pawel Krupa
- Institute of Physics Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland
| | - Nguyen Minh Hai
- Faculty of Physics and Engineering Physics, University of Science-VNU HCM, Ho Chi Minh City 700000, Vietnam
| | - Huynh Quang Linh
- Biomedical Engineering Department, Ho Chi Minh City University of Technology-VNU HCM, 268 Ly Thuong Kiet Street, Distr. 10, Ho Chi Minh City 700000, Vietnam
| | - Mai Suan Li
- Institute of Physics Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland
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17
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Arya S, Singh AK, Bhasne K, Dogra P, Datta A, Das P, Mukhopadhyay S. Femtosecond Hydration Map of Intrinsically Disordered α-Synuclein. Biophys J 2019; 114:2540-2551. [PMID: 29874605 DOI: 10.1016/j.bpj.2018.04.028] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 04/16/2018] [Accepted: 04/17/2018] [Indexed: 10/14/2022] Open
Abstract
Protein hydration water plays a fundamentally important role in protein folding, binding, assembly, and function. Little is known about the hydration water in intrinsically disordered proteins that challenge the conventional sequence-structure-function paradigm. Here, by combining experiments and simulations, we show the existence of dynamical heterogeneity of hydration water in an intrinsically disordered presynaptic protein, namely α-synuclein, implicated in Parkinson's disease. We took advantage of nonoccurrence of cysteine in the sequence and incorporated a number of cysteine residues at the N-terminal segment, the central amyloidogenic nonamyloid-β component (NAC) domain, and the C-terminal end of α-synuclein. We then labeled these cysteine variants using environment-sensitive thiol-active fluorophore and monitored the solvation dynamics using femtosecond time-resolved fluorescence. The site-specific femtosecond time-resolved experiments allowed us to construct the hydration map of α-synuclein. Our results show the presence of three dynamically distinct types of water: bulk, hydration, and confined water. The amyloidogenic NAC domain contains dynamically restrained water molecules that are strikingly different from the water molecules present in the other two domains. Atomistic molecular dynamics simulations revealed longer residence times for water molecules near the NAC domain and supported our experimental observations. Additionally, our simulations allowed us to decipher the molecular origin of the dynamical heterogeneity of water in α-synuclein. These simulations captured the quasi-bound water molecules within the NAC domain originating from a complex interplay between the local chain compaction and the sequence composition. Our findings from this synergistic experimental simulation approach suggest longer trapping of interfacial water molecules near the amyloidogenic hotspot that triggers the pathological conversion into amyloids via chain sequestration, chain desolvation, and entropic liberation of ordered water molecules.
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Affiliation(s)
- Shruti Arya
- Centre for Protein Science, Design and Engineering, Indian Institute of Science Education and Research (IISER) Mohali, Mohali, Punjab, India; Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Mohali, Punjab, India
| | - Avinash K Singh
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, India
| | - Karishma Bhasne
- Centre for Protein Science, Design and Engineering, Indian Institute of Science Education and Research (IISER) Mohali, Mohali, Punjab, India; Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Mohali, Punjab, India
| | - Priyanka Dogra
- Centre for Protein Science, Design and Engineering, Indian Institute of Science Education and Research (IISER) Mohali, Mohali, Punjab, India; Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Mohali, Punjab, India
| | - Anindya Datta
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, India.
| | - Payel Das
- Data Science Department, IBM Thomas J. Watson Research Center, Yorktown Heights, New York.
| | - Samrat Mukhopadhyay
- Centre for Protein Science, Design and Engineering, Indian Institute of Science Education and Research (IISER) Mohali, Mohali, Punjab, India; Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Mohali, Punjab, India; Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Mohali, Punjab, India.
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18
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Mehrazma B, Rauk A. Exploring Amyloid-β Dimer Structure Using Molecular Dynamics Simulations. J Phys Chem A 2019; 123:4658-4670. [PMID: 31082235 DOI: 10.1021/acs.jpca.8b11251] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
A major hallmark of Alzheimer's disease (AD) is the aggregation of amyloid-β peptides in the brains of people afflicted by the disease. The exact pathway to this catastrophic event is unknown. In this work, a total of 9.5 μs molecular dynamics simulations have been performed to investigate the structure and dynamics of the smallest form of toxic Aβ oligomers, i.e., the Aβ dimers. This study suggests that specific hydrophobic regions are vital in the aggregation process. Different possible structures for Aβ dimers are reported along with their relative binding affinity. These data may be used to design better Aβ-aggregation inhibitors. The diversity of the dimer structures suggests several aggregation pathways.
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Affiliation(s)
- Banafsheh Mehrazma
- Department of Chemistry , University of Calgary , Calgary AB , Canada T2N 1N4
| | - Arvi Rauk
- Department of Chemistry , University of Calgary , Calgary AB , Canada T2N 1N4
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19
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Liu C, Zhao W, Xing X, Shi H, Kang B, Liu H, Li P, Ai H. An Original Monomer Sampling from a Ready‐Made Aβ
42
NMR Fibril Suggests a Turn‐β‐Strand Synergetic Seeding Mechanism. Chemphyschem 2019; 20:1649-1660. [DOI: 10.1002/cphc.201801137] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Indexed: 01/15/2023]
Affiliation(s)
- Chengqiang Liu
- School of Chemistry and Chemical EngineeringUniversity of Jinan Jinan 250022 China
| | - Wei Zhao
- School of Chemistry and Chemical EngineeringUniversity of Jinan Jinan 250022 China
| | - Xiaofeng Xing
- School of Chemistry and Chemical EngineeringUniversity of Jinan Jinan 250022 China
| | - Hu Shi
- School of Chemistry and Chemical EngineeringShanxi University Taiyuan 030006 China
| | - Baotao Kang
- School of Chemistry and Chemical EngineeringUniversity of Jinan Jinan 250022 China
| | - Haiying Liu
- School of PhysicsUniversity of Jinan Jinan 250022 China
| | - Ping Li
- Key Laboratory of Life-Organic Analysis, School of Chemistry and Chemical EngineeringQufu Normal University Qufu 273165 China
| | - Hongqi Ai
- School of Chemistry and Chemical EngineeringUniversity of Jinan Jinan 250022 China
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20
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Semenyuk P, Muronetz V. Protein Interaction with Charged Macromolecules: From Model Polymers to Unfolded Proteins and Post-Translational Modifications. Int J Mol Sci 2019; 20:E1252. [PMID: 30871103 PMCID: PMC6429204 DOI: 10.3390/ijms20051252] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 03/05/2019] [Accepted: 03/07/2019] [Indexed: 12/18/2022] Open
Abstract
Interaction of proteins with charged macromolecules is involved in many processes in cells. Firstly, there are many naturally occurred charged polymers such as DNA and RNA, polyphosphates, sulfated glycosaminoglycans, etc., as well as pronouncedly charged proteins such as histones or actin. Electrostatic interactions are also important for "generic" proteins, which are not generally considered as polyanions or polycations. Finally, protein behavior can be altered due to post-translational modifications such as phosphorylation, sulfation, and glycation, which change a local charge of the protein region. Herein we review molecular modeling for the investigation of such interactions, from model polyanions and polycations to unfolded proteins. We will show that electrostatic interactions are ubiquitous, and molecular dynamics simulations provide an outstanding opportunity to look inside binding and reveal the contribution of electrostatic interactions. Since a molecular dynamics simulation is only a model, we will comprehensively consider its relationship with the experimental data.
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Affiliation(s)
- Pavel Semenyuk
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119234 Moscow, Russia.
| | - Vladimir Muronetz
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119234 Moscow, Russia.
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, 119234 Moscow, Russia.
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21
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Zhao X, Liao C, Ma YT, Ferrell JB, Schneebeli ST, Li J. Top-down Multiscale Approach To Simulate Peptide Self-Assembly from Monomers. J Chem Theory Comput 2019; 15:1514-1522. [PMID: 30677300 DOI: 10.1021/acs.jctc.8b01025] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Modeling peptide assembly from monomers on large time and length scales is often intractable at the atomistic resolution. To address this challenge, we present a new approach which integrates coarse-grained (CG), mixed-resolution, and all-atom (AA) modeling in a single simulation. We simulate the initial encounter stage with the CG model, while the further assembly and reorganization stages are simulated with the mixed-resolution and AA models. We have implemented this top-down approach with new tools to automate model transformations and to monitor oligomer formations. Further, a theory was developed to estimate the optimal simulation length for each stage using a model peptide, melittin. The assembly level, the oligomer distribution, and the secondary structures of melittin simulated by the optimal protocol show good agreement with prior experiments and AA simulations. Finally, our approach and theory have been successfully validated with three amyloid peptides (β-amyloid 16-22, GNNQQNY fragment from the yeast prion protein SUP35, and α-synuclein fibril 35-55), which highlight the synergy from modeling at multiple resolutions. This work not only serves as proof of concept for multiresolution simulation studies but also presents practical guidelines for further self-assembly simulations at more physically and chemically relevant scales.
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Affiliation(s)
- Xiaochuan Zhao
- Department of Chemistry , The University of Vermont , Burlington , Vermont 05405 , United States
| | - Chenyi Liao
- Department of Chemistry , The University of Vermont , Burlington , Vermont 05405 , United States
| | - Yong-Tao Ma
- Department of Chemistry , The University of Vermont , Burlington , Vermont 05405 , United States
| | - Jonathon B Ferrell
- Department of Chemistry , The University of Vermont , Burlington , Vermont 05405 , United States
| | - Severin T Schneebeli
- Department of Chemistry , The University of Vermont , Burlington , Vermont 05405 , United States
| | - Jianing Li
- Department of Chemistry , The University of Vermont , Burlington , Vermont 05405 , United States
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22
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Zhang S, Fox DM, Urbanc B. Elucidating the Role of Hydroxylated Phenylalanine in the Formation and Structure of Cross-Linked Aβ Oligomers. J Phys Chem B 2019; 123:1068-1084. [DOI: 10.1021/acs.jpcb.8b12120] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Shuting Zhang
- Department of Physics, Drexel University, Philadelphia, Pennsylvania 19104, United States
| | - Dillion M. Fox
- Department of Physics, Drexel University, Philadelphia, Pennsylvania 19104, United States
| | - Brigita Urbanc
- Department of Physics, Drexel University, Philadelphia, Pennsylvania 19104, United States
- Faculty of Mathematics and Physics, University of Ljubljana, Ljubljana, Slovenia
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23
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Jin Y, Sun Y, Chen Y, Lei J, Wei G. Molecular dynamics simulations reveal the mechanism of graphene oxide nanosheet inhibition of Aβ1–42 peptide aggregation. Phys Chem Chem Phys 2019; 21:10981-10991. [DOI: 10.1039/c9cp01803d] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Graphene oxide nanosheets inhibit Aβ1–42 aggregation by weakening inter-peptide interactions and reducing β-sheet contents mostly via salt bridge, hydrogen bonding and cation–π interactions with charged residues.
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Affiliation(s)
- Yibo Jin
- Department of Physics
- State Key Laboratory of Surface Physics
- Key Laboratory for Computational Physical Sciences (Ministry of Education)
- Fudan University
- Shanghai 200433
| | - Yunxiang Sun
- Department of Physics
- State Key Laboratory of Surface Physics
- Key Laboratory for Computational Physical Sciences (Ministry of Education)
- Fudan University
- Shanghai 200433
| | - Yujie Chen
- Department of Physics
- State Key Laboratory of Surface Physics
- Key Laboratory for Computational Physical Sciences (Ministry of Education)
- Fudan University
- Shanghai 200433
| | - Jiangtao Lei
- Department of Physics
- State Key Laboratory of Surface Physics
- Key Laboratory for Computational Physical Sciences (Ministry of Education)
- Fudan University
- Shanghai 200433
| | - Guanghong Wei
- Department of Physics
- State Key Laboratory of Surface Physics
- Key Laboratory for Computational Physical Sciences (Ministry of Education)
- Fudan University
- Shanghai 200433
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24
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Lu L, Deng Y, Li X, Li H, Karniadakis GE. Understanding the Twisted Structure of Amyloid Fibrils via Molecular Simulations. J Phys Chem B 2018; 122:11302-11310. [PMID: 30106299 DOI: 10.1021/acs.jpcb.8b07255] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Accumulation and aggregation of amyloid are associated with the pathogenesis of many human diseases, such as Alzheimer's disease and Type 2 diabetes mellitus. Therefore, a quantitative understanding of the molecular mechanisms causing different aggregated structures and biomechanical properties of amyloid fibrils could shed some light into the progression of these diseases. In this work, we develop coarse-grained molecular dynamics (CGMD) models to simulate the dynamic self-assembly of two types of amyloids (amylin and amyloid β (Aβ)). We investigate the structural and mechanical properties of different types of aggregated amyloid fibrils. Our simulations demonstrate that amyloid fibrils could result from longitudinal growth of protofilament bundles, confirming one of the hypotheses on the fibril formation. In addition, we find that the persistence length of amylin fibrils increases concurrently with their pitch length, suggesting that the bending stiffness of amylin fibrils becomes larger when the amylin fibrils are less twisted. Similar results are observed for Aβ fibrils. These findings quantify the connection between the structural and the biomechanical properties of the fibrils. The CGMD models developed in this work can be potentially used to examine efficacy of anti-aggregation drugs, which could help in developing new treatments.
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Affiliation(s)
- Lu Lu
- Division of Applied Mathematics , Brown University , Providence , Rhode Island 02912 , United States
| | - Yixiang Deng
- School of Engineering , Brown University , Providence , Rhode Island 02912 , United States
| | - Xuejin Li
- Division of Applied Mathematics , Brown University , Providence , Rhode Island 02912 , United States
| | - He Li
- Division of Applied Mathematics , Brown University , Providence , Rhode Island 02912 , United States
| | - George Em Karniadakis
- Division of Applied Mathematics , Brown University , Providence , Rhode Island 02912 , United States
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25
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Liao Q, Owen MC, Bali S, Barz B, Strodel B. Aβ under stress: the effects of acidosis, Cu 2+-binding, and oxidation on amyloid β-peptide dimers. Chem Commun (Camb) 2018; 54:7766-7769. [PMID: 29947363 DOI: 10.1039/c8cc02263a] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In light of the high affinity of Cu2+ for Alzheimer's Aβ1-42 and its ability to subsequently catalyze the formation of radicals, we examine the effects of Cu2+ binding, Aβ oxidation, and an acidic environment on the conformational dynamics of the smallest Aβ1-42 oligomer, the Aβ1-42 dimer. Transition networks calculated from Hamiltonian replica exchange molecular dynamics (H-REMD) simulations reveal that the decreased pH considerably increased the β-sheet content, whereas Cu2+ binding increased the exposed hydrophobic surface area, both of which can contribute to an increased oligomerization propensity and toxicity.
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Affiliation(s)
- Qinghua Liao
- Institute of Complex Systems, Structural Biochemistry (ICS-6), Forschungszentrum Jülich, 52425 Jülich, Germany.
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26
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Mittal S, Bravo-Rodriguez K, Sanchez-Garcia E. Mechanism of Inhibition of Beta Amyloid Toxicity by Supramolecular Tweezers. J Phys Chem B 2018; 122:4196-4205. [DOI: 10.1021/acs.jpcb.7b10530] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Sumit Mittal
- University of Duisburg-Essen, Universitätsstraße 2, 45141 Essen, Germany
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27
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Hane FT, Lee BY, Leonenko Z. Recent Progress in Alzheimer's Disease Research, Part 1: Pathology. J Alzheimers Dis 2018; 57:1-28. [PMID: 28222507 DOI: 10.3233/jad-160882] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The field of Alzheimer's disease (AD) research has grown exponentially over the past few decades, especially since the isolation and identification of amyloid-β from postmortem examination of the brains of AD patients. Recently, the Journal of Alzheimer's Disease (JAD) put forth approximately 300 research reports which were deemed to be the most influential research reports in the field of AD since 2010. JAD readers were asked to vote on these most influential reports. In this 3-part review, we review the results of the 300 most influential AD research reports to provide JAD readers with a readily accessible, yet comprehensive review of the state of contemporary research. Notably, this multi-part review identifies the "hottest" fields of AD research providing guidance for both senior investigators as well as investigators new to the field on what is the most pressing fields within AD research. Part 1 of this review covers pathogenesis, both on a molecular and macro scale. Part 2 review genetics and epidemiology, and part 3 covers diagnosis and treatment. This part of the review, pathology, reviews amyloid-β, tau, prions, brain structure, and functional changes with AD and the neuroimmune response of AD.
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Affiliation(s)
- Francis T Hane
- Department of Biology, University of Waterloo, Waterloo, ON, Canada.,Department of Chemistry, Lakehead University, Thunder Bay, ON, Canada
| | - Brenda Y Lee
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
| | - Zoya Leonenko
- Department of Biology, University of Waterloo, Waterloo, ON, Canada.,Department of Physics and Astronomy, University of Waterloo, Waterloo, ON, Canada
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28
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Barz B, Liao Q, Strodel B. Pathways of Amyloid-β Aggregation Depend on Oligomer Shape. J Am Chem Soc 2017; 140:319-327. [PMID: 29235346 DOI: 10.1021/jacs.7b10343] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
One of the main research topics related to Alzheimer's disease is the aggregation of the amyloid-β peptide, which was shown to follow different pathways for the two major alloforms of the peptide, Aβ40 and the more toxic Aβ42. Experimental studies emphasized that oligomers of specific sizes appear in the early aggregation process in different quantities and might be the key toxic agents for each of the two alloforms. We use transition networks derived from all-atom molecular dynamics simulations to show that the oligomers leading to the type of oligomer distributions observed in experiments originate from compact conformations. Extended oligomers, on the other hand, contribute more to the production of larger aggregates thus driving the aggregation process. We further demonstrate that differences in the aggregation pathways of the two Aβ alloforms occur as early as during the dimer stage. The higher solvent-exposure of hydrophobic residues in Aβ42 oligomers contributes to the different aggregation pathways of both alloforms and also to the increased cytotoxicity of Aβ42.
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Affiliation(s)
- Bogdan Barz
- Institute of Complex Systems: Structural Biochemistry (ICS-6), Forschungszentrum Jülich GmbH , 52425 Jülich, Germany.,Institute of Theoretical and Computational Chemistry, Heinrich Heine University Düsseldorf , 40225 Düsseldorf, Germany
| | - Qinghua Liao
- Institute of Complex Systems: Structural Biochemistry (ICS-6), Forschungszentrum Jülich GmbH , 52425 Jülich, Germany.,Department of Cell and Molecular Biology, Uppsala University , S-75124 Uppsala, Sweden
| | - Birgit Strodel
- Institute of Complex Systems: Structural Biochemistry (ICS-6), Forschungszentrum Jülich GmbH , 52425 Jülich, Germany.,Institute of Theoretical and Computational Chemistry, Heinrich Heine University Düsseldorf , 40225 Düsseldorf, Germany
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29
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Weber OC, Uversky VN. How accurate are your simulations? Effects of confined aqueous volume and AMBER FF99SB and CHARMM22/CMAP force field parameters on structural ensembles of intrinsically disordered proteins: Amyloid-β 42 in water. INTRINSICALLY DISORDERED PROTEINS 2017; 5:e1377813. [PMID: 30250773 DOI: 10.1080/21690707.2017.1377813] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 09/04/2017] [Accepted: 09/06/2017] [Indexed: 12/14/2022]
Abstract
Amyloid-β42 (Aβ42) is an intrinsically disordered peptide intimately related to the pathogenesis of several neurodegenerative diseases. Molecular dynamics (MD) simulations are extensively utilized in the characterization of the structures and conformational dynamics of intrinsically disordered proteins (IDPs) including Aβ42, with AMBER and CHARMM parameters being commonly used in these studies. Recently, comparison of the effects of force field parameters on the Aβ42 structures has started to gain significant attention. In this study, the structures of Aβ42 are simulated using AMBER FF99SB and CHARMM22/CMAP parameters via replica exchange MD simulations utilizing a widely used clustering algorithm. These analyses show that the structural properties (extent and positioning of the elements of secondary and tertiary structure), radius of gyration values, number and position of salt bridges are extremely dependent on the chosen force field parameters notably with the usage of clustering algorithms. For example, predicted secondary structure elements, which are of the great importance for better understanding of the molecular mechanisms of neurodegenerative diseases, deviate enormously in models generated using currently available force field parameters for proteins. Based on the derived models, chemical shift values are calculated and compared to the experimentally determined data. This comparison revealed that although both force field parameters yield results in agreement with experiments, the obtained structural properties were rather different using a clustering algorithm. In other words, these results show that the predicted structures depend heavily on the force field parameters. Importantly, since none of the force field parameters currently utilized in MD studies were developed specifically taking into account the disordered nature of IDPs, these findings clearly indicate that new force field parameters have to be developed for IDPs considering their rapid flexibility and dynamics with high amplitude. Furthermore, molecular simulations of IDPs are typically conducted using one water volume. We show that the confined aqueous volume impacts the predicted structural properties of Aβ42 in water. Although up to date, confined aqueous volume effects have been ignored in the MD simulations of IDPs in water, our data indicate that these effects have to be taken into account in predicting the structural and thermodynamic properties of disordered proteins in solution.
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Affiliation(s)
- Orkid Coskuner Weber
- Department of Chemistry and Neurosciences Institute, The University of Texas at San Antonio, San Antonio, TX, USA.,Institut für Physikalische Chemie, Universität zu Köln, Köln, Germany.,Molecular Biotechnology Division, Turkisch-Deutsche Universität, Istanbul Turkey
| | - Vladimir N Uversky
- Department of Molecular Medicine, USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL, USA.,Laboratory of New Methods in Biology, Institute for Biological Instrumentation, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
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30
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Cao Y, Jiang X, Han W. Self-Assembly Pathways of β-Sheet-Rich Amyloid-β(1-40) Dimers: Markov State Model Analysis on Millisecond Hybrid-Resolution Simulations. J Chem Theory Comput 2017; 13:5731-5744. [PMID: 29019683 DOI: 10.1021/acs.jctc.7b00803] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Early oligomerization during amyloid-β (Aβ) aggregation is essential for Aβ neurotoxicity. Understanding how unstructured Aβs assemble into oligomers, especially those rich in β-sheets, is essential but remains challenging as the assembly process is too transient for experimental characterization and too slow for molecular dynamics simulations. So far, atomic simulations are limited only to studies of either oligomer structures or assembly pathways for short Aβ segments. To overcome the computational challenge, we combine in this study a hybrid-resolution model and adaptive sampling techniques to perform over 2.7 ms of simulations of formation of full-length Aβ40 dimers that are the earliest toxic oligomeric species. The Markov state model is further employed to characterize the transition pathways and associated kinetics. Our results show that for two major forms of β-sheet-rich structures reported experimentally, the corresponding assembly mechanisms are markedly different. Hairpin-containing structures are formed by direct binding of soluble Aβ in β-hairpin-like conformations. Formation of parallel, in-register structures resembling fibrils occurs ∼100-fold more slowly and involves a rapid encounter of Aβ in arbitrary conformations followed by a slow structural conversion. The structural conversion proceeds via diverse pathways but always requires transient unfolding of encounter complexes. We find that the transition kinetics could be affected differently by intra-/intermolecular interactions involving individual residues in a conformation-dependent manner. In particular, the interactions involving Aβ's N-terminal part promote the assembly into hairpin-containing structures but delay the formation of fibril-like structures, thus explaining puzzling observations reported previously regarding the roles of this region in the early assembly process.
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Affiliation(s)
- Yang Cao
- Key Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School , Shenzhen, 518055, China
| | - Xuehan Jiang
- Key Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School , Shenzhen, 518055, China
| | - Wei Han
- Key Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School , Shenzhen, 518055, China
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31
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Chakraborty S, Das P. Emergence of Alternative Structures in Amyloid Beta 1-42 Monomeric Landscape by N-terminal Hexapeptide Amyloid Inhibitors. Sci Rep 2017; 7:9941. [PMID: 28855598 PMCID: PMC5577341 DOI: 10.1038/s41598-017-10212-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 08/04/2017] [Indexed: 02/01/2023] Open
Abstract
Alzheimer’s disease (AD) is characterized by deposition of amyloid beta (Aβ) peptides into senile plaques in the brain. While most familial mutations are associated with early-onset AD, recent studies report the AD-protective nature of two genetic human Aβ variants, i.e. A2T and A2V, in the heterozygous state. The mixture of A2V Aβ1-6 (Aβ6) hexapeptide and WT Aβ1–42 (Αβ42) is also found neuroprotective. Motivated by these findings, in this study we investigate the effects of WT, A2V, and A2T Aβ6 hexapeptide binding on the monomeric WT Aβ42 landscape. For this purpose, we have performed extensive atomistic Replica Exchange Molecular Dynamics simulations, elucidating preferential binding of Aβ42 with the A2V and A2T hexapeptides compared to WT Aβ6. A notable reorganization of the Aβ42 landscape is revealed due to hexapeptide association, as manifested by lowering of transient interactions between the central and C-terminal hydrophobic patches. Concurrently, Aβ6-bound Aβ42 monomer exhibits alternative structural features that are strongly dependent on the hexapeptide sequence. For example, a central helix is more frequently populated within the A2T-bound monomer, while A2V-bound Aβ42 is often enhanced in overall disorder. Taken together, the present simulations offer novel molecular insights onto the effect of the N-terminal hexapeptide binding on the Aβ42 monomer structure, which might help in explaining their reported amyloid inhibition properties.
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Affiliation(s)
| | - Payel Das
- IBM Thomas J. Watson Research Center, Yorktown Heights, NY, 10598, USA.
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32
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Voelker MJ, Barz B, Urbanc B. Fully Atomistic Aβ40 and Aβ42 Oligomers in Water: Observation of Porelike Conformations. J Chem Theory Comput 2017; 13:4567-4583. [DOI: 10.1021/acs.jctc.7b00495] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Matthew J. Voelker
- Department
of Physics, Drexel University, Philadelphia, Pennsylvania 19104, United States
| | - Bogdan Barz
- Institute
of Complex Systems, Structural Biochemistry ICS-6: Structural Biochemistry, Forschungzentrum Jülich GmbH, Jülich 52425, Germany
- Institute
of Theoretical and Computational Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf 40225, Germany
| | - Brigita Urbanc
- Department
of Physics, Drexel University, Philadelphia, Pennsylvania 19104, United States
- Faculty
of Mathematics and Physics, University of Ljubljana, Ljubljana 1000, Slovenia
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33
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Dorosh L, Stepanova M. Probing oligomerization of amyloid beta peptide in silico. MOLECULAR BIOSYSTEMS 2017; 13:165-182. [PMID: 27844078 DOI: 10.1039/c6mb00441e] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Aggregation of amyloid β (Aβ) peptide is implicated in fatal Alzheimer's disease, for which no cure is available. Understanding the mechanisms responsible for this aggregation is required in order for therapies to be developed. In an effort to better understand the molecular mechanisms involved in spontaneous aggregation of Aβ peptide, extensive molecular dynamics simulations are reported, and the results are analyzed through a combination of structural biology tools and a novel essential collective dynamics method. Several model systems composed of ten or twelve Aβ17-42 chains in water are investigated, and the influence of metal ions is probed. The results suggest that Aβ monomers tend to aggregate into stable globular-like oligomers with 13-23% of β-sheet content. Two stages of oligomer formation have been identified: quick collapse within the first 40 ns of the simulation, characterized by a decrease in inter-chain separation and build-up of β-sheets, and the subsequent slow relaxation of the oligomer structure. The resulting oligomers comprise a stable, coherently moving sub-aggregate of 6-9 strongly inter-correlated chains. Cu2+ and Fe2+ ions have been found to develop coordination bonds with carboxylate groups of E22, D23 and A42, which remain stable during 200 ns simulations. The presence of Fe2+, and particularly Cu2+ ions, in negatively charged cavities has been found to cause significant changes in the structure and dynamics of the oligomers. The results indicate, in particular, that formation of non-fibrillar oligomers might be involved in early template-free aggregation of Aβ17-42 monomers, with charged species such as Cu2+ or Fe2+ ions playing an important role.
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Affiliation(s)
- L Dorosh
- Department of Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta, Canada. and National Research Council of Canada, Edmonton, Alberta, Canada
| | - M Stepanova
- Department of Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta, Canada. and National Research Council of Canada, Edmonton, Alberta, Canada and Department of Physics, Astronomy, and Materials Science, Missouri State University, Springfield, MO, USA
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34
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Brown AM, Bevan DR. Molecular Dynamics Simulations of Amyloid β-Peptide (1-42): Tetramer Formation and Membrane Interactions. Biophys J 2017; 111:937-49. [PMID: 27602722 DOI: 10.1016/j.bpj.2016.08.001] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Revised: 07/29/2016] [Accepted: 08/02/2016] [Indexed: 01/10/2023] Open
Abstract
The aggregation cascade and peptide-membrane interactions of the amyloid β-peptide (Aβ) have been implicated as toxic events in the development and progression of Alzheimer's disease. Aβ42 forms oligomers and ultimately plaques, and it has been hypothesized that these oligomeric species are the main toxic species contributing to neuronal cell death. To better understand oligomerization events and subsequent oligomer-membrane interactions of Aβ42, we performed atomistic molecular-dynamics (MD) simulations to characterize both interpeptide interactions and perturbation of model membranes by the peptides. MD simulations were utilized to first show the formation of a tetramer unit by four separate Aβ42 peptides. Aβ42 tetramers adopted an oblate ellipsoid shape and showed a significant increase in β-strand formation in the final tetramer unit relative to the monomers, indicative of on-pathway events for fibril formation. The Aβ42 tetramer unit that formed in the initial simulations was used in subsequent MD simulations in the presence of a pure POPC or cholesterol-rich raft model membrane. Tetramer-membrane simulations resulted in elongation of the tetramer in the presence of both model membranes, with tetramer-raft interactions giving rise to the rearrangement of key hydrophobic regions in the tetramer and the formation of a more rod-like structure indicative of a fibril-seeding aggregate. Membrane perturbation by the tetramer was manifested in the form of more ordered, rigid membranes, with the pure POPC being affected to a greater extent than the raft membrane. These results provide critical atomistic insight into the aggregation pathway of Aβ42 and a putative toxic mechanism in the pathogenesis of Alzheimer's disease.
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Affiliation(s)
- Anne M Brown
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia
| | - David R Bevan
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia.
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35
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Man VH, Nguyen PH, Derreumaux P. High-Resolution Structures of the Amyloid-β 1-42 Dimers from the Comparison of Four Atomistic Force Fields. J Phys Chem B 2017; 121:5977-5987. [PMID: 28538095 DOI: 10.1021/acs.jpcb.7b04689] [Citation(s) in RCA: 110] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The dimer of the amyloid-β peptide Aβ of 42 residues is the smallest toxic species in Alzheimer's disease, but its equilibrium structures are unknown. Here we determined the equilibrium ensembles generated by the four atomistic OPLS-AA, CHARMM22*, AMBER99sb-ildn, and AMBERsb14 force fields with the TIP3P water model. On the basis of 144 μs replica exchange molecular dynamics simulations (with 750 ns per replica), we find that the four force fields lead to random coil ensembles with calculated cross-collision sections, hydrodynamics properties, and small-angle X-ray scattering profiles independent of the force field. There are, however, marked differences in secondary structure, with the AMBERsb14 and CHARMM22* ensembles overestimating the CD-derived helix content, and the OPLS-AA and AMBER99sb-ildn secondary structure contents in agreement with CD data. Also the intramolecular beta-hairpin content spanning residues 17-21 and 30-36 varies between 1.5% and 13%. Overall, there are significant differences in tertiary and quaternary conformations among all force fields, and the key finding, irrespective of the force field, is that the dimer is stabilized by nonspecific interactions, explaining therefore its possible transient binding to multiple cellular partners and, in part, its toxicity.
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Affiliation(s)
- Viet Hoang Man
- Department of Physics, North Carolina State University , Raleigh, North Carolina 27695-8202, United States
| | - Phuong H Nguyen
- Laboratoire de Biochimie Théorique, UPR 9080 CNRS, Université Paris Diderot , Sorbonne Paris Cité, IBPC, 13 Rue Pierre et Marie Curie, 75005 Paris, France
| | - Philippe Derreumaux
- Laboratoire de Biochimie Théorique, UPR 9080 CNRS, Université Paris Diderot , Sorbonne Paris Cité, IBPC, 13 Rue Pierre et Marie Curie, 75005 Paris, France
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36
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Man VH, Nguyen PH, Derreumaux P. Conformational Ensembles of the Wild-Type and S8C Aβ1-42 Dimers. J Phys Chem B 2017; 121:2434-2442. [PMID: 28245647 PMCID: PMC5944329 DOI: 10.1021/acs.jpcb.7b00267] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
We characterized the dimer of the amyloid-β wild-type (WT) peptide, Aβ, of 42 residues and its disulfide-bond-locked double mutant (S8C) by replica exchange molecular dynamics simulations. Aβ dimers are known to be the smallest toxic species in Alzheimer's disease, and the S8C mutant has been shown experimentally to form an exclusive homogeneous and neurotoxic dimer. Our 50 μs all-atom simulations reveal similar secondary structures and collision cross-sections but very different intramolecular and intermolecular conformations upon double S8C mutation. Both dimers are very dynamic with hundreds of free-energy minima that differ from the U-shape and S-shape conformations of the peptides in the fibrils. The only common structural feature, shared by both species with a probability of 4% in WT and 12% in S8C-S8C, is a three-stranded β-sheet spanning the 17-23, 29-36, and 39-41 residues, which does not exist in the Aβ40 WT dimers.
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Affiliation(s)
- Viet Hoang Man
- Department of Physics, North Carolina State University, Raleigh, North Carolina 27695-8202, United States
| | - Phuong H. Nguyen
- Laboratoire de Biochimie Théorique, UPR 9080 CNRS, Université Paris Diderot, Sorbonne Paris Cité, IBPC, 13 Rue Pierre et Marie Curie, 75005 Paris, France
| | - Philippe Derreumaux
- Laboratoire de Biochimie Théorique, UPR 9080 CNRS, Université Paris Diderot, Sorbonne Paris Cité, IBPC, 13 Rue Pierre et Marie Curie, 75005 Paris, France
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37
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Das P, Chacko AR, Belfort G. Alzheimer's Protective Cross-Interaction between Wild-Type and A2T Variants Alters Aβ 42 Dimer Structure. ACS Chem Neurosci 2017; 8:606-618. [PMID: 28292185 DOI: 10.1021/acschemneuro.6b00357] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Whole genome sequencing has recently revealed the protective effect of a single A2T mutation in heterozygous carriers against Alzheimer's disease (AD) and age-related cognitive decline. The impact of the protective cross-interaction between the wild-type (WT) and A2T variants on the dimer structure is therefore of high interest, as the Aβ dimers are the smallest known neurotoxic species. Toward this goal, extensive atomistic replica exchange molecular dynamics simulations of the solvated WT homo- and A2T hetero- Aβ1-42 dimers have been performed, resulting into a total of 51 μs of sampling for each system. Weakening of a set of transient, intrachain contacts formed between the central and C-terminal hydrophobic residues is observed in the heterodimeric system. The majority of the heterodimers with reduced interaction between central and C-terminal regions lack any significant secondary structure and display a weak interchain interface. Interestingly, the A2T N-terminus, particularly residue F4, is frequently engaged in tertiary and quaternary interactions with central and C-terminal hydrophobic residues in those distinct structures, leading to hydrophobic burial. This atypical involvement of the N-terminus within A2T heterodimer revealed in our simulations implies possible interference on Aβ42 aggregation and toxic oligomer formation, which is consistent with experiments. In conclusion, the present study provides detailed structural insights onto A2T Aβ42 heterodimer, which might provide molecular insights onto the AD protective effect of the A2T mutation in the heterozygous state.
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Affiliation(s)
- Payel Das
- IBM Thomas J. Watson Research Center, Yorktown Heights, New York 10598, United States
| | - Anita R. Chacko
- IBM Thomas J. Watson Research Center, Yorktown Heights, New York 10598, United States
| | - Georges Belfort
- Howard
P. Isermann Department of Chemical and Biological Engineering, and
Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York 12180-3590, United States
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38
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Abstract
The investigation of intrinsically disordered proteins (IDPs) is a new frontier in structural and molecular biology that requires a new paradigm to connect structural disorder to function. Molecular dynamics simulations and statistical thermodynamics potentially offer ideal tools for atomic-level characterizations and thermodynamic descriptions of this fascinating class of proteins that will complement experimental studies. However, IDPs display sensitivity to inaccuracies in the underlying molecular mechanics force fields. Thus, achieving an accurate structural characterization of IDPs via simulations is a challenge. It is also daunting to perform a configuration-space integration over heterogeneous structural ensembles sampled by IDPs to extract, in particular, protein configurational entropy. In this review, we summarize recent efforts devoted to the development of force fields and the critical evaluations of their performance when applied to IDPs. We also survey recent advances in computational methods for protein configurational entropy that aim to provide a thermodynamic link between structural disorder and protein activity.
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Affiliation(s)
- Song-Ho Chong
- Department of Chemistry, Sookmyung Women's University, Yongsan-Ku, Seoul 04310, Korea;
| | - Prathit Chatterjee
- Department of Chemistry, Sookmyung Women's University, Yongsan-Ku, Seoul 04310, Korea;
| | - Sihyun Ham
- Department of Chemistry, Sookmyung Women's University, Yongsan-Ku, Seoul 04310, Korea;
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39
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Urbanc B. Flexible N‐Termini of Amyloid β‐Protein Oligomers: A Link between Structure and Activity? Isr J Chem 2017. [DOI: 10.1002/ijch.201600097] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Brigita Urbanc
- Department of Physics Drexel University Philadelphia, PA 19104 USA
- Faculty of Mathematics and Physics Jadranska ulica 19 1000 Ljubljana Slovenia
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40
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Liao Q, Owen MC, Olubiyi OO, Barz B, Strodel B. Conformational Transitions of the Amyloid-β Peptide Upon Copper(II) Binding and pH Changes. Isr J Chem 2017. [DOI: 10.1002/ijch.201600108] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Qinghua Liao
- Institute of Complex Systems: Structural Biochemistry (ICS-6); Forschungszentrum Jülich GmbH; 52425 Jülich Germany
| | - Michael C. Owen
- Institute of Complex Systems: Structural Biochemistry (ICS-6); Forschungszentrum Jülich GmbH; 52425 Jülich Germany
| | - Olujide O. Olubiyi
- Department of Pharmacology and Therapeutics; College of Medicine and Health Sciences; Afe Babalola University; Nigeria
| | - Bogdan Barz
- Institute of Complex Systems: Structural Biochemistry (ICS-6); Forschungszentrum Jülich GmbH; 52425 Jülich Germany
- Institute of Theoretical and Computational Chemistry; Heinrich Heine University Düsseldorf; 40225 Düsseldorf Germany
| | - Birgit Strodel
- Institute of Complex Systems: Structural Biochemistry (ICS-6); Forschungszentrum Jülich GmbH; 52425 Jülich Germany
- Institute of Theoretical and Computational Chemistry; Heinrich Heine University Düsseldorf; 40225 Düsseldorf Germany
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41
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Zhang Y, Hashemi M, Lv Z, Lyubchenko YL. Self-assembly of the full-length amyloid Aβ42 protein in dimers. NANOSCALE 2016; 8:18928-18937. [PMID: 27714140 PMCID: PMC5114164 DOI: 10.1039/c6nr06850b] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The self-assembly of amyloid (Aβ) proteins into nano-aggregates is a hallmark of Alzheimer's disease (AD) development, yet the mechanism of how disordered monomers assemble into aggregates remains elusive. Here, we applied long-time molecular dynamics simulations to fully characterize the assembly of Aβ42 monomers into dimers. Monomers undergo conformational changes during their interaction, but the resulting dimer structures do not resemble those found in fibril structures. To identify natural conformations of dimers among a set of simulated ones, validation approaches were developed and applied, and a subset of dimer conformations were characterized. These dimers do not contain long β-strands that are usually found in fibrils. The dimers are stabilized primarily by interactions within the central hydrophobic regions and the C-terminal regions, with a contribution from local hydrogen bonding. The dimers are dynamic, as evidenced by the existence of a set of conformations and by the quantitative analyses of the dimer dissociation process.
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Affiliation(s)
- Yuliang Zhang
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, NE 69198, USA.
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42
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Huy PDQ, Vuong QV, La Penna G, Faller P, Li MS. Impact of Cu(II) Binding on Structures and Dynamics of Aβ 42 Monomer and Dimer: Molecular Dynamics Study. ACS Chem Neurosci 2016; 7:1348-1363. [PMID: 27454036 DOI: 10.1021/acschemneuro.6b00109] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The classical force field, which is compatible with the Amber force field 99SB, has been obtained for the interaction of Cu(II) with monomer and dimers of amyloid-β peptides using the coordination where Cu(II) is bound to His6, His13 (or His14), and Asp1 with distorted planar geometry. The newly developed force field and molecular dynamics simulation were employed to study the impact of Cu(II) binding on structures and dynamics of Aβ42 monomer and dimers. It was shown that in the presence of Cu(II) the β content of monomer is reduced substantially compared with the wild-type Aβ42 suggesting that, in accord with experiments, metal ions facilitate formation of amorphous aggregates rather than amyloid fibrils with cross-β structures. In addition, one possible mechanism for amorphous assembly is that the Asp23-Lys28 salt bridge, which plays a crucial role in β sheet formation, becomes more flexible upon copper ion binding to the Aβ N-terminus. The simulation of dimers was conducted with the Cu(II)/Aβ stoichiometric ratios of 1:1 and 1:2. For the 1:1 ratio Cu(II) delays the Aβ dimerization process as observed in a number of experiments. The mechanism underlying this phenomenon is associated with slow formation of interchain salt bridges in dimer as well as with decreased hydrophobicity of monomer upon Cu-binding.
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Affiliation(s)
- Pham Dinh Quoc Huy
- Institute
of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw, Poland
- Institute
for Computational Science and Technology, Quang Trung Software City, Tan Chanh Hiep Ward, District 12, Ho Chi
Minh City, Vietnam
| | - Quan Van Vuong
- Institute
for Computational Science and Technology, Quang Trung Software City, Tan Chanh Hiep Ward, District 12, Ho Chi
Minh City, Vietnam
- Department
of Chemistry, Nagoya University, Nagoya 464-8602, Japan
| | - Giovanni La Penna
- National Research Council of Italy CNR, Institute
for Chemistry of Organometallic Compounds ICCOM, 50019 Florence, Italy
- Italian Institute for Nuclear Physics INFN, Section
of Roma-Tor Vergata, 50019 Florence, Italy
| | - Peter Faller
- Biometals
and Biological Chemistry, Institute of Chemistry, University of Strasbourg, 4 rue B. Pascal, 67081 Strasbourg, France
| | - Mai Suan Li
- Institute
of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw, Poland
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43
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Žganec M, Žerovnik E, Urbanc B. Assembly of Stefin B into Polymorphic Oligomers Probed by Discrete Molecular Dynamics. J Chem Theory Comput 2016; 11:2355-66. [PMID: 26574430 DOI: 10.1021/acs.jctc.5b00067] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Assembly of an amyloidogenic protein stefin B into molten globule oligomers is studied by efficient discrete molecular dynamics. Consistent with in vitro findings, tetramers form primarily through dimer association, resulting in a decreased trimer abundance. Oligomers up to heptamers display elongated rod-like morphologies akin to protofibrils, whereas larger oligomers, decamers through dodecamers, form elongated, branched, as well as annular structures, providing structural insights into pore forming ability and toxicity of amyloidogenic proteins.
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Affiliation(s)
- Matjaž Žganec
- Faculty of Mathematics and Physics, University of Ljubljana , 1000 Ljubljana, Slovenia.,Department of Biochemistry and Molecular and Structural Biology, Jožef Stefan Institute , 1000 Ljubljana, Slovenia
| | - Eva Žerovnik
- Department of Biochemistry and Molecular and Structural Biology, Jožef Stefan Institute , 1000 Ljubljana, Slovenia
| | - Brigita Urbanc
- Faculty of Mathematics and Physics, University of Ljubljana , 1000 Ljubljana, Slovenia.,Department of Physics, Drexel University , Philadelphia, Pennsylvania 19104, United States
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44
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Chiricotto M, Tran TT, Nguyen PH, Melchionna S, Sterpone F, Derreumaux P. Coarse-grained and All-atom Simulations towards the Early and Late Steps of Amyloid Fibril Formation. Isr J Chem 2016. [DOI: 10.1002/ijch.201600048] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Mara Chiricotto
- Laboratoire de Biochimie Théorique, UPR 9080 CNRS; Université Paris Diderot, Sorbonne Paris Cité, IBPC; 13 Rue Pierre et Marie Curie 75005 Paris France
| | - Thanh Thuy Tran
- Laboratoire de Biochimie Théorique, UPR 9080 CNRS; Université Paris Diderot, Sorbonne Paris Cité, IBPC; 13 Rue Pierre et Marie Curie 75005 Paris France
| | - Phuong H. Nguyen
- Laboratoire de Biochimie Théorique, UPR 9080 CNRS; Université Paris Diderot, Sorbonne Paris Cité, IBPC; 13 Rue Pierre et Marie Curie 75005 Paris France
| | - Simone Melchionna
- Istituto Sistemi Complessi; Consiglio Nazionale delle Ricerche; P. le A. Moro 2 00185 Rome Italy
| | - Fabio Sterpone
- Laboratoire de Biochimie Théorique, UPR 9080 CNRS; Université Paris Diderot, Sorbonne Paris Cité, IBPC; 13 Rue Pierre et Marie Curie 75005 Paris France
| | - Philippe Derreumaux
- Laboratoire de Biochimie Théorique, UPR 9080 CNRS; Université Paris Diderot, Sorbonne Paris Cité, IBPC; 13 Rue Pierre et Marie Curie 75005 Paris France
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45
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Nguyen PH, Sterpone F, Campanera JM, Nasica-Labouze J, Derreumaux P. Impact of the A2V Mutation on the Heterozygous and Homozygous Aβ1-40 Dimer Structures from Atomistic Simulations. ACS Chem Neurosci 2016; 7:823-32. [PMID: 27007027 DOI: 10.1021/acschemneuro.6b00053] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The A2V mutation was reported to protect from Alzheimer's disease in its heterozygous form and cause an early Alzheimer's disease type dementia in its homozygous form. Experiments showed that the aggregation rate follows the order A2V > WT (wild-type) > A2V-WT. To understand the impact of this mutation, we carried out replica exchange molecular dynamics simulations of Aβ1-40 WT-A2V and A2V-A2V dimers and compared to the WT dimer. Our atomistic simulations reveal that the mean secondary structure remains constant, but there are substantial differences in the intramolecular and intermolecular conformations upon single and double A2V mutation. Upon single mutation, the intrinsic disorder is reduced, the intermolecular potential energies are reduced, the population of intramolecular three-stranded β-sheets is increased, and the number of all α dimer topologies is decreased. Taken together, these results offer an explanation for the reduced aggregation rate of the Aβ1-40 A2V-WT peptides and the protective effect of A2V in heterozygotes.
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Affiliation(s)
- Phuong H. Nguyen
- Laboratoire de
Biochimie Théorique, UPR 9080 CNRS, Université Paris
Diderot, Sorbonne Paris Cité, IBPC, 13 Rue Pierre et Marie Curie, 75005 Paris, France
| | - Fabio Sterpone
- Laboratoire de
Biochimie Théorique, UPR 9080 CNRS, Université Paris
Diderot, Sorbonne Paris Cité, IBPC, 13 Rue Pierre et Marie Curie, 75005 Paris, France
| | - Josep M. Campanera
- Departament
de Fisicoquimica, Facultat de Farmacia, Universitat de Barcelona, 08028 Barcelona, Catalonia, Spain
| | - Jessica Nasica-Labouze
- Laboratoire de
Biochimie Théorique, UPR 9080 CNRS, Université Paris
Diderot, Sorbonne Paris Cité, IBPC, 13 Rue Pierre et Marie Curie, 75005 Paris, France
| | - Philippe Derreumaux
- Laboratoire de
Biochimie Théorique, UPR 9080 CNRS, Université Paris
Diderot, Sorbonne Paris Cité, IBPC, 13 Rue Pierre et Marie Curie, 75005 Paris, France
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46
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Barz B, Strodel B. Understanding Amyloid-β Oligomerization at the Molecular Level: The Role of the Fibril Surface. Chemistry 2016; 22:8768-72. [PMID: 27135646 DOI: 10.1002/chem.201601701] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Indexed: 12/11/2022]
Abstract
The aggregation of the amyloid β-peptide into fibrils is a complex process that involves mechanisms such as primary and secondary nucleation, fibril elongation and fibril fragmentation. Some of these processes generate neurotoxic Aβ oligomers, which are involved in the development of Alzheimer's disease. Recent experimental studies have emphasized the role of the fibril as a catalytic surface for the production of highly toxic oligomers during secondary nucleation. By using molecular dynamics simulations, we show that it is the hydrophobic fibril region that causes the structural changes required for catalyzing the formation of β-sheet-rich Aβ1-42 oligomers on the fibril surface. These results reveal, for the first time, the molecular basis of the secondary nucleation pathway.
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Affiliation(s)
- Bogdan Barz
- Institute of Complex Systems: Structural Biochemistry (ICS-6), Forschungszentrum Jülich GmbH, 52425, Jülich, Germany
| | - Birgit Strodel
- Institute of Theoretical and Computational Chemistry, Heinrich Heine University Düsseldorf, Universitätstrasse 1, 40225, Düsseldorf, Germany. , .,Institute of Complex Systems: Structural Biochemistry (ICS-6), Forschungszentrum Jülich GmbH, 52425, Jülich, Germany. ,
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Amino acid substitutions [K16A] and [K28A] distinctly affect amyloid β-protein oligomerization. J Biol Phys 2016; 42:453-76. [PMID: 27155979 DOI: 10.1007/s10867-016-9417-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 03/28/2016] [Indexed: 10/21/2022] Open
Abstract
Amyloid β-protein (A β) assembles into oligomers that play a seminal role in Alzheimer's disease (AD), a leading cause of dementia among the elderly. Despite undisputed importance of A β oligomers, their structure and the basis of their toxicity remain elusive. Previous experimental studies revealed that the [K16A] substitution strongly inhibits toxicity of the two predominant A β alloforms in the brain, A β 40 and A β 42, whereas the [K28A] substitution exerts only a moderate effect. Here, folding and oligomerization of [A16]A β 40, [A28]A β 40, [A16]A β 42, and [A28]A β 42 are examined by discrete molecular dynamics (DMD) combined with a four-bead implicit solvent force field, DMD4B-HYDRA, and compared to A β 40 and A β 42 oligomer formation. Our results show that both substitutions promote A β 40 and A β 42 oligomerization and that structural changes to oligomers are substitution- and alloform-specific. The [K28A] substitution increases solvent-accessible surface area of hydrophobic residues and the intrapeptide N-to-C terminal distance within oligomers more than the [K16A] substitution. The [K16A] substitution decreases the overall β-strand content, whereas the [K28A] substitution exerts only a modest change. Substitution-specific tertiary and quaternary structure changes indicate that the [K16A] substitution induces formation of more compact oligomers than the [K28A] substitution. If the structure-function paradigm applies to A β oligomers, then the observed substitution-specific structural changes in A β 40 and A β 42 oligomers are critical for understanding the structural basis of A β oligomer toxicity and correct identification of therapeutic targets against AD.
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Sun Y, Qian Z, Wei G. The inhibitory mechanism of a fullerene derivative against amyloid-β peptide aggregation: an atomistic simulation study. Phys Chem Chem Phys 2016; 18:12582-91. [PMID: 27091578 DOI: 10.1039/c6cp01014h] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Alzheimer's disease (AD) is associated with the pathological self-assembly of amyloid-β (Aβ) peptides into β-sheet enriched fibrillar aggregates. Aβ dimers formed in the initial step of Aβ aggregation were reported to be the smallest toxic species. Inhibiting the formation of β-sheet-rich oligomers and fibrils is considered as the primary therapeutic strategy for AD. Previous studies reported that fullerene derivatives strongly inhibit Aβ fibrillation. However, the underlying inhibitory mechanism remains elusive. As a first step to understand fullerene-modulated full-length Aβ aggregation, we investigated the conformational ensemble of the Aβ1-42 dimer with and without 1,2-(dimethoxymethano)fullerene (DMF) - a more water-soluble fullerene derivative - by performing a 340 ns explicit-solvent replica exchange molecular dynamics simulation. Our simulations show that although disordered states are the most abundant conformations of the Aβ1-42 dimer, conformations containing diverse extended β-hairpins are also populated. The first most-populated β-hairpins involving residues L17-D23 and A30-V36 strongly resemble the engineered β-hairpin which is a building block of toxic Aβ oligomers. We find that the interaction of DMFs with Aβ peptides greatly impedes the formation of such β-hairpins and inter-peptide β-sheets. Binding energy analyses demonstrate that DMF preferentially binds not only to the central hydrophobic motif LVFFA of the Aβ peptide as suggested experimentally, but also to the aromatic residues including F4 and Y10 and the C-terminal hydrophobic region I31-V40. This study reveals a complete picture of the inhibitory mechanism of full-length Aβ1-42 aggregation by fullerenes, providing theoretical insights into the development of drug candidates against AD.
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Affiliation(s)
- Yunxiang Sun
- State Key Laboratory of Surface Physics, Key Laboratory for Computational Physical Sciences (MOE), and Department of Physics, Fudan University, 220 Handan Road, Shanghai, 200433, China.
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Nagel-Steger L, Owen MC, Strodel B. An Account of Amyloid Oligomers: Facts and Figures Obtained from Experiments and Simulations. Chembiochem 2016; 17:657-76. [PMID: 26910367 DOI: 10.1002/cbic.201500623] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Indexed: 12/27/2022]
Abstract
The deposition of amyloid in brain tissue in the context of neurodegenerative diseases involves the formation of intermediate species-termed oligomers-of lower molecular mass and with structures that deviate from those of mature amyloid fibrils. Because these oligomers are thought to be primarily responsible for the subsequent disease pathogenesis, the elucidation of their structure is of enormous interest. Nevertheless, because of the high aggregation propensity and the polydispersity of oligomeric species formed by the proteins or peptides in question, the preparation of appropriate samples for high-resolution structural methods has proven to be rather difficult. This is why theoretical approaches have been of particular importance in gaining insights into possible oligomeric structures for some time. Only recently has it been possible to achieve some progress with regard to the experimentally based structural characterization of defined oligomeric species. Here we discuss how theory and experiment are used to determine oligomer structures and what can be done to improve the integration of the two disciplines.
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Affiliation(s)
- Luitgard Nagel-Steger
- Institute of Complex Systems: Structural Biochemistry (ICS-6), Forschungszentrum Jülich, 52425, Jülich, Germany.,Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, Universitätstrasse 1, 40225, Düsseldorf, Germany
| | - Michael C Owen
- Institute of Complex Systems: Structural Biochemistry (ICS-6), Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Birgit Strodel
- Institute of Complex Systems: Structural Biochemistry (ICS-6), Forschungszentrum Jülich, 52425, Jülich, Germany. .,Institute of Theoretical and Computational Chemistry, Heinrich Heine University Düsseldorf, Universitätstrasse 1, 40225, Düsseldorf, Germany.
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Williams TL, Choi JK, Surewicz K, Surewicz WK. Soluble Prion Protein Binds Isolated Low Molecular Weight Amyloid-β Oligomers Causing Cytotoxicity Inhibition. ACS Chem Neurosci 2015; 6:1972-80. [PMID: 26466138 DOI: 10.1021/acschemneuro.5b00229] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
A growing number of observations indicate that soluble amyloid-β (Aβ) oligomers play a major role in Alzheimer's disease. Recent studies strongly suggest that at least some of the neurotoxic effects of these oligomers are mediated by cellular, membrane-anchored prion protein and that Aβ neurotoxicity can be inhibited by soluble recombinant prion protein (rPrP) and its fragments. However, the mechanism by which rPrP interacts with Aβ oligomers and prevents their toxicity is largely unknown, and studies in this regard are hindered by the large structural heterogeneity of Aβ oligomers. To overcome this difficulty, here we used photoinduced cross-linking of unmodified proteins (PICUP) to isolate well-defined oligomers of Aβ42 and characterize these species with regard to their cytotoxicity and interaction with rPrP, as well the mechanism by which rPrP inhibits Aβ42 cytotoxicity. Our data shows that the addition of rPrP to the assembling Aβ42 results in a shift in oligomer size distribution, decreasing the population of toxic tetramers and higher order oligomers and increasing the population of nontoxic (and possibly neuroprotective) monomers. Isolated oligomeric species of Aβ42 are cytotoxic to primary neurons and cause permeation of model lipid bilayers. These toxic effects, which are oligomer size-dependent, can be inhibited by the addition of rPrP, and our data suggest potential mechanisms of this inhibitory action. This insight should help in current efforts to develop PrP-based therapeutics for Alzheimer's disease.
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Affiliation(s)
- Thomas L. Williams
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Jin-Kyu Choi
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Krystyna Surewicz
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Witold K. Surewicz
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio 44106, United States
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