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Kurakin S, Ivankov O, Dushanov E, Murugova T, Ermakova E, Efimov S, Mukhametzyanov T, Smerdova S, Klochkov V, Kuklin A, Kučerka N. Calcium ions do not influence the Aβ(25-35) triggered morphological changes of lipid membranes. Biophys Chem 2024; 313:107292. [PMID: 39018778 DOI: 10.1016/j.bpc.2024.107292] [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: 03/06/2024] [Revised: 07/04/2024] [Accepted: 07/09/2024] [Indexed: 07/19/2024]
Abstract
We have studied the effect of calcium ions (Ca2+) at various concentrations on the structure of lipid vesicles in the presence of amyloid-beta peptide Aβ(25-35). In particular, we have investigated the influence of calcium ions on the formation of recently documented bicelle-like structures (BLSs) emerged as a result of Aβ(25-35) triggered membrane disintegration. First, we have shown by using small-angle X-ray and neutron scattering that peptide molecules rigidify the lipid bilayer of gel phase DPPC unilamellar vesicles (ULVs), while addition of the calcium ions to the system hinders this effect of Aβ(25-35). Secondly, the Aβ(25-35) demonstrates a critical peptide concentration at which the BLSs reorganize from ULVs due to heating and cooling the samples through the lipid main phase transition temperature (Tm). However, addition of calcium ions does not affect noticeably the Aβ-induced formation of BLSs and their structural parameters, though the changes in peptide's secondary structure, e.g. the increased α-helix fraction, has been registered by circular dichroism spectroscopy. Finally, according to 31P nuclear magnetic resonance (NMR) measurements, calcium ions do not affect the lipid-peptide arrangement in BLSs and their ability to align in the magnetic field of NMR spectrometer. The influences of various concentrations of calcium ions on the lipid-peptide interactions may prove biologically important because their local concentrations vary widely in in-vivo conditions. In the present work, calcium ions were investigated as a possible tool aimed at regulating the lipid-peptide interactions that demonstrated the disruptive effect of Aβ(25-35) on lipid membranes.
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Affiliation(s)
- Sergei Kurakin
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Joliot-Curie 6, Dubna, Moscow Region 141980, Russia; Institute of Physics, Kazan Federal University, Kremlevskaya 18, Kazan 420008, Russia.
| | - Oleksandr Ivankov
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Joliot-Curie 6, Dubna, Moscow Region 141980, Russia
| | - Ermuhammad Dushanov
- Laboratory of Radiation Biology, Joint Institute for Nuclear Research, Joliot-Curie 6, Dubna, Moscow Region 141980, Russia; Department of Biophysics, Dubna State University, Universitetskaya 19, Dubna, Moscow Region 141982, Russia
| | - Tatiana Murugova
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Joliot-Curie 6, Dubna, Moscow Region 141980, Russia
| | - Elena Ermakova
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Joliot-Curie 6, Dubna, Moscow Region 141980, Russia
| | - Sergey Efimov
- Institute of Physics, Kazan Federal University, Kremlevskaya 18, Kazan 420008, Russia
| | - Timur Mukhametzyanov
- Butlerov Chemistry Institute, Kazan Federal University, Kremlevskaya 18, Kazan 420008, Russia
| | - Svetlana Smerdova
- Kazan National Research Technological University, Karl Marx 68, Kazan 420015, Russia
| | - Vladimir Klochkov
- Institute of Physics, Kazan Federal University, Kremlevskaya 18, Kazan 420008, Russia
| | - Alexander Kuklin
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Joliot-Curie 6, Dubna, Moscow Region 141980, Russia; Moscow Institute of Physics and Technology, Instytutskiy Pereulok 9, Dolgoprudny, Moscow Region 141701, Russia
| | - Norbert Kučerka
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Joliot-Curie 6, Dubna, Moscow Region 141980, Russia; Department of Physical Chemistry of Drugs, Faculty of Pharmacy, Comenius University Bratislava, Odbojárov 10, Bratislava 832 32, Slovakia.
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Zeng J, Tang Y, Dong X, Li F, Wei G. Influence of ALS-linked M337V mutation on the conformational ensembles of TDP-43 321-340 peptide monomer and dimer. Proteins 2023. [PMID: 36841957 DOI: 10.1002/prot.26482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 02/12/2023] [Accepted: 02/19/2023] [Indexed: 02/27/2023]
Abstract
The transactive response (TAR) DNA/RNA-binding protein 43 (TDP-43) can self-assemble into both functional stress granules via liquid-liquid phase separation (LLPS) and pathogenic amyloid fibrillary aggregates that are closely linked to amyotrophic lateral sclerosis. Previous experimental studies reported that the low complexity domain (LCD) of TDP-43 plays an essential role in the LLPS and aggregation of the full-length protein, and it alone can also undergo LLPS to form liquid droplets mainly via intermolecular interactions in the 321-340 region. And the ALS-associated M337V mutation impairs LCD's LLPS and facilitates liquid-solid phase transition. However, the underlying atomistic mechanism is not well understood. Herein, as a first step to understand the M337V-caused LLPS disruption of TDP-43 LCD mediated by the 321-340 region and the fibrillization enhancement, we investigated the conformational properties of monomer/dimer of TDP-43321-340 peptide and its M337V mutant by performing extensive all-atom explicit-solvent replica exchange molecular dynamic simulations. Our simulations demonstrate that M337V mutation alters the residue regions with high helix/β-structure propensities and thus affects the conformational ensembles of both monomer and dimer. M337V mutation inhibits helix formation in the N-terminal Ala-rich region and the C-terminal mutation site region, while facilitating their long β-sheet formation, albeit with a minor impact on the average probability of both helix structure and β-structure. Further analysis of dimer system shows that M337V mutation disrupts inter-molecular helix-helix interactions and W334-W334 π-π stacking interactions which were reported to be important for the LLPS of TDP-43 LCD, whereas enhances the overall peptide residue-residue interactions and weakens peptide-water interactions, which is conducive to peptide fibrillization. This study provides mechanistic insights into the M337V-mutation-induced impairment of phase separation and facilitation of fibril formation of TDP-43 LCD.
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Affiliation(s)
- Jiyuan Zeng
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai, China
| | - Yiming Tang
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai, China
| | - Xuewei Dong
- Center for Soft Condensed Matter Physics and Interdisciplinary Research & School of Physical Science and Technology, Soochow University, Suzhou, Jiangsu, China
| | - Fangying Li
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai, China
| | - Guanghong Wei
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai, China
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Liu X, Ganguly P, Jin Y, Jhatro MJ, Shea JE, Buratto SK, Bowers MT. Tachykinin Neuropeptides and Amyloid β (25-35) Assembly: Friend or Foe? J Am Chem Soc 2022; 144:14614-14626. [PMID: 35917596 DOI: 10.1021/jacs.2c03845] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Amyloid β (Aβ) protein is responsible for Alzheimer's disease, and one of its important fragments, Aβ(25-35), is found in the brain and has been shown to be neurotoxic. Tachykinin neuropeptides, including Neuromedin K (NK), Kassinin, and Substance P, have been reported to reduce Aβ(25-35)'s toxicity in cells even though they share similar primary structures with Aβ(25-35). Here, we seek to understand the molecular mechanisms of how these peptides interact with Aβ(25-35) and to shed light on why some peptides with similar primary structures are toxic and others nontoxic. We use both experimental and computational methods, including ion mobility mass spectrometry and enhanced-sampling replica-exchange molecular dynamics simulations, to study the aggregation pathways of Aβ(25-35), NK, Kassinin, Substance P, and mixtures of the latter three with Aβ(25-35). NK and Substance P were observed to remove the higher-order oligomers (i.e., hexamers and dodecamers) of Aβ(25-35), which are related to its toxicity, although Substance P did so more slowly. In contrast, Kassinin was found to promote the formation of these higher-order oligomers. This result conflicts with what is expected and is elaborated on in the text. We also observe that even though they have significant structural homology with Aβ(25-35), NK, Kassinin, and Substance P do not form hexamers with a β-sheet structure like Aβ(25-35). The hexamer structure of Aβ(25-35) has been identified as a cylindrin, and this structure has been strongly correlated to toxic species. The reasons why the three tachykinin peptides behave so differently when mixed with Aβ(25-35) are discussed.
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Affiliation(s)
- Xikun Liu
- Department of Chemistry & Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Pritam Ganguly
- Department of Chemistry & Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Yingying Jin
- Department of Chemistry & Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Michael J Jhatro
- Department of Chemistry & Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Joan-Emma Shea
- Department of Chemistry & Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Steven K Buratto
- Department of Chemistry & Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Michael T Bowers
- Department of Chemistry & Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, United States
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Lao Z, Dong X, Liu X, Li F, Chen Y, Tang Y, Wei G. Insights into the Atomistic Mechanisms of Phosphorylation in Disrupting Liquid-Liquid Phase Separation and Aggregation of the FUS Low-Complexity Domain. J Chem Inf Model 2022; 62:3227-3238. [PMID: 35709363 DOI: 10.1021/acs.jcim.2c00414] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Fused in sarcoma (FUS), a nuclear RNA binding protein, can not only undergo liquid-liquid phase separation (LLPS) to form dynamic biomolecular condensates but also aggregate into solid amyloid fibrils which are associated with the pathology of amyotrophic lateral sclerosis and frontotemporal lobar degeneration diseases. Phosphorylation in the FUS low-complexity domain (FUS-LC) inhibits FUS LLPS and aggregation. However, it remains largely elusive what are the underlying atomistic mechanisms of this inhibitory effect and whether phosphorylation can disrupt preformed FUS fibrils, reversing the FUS gel/solid phase toward the liquid phase. Herein, we systematically investigate the impacts of phosphorylation on the conformational ensemble of the FUS37-97 monomer and dimer and the structure of the FUS37-97 fibril by performing extensive all-atom molecular dynamics simulations. Our simulations reveal three key findings: (1) phosphorylation shifts the conformations of FUS37-97 from the β-rich, fibril-competent state toward a helix-rich, fibril-incompetent state; (2) phosphorylation significantly weakens protein-protein interactions and enhances protein-water interactions, which disfavor FUS-LC LLPS as well as aggregation and facilitate the dissolution of the preformed FUS-LC fibril; and (3) the FUS37-97 peptide displays a high β-strand probability in the region spanning residues 52-67, and phosphorylation at S54 and S61 residues located in this region is crucial for the disruption of LLPS and aggregation of FUS-LC. This study may pave the way for ameliorating phase-separation-related pathologies via site-specific phosphorylation.
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Affiliation(s)
- Zenghui Lao
- Department of Physics, State Key Laboratory of Surface Physics, Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai 200433, People's Republic of China
| | - Xuewei Dong
- Department of Physics, State Key Laboratory of Surface Physics, Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai 200433, People's Republic of China
| | - Xianshi Liu
- Department of Physics, State Key Laboratory of Surface Physics, Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai 200433, People's Republic of China
| | - Fangying Li
- Department of Physics, State Key Laboratory of Surface Physics, Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai 200433, People's Republic of China
| | - Yujie Chen
- Department of Physics, State Key Laboratory of Surface Physics, Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai 200433, People's Republic of China
| | - Yiming Tang
- Department of Physics, State Key Laboratory of Surface Physics, Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai 200433, People's Republic of China
| | - Guanghong Wei
- Department of Physics, State Key Laboratory of Surface Physics, Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai 200433, People's Republic of China
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Zou Y, Guan L. Unraveling the Influence of K280 Acetylation on the Conformational Features of Tau Core Fragment: A Molecular Dynamics Simulation Study. Front Mol Biosci 2021; 8:801577. [PMID: 34966788 PMCID: PMC8710698 DOI: 10.3389/fmolb.2021.801577] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Accepted: 11/22/2021] [Indexed: 01/16/2023] Open
Abstract
Abnormal aggregation of the microtubule-associated protein Tau is closely associated with tauopathies, including Alzheimer's disease and chronic traumatic encephalopathy. The hexapeptide 275VQIINK280 (PHF6*), a fibril-nucleating core motif of Tau, has been shown to play a vital role in the aggregation of Tau. Mounting experiment evidence demonstrated the acetylation of a single-lysine residue K280 in the PHF6* was a critical event for the formation of pathological Tau amyloid deposits. However, the underlying mechanisms by which K280 acetylation affects Tau aggregation at the atomic level remain elusive. In this work, we performed replica exchange molecular dynamics simulations to investigate the influence of acetylation of K280 on the aggregation of PHF6*. Our simulations show that acetylation of K280 not only enhances the self-assembly capability of PHF6* peptides but also increases the β-sheet structure propensity of the PHF6*. The inter-molecular interactions among PHF6* peptides are strengthened by the acetylation of K280, resulting in an increased ordered β-sheet-rich conformations of the PHF6* assemblies along with a decrease of the structural diversity. The residue-pairwise contact frequency analysis shows that K280 acetylation increases the interactions among the hydrophobic chemical groups from PHF6* peptides, which promotes the aggregation of PHF6*. This study offers mechanistic insights into the effects of acetylation on the aggregation of PHF6*, which will be helpful for an in-depth understanding of the relationship between acetylation and Tau aggregation at the molecular level.
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Affiliation(s)
- Yu Zou
- Department of Sport and Exercise Science, College of Education, Zhejiang University, Hangzhou, China
| | - Lulu Guan
- Department of Sport and Exercise Science, College of Education, Zhejiang University, Hangzhou, China
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Lei J, Cai M, Shen Y, Lin D, Deng X. Molecular dynamics study on the inhibition mechanisms of ReACp53 peptide for p53-R175H mutant aggregation. Phys Chem Chem Phys 2021; 23:23032-23041. [PMID: 34612239 DOI: 10.1039/d1cp03094a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
p53 mutant aggregation can lead to loss-of-function (LoF), dominant-negative (DN) and gain-of-function (GoF) effects, involving in tumor growth. Finding inhibition methods of p53 mutant aggregation is a key step for developing new therapeutics against aggregation-associated cancers. Recent studies have shown that a cell-permeable peptide, ReACp53, can inhibit aggregation of the p53 mutant and restore p53 nuclear function as a transcriptional factor, showing extraordinary therapeutic potential. However, the molecular mechanism underlying the inhibition of p53 mutant aggregation by the ReAp53 peptide is unclear. In this work, we used all-atom molecular dynamics (MD) simulations to investigate the effect of ReACp53 peptide on the structural and dynamic properties of the p53 core domain (p53C) of the aggregation-prone R175H mutant. Our simulations revealed that the ReACp53 peptide can stabilize the ordered secondary structure and decrease the flexibility of disordered loops of the R175H mutant through increasing the intra-interactions of p53C. Moreover, we found that ReACp53 peptide specifically binds to the fragment (residues 180-233) of the R175H mutant through strong hydrophobic interactions with residues L188 and L201 and a salt bridge or hydrogen bond formation with residues D186, E198, D204, E221 and E224. The specific binding pattern protects the aggregation-prone fragment (residues 182-213) from exposure to water. Hence, we suggested that the ReACp53 peptide inhibits aggregation of the R175H mutant by restoring the wild-type conformation from an aggregation-prone state and reducing the exposure of the aggregation-prone segment. These results provide molecular mechanistic insight into inhibition of the ReACp53 peptide on amyloid aggregation of the R175H mutant.
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Affiliation(s)
- Jiangtao Lei
- Institute of Space Science and Technology, Nanchang University, Xuefu Avenue 999, Nanchang City 330031, China.
| | - Mengqiang Cai
- Institute of Space Science and Technology, Nanchang University, Xuefu Avenue 999, Nanchang City 330031, China.
| | - Yun Shen
- Department of Physics, School of Sciences, Nanchang University, Xuefu Avenue 999, Nanchang City 330031, China
| | - Dongdong Lin
- Department of Physics and Qian Xuesen Collaborative Research Center of Astrochemistry and Space Life Sciences, Ningbo University, Ningbo, Zhejiang City 315211, China
| | - Xiaohua Deng
- Institute of Space Science and Technology, Nanchang University, Xuefu Avenue 999, Nanchang City 330031, China.
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Sorout N, Chandra A. Interactions of the Aβ(1-42) Peptide with Boron Nitride Nanoparticles of Varying Curvature in an Aqueous Medium: Different Pathways to Inhibit β-Sheet Formation. J Phys Chem B 2021; 125:11159-11178. [PMID: 34605235 DOI: 10.1021/acs.jpcb.1c05805] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The aggregation of amyloid β (Aβ) peptide triggered by its conformational changes leads to the commonly known neurodegenerative disease of Alzheimer's. It is believed that the formation of β sheets of the peptide plays a key role in its aggregation and subsequent fibrillization. In the current study, we have investigated the interactions of the Aβ(1-42) peptide with boron nitride nanoparticles and the effects of the latter on conformational transitions of the peptide through a series of molecular dynamics simulations. In particular, the effects of curvature of the nanoparticle surface are studied by considering boron nitride nanotubes (BNNTs) of varying diameter and also a planar boron nitride nanosheet (BNNS). Altogether, the current study involves the generation and analysis of 9.5 μs of dynamical trajectories of peptide-BNNT/BNNS pairs in an aqueous medium. It is found that BN nanoparticles of different curvatures that are studied in the present work inhibit the conformational transition of the peptide to its β-sheet form. However, such an inhibition effect follows different pathways for BN nanoparticles of different curvatures. For the BNNT with the highest surface curvature, i.e., (3,3) BNNT, the nanoparticle is found to inhibit β-sheet formation by stabilizing the helical structure of the peptide, whereas for planar BNNS, the β-sheet formation is prevented by making more favorable pathways available for transitions of the peptide to conformations of random coils and turns. The BNNTs with intermediate curvatures are found to exhibit diverse pathways of their interactions with the peptide, but in all cases, essentially no formation of the β sheet is found whereas substantial β-sheet formation is observed for Aβ(1-42) in water in the absence of any nanoparticle. The current study shows that BN nanoparticles have the potential to act as effective tools to prevent amyloid formation from Aβ peptides.
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Affiliation(s)
- Nidhi Sorout
- Department of Chemistry, Indian Institute of Technology Kanpur, Uttar Pradesh, India 208016
| | - Amalendu Chandra
- Department of Chemistry, Indian Institute of Technology Kanpur, Uttar Pradesh, India 208016
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Dong X, Qi R, Qiao Q, Li X, Li F, Wan J, Zhang Q, Wei G. Heparin remodels the microtubule-binding repeat R3 of Tau protein towards fibril-prone conformations. Phys Chem Chem Phys 2021; 23:20406-20418. [PMID: 34494046 DOI: 10.1039/d1cp02651h] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Abnormal aggregation of proteins into pathological amyloid fibrils is implicated in a wide range of devastating human neurodegenerative diseases. Intracellular fibrillary inclusions formed by Tau protein are characterized as the hallmark of tauopathies, including Alzheimer's disease and frontotemporal dementia. Heparin has been often used to trigger Tau aggregation in in vitro studies. However, the conformational changes induced by heparin and the underlying mechanism of promotion of Tau aggregation by heparin are not well understood. Structural characterization of Tau oligomers in the early stage of fibrillation is of great importance but remains challenging due to their dynamic and heterogeneous nature. R3, the third microtubule-binding repeat of Tau, contains the fibril-nucleating core (PHF6) and is crucial for Tau aggregation. In this study, utilizing extensive all-atom replica-exchange molecular dynamic simulations, we explored the conformational ensembles of R3 monomer/dimer in the absence and presence of heparin. Our results show that without heparin, both monomeric and dimeric R3 preferentially adopt collapsed β-sheet-containing conformations and PHF6 plays an important role in the formation of interchain β-sheet structures, while in the presence of heparin, R3 can populate relatively extended disordered states where chain dimension is similar to that of R3 in Tau filaments. Through electrostatic, hydrogen-bonding and hydrophobic interactions, heparin has a preference for interacting with residues V306/Q307/K317/K321/H329/H330/K331 which distribute throughout the entire sequence of R3, in turn acting as a template to extend R3 conformations. More importantly, heparin alters intramolecular/intermolecular interaction patterns of R3 and increases the intermolecular contact regions. Our results suggest that heparin remodels the conformations of R3 towards fibril-prone structures by increasing chain dimension and intermolecular contact regions, which may shed light on the atomic mechanism of heparin-induced amyloid fibrillization of Tau protein.
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Affiliation(s)
- Xuewei Dong
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai 200438, People's Republic of China.
| | - Ruxi Qi
- Cryo-EM Center, Southern University of Science and Technology, Shenzhen, 518055, People's Republic of China
| | - Qin Qiao
- Digital Medical Research Center, School of Basic Medical Sciences, Shanghai Key Laboratory of Medical Imaging Computing and Computer Assisted Intervention, Fudan University, Shanghai 200032, People's Republic of China
| | - Xuhua Li
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Physics, Xi'an Jiaotong University, Xi'an 710049, People's Republic of China
| | - Fangying Li
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai 200438, People's Republic of China.
| | - Jiaqian Wan
- College of Physical Education and Training, Shanghai University of Sport, Shanghai 200438, People's Republic of China
| | - Qingwen Zhang
- College of Physical Education and Training, Shanghai University of Sport, Shanghai 200438, People's Republic of China
| | - Guanghong Wei
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai 200438, People's Republic of China.
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Ghosh S, Verma S. Carvedilol inhibits Aβ 25-35 fibrillation by intervening the early stage helical intermediate formation: A biophysical investigation. Int J Biol Macromol 2021; 188:263-271. [PMID: 34371042 DOI: 10.1016/j.ijbiomac.2021.08.028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Revised: 07/16/2021] [Accepted: 08/03/2021] [Indexed: 12/28/2022]
Abstract
Self-assembly of disordered amyloid-beta (Aβ) peptides results in highly ordered amyloid fibrils. The structural information of the early-stage events and also in the presence of inhibitors is of great significance. It is challenging to acquire due to the nature of the amyloids and experimental constraints. Here, we demonstrate the cascade of aggregation (early to late) of the Aβ25-35 peptide in the absence and presence of carvedilol, a nonselective β-adrenergic receptor blocker. The aggregation process of Aβ25-35 peptide is monitored using Thioflavin T (ThT) fluorescence, dynamic light scattering (DLS), circular dichroism (CD), Raman spectroscopic techniques, and imaging experiments. We find that the Aβ25-35 peptide undergoes an early-stage (3-6 h) helical intermediate formation across the fibrillation pathway using CD and Raman measurements. Carvedilol obstructs the helical intermediate formation of Aβ25-35 peptide resulting in inhibition. CD spectra and deconvolution of the Raman bands suggest the β-sheet formation (24-100 h) in the absence of carvedilol. Spectroscopic results indicate a disordered structure for the peptide in the presence of carvedilol (24-100 h). Electron microscopy (EM) shows the formation of polymorphic fibrils for the peptide alone and non-amyloidal aggregates in the presence of carvedilol. Molecular docking study suggests that the plausible mode of interaction with carvedilol involves the C-terminal residues of the peptide.
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Affiliation(s)
- Sudeshna Ghosh
- Department of Chemistry, Indian Institute of Technology Kanpur, UP 208016, India.
| | - Sandeep Verma
- Department of Chemistry, Indian Institute of Technology Kanpur, UP 208016, India.
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Feng B, Freitas AE, Gorodetski L, Wang J, Tian R, Lee YR, Grewal AS, Zou Y. Planar cell polarity signaling components are a direct target of β-amyloid-associated degeneration of glutamatergic synapses. SCIENCE ADVANCES 2021; 7:7/34/eabh2307. [PMID: 34407949 PMCID: PMC8373119 DOI: 10.1126/sciadv.abh2307] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 06/28/2021] [Indexed: 06/13/2023]
Abstract
The signaling pathway directly controlling the maintenance of adult glutamatergic synapses has not been well understood. Planar cell polarity (PCP) signaling components were recently shown to play essential roles in the formation of glutamatergic synapses. Here, we show that they are localized in the adult synapses and are essential for their maintenance. Synapse loss at early stages of Alzheimer's disease is thought to be induced by β-amyloid (Aβ) pathology. We found that oligomeric Aβ binds to Celsr3 and assists Vangl2 in disassembling synapses. Moreover, a Wnt receptor and regulator of PCP signaling, Ryk, is also required for Aβ-induced synapse loss. In the 5XFAD mouse model of Alzheimer's disease, Ryk conditional knockout or a function-blocking monoclonal Ryk antibody protected synapses and preserved cognitive function. We propose that tipping of the fine balance of Wnt/PCP signaling components in glutamatergic synapses may cause synapse degeneration in neurodegenerative disorders with Aβ pathology.
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Affiliation(s)
- Bo Feng
- Neurobiology Section, Biological Sciences Division, University of California, San Diego, La Jolla, CA 92093, USA
| | - Andiara E Freitas
- Neurobiology Section, Biological Sciences Division, University of California, San Diego, La Jolla, CA 92093, USA
| | - Lilach Gorodetski
- Neurobiology Section, Biological Sciences Division, University of California, San Diego, La Jolla, CA 92093, USA
| | - Jingyi Wang
- Neurobiology Section, Biological Sciences Division, University of California, San Diego, La Jolla, CA 92093, USA
| | - Runyi Tian
- Neurobiology Section, Biological Sciences Division, University of California, San Diego, La Jolla, CA 92093, USA
| | - Yeo Rang Lee
- Neurobiology Section, Biological Sciences Division, University of California, San Diego, La Jolla, CA 92093, USA
| | - Akumbir S Grewal
- Neurobiology Section, Biological Sciences Division, University of California, San Diego, La Jolla, CA 92093, USA
| | - Yimin Zou
- Neurobiology Section, Biological Sciences Division, University of California, San Diego, La Jolla, CA 92093, USA.
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Michno W, Blennow K, Zetterberg H, Brinkmalm G. Refining the amyloid β peptide and oligomer fingerprint ambiguities in Alzheimer's disease: Mass spectrometric molecular characterization in brain, cerebrospinal fluid, blood, and plasma. J Neurochem 2021; 159:234-257. [PMID: 34245565 DOI: 10.1111/jnc.15466] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 06/11/2021] [Accepted: 07/06/2021] [Indexed: 01/05/2023]
Abstract
Since its discovery, amyloid-β (Aβ) has been the principal target of investigation of in Alzheimer's disease (AD). Over the years however, no clear correlation was found between the Aβ plaque burden and location, and AD-associated neurodegeneration and cognitive decline. Instead, diagnostic potential of specific Aβ peptides and/or their ratio, was established. For instance, a selective reduction in the concentration of the aggregation-prone 42 amino acid-long Aβ peptide (Aβ42) in cerebrospinal fluid (CSF) was put forward as reflective of Aβ peptide aggregation in the brain. With time, Aβ oligomers-the proposed toxic Aβ intermediates-have emerged as potential drivers of synaptic dysfunction and neurodegeneration in the disease process. Oligomers are commonly agreed upon to come in different shapes and sizes, and are very poorly characterized when it comes to their composition and their "toxic" properties. The concept of structural polymorphism-a diversity in conformational organization of amyloid aggregates-that depends on the Aβ peptide backbone, makes the characterization of Aβ aggregates and their role in AD progression challenging. In this review, we revisit the history of Aβ discovery and initial characterization and highlight the crucial role mass spectrometry (MS) has played in this process. We critically review the common knowledge gaps in the molecular identity of the Aβ peptide, and how MS is aiding the characterization of higher order Aβ assemblies. Finally, we go on to present recent advances in MS approaches for characterization of Aβ as single peptides and oligomers, and convey our optimism, as to how MS holds a promise for paving the way for progress toward a more comprehensive understanding of Aβ in AD research.
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Affiliation(s)
- Wojciech Michno
- Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, the Sahlgrenska Academy at the University of Gothenburg, Mölndal, Sweden.,Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK.,Department of Pediatrics, Stanford University School of Medicine, Stanford University, Stanford, CA, USA
| | - Kaj Blennow
- Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, the Sahlgrenska Academy at the University of Gothenburg, Mölndal, Sweden.,Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Mölndal, Sweden
| | - Henrik Zetterberg
- Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, the Sahlgrenska Academy at the University of Gothenburg, Mölndal, Sweden.,Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Mölndal, Sweden.,Department of Neurodegenerative Disease, UCL Institute of Neurology, Queen Square, London, UK.,UK Dementia Research Institute at UCL, London, UK
| | - Gunnar Brinkmalm
- Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, the Sahlgrenska Academy at the University of Gothenburg, Mölndal, Sweden.,Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Mölndal, Sweden
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12
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Mohammadi F, Takalloo Z, Rahmani H, Nasiri Khalili MA, Khajeh K, Riazi G, H Sajedi R. Interplay of isoform 1N4R tau protein and amyloid-β peptide fragment 25-35 in reducing and non-reducing conditions. J Biochem 2021; 169:119-134. [PMID: 32857841 DOI: 10.1093/jb/mvaa101] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 08/14/2020] [Indexed: 11/13/2022] Open
Abstract
Amyloid-β (Aβ) peptide and tau protein are two hallmark proteins in Alzheimer's disease (AD); however, the parameters, which mediate the abnormal aggregation of Aβ and tau, have not been fully discovered. Here, we have provided an optimum method to purify tau protein isoform 1N4R by using nickel-nitrilotriacetic acid agarose chromatography under denaturing condition. The biochemical and biophysical properties of the purified protein were further characterized using in vitro tau filament assembly, tubulin polymerization assay, circular dichroism (CD) spectroscopy and atomic force microscopy. Afterwards, we investigated the effect of tau protein on aggregation of Aβ (25-35) peptide using microscopic imaging and cell viability assay. Incubation of tau at physiologic and supra-physiologic concentrations with Aβ25-35 for 40 days under reducing and non-reducing conditions revealed formation of two types of aggregates with distinct morphologies and dimensions. In non-reducing condition, the co-incubated sample showed granular aggregates, while in reducing condition, they formed annular protofibrils. Results from cell viability assay revealed the increased cell viability for the co-incubated sample. Therefore, the disassembling action shown by tau protein on Aβ25-35 suggests the possibility that tau may have a protective role in preventing Aβ peptide from acquiring the cytotoxic, aggregated form against oxidative stress damages.
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Affiliation(s)
- Fatemeh Mohammadi
- Department of Biochemistry, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Jalal AleAhmad Highway, P.O.Box: 14115-111, Iran
| | - Zeinab Takalloo
- Department of Biochemistry, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Jalal AleAhmad Highway, P.O.Box: 14115-111, Iran
| | - Hossein Rahmani
- Department of Biochemistry, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Jalal AleAhmad Highway, P.O.Box: 14115-111, Iran
| | - Mohammad Ali Nasiri Khalili
- Department of Bioscience and Biotechnology, Malek Ashtar University of Technology, Tehran, Lavizan, Babaei Highway, P.O.Box: 15875-1774, Iran
| | - Khosro Khajeh
- Department of Biochemistry, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Jalal AleAhmad Highway, P.O.Box: 14115-111, Iran
| | - Gholamhossein Riazi
- Institute of Biochemistry and Biophysics (IBB), University of Tehran, Tehran, Enghelab Square, Postal Code: 1417466191, Iran
| | - Reza H Sajedi
- Department of Biochemistry, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Jalal AleAhmad Highway, P.O.Box: 14115-111, Iran
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13
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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: 26] [Impact Index Per Article: 8.7] [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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14
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Yamauchi M, Okumura H. Dimerization of α-Synuclein Fragments Studied by Isothermal-Isobaric Replica-Permutation Molecular Dynamics Simulation. J Chem Inf Model 2021; 61:1307-1321. [PMID: 33625841 DOI: 10.1021/acs.jcim.0c01056] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Aggregates and fibrils of intrinsically disordered α-synuclein are associated with Parkinson's disease. Within a non-amyloid β component (NAC) spanning from the 61st to the 95th residue of α-synuclein, an 11-residue segment called NACore (68GAVVTGVTAVA78) is an essential region for both fibril formation and cytotoxicity. Although NACore peptides alone are known to form aggregates and amyloid fibrils, the mechanisms of aggregation and fibrillation remain unknown. This study investigated the dimerization process of NACore peptides as the initial stage of the aggregation and fibrillation processes. We performed an isothermal-isobaric replica-permutation molecular dynamics simulation, which is one of the efficient sampling methods, for the two NACore peptides in explicit water over 96 μs. The simulation succeeded in sampling a variety of dimer structures. An analysis of secondary structure revealed that most of the NACore dimers form intermolecular β-bridges. In particular, more antiparallel β-bridges were observed than parallel β-bridges. We also found that intramolecular secondary structures such as α-helix and antiparallel β-bridge are stabilized in the pre-dimer state. However, we identified that the intermolecular β-bridges tend to form directly between residues with no specific structure rather than via the intramolecular β-bridges. This is because the NACore peptides still have a low propensity to form the intramolecular secondary structures even though they are stabilized in the pre-dimer state.
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Affiliation(s)
- Masataka Yamauchi
- Department of Structural Molecular Science, The Graduate University for Advanced Studies(SOKENDAI), Okazaki, Aichi 444-8787, Japan.,Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan.,Institute for Molecular Science (IMS), National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan
| | - Hisashi Okumura
- Department of Structural Molecular Science, The Graduate University for Advanced Studies(SOKENDAI), Okazaki, Aichi 444-8787, Japan.,Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan.,Institute for Molecular Science (IMS), National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan
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15
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Loskutov AI, Lokshin BV, Sazonova NM, Pinargote NS, Vysotskii VV, Loskutov SA. Features of the crystallization of multicomponent solutions: a dipeptide, its salt and potassium carbonate. CrystEngComm 2021. [DOI: 10.1039/d1ce00491c] [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
Various stages of crystallization of the dipeptide potassium salt on graphite and gold. Possible molecular structures of the dipeptide (a) and its potassium salt (b).
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Affiliation(s)
- Alexander I. Loskutov
- Moscow State Technological University STANKIN, Vadkovskii per. 1, Moscow, 127994 Russia
| | - Boris V. Lokshin
- A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov str. 28, Moscow, 119991 Russia
| | - Nellya M. Sazonova
- V. V. Zakusov Scientific Research Institute of Pharmacology, Russian Academy of Medical Sciences, Baltiiskaya str. 8, Moscow, 125315 Russia
| | | | - Vladimir V. Vysotskii
- Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninskii pr. 31, Moscow, 119991 Russia
| | - Sergei A. Loskutov
- Moscow State Technological University STANKIN, Vadkovskii per. 1, Moscow, 127994 Russia
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16
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Tang C, Li Q, Deng X, Wu W, Liao L, Liang K, Huo R, Li C, Han J, Tang W, Jiang N. Discovery of lixisenatide analogues as long-acting hypoglycemic agents using novel peptide half-life extension technology based on mycophenolic acid. RSC Adv 2020; 10:12089-12104. [PMID: 35496622 PMCID: PMC9050719 DOI: 10.1039/d0ra01002b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2020] [Accepted: 03/18/2020] [Indexed: 12/20/2022] Open
Abstract
Noncovalent binding of peptides to human serum albumin protects against renal clearance and enzymatic degradation. Herein, we investigated the effect of mycophenolic acid (MPA) albumin binders for improving the stability of peptides. For proof-of-principle, the short acting glucagon-like peptide-1 (GLP-1) receptor agonist lixisenatide was selected and functionalized with different MPA albumin binders. In vitro, all lixisenatide analogues showed well preserved GLP-1 receptor activation potency. High performance affinity chromatography (HPAC) and ultrafiltration analyses indicated that DiMPA was able to confer high albumin affinity to lixisenatide and revealed that affinity is increased for DiMPA modified lixisenatide analogues containing OEG spacers. In db/db mice, the selected peptide 2c showed comparable efficacies to lixisenatide with respect to glucose-lowering and insulinotropic activities. Furthermore, the duration of action of glucose homeostasis of 2c was comparable to semaglutide in db/db mice. Importantly, DiMPA albumin binder did not bring significant toxicity of lixisenatide, as reflected by the comparable toxicity indexes in 2c and semaglutide groups after 2 weeks dosing in normal Kunming mice. Short-term study (21 days) conducted on db/db mice showed the better therapeutic efficacies of 2c than semaglutide on pancreas islets protection. Importantly, in chronic studies (84 days) on db/db mice, 2c exhibited a sustained improvement in glycaemic control, to a greater extent than that of semaglutide. Thus, we propose DiMPA modification as a novel and general method for development of long-acting GLP-1 receptor agonists for type 2 diabetes treatments, and 2c as a promising antidiabetic candidate. DiMPA albumin binders were effectively applied to lixisenatide to make 2c as a long-acting antidiabetic agent.![]()
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Affiliation(s)
- Chunli Tang
- Department of Pharmacy, Affiliated Tumor Hospital of Guangxi Medical University Nanning PR China .,Editorial Department, Affiliated Tumor Hospital of Guangxi Medical University Nanning PR China
| | - Qing Li
- Pharmaceutical College, Guangxi Medical University Nanning 530021 China
| | - Xiaoyan Deng
- Pharmaceutical College, Guangxi Medical University Nanning 530021 China
| | - Weiwei Wu
- Department of Pharmacy, Affiliated Tumor Hospital of Guangxi Medical University Nanning PR China
| | - Liufeng Liao
- Department of Pharmacy, Affiliated Tumor Hospital of Guangxi Medical University Nanning PR China
| | - Kai Liang
- Department of Pharmacy, Affiliated Tumor Hospital of Guangxi Medical University Nanning PR China
| | - Rongrui Huo
- Editorial Department, Affiliated Tumor Hospital of Guangxi Medical University Nanning PR China
| | - Chenglin Li
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical University Xuzhou China
| | - Jing Han
- School of Chemistry & Materials Science, Jiangsu Normal University Xuzhou 221116 PR China
| | - Weizhong Tang
- Department of Gastrointestinal Surgery, Affiliated Tumor Hospital of Guangxi Medical University Nanning PR China
| | - Neng Jiang
- Department of Pharmacy, Affiliated Tumor Hospital of Guangxi Medical University Nanning PR China
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17
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Deng L, Wang Y. Multiscale computational prediction of β-sheet peptide self-assembly morphology. MOLECULAR SIMULATION 2020. [DOI: 10.1080/08927022.2020.1738426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- Li Deng
- BGI-Qingdao, Qingdao, People’s Republic of China
- State Key Laboratory of Agricultural Genomics, Shenzhen, People’s Republic of China
- China National GeneBank, Shenzhen, People’s Republic of China
| | - Yanting Wang
- CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing, People’s Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, People’s Republic of China
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18
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Jakubowski J, Orr AA, Le DA, Tamamis P. Interactions between Curcumin Derivatives and Amyloid-β Fibrils: Insights from Molecular Dynamics Simulations. J Chem Inf Model 2020; 60:289-305. [PMID: 31809572 PMCID: PMC7732148 DOI: 10.1021/acs.jcim.9b00561] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Indexed: 12/24/2022]
Abstract
The aggregation of amyloid-β (Aβ) peptides into senile plaques is a hallmark of Alzheimer's disease (AD) and is hypothesized to be the primary cause of AD related neurodegeneration. Previous studies have shown the ability of curcumin to both inhibit the aggregation of Aβ peptides into oligomers or fibrils and reduce amyloids in vivo. Despite the promise of curcumin and its derivatives to serve as diagnostic, preventative, and potentially therapeutic AD molecules, the mechanism by which curcumin and its derivatives bind to and inhibit Aβ fibrils' formation remains elusive. Here, we investigated curcumin and a set of curcumin derivatives in complex with a hexamer peptide model of the Aβ1-42 fibril using nearly exhaustive docking, followed by multi-ns molecular dynamics simulations, to provide atomistic-detail insights into the molecules' binding and inhibitory properties. In the vast majority of the simulations, curcumin and its derivatives remain firmly bound in complex with the fibril through primarily three different principle binding modes, in which the molecules interact with residue domain 17LVFFA21, in line with previous experiments. In a small subset of these simulations, the molecules partly dissociate the outermost peptide of the Aβ1-42 fibril by disrupting β-sheets within the residue domain 12VHHQKLVFF20. A comparison between binding modes leading or not leading to partial dissociation of the outermost peptide suggests that the latter is attributed to a few subtle key structural and energetic interaction-based differences. Interestingly, partial dissociation appears to be either an outcome of high affinity interactions or a cause leading to high affinity interactions between the molecules and the fibril, which could partly serve as a compensation for the energy loss in the fibril due to partial dissociation. In conjunction with this, we suggest a potential inhibition mechanism of Αβ1-42 aggregation by the molecules, where the partially dissociated 16KLVFF20 domain of the outermost peptide could either remain unstructured or wrap around to form intramolecular interactions with the same peptide's 29GAIIG33 domain, while the molecules could additionally act as a patch against the external edge of the second outermost peptide's 16KLVFF20 domain. Thereby, individually or concurrently, these could prohibit fibril elongation.
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Affiliation(s)
| | | | - Doan A. Le
- Artie McFerrin Department
of Chemical Engineering, Texas A&M University, College Station, Texas 77843-3122, United States
| | - Phanourios Tamamis
- Artie McFerrin Department
of Chemical Engineering, Texas A&M University, College Station, Texas 77843-3122, United States
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19
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Madhu P, Mukhopadhyay S. Preferential Recruitment of Conformationally Distinct Amyloid-β Oligomers by the Intrinsically Disordered Region of the Human Prion Protein. ACS Chem Neurosci 2020; 11:86-98. [PMID: 31808343 DOI: 10.1021/acschemneuro.9b00646] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Soluble oligomeric species of the amyloid-β (Aβ) peptide exhibit pronounced neurotoxic effects in Alzheimer's disease. Recent studies have indicated that the prion protein (PrP) is one of the cell-surface receptors, so-called a bad receptor, of Aβ oligomers that mediates downstream cellular toxicity. A rational classification of Aβ oligomers on the basis of conformation indicates that there are two distinct types of oligomers, namely, prefibrillar and fibrillar oligomers that are positive to A11 and OC conformation-dependent antibodies, respectively. The mechanism of heterotypic assembly of conformationally distinct oligomers and PrP is poorly understood. In this work, using an array of biophysical and biochemical tools, we dissect the molecular mechanism of the interaction of A11- and OC-positive Aβ42 oligomers with human PrP. Using site-specific binding titrations, we show that the recruitment of Aβ oligomers primarily occurs via the electrostatic interaction between the N-terminal intrinsically disordered region of PrP and Aβ oligomers. Our results demonstrate that OC-positive fibrillar oligomers possessing in-register parallel β-sheet packing displayed ∼30 times stronger binding with PrP compared to A11-positive oligomers. We also show that these OC-positive oligomers exacerbate their toxic effects on mammalian cells upon binding to PrP. On the contrary, the addition of PrP does not alter the toxicity exhibited by A11-positive oligomers. Our findings suggest that strategies targeting the interaction between PrP and OC-positive oligomers, which have been shown to be highly concentrated in the vicinity of amyloid plaques, may have therapeutic potential against Alzheimer's disease.
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20
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Structure of amyloid β 25-35 in lipid environment and cholesterol-dependent membrane pore formation. Sci Rep 2019; 9:2689. [PMID: 30804528 PMCID: PMC6389947 DOI: 10.1038/s41598-019-38749-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 01/08/2019] [Indexed: 01/14/2023] Open
Abstract
The amyloid β (Aβ) peptide and its shorter variants, including a highly cytotoxic Aβ25–35 peptide, exert their neurotoxic effect during Alzheimer’s disease by various mechanisms, including cellular membrane permeabilization. The intrinsic polymorphism of Aβ has prevented the identification of the molecular basis of Aβ pore formation by direct structural methods, and computational studies have led to highly divergent pore models. Here, we have employed a set of biophysical techniques to directly monitor Ca2+-transporting Aβ25–35 pores in lipid membranes, to quantitatively characterize pore formation, and to identify the key structural features of the pore. Moreover, the effect of membrane cholesterol on pore formation and the structure of Aβ25–35 has been elucidated. The data suggest that the membrane-embedded peptide forms 6- or 8-stranded β-barrel like structures. The 8-stranded barrels may conduct Ca2+ ions through an inner cavity, whereas the tightly packed 6-stranded barrels need to assemble into supramolecular structures to form a central pore. Cholesterol affects Aβ25–35 pore formation by a dual mechanism, i.e., by direct interaction with the peptide and by affecting membrane structure. Collectively, our data illuminate the molecular basis of Aβ membrane pore formation, which should advance both basic and clinical research on Alzheimer’s disease and membrane-associated pathologies in general.
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21
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Itoh SG, Yagi-Utsumi M, Kato K, Okumura H. Effects of a Hydrophilic/Hydrophobic Interface on Amyloid-β Peptides Studied by Molecular Dynamics Simulations and NMR Experiments. J Phys Chem B 2019; 123:160-169. [PMID: 30543290 DOI: 10.1021/acs.jpcb.8b11609] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Oligomer formation of amyloid-β peptides (Aβ) is accelerated at a hydrophilic/hydrophobic interface. However, details of the acceleration mechanism have not been elucidated. To understand the effects of the interface on oligomerization at the atomic level, we performed molecular dynamics simulations for an Aβ40 monomer in the presence and absence of the hydrophilic/hydrophobic interface. Nuclear magnetic resonance experiments of Aβ40 peptides with gangliosidic micelles were also carried out. In the simulations and experiments, the hydrophobic residues of Aβ40 bound to the interface stably. Moreover, we found that Aβ40 formed a hairpin structure at the interface more readily than in bulk water. From these results, we discussed the acceleration mechanism of the oligomer formation at the interface.
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Affiliation(s)
- Satoru G Itoh
- Institute for Molecular Science (IMS) , National Institutes of Natural Sciences , Okazaki , Aichi 444-8585 , Japan.,Exploratory Research Center on Life and Living Systems (ExCELLS) , National Institutes of Natural Sciences , Okazaki , Aichi 444-8787 , Japan.,Department of Structural Molecular Science , SOKENDAI (The Graduate University for Advanced Studies) , Okazaki , Aichi 444-8585 , Japan
| | - Maho Yagi-Utsumi
- Institute for Molecular Science (IMS) , National Institutes of Natural Sciences , Okazaki , Aichi 444-8585 , Japan.,Exploratory Research Center on Life and Living Systems (ExCELLS) , National Institutes of Natural Sciences , Okazaki , Aichi 444-8787 , Japan.,Department of Functional Molecular Science , SOKENDAI (The Graduate University for Advanced Studies) , Okazaki , Aichi 444-8787 , Japan.,Graduate School of Pharmaceutical Sciences , Nagoya City University , Nagoya , Aichi 465-8603 , Japan
| | - Koichi Kato
- Institute for Molecular Science (IMS) , National Institutes of Natural Sciences , Okazaki , Aichi 444-8585 , Japan.,Exploratory Research Center on Life and Living Systems (ExCELLS) , National Institutes of Natural Sciences , Okazaki , Aichi 444-8787 , Japan.,Department of Functional Molecular Science , SOKENDAI (The Graduate University for Advanced Studies) , Okazaki , Aichi 444-8787 , Japan.,Graduate School of Pharmaceutical Sciences , Nagoya City University , Nagoya , Aichi 465-8603 , Japan
| | - Hisashi Okumura
- Institute for Molecular Science (IMS) , National Institutes of Natural Sciences , Okazaki , Aichi 444-8585 , Japan.,Exploratory Research Center on Life and Living Systems (ExCELLS) , National Institutes of Natural Sciences , Okazaki , Aichi 444-8787 , Japan.,Department of Structural Molecular Science , SOKENDAI (The Graduate University for Advanced Studies) , Okazaki , Aichi 444-8585 , Japan
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22
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John T, Gladytz A, Kubeil C, Martin LL, Risselada HJ, Abel B. Impact of nanoparticles on amyloid peptide and protein aggregation: a review with a focus on gold nanoparticles. NANOSCALE 2018; 10:20894-20913. [PMID: 30225490 DOI: 10.1039/c8nr04506b] [Citation(s) in RCA: 90] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Society is increasingly exposed to nanoparticles as they are ubiquitous in nature and introduced as man-made air pollutants and as functional ingredients in cosmetic products as well as in nanomedicine. Nanoparticles differ in size, shape and material properties. In addition to their intended function, the side effects on biochemical processes in organisms remain unclear. Nanoparticles can significantly influence the nucleation and aggregation process of peptides. The development of several neurodegenerative diseases, such as Alzheimer's disease, is related to the aggregation of peptides into amyloid fibrils. However, there is no comprehensive or universal mechanism to predict or explain apparent acceleration or inhibition of these aggregation processes. In this work, selected studies and possible mechanisms for amyloid peptide nucleation and aggregation, in the presence of nanoparticles, are highlighted. These studies are discussed in the context of recent data from our group on the role of gold nanoparticles in amyloid peptide aggregation using experimental methods and large-scale molecular dynamics simulations. A complex interplay of the surface properties of the nanoparticles, the properties of the peptides, as well as the resulting forces between both the nanoparticles and the peptides, appear to determine whether amyloid peptide aggregation is influenced, catalysed or inhibited by the presence of nanoparticles.
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Affiliation(s)
- Torsten John
- Leibniz Institute of Surface Engineering (IOM), Permoserstraße 15, 04318 Leipzig, Germany.
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23
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Peter EK. Adaptive enhanced sampling with a path-variable for the simulation of protein folding and aggregation. J Chem Phys 2018; 147:214902. [PMID: 29221375 DOI: 10.1063/1.5000930] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
In this article, we present a novel adaptive enhanced sampling molecular dynamics (MD) method for the accelerated simulation of protein folding and aggregation. We introduce a path-variable L based on the un-biased momenta p and displacements dq for the definition of the bias s applied to the system and derive 3 algorithms: general adaptive bias MD, adaptive path-sampling, and a hybrid method which combines the first 2 methodologies. Through the analysis of the correlations between the bias and the un-biased gradient in the system, we find that the hybrid methodology leads to an improved force correlation and acceleration in the sampling of the phase space. We apply our method on SPC/E water, where we find a conservation of the average water structure. We then use our method to sample dialanine and the folding of TrpCage, where we find a good agreement with simulation data reported in the literature. Finally, we apply our methodologies on the initial stages of aggregation of a hexamer of Alzheimer's amyloid β fragment 25-35 (Aβ 25-35) and find that transitions within the hexameric aggregate are dominated by entropic barriers, while we speculate that especially the conformation entropy plays a major role in the formation of the fibril as a rate limiting factor.
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Affiliation(s)
- Emanuel K Peter
- Department of Pharmacy and Chemistry, Institute of Physical and Theoretical Chemistry, University of Regensburg, Regensburg, Germany
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24
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Han J, Zhou F, Fei Y, Chen X, Fu J, Qian H. Preparation and Pharmaceutical Characterizations of Lipidated Dimeric Xenopus Glucagon-Like Peptide-1 Conjugates. Bioconjug Chem 2018; 29:390-402. [DOI: 10.1021/acs.bioconjchem.7b00712] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Jing Han
- School
of Chemistry and Materials Science, Jiangsu Normal University, Xuzhou 221116, PR China
| | - Feng Zhou
- School
of Chemistry and Materials Science, Jiangsu Normal University, Xuzhou 221116, PR China
| | - Yingying Fei
- School
of Chemistry and Materials Science, Jiangsu Normal University, Xuzhou 221116, PR China
| | - Xinyu Chen
- School
of Chemistry and Materials Science, Jiangsu Normal University, Xuzhou 221116, PR China
| | - Junjie Fu
- Department
of Medicinal Chemistry, School of Pharmacy, Nanjing Medical University, Nanjing 211166, PR China
- Center
of Drug Discovery, China Pharmaceutical University, Nanjing 210009, PR China
| | - Hai Qian
- Center
of Drug Discovery, China Pharmaceutical University, Nanjing 210009, PR China
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25
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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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26
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Sun Y, Wang B, Ge X, Ding F. Distinct oligomerization and fibrillization dynamics of amyloid core sequences of amyloid-beta and islet amyloid polypeptide. Phys Chem Chem Phys 2017; 19:28414-28423. [PMID: 29038815 PMCID: PMC5657190 DOI: 10.1039/c7cp05695h] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
A direct observation of amyloid aggregation from isolated peptides to cross-β fibrils is crucial for understanding the nucleation-dependence process, but the corresponding macroscopic timescales impose a major computational challenge. Using rapid all-atom discrete molecular dynamics simulations, we capture the oligomerization and fibrillization dynamics of the amyloid core sequences of amyloid-β (Aβ) in Alzheimer's disease and islet amyloid polypeptide (IAPP) in type-2 diabetes, namely Aβ16-22 and IAPP22-28. Both peptides and their mixture spontaneously assemble into cross-β aggregates in silico, but follow distinct pathways. Aβ16-22 is highly aggregation-prone with a funneled free energy basin toward multi-layer β-sheet aggregates. IAPP22-28, on the other hand, features the accumulation of unstructured oligomers before the nucleation of β-sheets and growth into double-layer β-sheet aggregates. In the presence of Aβ16-22, the aggregation of IAPP22-28 is promoted by forming co-aggregated multi-layer β-sheets. Our study offers a detailed molecular insight to the long-postulated oligomerization-nucleation process in the amyloid aggregations.
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Affiliation(s)
- Yunxiang Sun
- Department of Physics and Astronomy, Clemson University, Clemson, SC, USA.
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27
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Steckmann T, Bhandari YR, Chapagain PP, Gerstman BS. Cooperative structural transitions in amyloid-like aggregation. J Chem Phys 2017; 146:135103. [DOI: 10.1063/1.4979516] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
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28
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Zhu Z, Sheng N, Fang H, Wan R. Colored spectrum characteristics of thermal noise on the molecular scale. Phys Chem Chem Phys 2016; 18:30189-30195. [PMID: 27779258 DOI: 10.1039/c6cp04433f] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Thermal noise is of fundamental importance to many processes. Traditionally, thermal noise has been treated as white noise on the macroscopic scale. Using molecular dynamics simulations and power spectrum analysis, we show that the thermal noise of solute molecules in water is non-white on the molecular scale, which is in contrast to the conventional theory. In the frequency domain from 2 × 1011 Hz to 1013 Hz, the power spectrum of thermal noise for polar solute molecules resembles the spectrum of 1/f noise. The power spectrum of thermal noise for non-polar solute molecules deviates only slightly from the spectrum of white noise. The key to this phenomenon is the existence of hydrogen bonds between polar solute molecules and solvent water molecules. Furthermore, for polar solute molecules, the degree of power spectrum deviation from that of white noise is associated with the average lifetime of the hydrogen bonds between the solute and the solvent molecules.
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Affiliation(s)
- Zhi Zhu
- Division of Interfacial Water and Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P.O. Box 800-204, Shanghai 201800, China. and University of Chinese Academy of Sciences, Beijing 100049, China
| | - Nan Sheng
- Division of Interfacial Water and Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P.O. Box 800-204, Shanghai 201800, China.
| | - Haiping Fang
- Division of Interfacial Water and Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P.O. Box 800-204, Shanghai 201800, China.
| | - Rongzheng Wan
- Division of Interfacial Water and Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P.O. Box 800-204, Shanghai 201800, China.
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29
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Ozgur B, Sayar M. Assembly of Triblock Amphiphilic Peptides into One-Dimensional Aggregates and Network Formation. J Phys Chem B 2016; 120:10243-10257. [PMID: 27635660 DOI: 10.1021/acs.jpcb.6b07545] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Peptide assembly plays a key role in both neurological diseases and development of novel biomaterials with well-defined nanostructures. Synthetic model peptides provide a unique platform to explore the role of intermolecular interactions in the assembly process. A triblock peptide architecture designed by the Hartgerink group is a versatile system which relies on Coulomb interactions, hydrogen bonding, and hydrophobicity to guide these peptides' assembly at three different length scales: β-sheets, double-wall ribbon-like aggregates, and finally a highly porous network structure which can support gels with ≤1% by weight peptide concentration. In this study, by using molecular dynamics simulations of a structure based implicit solvent coarse grained model, we analyzed this hierarchical assembly process. Parametrization of our CG model is based on multiple-state points from atomistic simulations, which enables this model to represent the conformational adaptability of the triblock peptide molecule based on the surrounding medium. Our results indicate that emergence of the double-wall β-sheet packing mechanism, proposed in light of the experimental evidence, strongly depends on the subtle balance of the intermolecular forces. We demonstrate that, even though backbone hydrogen bonding dominates the early nucleation stages, depending on the strength of the hydrophobic and Coulomb forces, alternative structures such as zero-dimensional aggregates with two β-sheets oriented orthogonally (which we refer to as a cross-packed structure) and β-sheets with misoriented hydrophobic side chains are also feasible. We discuss the implications of these competing structures for the three different length scales of assembly by systematically investigating the influence of density, counterion valency, and hydrophobicity.
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Affiliation(s)
| | - Mehmet Sayar
- College of Engineering, Koc University , Istanbul, Turkey.,Chemical & Biological Engineering and Mechanical Engineering Departments, Koc University , Istanbul, Turkey
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30
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Wei G, Xi W, Nussinov R, Ma B. Protein Ensembles: How Does Nature Harness Thermodynamic Fluctuations for Life? The Diverse Functional Roles of Conformational Ensembles in the Cell. Chem Rev 2016; 116:6516-51. [PMID: 26807783 PMCID: PMC6407618 DOI: 10.1021/acs.chemrev.5b00562] [Citation(s) in RCA: 253] [Impact Index Per Article: 31.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
All soluble proteins populate conformational ensembles that together constitute the native state. Their fluctuations in water are intrinsic thermodynamic phenomena, and the distributions of the states on the energy landscape are determined by statistical thermodynamics; however, they are optimized to perform their biological functions. In this review we briefly describe advances in free energy landscape studies of protein conformational ensembles. Experimental (nuclear magnetic resonance, small-angle X-ray scattering, single-molecule spectroscopy, and cryo-electron microscopy) and computational (replica-exchange molecular dynamics, metadynamics, and Markov state models) approaches have made great progress in recent years. These address the challenging characterization of the highly flexible and heterogeneous protein ensembles. We focus on structural aspects of protein conformational distributions, from collective motions of single- and multi-domain proteins, intrinsically disordered proteins, to multiprotein complexes. Importantly, we highlight recent studies that illustrate functional adjustment of protein conformational ensembles in the crowded cellular environment. We center on the role of the ensemble in recognition of small- and macro-molecules (protein and RNA/DNA) and emphasize emerging concepts of protein dynamics in enzyme catalysis. Overall, protein ensembles link fundamental physicochemical principles and protein behavior and the cellular network and its regulation.
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Affiliation(s)
- Guanghong Wei
- State Key Laboratory of Surface Physics, Key Laboratory for Computational Physical Sciences (MOE), and Department of Physics, Fudan University, Shanghai, P. R. China
| | - Wenhui Xi
- State Key Laboratory of Surface Physics, Key Laboratory for Computational Physical Sciences (MOE), and Department of Physics, Fudan University, Shanghai, P. R. China
| | - Ruth Nussinov
- Basic Science Program, Leidos Biomedical Research, Inc. Cancer and Inflammation Program, National Cancer Institute, Frederick, Maryland 21702, USA
- Sackler Inst. of Molecular Medicine Department of Human Genetics and Molecular Medicine Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Buyong Ma
- Basic Science Program, Leidos Biomedical Research, Inc. Cancer and Inflammation Program, National Cancer Institute, Frederick, Maryland 21702, USA
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31
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Lei J, Qi R, Wei G, Nussinov R, Ma B. Self-aggregation and coaggregation of the p53 core fragment with its aggregation gatekeeper variant. Phys Chem Chem Phys 2016; 18:8098-107. [PMID: 26923710 PMCID: PMC6456058 DOI: 10.1039/c5cp06538k] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Recent studies suggested that p53 aggregation can lead to loss-of-function (LoF), dominant-negative (DN) and gain-of-function (GoF) effects, with adverse cancer consequences. The p53 aggregation-nucleating (251)ILTIITL(257) fragment is a key segment in wild-type p53 aggregation; however, an I254R mutation can prevent it. It was suggested that self-assembly of wild-type p53 and its cross-interaction with mutants differ from the classical amyloid nucleation-growth mechanism. Here, using replica exchange molecular dynamics (REMD) simulations, we studied the cross-interactions of this p53 core fragment and its aggregation rescue I254R mutant. We found that the core fragment displays strong aggregation propensity, whereas the gatekeeper I254R mutant tends to be disordered, consistent with experiments. Our cross-interaction results reveal that the wild-type p53 fragment promotes β-sheet formation of the I254R mutant by shifting the disordered mutant peptides into aggregating states. As a result, the system has similar oligomeric structures, inter-peptide interactions and free energy landscape as the wild type fragment does, revealing a prion-like process. We also found that in the cross-interaction system, the wild-type species has higher tendency to interact with the mutant than with itself. This phenomenon illustrates synergistic effects between the p53 (251)ILTIITL(257) fragment and the mutant resembling prion cross-species propagation, cautioning against exploiting it in drug discovery.
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Affiliation(s)
- Jiangtao Lei
- State Key Laboratory of Surface Physics, Key Laboratory for Computational Physical Sciences (MOE), and Department of Physics, Fudan University, Shanghai, P. R. China.
| | - Ruxi Qi
- State Key Laboratory of Surface Physics, Key Laboratory for Computational Physical Sciences (MOE), and Department of Physics, Fudan University, Shanghai, P. R. China.
| | - Guanghong Wei
- State Key Laboratory of Surface Physics, Key Laboratory for Computational Physical Sciences (MOE), and Department of Physics, Fudan University, Shanghai, P. R. China.
| | - Ruth Nussinov
- Basic Science Program, Leidos Biomedical Research, Inc., Cancer and Inflammation Program, National Cancer Institute, Frederick, Maryland 21702, USA. and Sackler Inst. of Molecular Medicine Department of Human Genetics and Molecular Medicine Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Buyong Ma
- Basic Science Program, Leidos Biomedical Research, Inc., Cancer and Inflammation Program, National Cancer Institute, Frederick, Maryland 21702, USA.
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32
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Carballo-Pacheco M, Strodel B. Advances in the Simulation of Protein Aggregation at the Atomistic Scale. J Phys Chem B 2016; 120:2991-9. [PMID: 26965454 DOI: 10.1021/acs.jpcb.6b00059] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Protein aggregation into highly structured amyloid fibrils is associated with various diseases including Alzheimer's disease, Parkinson's disease, and type II diabetes. Amyloids can also have normal biological functions and, in the future, could be used as the basis for novel nanoscale materials. However, a full understanding of the physicochemical forces that drive protein aggregation is still lacking. Such understanding is crucial for the development of drugs that can effectively inhibit aberrant amyloid aggregation and for the directed design of functional amyloids. Atomistic simulations can help understand protein aggregation. In particular, atomistic simulations can be used to study the initial formation of toxic oligomers which are hard to characterize experimentally and to understand the difference in aggregation behavior between different amyloidogenic peptides. Here, we review the latest atomistic simulations of protein aggregation, concentrating on amyloidogenic protein fragments, and provide an outlook for the future in this field.
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Affiliation(s)
- Martín Carballo-Pacheco
- Institute of Complex Systems: Structural Biochemistry , Forschungszentrum Jülich, 52425 Jülich, Germany.,AICES Graduate School, RWTH Aachen University , Schinkelstraße 2, 52062 Aachen, Germany
| | - Birgit Strodel
- Institute of Complex Systems: Structural Biochemistry , Forschungszentrum Jülich, 52425 Jülich, Germany.,Institute of Theoretical and Computational Chemistry, Heinrich Heine University Düsseldorf , Universitätsstrasse 1, 40225 Düsseldorf, Germany
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33
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Zou Y, Sun Y, Zhu Y, Ma B, Nussinov R, Zhang Q. Critical Nucleus Structure and Aggregation Mechanism of the C-terminal Fragment of Copper-Zinc Superoxide Dismutase Protein. ACS Chem Neurosci 2016; 7:286-96. [PMID: 26815332 PMCID: PMC7842942 DOI: 10.1021/acschemneuro.5b00242] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The aggregation of the copper-zinc superoxide dismutase (SOD1) protein is linked to familial amyotrophic lateral sclerosis, a progressive neurodegenerative disease. A recent experimental study has shown that the (147)GVIGIAQ(153) SOD1 C-terminal segment not only forms amyloid fibrils in isolation but also accelerates the aggregation of full-length SOD1, while substitution of isoleucine at site 149 by proline blocks its fibril formation. Amyloid formation is a nucleation-polymerization process. In this study, we investigated the oligomerization and the nucleus structure of this heptapeptide. By performing extensive replica-exchange molecular dynamics (REMD) simulations and conventional MD simulations, we found that the GVIGIAQ hexamers can adopt highly ordered bilayer β-sheets and β-barrels. In contrast, substitution of I149 by proline significantly reduces the β-sheet probability and results in the disappearance of bilayer β-sheet structures and the increase of disordered hexamers. We identified mixed parallel-antiparallel bilayer β-sheets in both REMD and conventional MD simulations and provided the conformational transition from the experimentally observed parallel bilayer sheets to the mixed parallel-antiparallel bilayer β-sheets. Our simulations suggest that the critical nucleus consists of six peptide chains and two additional peptide chains strongly stabilize this critical nucleus. The stabilized octamer is able to recruit additional random peptides into the β-sheet. Therefore, our simulations provide insights into the critical nucleus formation and the smallest stable nucleus of the (147)GVIGIAQ(153) peptide.
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Affiliation(s)
- Yu Zou
- College of Physical Education and Training, Shanghai University of Sport, 399 Chang Hai Road, Shanghai 200438, China
| | - Yunxiang Sun
- Department of Physics, Fudan University, 220 Handan Road, Shanghai 200433, China
| | - Yuzhen Zhu
- College of Physical Education and Training, Shanghai University of Sport, 399 Chang Hai Road, Shanghai 200438, China
| | - Buyong Ma
- Basic Science Program, Leidos Biomedical Research, Inc., Cancer and Inflammation Program, National Cancer Institute, Frederick, Maryland 21702, United States
| | - Ruth Nussinov
- Basic Science Program, Leidos Biomedical Research, Inc., Cancer and Inflammation Program, National Cancer Institute, Frederick, Maryland 21702, United States
- Sackler Inst. of Molecular Medicine, Department of Human Genetics and Molecular Medicine, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Qingwen Zhang
- College of Physical Education and Training, Shanghai University of Sport, 399 Chang Hai Road, Shanghai 200438, China
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34
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Wineman-Fisher V, Miller Y. Structural Insights into the Polymorphism of Self-Assembled Amylin Oligomers. Isr J Chem 2016. [DOI: 10.1002/ijch.201500091] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- Vered Wineman-Fisher
- Department of Chemistry
- Ilse Katz Institute for Nanoscale Science and Technology; Ben-Gurion University of the Negev; 84105 Beer-Sheva Israel
| | - Yifat Miller
- Department of Chemistry
- Ilse Katz Institute for Nanoscale Science and Technology; Ben-Gurion University of the Negev; 84105 Beer-Sheva Israel
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35
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de Almeida NEC, Do TD, Tro M, LaPointe NE, Feinstein SC, Shea JE, Bowers MT. Opposing Effects of Cucurbit[7]uril and 1,2,3,4,6-Penta-O-galloyl-β-d-glucopyranose on Amyloid β25-35 Assembly. ACS Chem Neurosci 2016; 7:218-26. [PMID: 26629788 PMCID: PMC4758880 DOI: 10.1021/acschemneuro.5b00280] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Alzheimer's disease (AD) is a neurodegenerative disease characterized by extracellular deposits of amyloid β protein (Aβ) in the brain. The conversion of soluble monomers to amyloid Aβ fibrils is a complicated process and involves several transient oligomeric species, which are widely believed to be highly toxic and play a crucial role in the etiology of AD. The development of inhibitors to prevent formation of small and midsized oligomers is a promising strategy for AD treatment. In this work, we employ ion mobility spectrometry (IMS), transmission electron microscopy (TEM), and molecular dynamics (MD) simulations to elucidate the structural modulation promoted by two potential inhibitors of Aβ oligomerization, cucurbit[7]uril (CB[7]) and 1,2,3,4,6-penta-O-galloyl-β-d-glucopyranose (PGG), on early oligomer and fibril formation of the Aβ25-35 fragment. One and two CB[7] molecules bind to Aβ25-35 monomers and dimers, respectively, and suppress aggregation by remodeling early oligomer structures and inhibiting the formation of higher-order oligomers. On the other hand, nonselective binding was observed between PGG and Aβ25-35. The interactions between PGG and Aβ25-35, surprisingly, enhanced the formation of Aβ aggregates by promoting extended Aβ25-35 conformations in both homo- and hetero-oligomers. When both ligands were present, the inhibitory effect of CB[7] overrode the stimulatory effect of PGG on Aβ25-35 aggregation, suppressing the formation of large amyloid oligomers and eliminating the structural conversion from isotropic to β-rich topologies induced by PGG. Our results provide mechanistic insights into CB[7] and PGG action on Aβ oligomerization. They also demonstrate the power of the IMS technique to investigate mechanisms of multiple small-molecule agents on the amyloid formation process.
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Affiliation(s)
- Natália E. C. de Almeida
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
| | - Thanh D. Do
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
| | - Michael Tro
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
| | - Nichole E. LaPointe
- Neuroscience Research Institute and Department of Molecular Cellular and Developmental Biology, University of California, Santa Barbara, California 93106, United States
| | - Stuart C. Feinstein
- Neuroscience Research Institute and Department of Molecular Cellular and Developmental Biology, University of California, Santa Barbara, California 93106, United States
| | - Joan-Emma Shea
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
| | - Michael T. Bowers
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
- Corresponding author: Michael T. Bowers. Tel: +1-805-893-2673;
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36
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Nucleation of polymorphic amyloid fibrils. Biophys J 2016; 108:1176-86. [PMID: 25762329 DOI: 10.1016/j.bpj.2015.01.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Revised: 01/09/2015] [Accepted: 01/13/2015] [Indexed: 11/23/2022] Open
Abstract
One and the same protein can self-assemble into amyloid fibrils with different morphologies. The phenomenon of fibril polymorphism is relevant biologically because different fibril polymorphs can have different toxicity, but there is no tool for predicting which polymorph forms and under what conditions. Here, we consider the nucleation of polymorphic amyloid fibrils occurring by direct polymerization of monomeric proteins into fibrils. We treat this process within the framework of our newly developed nonstandard nucleation theory, which allows prediction of the concentration dependence of the nucleation rate for different fibril polymorphs. The results highlight that the concentration dependence of the nucleation rate is closely linked with the protein solubility and a threshold monomer concentration below which fibril formation becomes biologically irrelevant. The relation between the nucleation rate, the fibril solubility, the threshold concentration, and the binding energies of the fibril building blocks within fibrils might prove a valuable tool for designing new experiments to control the formation of particular fibril polymorphs.
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37
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Mori T, Miyashita N, Im W, Feig M, Sugita Y. Molecular dynamics simulations of biological membranes and membrane proteins using enhanced conformational sampling algorithms. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:1635-51. [PMID: 26766517 DOI: 10.1016/j.bbamem.2015.12.032] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2015] [Revised: 12/24/2015] [Accepted: 12/29/2015] [Indexed: 12/15/2022]
Abstract
This paper reviews various enhanced conformational sampling methods and explicit/implicit solvent/membrane models, as well as their recent applications to the exploration of the structure and dynamics of membranes and membrane proteins. Molecular dynamics simulations have become an essential tool to investigate biological problems, and their success relies on proper molecular models together with efficient conformational sampling methods. The implicit representation of solvent/membrane environments is reasonable approximation to the explicit all-atom models, considering the balance between computational cost and simulation accuracy. Implicit models can be easily combined with replica-exchange molecular dynamics methods to explore a wider conformational space of a protein. Other molecular models and enhanced conformational sampling methods are also briefly discussed. As application examples, we introduce recent simulation studies of glycophorin A, phospholamban, amyloid precursor protein, and mixed lipid bilayers and discuss the accuracy and efficiency of each simulation model and method. This article is part of a Special Issue entitled: Membrane Proteins edited by J.C. Gumbart and Sergei Noskov.
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Affiliation(s)
- Takaharu Mori
- iTHES Research Group and Theoretical Molecular Science Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Naoyuki Miyashita
- Laboratory for Biomolecular Function Simulation, RIKEN Quantitative Biology Center, Integrated Innovation Building 7F, 6-7-1 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan; Faculty of Biology-Oriented Science and Technology, KINDAI University, 930 Nishimitani, Kinokawa, Wakayama 649-6493, Japan
| | - Wonpil Im
- Department of Molecular Sciences and Center for Computational Biology, The University of Kansas, 2030 Becker Drive, Lawrence, KS 66047, United States
| | - Michael Feig
- Laboratory for Biomolecular Function Simulation, RIKEN Quantitative Biology Center, Integrated Innovation Building 7F, 6-7-1 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan; Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, United States; Department of Chemistry, Michigan State University, East Lansing, MI 48824, United States
| | - Yuji Sugita
- iTHES Research Group and Theoretical Molecular Science Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan; Laboratory for Biomolecular Function Simulation, RIKEN Quantitative Biology Center, Integrated Innovation Building 7F, 6-7-1 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan; Department of Chemistry, Michigan State University, East Lansing, MI 48824, United States; Computational Biophysics Research Team, RIKEN Advanced Institute for Computational Science, 7-1-26 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan.
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38
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Zhou P, Deng L, Wang Y, Lu JR, Xu H. Different nanostructures caused by competition of intra- and inter-β-sheet interactions in hierarchical self-assembly of short peptides. J Colloid Interface Sci 2015; 464:219-28. [PMID: 26619132 DOI: 10.1016/j.jcis.2015.11.030] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Revised: 11/12/2015] [Accepted: 11/13/2015] [Indexed: 10/22/2022]
Abstract
To understand how molecular interactions lead to the self-assembly of twisted, helical and flat nanoribbons, we have compared the hierarchical self-assembly processes of three selected octapeptides with the same amino acid composition but different sequences by both experiments and molecular dynamics (MD) simulations. KE-F8 (NH2-KEFFFFKE-CONH2) and EK-F8 (NH2-KEFFFFEK-CONH2) have the same distribution of hydrophobic residues and only differ by swapping the positive and negative charged residues at their C-terminals, while KFE-8 (NH2-KFEFKFEF-CONH2) differs from KE-F8 and EK-F8 by having all hydrophobic and charged residues evenly distributed. MD simulations indicated that the competition between electrostatic and hydrophobic interactions at the molecular level results in different initial packing modes: KE-F8 monomers form completely matched anti-parallel β-sheets, EK-F8 monomers align with one residue shifting, and KFE-8 monomers pack β-sheets with two heterogeneous surfaces, consistent with previously suggested models. Driven by inter-strand and inter-sheet interactions, further growth of these molecular templates leads to larger oligomers with different twisting and stacking degrees, which are structurally consistent with the experimentally observed self-assembled morphologies. Further MD simulations showed that the competition between intra-β-sheet and inter-β-sheet interactions is responsible for the different twisting and stacking degrees of β-sheets and the subsequent formation of different nanostructures (twisted ribbons for KE-F8, helical ribbons/tubes for EK-F8 and flat ribbons for KFE-8). This study thus provided an important mechanistic insight into the fine tuning of molecular packing and interactions via peptide sequence variation leading to controllable self-assembly of twisted, helical and flat nanostructures.
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Affiliation(s)
- Peng Zhou
- State Key Laboratory of Heavy Oil Processing and Centre for Bioengineering and Biotechnology, China University of Petroleum (East China), 66 Changjiang West Road, Qingdao 266580, China
| | - Li Deng
- State Key Laboratory of Heavy Oil Processing and Centre for Bioengineering and Biotechnology, China University of Petroleum (East China), 66 Changjiang West Road, Qingdao 266580, China
| | - Yanting Wang
- State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, 55 East Zhongguancun Road, P.O. Box 2735, Beijing 100190, China.
| | - Jian R Lu
- Biological Physics Group, School of Physics and Astronomy, The University of Manchester, Manchester M13 9PL, United Kingdom.
| | - Hai Xu
- State Key Laboratory of Heavy Oil Processing and Centre for Bioengineering and Biotechnology, China University of Petroleum (East China), 66 Changjiang West Road, Qingdao 266580, China.
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39
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Zheng X, Wu C, Liu D, Li H, Bitan G, Shea JE, Bowers MT. Mechanism of C-Terminal Fragments of Amyloid β-Protein as Aβ Inhibitors: Do C-Terminal Interactions Play a Key Role in Their Inhibitory Activity? J Phys Chem B 2015; 120:1615-23. [PMID: 26439281 DOI: 10.1021/acs.jpcb.5b08177] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Targeting the early oligomerization of amyloid β protein (Aβ) is a promising therapeutic strategy for Alzheimer's disease (AD). Recently, certain C-terminal fragments (CTFs) derived from Aβ42 were shown to be potent inhibitors of Aβ-induced toxicity. The shortest peptide studied, Aβ(39-42), has been shown to modulate Aβ oligomerization and inhibit Aβ toxicity. Understanding the mechanism of these CTFs, especially Aβ(39-42), is of significance for future therapeutic development of AD and peptidomimetic-based drug development. Here we used ion mobility spectrometry-mass spectrometry to investigate the interactions between two modified Aβ(39-42) derivatives, VVIA-NH2 and Ac-VVIA, and full-length Aβ42. VVIA-NH2 was previously shown to inhibit Aβ toxicity, whereas Ac-VVIA did not. Our mass spectrometry analysis revealed that VVIA-NH2 binds directly to Aβ42 monomer and small oligomers while Ac-VVIA binds only to Aβ42 monomer. Ion mobility studies showed that VVIA-NH2 modulates Aβ42 oligomerization by not only inhibiting the dodecamer formation but also disaggregating preformed Aβ42 dodecamer. Ac-VVIA also inhibits and removes preformed Aβ42 dodecamer. However, the Aβ42 sample with the addition of Ac-VVIA clogged the nanospray tip easily, indicating that larger aggregates are formed in the solution in the presence of Ac-VVIA. Molecular dynamics simulations suggested that VVIA-NH2 binds specifically to the C-terminal region of Aβ42 while Ac-VVIA binds dispersedly to multiple regions of Aβ42. This work implies that C-terminal interactions and binding to Aβ oligomers are important for C-terminal fragment inhibitors.
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Affiliation(s)
- Xueyun Zheng
- Department of Chemistry and Biochemistry and ∥Department of Physics, University of California , Santa Barbara, California 93106, United States.,Department of Neurology, David Geffen School of Medicine, §Brain Research Institute, and Molecular Biology Institute, University of California at Los Angeles , Los Angeles, California 90095, United States
| | - Chun Wu
- Department of Chemistry and Biochemistry and ∥Department of Physics, University of California , Santa Barbara, California 93106, United States.,Department of Neurology, David Geffen School of Medicine, §Brain Research Institute, and Molecular Biology Institute, University of California at Los Angeles , Los Angeles, California 90095, United States
| | - Deyu Liu
- Department of Chemistry and Biochemistry and ∥Department of Physics, University of California , Santa Barbara, California 93106, United States.,Department of Neurology, David Geffen School of Medicine, §Brain Research Institute, and Molecular Biology Institute, University of California at Los Angeles , Los Angeles, California 90095, United States
| | - Huiyuan Li
- Department of Chemistry and Biochemistry and ∥Department of Physics, University of California , Santa Barbara, California 93106, United States.,Department of Neurology, David Geffen School of Medicine, §Brain Research Institute, and Molecular Biology Institute, University of California at Los Angeles , Los Angeles, California 90095, United States
| | - Gal Bitan
- Department of Chemistry and Biochemistry and ∥Department of Physics, University of California , Santa Barbara, California 93106, United States.,Department of Neurology, David Geffen School of Medicine, §Brain Research Institute, and Molecular Biology Institute, University of California at Los Angeles , Los Angeles, California 90095, United States
| | - Joan-Emma Shea
- Department of Chemistry and Biochemistry and ∥Department of Physics, University of California , Santa Barbara, California 93106, United States.,Department of Neurology, David Geffen School of Medicine, §Brain Research Institute, and Molecular Biology Institute, University of California at Los Angeles , Los Angeles, California 90095, United States
| | - Michael T Bowers
- Department of Chemistry and Biochemistry and ∥Department of Physics, University of California , Santa Barbara, California 93106, United States.,Department of Neurology, David Geffen School of Medicine, §Brain Research Institute, and Molecular Biology Institute, University of California at Los Angeles , Los Angeles, California 90095, United States
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40
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Carballo-Pacheco M, Ismail AE, Strodel B. Oligomer Formation of Toxic and Functional Amyloid Peptides Studied with Atomistic Simulations. J Phys Chem B 2015; 119:9696-705. [PMID: 26130191 DOI: 10.1021/acs.jpcb.5b04822] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Amyloids are associated with diseases, including Alzheimer's, as well as functional roles such as storage of peptide hormones. It is still unclear what differences exist between aberrant and functional amyloids. However, it is known that soluble oligomers formed during amyloid aggregation are more toxic than the final fibrils. Here, we perform molecular dynamics simulations to study the aggregation of the amyloid-β peptide Aβ25-35, associated with Alzheimer's disease, and two functional amyloid-forming tachykinin peptides: kassinin and neuromedin K. Although the three peptides have similar primary sequences, tachykinin peptides, in contrast to Aβ25-35, form nontoxic amyloids. Our simulations reveal that the charge of the C-terminus is essential to controlling the aggregation process. In particular, when the kassinin C-terminus is not amidated, the aggregation kinetics decreases considerably. In addition, we observe that the monomeric peptides in extended conformations aggregate faster than those in collapsed hairpin-like conformations.
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Affiliation(s)
- Martín Carballo-Pacheco
- †AICES Graduate School and Aachener Verfahrenstechnik: Molecular Simulations and Transformations, RWTH Aachen University, Schinkelstraße 2, 52062 Aachen, Germany.,‡Institute of Complex Systems: Structural Biochemistry (ICS-6), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Ahmed E Ismail
- †AICES Graduate School and Aachener Verfahrenstechnik: Molecular Simulations and Transformations, RWTH Aachen University, Schinkelstraße 2, 52062 Aachen, 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, Universitätstraße 1, 40225 Düsseldorf, Germany
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41
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Effect of pH on the Aggregation of α-syn12 Dimer in Explicit Water by Replica-Exchange Molecular Dynamics Simulation. Int J Mol Sci 2015; 16:14291-304. [PMID: 26114384 PMCID: PMC4519842 DOI: 10.3390/ijms160714291] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 06/09/2015] [Accepted: 06/10/2015] [Indexed: 01/22/2023] Open
Abstract
The dimeric structure of the N-terminal 12 residues drives the interaction of α-synuclein protein with membranes. Moreover, experimental studies indicated that the aggregation of α-synuclein is faster at low pH than neutral pH. Nevertheless, the effects of different pH on the structural characteristics of the α-syn12 dimer remain poorly understood. We performed 500 ns temperature replica exchange molecular dynamics (T-REMD) simulations of two α-syn12 peptides in explicit solvent. The free energy surfaces contain ten highly populated regions at physiological pH, while there are only three highly populated regions contained at acidic pH. The anti-parallel β-sheet conformations were found as the lowest free energy state. Additionally, these states are nearly flat with a very small barrier which indicates that these states can easily transit between themselves. The dimer undergoes a disorder to order transition from physiological pH to acidic pH and the α-syn12 dimer at acidic pH involves a faster dimerization process. Further, the Lys6–Asp2 contact may prevent the dimerization.
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42
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Xu L, Shan S, Chen Y, Wang X, Nussinov R, Ma B. Coupling of Zinc-Binding and Secondary Structure in Nonfibrillar Aβ40 Peptide Oligomerization. J Chem Inf Model 2015; 55:1218-30. [PMID: 26017140 PMCID: PMC6407634 DOI: 10.1021/acs.jcim.5b00063] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Nonfibrillar neurotoxic amyloid β (Aβ) oligomer structures are typically rich in β-sheets, which could be promoted by metal ions like Zn(2+). Here, using molecular dynamics (MD) simulations, we systematically examined combinations of Aβ40 peptide conformations and Zn(2+) binding modes to probe the effects of secondary structure on Aβ dimerization energies and kinetics. We found that random conformations do not contribute to dimerization either thermodynamically or kinetically. Zn(2+) couples with preformed secondary structures (α-helix and β-hairpin) to speed dimerization and stabilize the resulting dimer. Partial α-helices increase the dimerization speed, and dimers with α-helix rich conformations have the lowest energy. When Zn(2+) coordinates with residues D1, H6, H13, and H14, Aβ40 β-hairpin monomers have the fastest dimerization speed. Dimers with experimentally observed zinc coordination (E11, H6, H13, and H14) form with slower rate but have lower energy. Zn(2+) cannot stabilize fibril-like β-arch dimers. However, Zn(2+)-bound β-arch tetramers have the lowest energy. Collectively, zinc-stabilized β-hairpin oligomers could be important in the nucleation-polymerization of cross-β structures. Our results are consistent with experimental findings that α-helix to β-structural transition should accompany Aβ aggregation in the presence of zinc ions and that Zn(2+) stabilizes nonfibrillar Aβ oligomers and, thus, inhibits formation of less toxic Aβ fibrils.
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Affiliation(s)
- Liang Xu
- School of Chemistry, Dalian University of Technology, Dalian, China
| | - Shengsheng Shan
- School of Chemistry, Dalian University of Technology, Dalian, China
| | - Yonggang Chen
- Network and Information Center, Dalian University of Technology, Dalian, China
| | - Xiaojuan Wang
- School of Chemical Machinery, Dalian University of Technology, Dalian, China
| | - Ruth Nussinov
- Sackler Inst. of Molecular Medicine Department of Human Genetics and Molecular Medicine Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
- Basic Science Program, Leidos Biomedical Research, Inc. Cancer and Inflammation Program, National Cancer Institute, Frederick, Maryland 21702
| | - Buyong Ma
- Basic Science Program, Leidos Biomedical Research, Inc. Cancer and Inflammation Program, National Cancer Institute, Frederick, Maryland 21702
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43
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Ning L, Pan D, Zhang Y, Wang S, Liu H, Yao X. Effects of the Pathogenic Mutation A117V and the Protective Mutation H111S on the Folding and Aggregation of PrP106-126: Insights from Replica Exchange Molecular Dynamics Simulations. PLoS One 2015; 10:e0125899. [PMID: 25993001 PMCID: PMC4439087 DOI: 10.1371/journal.pone.0125899] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 03/24/2015] [Indexed: 11/19/2022] Open
Abstract
The fragment 106-126 of prion protein exhibits similar properties to full-length prion. Experiments have shown that the A117V mutation enhances the aggregation of PrP106-126, while the H111S mutation abolishes the assembly. However, the mechanism of the change in the aggregation behavior of PrP106-126 upon the two mutations is not fully understood. In this study, replica exchange molecular dynamics simulations were performed to investigate the conformational ensemble of the WT PrP106-126 and its two mutants A117V and H111S. The obtained results indicate that the three species are all intrinsically disordered but they have distinct morphological differences. The A117V mutant has a higher propensity to form β-hairpin structures than the WT, while the H111S mutant has a higher population of helical structures. Furthermore, the A117V mutation increases the hydrophobic solvent accessible surface areas of PrP106-126 and the H111S mutation reduces the exposure of hydrophobic residues. It can be concluded that the difference in populations of β-hairpin structures and the change of hydrophobic solvent accessible areas may induce the different aggregation behaviors of the A117V and the H111S mutated PrP106-126. Understanding why the two mutations have contrary effects on the aggregation of PrP106-126 is very meaningful for further elucidation of the mechanism underlying aggregation and design of inhibitor against aggregation process.
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Affiliation(s)
- Lulu Ning
- State Key Laboratory of Applied Organic Chemistry and Department of Chemistry, Lanzhou University, Lanzhou, China
| | - Dabo Pan
- State Key Laboratory of Applied Organic Chemistry and Department of Chemistry, Lanzhou University, Lanzhou, China
- School of pharmaceutical technology, Qiandongnan National Polytechnic, Kaili, China
| | - Yan Zhang
- School of Pharmacy, Lanzhou University, Lanzhou, China
| | - Shaopeng Wang
- State Key Laboratory of Applied Organic Chemistry and Department of Chemistry, Lanzhou University, Lanzhou, China
| | - Huanxiang Liu
- School of Pharmacy, Lanzhou University, Lanzhou, China
- * E-mail: (HL); (XY)
| | - Xiaojun Yao
- State Key Laboratory of Applied Organic Chemistry and Department of Chemistry, Lanzhou University, Lanzhou, China
- State Key Laboratory of Quality Research in Chinese Medicine, Macau Institute for Applied Research in Medicine and Health, Macau University of Science and Technology, Taipa, Macau, China
- * E-mail: (HL); (XY)
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44
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Jana AK, Sengupta N. Aβ self-association and adsorption on a hydrophobic nanosurface: competitive effects and the detection of small oligomers via electrical response. SOFT MATTER 2015; 11:269-279. [PMID: 25407676 DOI: 10.1039/c4sm01845a] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Treatment of Alzheimer's disease (AD) is impeded by the lack of effective early diagnostic methods. Small, soluble Aβ globulomers play a major role in AD neurotoxicity, and detecting their presence in aqueous fluids could lead to suitable sensors. We evaluate the adsorption behavior of small Aβ oligomers on the surface of a single walled carbon nanotube of high curvature. While the intrinsic self-assembly propensity of Aβ is markedly hindered by adsorption, the oligomeric units show high degrees of surface immobilization. Immobilized complexes are capable of oligomeric growth, but with a shifted monomer-oligomer equilibrium compared to the free states. In the presence of an ionic solution and suitable external electric fields, magnitudes of the current blockades are found to be sensitive to the oligomeric number of the adsorbed complex. However, this sensitivity gradually diminishes with increasing oligomeric size. The results provide a proof-of-concept basis for further investigations in the design of sensors for detecting the toxic small oligomers of Aβ.
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Affiliation(s)
- Asis K Jana
- Physical Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008, India.
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45
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Wang L, Zeng R, Pang X, Gu Q, Tan W. The mechanisms of flavonoids inhibiting conformational transition of amyloid-β42monomer: a comparative molecular dynamics simulation study. RSC Adv 2015. [DOI: 10.1039/c5ra12328c] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Flavonoids can bind Aβ42to inhibit the aggregation of Aβ42monomer.
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Affiliation(s)
- Ling Wang
- Guangdong Provincial Key Laboratory of Fermentation and Enzyme Engineering
- School of Bioscience and Bioengineering
- South China University of Technology
- Guangzhou 510006
- China
| | - Ranran Zeng
- Guangdong Provincial Key Laboratory of Fermentation and Enzyme Engineering
- School of Bioscience and Bioengineering
- South China University of Technology
- Guangzhou 510006
- China
| | - Xiaoqian Pang
- Guangdong Provincial Key Laboratory of Fermentation and Enzyme Engineering
- School of Bioscience and Bioengineering
- South China University of Technology
- Guangzhou 510006
- China
| | - Qiong Gu
- Research Center for Drug Discovery
- School of Pharmaceutical Sciences
- Sun Yat-Sen University
- Guangzhou 510006
- China
| | - Wen Tan
- Guangdong Provincial Key Laboratory of Fermentation and Enzyme Engineering
- School of Bioscience and Bioengineering
- South China University of Technology
- Guangzhou 510006
- China
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46
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Deng L, Zhou P, Zhao Y, Wang Y, Xu H. Molecular Origin of the Self-Assembled Morphological Difference Caused by Varying the Order of Charged Residues in Short Peptides. J Phys Chem B 2014; 118:12501-10. [PMID: 25296386 DOI: 10.1021/jp506385j] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Li Deng
- Centre
for Bioengineering and Biotechnology, China University of Petroleum (East China), 66 Changjiang West Road, Qingdao 266580, China
| | - Peng Zhou
- Centre
for Bioengineering and Biotechnology, China University of Petroleum (East China), 66 Changjiang West Road, Qingdao 266580, China
| | - Yurong Zhao
- Centre
for Bioengineering and Biotechnology, China University of Petroleum (East China), 66 Changjiang West Road, Qingdao 266580, China
| | - Yanting Wang
- State
Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, 55 East Zhongguancun Road, P.O.
Box 2735, Beijing 100190, China
| | - Hai Xu
- Centre
for Bioengineering and Biotechnology, China University of Petroleum (East China), 66 Changjiang West Road, Qingdao 266580, China
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47
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Itoh SG, Okumura H. Dimerization process of amyloid-β(29-42) studied by the Hamiltonian replica-permutation molecular dynamics simulations. J Phys Chem B 2014; 118:11428-36. [PMID: 25192386 DOI: 10.1021/jp505984e] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The amyloid-β peptides form amyloid fibrils which are associated with Alzheimer's disease. Amyloid-β(29-42) is its C-terminal fragment and a critical determinant of the amyloid formation rate. This fragment forms the amyloid fibril by itself. However, the fragment conformation in the fibril has yet to be determined. The oligomerization process including the dimerization process is also still unknown. The dimerization process corresponds to an early process of the amyloidogenesis. In order to investigate the dimerization process and conformations, we applied the Hamiltonian replica-permutation method, which is a better alternative to the Hamiltonian replica-exchange method, to two amyloid-β(29-42) molecules in explicit water solvent. At the first step of the dimerization process, two amyloid-β(29-42) molecules came close to each other and had intermolecular side chain contacts. When two molecules had the intermolecular side chain contacts, the amyloid-β(29-42) tended to have intramolecular secondary structures, especially β-hairpin structures. The two molecules had intermolecular β-bridge structures by coming much closer at the second step of the dimerization process. Formation of these intermolecular β-bridge structures was induced by the β-hairpin structures. The intermolecular β-sheet structures elongated at the final step. Structures of the amyloid-β(29-42) in the monomer and dimer states are also shown with the free-energy landscapes, which were obtained by performing efficient sampling in the conformational space in our simulations.
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Affiliation(s)
- Satoru G Itoh
- Department of Theoretical and Computational Molecular Science, Institute for Molecular Science , Okazaki, Aichi 444-8585, Japan
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48
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Do TD, Economou NJ, Chamas A, Buratto SK, Shea JE, Bowers MT. Interactions between amyloid-β and Tau fragments promote aberrant aggregates: implications for amyloid toxicity. J Phys Chem B 2014; 118:11220-30. [PMID: 25153942 PMCID: PMC4174992 DOI: 10.1021/jp506258g] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
![]()
We have investigated at the oligomeric
level interactions between
Aβ(25–35) and Tau(273–284), two important fragments
of the amyloid-β and Tau proteins, implicated in Alzheimer’s
disease. We are able to directly observe the coaggregation of these
two peptides by probing the conformations of early heteroligomers
and the macroscopic morphologies of the aggregates. Ion-mobility experiment
and theoretical modeling indicate that the interactions of the two
fragments affect the self-assembly processes of both peptides. Tau(273–284)
shows a high affinity to form heteroligomers with existing Aβ(25–35)
monomer and oligomers in solution. The configurations and characteristics
of the heteroligomers are determined by whether the population of
Aβ(25–35) or Tau(273–284) is dominant. As a result,
two types of aggregates are observed in the mixture with distinct
morphologies and dimensions from those of pure Aβ(25–35)
fibrils. The incorporation of some Tau into β-rich Aβ(25–35)
oligomers reduces the aggregation propensity of Aβ(25–35)
but does not fully abolish fibril formation. On the other hand, by
forming complexes with Aβ(25–35), Tau monomers and dimers
can advance to larger oligomers and form granular aggregates. These
heteroligomers may contribute to toxicity through loss of normal function
of Tau or inherent toxicity of the aggregates themselves.
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Affiliation(s)
- Thanh D Do
- Department of Chemistry and Biochemistry and ‡Department of Physics, University of California , Santa Barbara, California 93106, United States
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49
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Pryor NE, Moss MA, Hestekin CN. Capillary electrophoresis for the analysis of the effect of sample preparation on early stages of Aβ1-40 aggregation. Electrophoresis 2014; 35:1814-20. [PMID: 24729203 DOI: 10.1002/elps.201400012] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Revised: 03/17/2014] [Accepted: 03/18/2014] [Indexed: 11/05/2022]
Abstract
Aggregation of the amyloid-β protein (Aβ) contributes to the neurodegeneration characteristic of Alzheimer's disease. Of particular importance are the early stages of aggregation, which involve the formation of soluble oligomers and protofibrils. In these studies, we demonstrate the potential for CE with UV detection using a polyethylene oxide separation matrix to identify the evolution of various oligomeric species of Aβ1-40 . To demonstrate the efficacy of this technique, UV-CE was utilized to compare two methods commonly used to prepare Aβ for aggregation experiments and their effect on the formation of early aggregates. SEC-purified Aβ1-40 initially contained more small species, including monomer, than did freshly dissolved Aβ1-40 pretreated with hexafluoroisopropanol. Strikingly, the lag time to oligomer formation for SEC-isolated Aβ1-40 samples was ∼23 h shorter compared to freshly dissolved Aβ1-40 samples. Furthermore, oligomers formed from the aggregation of SEC-purified Aβ1-40 persisted within solution for a longer period of time. These results indicate that the initial sample preparation has a drastic influence on the early stages of Aβ1-40 aggregation. This is the first report of the use of UV-CE with a separation matrix to study the effect of sample preparation on early aggregation of Aβ1-40 . UV-CE was also used in parallel with dot blot analysis and inhibitory compounds to discern structural characteristics of individual oligomer peaks, demonstrating the capacity of UV-CE as a complimentary technique to further understand the aggregation process.
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Affiliation(s)
- N Elizabeth Pryor
- Ralph E. Martin Department of Chemical Engineering, University of Arkansas, Fayetteville, AR, USA
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50
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Socher E, Sticht H, Horn AHC. The conformational stability of nonfibrillar amyloid-β peptide oligomers critically depends on the C-terminal peptide length. ACS Chem Neurosci 2014; 5:161-7. [PMID: 24494584 DOI: 10.1021/cn400208r] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The amyloid-β (Aβ) peptide is one key molecule in the pathogenesis of Alzheimer's disease. We investigated the conformational stability of a nonfibrillar tetrameric Aβ structure by molecular dynamics (MD) simulations revealing that the stability of the Aβ tetramer depends critically on the C-terminal length. In contrast to the Aβ17-40 tetramer, which proved to be instable, the simulations demonstrate structural integrity of the Aβ17-42 and Aβ17-43 tetramers. These differences in stability can be attributed to an extension of the middle strand of a three-stranded antiparallel β sheet through residues 41-43, only present in the longer Aβ species that aggregate faster and are more neurotoxic. Additional MD simulations demonstrate that this higher stability is also present in the monomers forming the tetramer. In conclusion, our findings suggest the existence of a nonfibrillar oligomer topology that is significantly more stable for the longer Aβ species, thus offering a structural explanation for their higher neurotoxicity.
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Affiliation(s)
- Eileen Socher
- Bioinformatik,
Institut für Biochemie, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Fahrstraße 17, 91054 Erlangen, Germany
| | - Heinrich Sticht
- Bioinformatik,
Institut für Biochemie, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Fahrstraße 17, 91054 Erlangen, Germany
| | - Anselm H. C. Horn
- Bioinformatik,
Institut für Biochemie, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Fahrstraße 17, 91054 Erlangen, Germany
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