1
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Tanimoto S, Okumura H. Why Is Arginine the Only Amino Acid That Inhibits Polyglutamine Monomers from Taking on Toxic Conformations? ACS Chem Neurosci 2024; 15:2925-2935. [PMID: 39009034 PMCID: PMC11311134 DOI: 10.1021/acschemneuro.4c00276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2024] [Revised: 06/09/2024] [Accepted: 06/13/2024] [Indexed: 07/17/2024] Open
Abstract
Polyglutamine (polyQ) diseases are devastating neurodegenerative disorders characterized by abnormal expansion of glutamine repeats within specific proteins. The aggregation of polyQ proteins is a critical pathological hallmark of these diseases. Arginine was identified as a promising inhibitory compound because it prevents polyQ-protein monomers from forming intra- and intermolecular β-sheet structures and hinders polyQ proteins from aggregating to form oligomers. Such an aggregation inhibitory effect was not observed in other amino acids. However, the underlying molecular mechanism of the aggregation inhibition and the factors that differentiate arginine from other amino acids, in terms of the inhibition of the polyQ-protein aggregation, remain poorly understood. Here, we performed replica-permutation molecular dynamics simulations to elucidate the molecular mechanism by which arginine inhibits the formation of the intramolecular β-sheet structure of a polyQ monomer. We found that the intramolecular β-sheet structure with more than four β-bridges of the polyQ monomer with arginine is more unstable than without any ligand and with lysine. We also found that arginine has 1.6-2.1 times more contact with polyQ than lysine. In addition, we revealed that arginine forms more hydrogen bonds with the main chain of the polyQ monomer than lysine. More hydrogen bonds formed between arginine and polyQ inhibit polyQ from forming the long intramolecular β-sheet structure. It is known that intramolecular β-sheet structure enhances intermolecular β-sheet structure between proteins. These effects are thought to be the reason for the inhibition of polyQ aggregation. This study provides insights into the molecular events underlying arginine's inhibition of polyQ-protein aggregation.
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Affiliation(s)
- Shoichi Tanimoto
- Exploratory
Research Center on Life and Living Systems, National Institutes of Natural Sciences, Okazaki 444-8787, Aichi, Japan
| | - Hisashi Okumura
- Exploratory
Research Center on Life and Living Systems, National Institutes of Natural Sciences, Okazaki 444-8787, Aichi, Japan
- National
Institutes of Natural Sciences, Institute
for Molecular Science, Okazaki 444-8787, Aichi, Japan
- Graduate
Institute for Advanced Studies, SOKENDAI, Okazaki 444-8787, Aichi, Japan
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2
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Moldovean-Cioroianu NS. Reviewing the Structure-Function Paradigm in Polyglutamine Disorders: A Synergistic Perspective on Theoretical and Experimental Approaches. Int J Mol Sci 2024; 25:6789. [PMID: 38928495 PMCID: PMC11204371 DOI: 10.3390/ijms25126789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2024] [Revised: 06/13/2024] [Accepted: 06/17/2024] [Indexed: 06/28/2024] Open
Abstract
Polyglutamine (polyQ) disorders are a group of neurodegenerative diseases characterized by the excessive expansion of CAG (cytosine, adenine, guanine) repeats within host proteins. The quest to unravel the complex diseases mechanism has led researchers to adopt both theoretical and experimental methods, each offering unique insights into the underlying pathogenesis. This review emphasizes the significance of combining multiple approaches in the study of polyQ disorders, focusing on the structure-function correlations and the relevance of polyQ-related protein dynamics in neurodegeneration. By integrating computational/theoretical predictions with experimental observations, one can establish robust structure-function correlations, aiding in the identification of key molecular targets for therapeutic interventions. PolyQ proteins' dynamics, influenced by their length and interactions with other molecular partners, play a pivotal role in the polyQ-related pathogenic cascade. Moreover, conformational dynamics of polyQ proteins can trigger aggregation, leading to toxic assembles that hinder proper cellular homeostasis. Understanding these intricacies offers new avenues for therapeutic strategies by fine-tuning polyQ kinetics, in order to prevent and control disease progression. Last but not least, this review highlights the importance of integrating multidisciplinary efforts to advancing research in this field, bringing us closer to the ultimate goal of finding effective treatments against polyQ disorders.
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Affiliation(s)
- Nastasia Sanda Moldovean-Cioroianu
- Institute of Materials Science, Bioinspired Materials and Biosensor Technologies, Kiel University, Kaiserstraße 2, 24143 Kiel, Germany;
- Faculty of Physics, Babeș-Bolyai University, Kogălniceanu 1, RO-400084 Cluj-Napoca, Romania
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3
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Okumura H, Itoh SG, Zen H, Nakamura K. Dissociation process of polyalanine aggregates by free electron laser irradiation. PLoS One 2023; 18:e0291093. [PMID: 37683014 PMCID: PMC10491298 DOI: 10.1371/journal.pone.0291093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 08/22/2023] [Indexed: 09/10/2023] Open
Abstract
Polyalanine (polyA) disease-causative proteins with an expansion of alanine repeats can be aggregated. Although curative treatments for polyA diseases have not been explored, the dissociation of polyA aggregates likely reduces the cytotoxicity of polyA. Mid-infrared free electron laser (FEL) successfully dissociated multiple aggregates. However, whether the FEL dissociates polyA aggregates like other aggregates has not been tested. Here, we show that FEL at 6.1 μm experimentally weakened the extent of aggregation of a peptide with 13 alanine repeats (13A), and the irradiated 13A exerted lesser cytotoxicity to neuron-like cells than non-irradiated 13A. Then, we applied molecular dynamics (MD) simulation to follow the dissociation process by FEL. We successfully observed how the intermolecular β-sheet of polyA aggregates was dissociated and separated into monomers with helix structures upon FEL irradiation. After the dissociation by FEL, water molecules inhibited the reformation of polyA aggregates. We recently verified the same dissociation process using FEL-treated amyloid-β aggregates. Thus, a common mechanism underlies the dissociation of different protein aggregates that cause different diseases, polyA disease and Alzheimer's disease. However, MD simulation indicated that polyA aggregates are less easily dissociated than amyloid-β aggregates and require longer laser irradiation due to hydrophobic alanine repeats.
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Affiliation(s)
- Hisashi Okumura
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, Okazaki, Aichi, Japan
- Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki, Aichi, Japan
- Graduate Institute for Advanced Studies, SOKENDAI, Okazaki, Aichi, Japan
| | - Satoru G Itoh
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, Okazaki, Aichi, Japan
- Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki, Aichi, Japan
- Graduate Institute for Advanced Studies, SOKENDAI, Okazaki, Aichi, Japan
| | - Heishun Zen
- Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto, Japan
| | - Kazuhiro Nakamura
- Department of Laboratory Sciences, Gunma University Graduate School of Health Sciences, Maebashi, Gunma, Japan
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4
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Yagi-Utsumi M, Itoh SG, Okumura H, Yanagisawa K, Kato K, Nishimura K. The Double-Layered Structure of Amyloid-β Assemblage on GM1-Containing Membranes Catalytically Promotes Fibrillization. ACS Chem Neurosci 2023; 14:2648-2657. [PMID: 37482658 PMCID: PMC10401643 DOI: 10.1021/acschemneuro.3c00192] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Accepted: 07/11/2023] [Indexed: 07/25/2023] Open
Abstract
Alzheimer's disease (AD) is associated with progressive accumulation of amyloid-β (Aβ) cross-β fibrils in the brain. Aβ species tightly associated with GM1 ganglioside, a glycosphingolipid abundant in neuronal membranes, promote amyloid fibril formation; therefore, they could be attractive clinical targets. However, the active conformational state of Aβ in GM1-containing lipid membranes is still unknown. The present solid-state nuclear magnetic resonance study revealed a nonfibrillar Aβ assemblage characterized by a double-layered antiparallel β-structure specifically formed on GM1 ganglioside clusters. Our data show that this unique assemblage was not transformed into fibrils on GM1-containing membranes but could promote conversion of monomeric Aβ into fibrils, suggesting that a solvent-exposed hydrophobic layer provides a catalytic surface evoking Aβ fibril formation. Our findings offer structural clues for designing drugs targeting catalytically active Aβ conformational species for the development of anti-AD therapeutics.
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Affiliation(s)
- Maho Yagi-Utsumi
- 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 444-8585, Japan
- Graduate
School of Pharmaceutical Sciences, Nagoya
City University, Nagoya, Aichi 467-8603, Japan
| | - Satoru G. Itoh
- 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 444-8585, Japan
| | - Hisashi Okumura
- 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 444-8585, Japan
| | - Katsuhiko Yanagisawa
- Research
and Development Center for Precision Medicine, University of Tsukuba, Tsukuba, Ibaraki 305-8550, Japan
- Research
Institute, National Center for Geriatrics
and Gerontology, Obu, Aichi 474-8511, Japan
| | - Koichi Kato
- 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 444-8585, Japan
- Graduate
School of Pharmaceutical Sciences, Nagoya
City University, Nagoya, Aichi 467-8603, Japan
| | - Katsuyuki Nishimura
- Institute
for Molecular Science (IMS), National Institutes
of Natural Sciences, Okazaki, Aichi 444-8585, Japan
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5
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Fukuhara D, Yamauchi M, Itoh SG, Okumura H. Ingenuity in performing replica permutation: How to order the state labels for improving sampling efficiency. J Comput Chem 2023; 44:534-545. [PMID: 36346137 PMCID: PMC10099539 DOI: 10.1002/jcc.27020] [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: 07/22/2022] [Revised: 09/19/2022] [Accepted: 09/21/2022] [Indexed: 11/11/2022]
Abstract
In the replica-permutation method, an advanced version of the replica-exchange method, all combinations of replicas and parameters are considered for parameter permutation, and a list of all the combinations is prepared. Here, we report that the temperature transition probability depends on how the list is created, especially in replica permutation with solute tempering (RPST). We found that the transition probabilities decrease at large replica indices when the combinations are sequentially assigned to the state labels as in the originally proposed list. To solve this problem, we propose to modify the list by randomly assigning the combinations to the state labels. We performed molecular dynamics simulations of amyloid-β(16-22) peptides using RPST with the "randomly assigned" list (RPST-RA) and RPST with the "sequentially assigned" list (RPST-SA). The results show the decreases in the transition probabilities in RPST-SA are eliminated, and the sampling efficiency is improved in RPST-RA.
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Affiliation(s)
- Daiki Fukuhara
- Department of Structural Molecular Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Japan.,Department of Theoretical and Computational Molecular Science, Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki, Japan
| | - Masataka Yamauchi
- Department of Structural Molecular Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Japan.,Department of Theoretical and Computational Molecular Science, Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki, Japan
| | - Satoru G Itoh
- Department of Structural Molecular Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Japan.,Department of Theoretical and Computational Molecular Science, Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki, Japan.,Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, Okazaki, Japan
| | - Hisashi Okumura
- Department of Structural Molecular Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Japan.,Department of Theoretical and Computational Molecular Science, Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki, Japan.,Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, Okazaki, Japan
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6
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Abstract
It is known that oligomers of amyloid-β (Aβ) peptide are associated with Alzheimer's disease. Aβ has two isoforms: Aβ40 and Aβ42. Although the difference between Aβ40 and Aβ42 is only two additional C-terminal residues, Aβ42 aggregates much faster than Aβ40. It is unknown what role the C-terminal two residues play in accelerating aggregation. Since Aβ42 is more toxic than Aβ40, its oligomerization process needs to be clarified. Moreover, clarifying the differences between the oligomerization processes of Aβ40 and Aβ42 is essential to elucidate the key factors of oligomerization. Therefore, to investigate the dimerization process, which is the early oligomerization process, Hamiltonian replica-permutation molecular dynamics simulations were performed for Aβ40 and Aβ42. We identified a key residue, Arg5, for the Aβ42 dimerization. The two additional residues in Aβ42 allow the C-terminus to form contact with Arg5 because of the electrostatic attraction between them, and this contact stabilizes the β-hairpin. This β-hairpin promotes dimer formation through the intermolecular β-bridges. Thus, we examined the effects of amino acid substitutions of Arg5, thereby confirming that the mutations remarkably suppressed the aggregation of Aβ42. Moreover, the mutations of Arg5 suppressed the Aβ40 aggregation. It was found by analyzing the simulations that Arg5 is important for Aβ40 to form intermolecular contacts. Thus, it was clarified that the role of Arg5 in the oligomerization process varies due to the two additional C-terminal residues.
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Affiliation(s)
- Satoru
G. Itoh
- Institute
for Molecular Science, National Institutes
of Natural Sciences, Okazaki, Aichi 444-8787, 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 444-8787, Japan
| | - Maho Yagi-Utsumi
- Institute
for Molecular Science, National Institutes
of Natural Sciences, Okazaki, Aichi 444-8787, 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, National Institutes
of Natural Sciences, Okazaki, Aichi 444-8787, 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, National Institutes
of Natural Sciences, Okazaki, Aichi 444-8787, 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 444-8787, Japan,
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7
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Tanimoto S, Itoh SG, Okumura H. State-of-the-Art Molecular Dynamics Simulation Studies of RNA-Dependent RNA Polymerase of SARS-CoV-2. Int J Mol Sci 2022; 23:ijms231810358. [PMID: 36142270 PMCID: PMC9499461 DOI: 10.3390/ijms231810358] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 08/26/2022] [Accepted: 08/31/2022] [Indexed: 01/18/2023] Open
Abstract
Molecular dynamics (MD) simulations are powerful theoretical methods that can reveal biomolecular properties, such as structure, fluctuations, and ligand binding, at the level of atomic detail. In this review article, recent MD simulation studies on these biomolecular properties of the RNA-dependent RNA polymerase (RdRp), which is a multidomain protein, of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are presented. Although the tertiary structures of RdRps in SARS-CoV-2 and SARS-CoV are almost identical, the RNA synthesis activity of RdRp of SARS-CoV is higher than SARS-CoV-2. Recent MD simulations observed a difference in the dynamic properties of the two RdRps, which may cause activity differences. RdRp is also a drug target for Coronavirus disease 2019 (COVID-19). Nucleotide analogs, such as remdesivir and favipiravir, are considered to be taken up by RdRp and inhibit RNA replication. Recent MD simulations revealed the recognition mechanism of RdRp for these drug molecules and adenosine triphosphate (ATP). The ligand-recognition ability of RdRp decreases in the order of remdesivir, favipiravir, and ATP. As a typical recognition process, it was found that several lysine residues of RdRp transfer these ligand molecules to the binding site such as a “bucket brigade.” This finding will contribute to understanding the mechanism of the efficient ligand recognition by RdRp. In addition, various simulation studies on the complexes of SARS-CoV-2 RdRp with several nucleotide analogs are reviewed, and the molecular mechanisms by which these compounds inhibit the function of RdRp are discussed. The simulation studies presented in this review will provide useful insights into how nucleotide analogs are recognized by RdRp and inhibit the RNA replication.
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Affiliation(s)
- Shoichi Tanimoto
- Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki 444-8787, Aichi, Japan
- Exploratory Research Center on Life and Living Systems, National Institutes of Natural Sciences, Okazaki 444-8787, Aichi, Japan
| | - Satoru G. Itoh
- Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki 444-8787, Aichi, Japan
- Exploratory Research Center on Life and Living Systems, National Institutes of Natural Sciences, Okazaki 444-8787, Aichi, Japan
- Department of Structural Molecular Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki 444-8787, Aichi, Japan
| | - Hisashi Okumura
- Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki 444-8787, Aichi, Japan
- Exploratory Research Center on Life and Living Systems, National Institutes of Natural Sciences, Okazaki 444-8787, Aichi, Japan
- Department of Structural Molecular Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki 444-8787, Aichi, Japan
- Correspondence:
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8
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Molecular Dynamics Simulation Studies on the Aggregation of Amyloid-β Peptides and Their Disaggregation by Ultrasonic Wave and Infrared Laser Irradiation. Molecules 2022; 27:molecules27082483. [PMID: 35458686 PMCID: PMC9030874 DOI: 10.3390/molecules27082483] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 03/29/2022] [Accepted: 04/07/2022] [Indexed: 01/02/2023] Open
Abstract
Alzheimer’s disease is understood to be caused by amyloid fibrils and oligomers formed by aggregated amyloid-β (Aβ) peptides. This review article presents molecular dynamics (MD) simulation studies of Aβ peptides and Aβ fragments on their aggregation, aggregation inhibition, amyloid fibril conformations in equilibrium, and disruption of the amyloid fibril by ultrasonic wave and infrared laser irradiation. In the aggregation of Aβ, a β-hairpin structure promotes the formation of intermolecular β-sheet structures. Aβ peptides tend to exist at hydrophilic/hydrophobic interfaces and form more β-hairpin structures than in bulk water. These facts are the reasons why the aggregation is accelerated at the interface. We also explain how polyphenols, which are attracting attention as aggregation inhibitors of Aβ peptides, interact with Aβ. An MD simulation study of the Aβ amyloid fibrils in equilibrium is also presented: the Aβ amyloid fibril has a different structure at one end from that at the other end. The amyloid fibrils can be destroyed by ultrasonic wave and infrared laser irradiation. The molecular mechanisms of these amyloid fibril disruptions are also explained, particularly focusing on the function of water molecules. Finally, we discuss the prospects for developing treatments for Alzheimer’s disease using MD simulations.
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9
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Miyazawa K, Itoh SG, Yoshida Y, Arakawa K, Okumura H. Tardigrade Secretory-Abundant Heat-Soluble Protein Varies Entrance Propensity Depending on the Amino-Acid Sequence. J Phys Chem B 2022; 126:2361-2368. [PMID: 35316056 DOI: 10.1021/acs.jpcb.1c10788] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Secretory-abundant heat-soluble (SAHS) proteins, which constitute a protein family unique to tardigrades, are thought to be essential for anhydrobiosis. Our previous study has revealed that one of the SAHS proteins of Ramazzottius varieornatus (RvSAHS1) has a more flexible entrance than a mammalian fatty-acid-binding protein, which has a crystal structure similar to that of RvSAHS1. Recently, SAHS paralogs that are expressed abundantly and specifically in the early embryos of this tardigrade and Hypsibius exemplaris have been identified. Comparing these amino-acid sequences with that of RvSAHS1, we have found characteristic differences as I113F and D146T. In this study, we investigate I113F and D146T mutants' properties of RvSAHS1 using molecular dynamics simulations and compare the structures and fluctuations of their entrances with those of the wild type. The two mutants exhibit different properties at the entrance of the β-barrel structure. The I113F mutant tends to close the entrance more than the wild type due to the enhanced hydrophobic network inside the cavity. The D146T mutant, in contrast to the I113F mutant, tends to open the entrance. The mechanism by which this mutation opens the entrance is also discussed. Even though only a single mutation located far from the entrance is added to the wild type, there is a clear difference in the tendency to open and close the β-barrel entrance. It indicates that the entrance properties of the SAHS protein are sensitive to the amino-acid sequence.
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Affiliation(s)
- Kazuhisa Miyazawa
- 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 444-8585, Japan
| | - Satoru G Itoh
- 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 444-8585, Japan
| | - Yuki Yoshida
- Institute for Advanced Biosciences, Keio University, Tsuruoka 997-0017, Japan.,Systems Biology Program, Graduate School of Media and Governance, Keio University, Fujisawa 252-0882, Japan
| | - Kazuharu Arakawa
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan.,Institute for Advanced Biosciences, Keio University, Tsuruoka 997-0017, Japan.,Systems Biology Program, Graduate School of Media and Governance, Keio University, Fujisawa 252-0882, Japan.,Faculty of Environment and Information Studies, Keio University, Fujisawa 252-0882, 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 444-8585, Japan
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10
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Fukuhara D, Itoh SG, Okumura H. Replica permutation with solute tempering for molecular dynamics simulation and its application to the dimerization of amyloid-β fragments. J Chem Phys 2022; 156:084109. [DOI: 10.1063/5.0081686] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
We propose the replica permutation with solute tempering (RPST) by combining the replica-permutation method (RPM) and the replica exchange with solute tempering (REST). Temperature permutations are performed among more than two replicas in RPM, whereas temperature exchanges are performed between two replicas in the replica-exchange method (REM). The temperature transition in RPM occurs more efficiently than in REM. In REST, only the temperatures of the solute region, the solute temperatures, are exchanged to reduce the number of replicas compared to REM. Therefore, RPST is expected to be an improved method taking advantage of these methods. For comparison, we applied RPST, REST, RPM, and REM to two amyloid-β(16–22) peptides in explicit water. We calculated the transition ratio and the number of tunneling events in the temperature space and the number of dimerization events of amyloid-β(16–22) peptides. The results indicate that, in RPST, the number of replicas necessary for frequent random walks in the temperature and conformational spaces is reduced compared to the other three methods. In addition, we focused on the dimerization process of amyloid-β(16–22) peptides. The RPST simulation with a relatively small number of replicas shows that the two amyloid-β(16–22) peptides form the intermolecular antiparallel β-bridges due to the hydrophilic side-chain contact between Lys and Glu and hydrophobic side-chain contact between Leu, Val, and Phe, which stabilizes the dimer of the peptides.
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Affiliation(s)
- Daiki Fukuhara
- Department of Structural Molecular Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Aichi 444-8787, Japan
- Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan
| | - Satoru G. Itoh
- Department of Structural Molecular Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Aichi 444-8787, Japan
- Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan
| | - Hisashi Okumura
- Department of Structural Molecular Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Aichi 444-8787, Japan
- Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan
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11
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All-Atom Molecular Dynamics Simulation Methods for the Aggregation of Protein and Peptides: Replica Exchange/Permutation and Nonequilibrium Simulations. METHODS IN MOLECULAR BIOLOGY (CLIFTON, N.J.) 2022; 2340:197-220. [PMID: 35167076 DOI: 10.1007/978-1-0716-1546-1_10] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Protein aggregates are associated with more than 40 serious human diseases. To understand the formation mechanism of protein aggregates at atomic level, all-atom molecular dynamics (MD) simulation is a powerful computational tool. In this chapter, we review the all-atom MD simulation methods that are useful for study on the protein aggregation. We first explain conventional MD simulation methods in physical statistical ensembles, such as the canonical and isothermal-isobaric ensembles. We then describe the generalized-ensemble algorithms such as replica-exchange and replica-permutation MD methods. These methods can overcome a difficulty, in which simulations tend to get trapped in local-minimum free-energy states. Finally we explain the nonequilibrium MD method. Some simulation results based on these methods are also presented.
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12
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Tachi Y, Itoh SG, Okumura H. Molecular dynamics simulations of amyloid-β peptides in heterogeneous environments. Biophys Physicobiol 2022; 19:1-18. [PMID: 35666692 PMCID: PMC9135617 DOI: 10.2142/biophysico.bppb-v19.0010] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 03/31/2022] [Indexed: 12/01/2022] Open
Affiliation(s)
- Yuhei Tachi
- Department of Physics, Graduate school of Science, Nagoya University
| | - Satoru G. Itoh
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences
| | - Hisashi Okumura
- Institute for Molecular Science, National Institutes of Natural Sciences
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13
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Tanimoto S, Itoh SG, Okumura H. "Bucket brigade" using lysine residues in RNA-dependent RNA polymerase of SARS-CoV-2. Biophys J 2021; 120:3615-3627. [PMID: 34339634 PMCID: PMC8324383 DOI: 10.1016/j.bpj.2021.07.026] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 06/07/2021] [Accepted: 07/27/2021] [Indexed: 01/18/2023] Open
Abstract
The RNA-dependent RNA polymerase (RdRp) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a promising drug target for coronavirus disease 2019 (COVID-19) because it plays the most important role in the replication of the RNA genome. Nucleotide analogs such as remdesivir and favipiravir are thought to interfere with the RNA replication by RdRp. More specifically, they are expected to compete with nucleoside triphosphates, such as ATP. However, the process in which these drug molecules and nucleoside triphosphates are taken up by RdRp remains unknown. In this study, we performed all-atom molecular dynamics simulations to clarify the recognition mechanism of RdRp for these drug molecules and ATP that were at a distance. The ligand recognition ability of RdRp decreased in the order of remdesivir, favipiravir, and ATP. We also identified six recognition paths. Three of them were commonly found in all ligands, and the remaining three paths were ligand-dependent ones. In the common two paths, it was observed that the multiple lysine residues of RdRp carried the ligands to the binding site like a "bucket brigade." In the remaining common path, the ligands directly reached the binding site. Our findings contribute to the understanding of the efficient ligand recognition by RdRp at the atomic level.
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Affiliation(s)
- Shoichi Tanimoto
- Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki, Aichi, Japan
| | - Satoru G Itoh
- Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki, Aichi, Japan; Exploratory Research Center on Life and Living Systems, National Institutes of Natural Sciences, Okazaki, Aichi, Japan; Department of Structural Molecular Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Aichi, Japan
| | - Hisashi Okumura
- Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki, Aichi, Japan; Exploratory Research Center on Life and Living Systems, National Institutes of Natural Sciences, Okazaki, Aichi, Japan; Department of Structural Molecular Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Aichi, Japan.
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14
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Dynamic properties of SARS-CoV and SARS-CoV-2 RNA-dependent RNA polymerases studied by molecular dynamics simulations. Chem Phys Lett 2021; 778:138819. [PMID: 34127868 PMCID: PMC8189741 DOI: 10.1016/j.cplett.2021.138819] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 06/01/2021] [Accepted: 06/07/2021] [Indexed: 01/18/2023]
Abstract
One of the promising drug targets against COVID-19 is an RNA-dependent RNA polymerase (RdRp) of SARS-CoV-2. The tertiary structures of the SARS-CoV-2 and SARS-CoV RdRps are almost the same. However, the RNA-synthesizing activity of the SARS-CoV RdRp is higher than that of the SARS-CoV-2 RdRp. We performed molecular dynamics simulations and found differences in their dynamic properties. In the SARS-CoV RdRp, motifs A-G, which form the active site, are up to 63% closer to each other. We also observed cooperative domain motion in the SARS-CoV RdRp. Such dynamic differences may cause the activity differences between the two RdRps.
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15
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Miyazawa K, Itoh SG, Watanabe H, Uchihashi T, Yanaka S, Yagi-Utsumi M, Kato K, Arakawa K, Okumura H. Tardigrade Secretory-Abundant Heat-Soluble Protein Has a Flexible β-Barrel Structure in Solution and Keeps This Structure in Dehydration. J Phys Chem B 2021; 125:9145-9154. [PMID: 34375104 DOI: 10.1021/acs.jpcb.1c04850] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Secretory-abundant heat-soluble (SAHS) proteins are unique heat-soluble proteins of Tardigrada and are believed to play an essential role in anhydrobiosis, a latent state of life induced by desiccation. To investigate the dynamic properties, molecular dynamics (MD) simulations of a SAHS protein, RvSAHS1, were performed in solution and under dehydrating conditions. For comparison purposes, MD simulations of a human liver-type fatty-acid binding protein (LFABP) were performed in solution. Furthermore, high-speed atomic force microscopy observations were conducted to ascertain the results of the MD simulations. Three properties of RvSAHS1 were found as follows. (1) The entrance region of RvSAHS1 is more flexible and can be more extensive in solutions compared with that of a human LFABP because there is no salt bridge between the βD and βE strands. (2) The intrinsically disordered domain in the N-terminal region significantly fluctuates and can form an amphiphilic α-helix. (3) The size of the entrance region gets smaller along with dehydration, keeping the β-barrel structure. Overall, the obtained results provide atomic-level dynamics of SAHS proteins.
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Affiliation(s)
- Kazuhisa Miyazawa
- 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 444-8585, Japan
| | - Satoru G Itoh
- 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 444-8585, Japan
| | - Hiroki Watanabe
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan.,Department of Physics, Nagoya University, Nagoya 464-8602, Japan
| | - Takayuki Uchihashi
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan.,Department of Physics, Nagoya University, Nagoya 464-8602, Japan.,Institute for Glyco-core Research (iGCORE), Nagoya University, Nagoya 464-8601, Japan
| | - Saeko Yanaka
- 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 444-8585, Japan.,Department of Functional Molecular Science, The Graduate University for Advanced Studies (SOKENDAI), Okazaki, Aichi 444-8787, Japan.,Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Aichi 465-8603, Japan
| | - Maho Yagi-Utsumi
- 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 444-8585, Japan.,Department of Functional Molecular Science, The Graduate University for Advanced Studies (SOKENDAI), Okazaki, Aichi 444-8787, Japan.,Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Aichi 465-8603, Japan
| | - Koichi Kato
- 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 444-8585, Japan.,Department of Functional Molecular Science, The Graduate University for Advanced Studies (SOKENDAI), Okazaki, Aichi 444-8787, Japan.,Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Aichi 465-8603, Japan
| | - Kazuharu Arakawa
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan.,Institute for Advanced Biosciences, Keio University, Tsuruoka 997-0017, Japan.,Faculty of Environment and Information Studies, Keio University, Fujisawa 252-0882, Japan.,Systems Biology Program, Graduate School of Media and Governance, Keio University, Fujisawa 252-0882, 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 444-8585, Japan
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16
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Okumura H, Itoh SG. Molecular dynamics simulations of amyloid-β(16-22) peptide aggregation at air-water interfaces. J Chem Phys 2021; 152:095101. [PMID: 33480728 DOI: 10.1063/1.5131848] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Oligomers of amyloid-β (Aβ) peptides are known to be related to Alzheimer's disease, and their formation is accelerated at hydrophilic-hydrophobic interfaces, such as the cell membrane surface and air-water interface. Here, we report molecular dynamics simulations of aggregation of Aβ(16-22) peptides at air-water interfaces. First, 100 randomly distributed Aβ(16-22) peptides moved to the interface. The high concentration of peptides then accelerated their aggregation and formation of antiparallel β-sheets. Two layers of oligomers were observed near the interface. In the first layer from the interface, the oligomer with less β-bridges exposed the hydrophobic residues to the air. The second layer consisted of oligomers with more β-bridges that protruded into water. They are more soluble in water because the hydrophobic residues are covered by N- and C-terminal hydrophilic residues that are aligned well along the oligomer edge. These results indicate that amyloid protofibril formation mainly occurs in the second layer.
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Affiliation(s)
- Hisashi Okumura
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan
| | - Satoru G Itoh
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan
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17
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Okumura H, Itoh SG, Nakamura K, Kawasaki T. Role of Water Molecules and Helix Structure Stabilization in the Laser-Induced Disruption of Amyloid Fibrils Observed by Nonequilibrium Molecular Dynamics Simulations. J Phys Chem B 2021; 125:4964-4976. [PMID: 33961416 DOI: 10.1021/acs.jpcb.0c11491] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Water plays a crucial role in the formation and destruction of biomolecular structures. The mechanism for destroying biomolecular structures was thought to be an active breaking of hydrogen bonds by water molecules. However, using nonequilibrium molecular dynamics simulations, in which an amyloid-β amyloid fibril was destroyed via infrared free-electron laser (IR-FEL) irradiation, we discovered a new mechanism, in which water molecules disrupt protein aggregates. The intermolecular hydrogen bonds formed by C═O and N-H in the fibril are broken at each pulse of laser irradiation. These bonds spontaneously re-form after the irradiation in many cases. However, when a water molecule happens to enter the gap between C═O and N-H, it inhibits the re-formation of the hydrogen bonds. Such sites become defects in the regularly aligned hydrogen bonds, from which all hydrogen bonds in the intermolecular β-sheet are broken as the fraying spreads. This role of water molecules is entirely different from other known mechanisms. This new mechanism can explain the recent experiments showing that the amyloid fibrils are not destroyed by laser irradiation under dry conditions. Additionally, we found that helix structures form more after the amyloid disruption; this is because the resonance frequency is different in a helix structure. Our findings provide a theoretical basis for the application of IR-FEL to the future treatment of amyloidosis.
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Affiliation(s)
- Hisashi Okumura
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan.,Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan.,Department of Structural Molecular Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Aichi 444-8787, Japan
| | - Satoru G Itoh
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan.,Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan.,Department of Structural Molecular Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Aichi 444-8787, Japan
| | - Kazuhiro Nakamura
- Department of Laboratory Sciences, Graduate School of Health Sciences, Gunma University, Maebashi, Gunma 371-8514, Japan
| | - Takayasu Kawasaki
- IR Free Electron Laser Research Center, Research Institute for Science and Technology, Organization for Research Advancement, Tokyo University of Science, Noda, Chiba 278-8510, Japan
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18
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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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19
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Promotion and Inhibition of Amyloid-β Peptide Aggregation: Molecular Dynamics Studies. Int J Mol Sci 2021; 22:ijms22041859. [PMID: 33668406 PMCID: PMC7918115 DOI: 10.3390/ijms22041859] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 02/10/2021] [Accepted: 02/11/2021] [Indexed: 01/06/2023] Open
Abstract
Aggregates of amyloid-β (Aβ) peptides are known to be related to Alzheimer’s disease. Their aggregation is enhanced at hydrophilic–hydrophobic interfaces, such as a cell membrane surface and air-water interface, and is inhibited by polyphenols, such as myricetin and rosmarinic acid. We review molecular dynamics (MD) simulation approaches of a full-length Aβ peptide, Aβ40, and Aβ(16–22) fragments in these environments. Since these peptides have both hydrophilic and hydrophobic amino acid residues, they tend to exist at the interfaces. The high concentration of the peptides accelerates the aggregation there. In addition, Aβ40 forms a β-hairpin structure, and this structure accelerates the aggregation. We also describe the inhibition mechanism of the Aβ(16–22) aggregation by polyphenols. The aggregation of Aβ(16–22) fragments is caused mainly by the electrostatic attraction between charged amino acid residues known as Lys16 and Glu22. Since polyphenols form hydrogen bonds between their hydroxy and carboxyl groups and these charged amino acid residues, they inhibit the aggregation.
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20
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Ngoc LLN, Itoh SG, Sompornpisut P, Okumura H. Replica-permutation molecular dynamics simulations of an amyloid-β(16–22) peptide and polyphenols. Chem Phys Lett 2020. [DOI: 10.1016/j.cplett.2020.137913] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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21
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Chakraborty D, Chebaro Y, Wales DJ. A multifunnel energy landscape encodes the competing α-helix and β-hairpin conformations for a designed peptide. Phys Chem Chem Phys 2020; 22:1359-1370. [PMID: 31854397 DOI: 10.1039/c9cp04778f] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Depending on the amino acid sequence, as well as the local environment, some peptides have the capability to fold into multiple secondary structures. Conformational switching between such structures is a key element of protein folding and aggregation. Specifically, understanding the molecular mechanism underlying the transition from an α-helix to a β-hairpin is critical because it is thought to be a harbinger of amyloid assembly. In this study, we explore the energy landscape for an 18-residue peptide (DP5), designed by Araki and Tamura to exhibit equal propensities for the α-helical and β-hairpin forms. We find that the degeneracy is encoded in the multifunnel nature of the underlying free energy landscape. In agreement with experiment, we also observe that mutation of tyrosine at position 12 to serine shifts the equilibrium in favor of the α-helix conformation, by altering the landscape topography. The transition from the α-helix to the β-hairpin is a complex stepwise process, and occurs via collapsed coil-like intermediates. Our findings suggest that even a single mutation can tune the emergent features of the landscape, providing an efficient route to protein design. Interestingly, the transition pathways for the conformational switch seem to be minimally perturbed upon mutation, suggesting that there could be universal microscopic features that are conserved among different switch-competent protein sequences.
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Affiliation(s)
- Debayan Chakraborty
- Department of Chemistry, University of Cambridge, Lensfield Road, CB2 1EW, UK.
| | - Yassmine Chebaro
- Department of Integrative Structural Biology, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), CNRS UMR 7104, INSERM U964, Université de Strasbourg, 67404 Illkirch, France
| | - David J Wales
- Department of Chemistry, University of Cambridge, Lensfield Road, CB2 1EW, UK.
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22
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Minh Thu TT, Huang SH, Tu LA, Fang ST, Li MS, Chen YC. G37V mutation of Aβ42 induces a nontoxic ellipse-like aggregate: An in vitro and in silico study. Neurochem Int 2019; 129:104512. [PMID: 31374231 DOI: 10.1016/j.neuint.2019.104512] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 07/23/2019] [Accepted: 07/28/2019] [Indexed: 11/17/2022]
Abstract
The glycine zipper motif at the C-terminus of the β-amyloid (Aβ) peptide have been shown to strongly influence the formation of neurotoxic aggregates. A previous study showed that the G37L mutation dramatically reduces the Aβ toxicity in vivo and in vitro. However, the primary cause and mechanism of the glycine zipper motif on Aβ properties remain unknown. To gain molecular insights into the impact of glycine zipper on Aβ properties, we substituted the residue 37 of Glycine by Valine and studied the structural and biochemical properties of G37V mutation, Aβ42(37V), by using in vitro and in silico approaches. Unlike G37L mutation, the G37V mutation reduced toxicity substantially but did not significantly accelerate the aggregation rate or change the content of secondary structures. Further TEM analyses showed that the G37V mutation formed an ellipse-like aggregate rather than a network-like fibril as wild type or G37L mutation of Aβ42 form. This different aggregation morphology may be highly linked with the reduction of toxicity. To gain the insight for the different properties of Aβ42(37V), we studied the structure of Aβ42 and G37V mutation using the replica exchange molecular dynamics simulation. Our results demonstrate that although the overall secondary structure population is similar with Aβ42 and Aβ42(G37V), Aβ42(G37V) shows an increase in the β-turn and β-hairpin at residues 36-37 and the flexibility of the Asp23-Lys28 salt bridge. These unique structural features may be the possible reason to account for the ellipse-like morphology.
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Affiliation(s)
- Tran Thi Minh Thu
- Institute for Computational Science and Technology, SBI Building, Quang Trung Software City, Tan Chanh Hiep Ward, District 12, Ho Chi Minh City, Viet Nam; Department of Applied Physics, Faculty of Applied Science, Ho Chi Minh City University of Technology - VNU HCM, 268 Ly Thuong Kiet Street, District 10, Ho Chi Minh City, Viet Nam; Department of Materials Science and Technology, University of Science-VNUHCM, 227 Nguyen Van Cu, District 5, Ho Chi Minh City, Viet Nam
| | - Shu-Hsiang Huang
- Department of Medicine, MacKay Medical College, New Taipei City, 252, Taiwan
| | - Ly Anh Tu
- Department of Applied Physics, Faculty of Applied Science, Ho Chi Minh City University of Technology - VNU HCM, 268 Ly Thuong Kiet Street, District 10, Ho Chi Minh City, Viet Nam
| | - Shang-Ting Fang
- Department of Medicine, MacKay Medical College, New Taipei City, 252, Taiwan
| | - Mai Suan Li
- Institute for Computational Science and Technology, SBI Building, Quang Trung Software City, Tan Chanh Hiep Ward, District 12, Ho Chi Minh City, Viet Nam; Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668, Warsaw, Poland.
| | - Yi-Cheng Chen
- Department of Medicine, MacKay Medical College, New Taipei City, 252, Taiwan.
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23
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Nishikawa N, Sakae Y, Gouda T, Tsujimura Y, Okamoto Y. Structural Analysis of a Trimer of β 2-Microgloblin Fragment by Molecular Dynamics Simulations. Biophys J 2019; 116:781-790. [PMID: 30771855 DOI: 10.1016/j.bpj.2018.11.3143] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2017] [Revised: 06/08/2018] [Accepted: 11/06/2018] [Indexed: 01/22/2023] Open
Abstract
A peptide β2-m21-31, which is a fragment from residue 21 to residue 31 of β2-microgloblin, is experimentally known to self-assemble and form amyloid fibrils. In order to understand the mechanism of amyloid fibril formations, we applied the replica-exchange molecular dynamics method to the system consisting of three fragments of β2-m21-31. From the analyses on the temperature dependence, we found that there is a clear phase transition temperature in which the peptides aggregate with each other. Moreover, we found by the free energy analyses that there are two major stable states: One of them is like amyloid fibrils and the other is amorphous aggregates.
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Affiliation(s)
- Naohiro Nishikawa
- Department of Physics, Graduate School of Science, Nagoya University, Nagoya, Aichi, Japan; Department of Theoretical and Computational Molecular Science, Institute for Molecular Science, Okazaki, Aichi, Japan
| | - Yoshitake Sakae
- Department of Physics, Graduate School of Science, Nagoya University, Nagoya, Aichi, Japan
| | - Takuya Gouda
- Department of Physics, Graduate School of Science, Nagoya University, Nagoya, Aichi, Japan
| | - Yuichiro Tsujimura
- Department of Physics, Graduate School of Science, Nagoya University, Nagoya, Aichi, Japan
| | - Yuko Okamoto
- Department of Physics, Graduate School of Science, Nagoya University, Nagoya, Aichi, Japan; Structural Biology Research Center, Graduate School of Science, Nagoya University, Nagoya, Aichi, Japan; Center for Computational Science, Graduate School of Engineering, Nagoya University, Nagoya, Aichi, Japan; Information Technology Center, Nagoya University, Nagoya, Aichi, Japan; JST-CREST, Nagoya, Aichi, Japan.
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24
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Priya SB, Gromiha MM. Structural insights into the aggregation mechanism of huntingtin exon 1 protein fragment with different polyQ-lengths. J Cell Biochem 2019; 120:10519-10529. [PMID: 30672003 DOI: 10.1002/jcb.28338] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 11/29/2018] [Indexed: 12/19/2022]
Abstract
Huntington disease is a neurodegenerative disorder caused by the expansion of polyglutamine (polyQ) at the N-terminal of the huntingtin exon 1 protein. The detailed structure and the mechanism behind this aggregation remain unclear and it is assumed that the polyQ undergoes a conformational transition to the β-sheet structure when it aggregates. Investigating the misfolding of polyQ facilitates the determination of the molecular mechanism of aggregation and can potentially help in developing a novel approach to inhibit polyQ aggregation. Moreover, the flanking sequences of the polyQ region play a vital role in structural changes and the aggregation mechanism. We performed all-atom molecular dynamics simulations to gain structural insights into the aggregation mechanism using eight different models with glutamine repeat lengths Q27 , Q27 P11 , Q34 , Q35 , Q36 , Q40 , Q50 , and Q50 P11 . In the models without flanking polyPs, we noticed that the transformation of a random coil to β-sheet occurs when the number of Q increases. We also found that the flanking polyPs prevent aggregation by decreasing the probability of forming a β-sheet structure. When polyQ length increases, the 17 N-terminal flanking residues are more likely to adopt a β-sheet conformation from α-helix and coil. From our simulations, we suggest that at least 34 glutamines are required for initiating aggregation and 40 residues length is critical for the aggregation of huntingtin exon 1 protein for disease onset. This study provides structural insights into misfolding and the role of flanking sequences in huntingtin aggregation which will further help in developing therapeutic strategies for Huntington's disease.
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Affiliation(s)
- S Binny Priya
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai, Tamil Nadu, India
| | - M Michael Gromiha
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai, Tamil Nadu, India.,Advanced Computational Drug Discovery Unit (ACDD), Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Kanagawa, Japan
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25
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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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Okumura H, Higashi M, Yoshida Y, Sato H, Akiyama R. Theoretical approaches for dynamical ordering of biomolecular systems. Biochim Biophys Acta Gen Subj 2017; 1862:212-228. [PMID: 28988931 DOI: 10.1016/j.bbagen.2017.10.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 09/30/2017] [Accepted: 10/04/2017] [Indexed: 01/21/2023]
Abstract
BACKGROUND Living systems are characterized by the dynamic assembly and disassembly of biomolecules. The dynamical ordering mechanism of these biomolecules has been investigated both experimentally and theoretically. The main theoretical approaches include quantum mechanical (QM) calculation, all-atom (AA) modeling, and coarse-grained (CG) modeling. The selected approach depends on the size of the target system (which differs among electrons, atoms, molecules, and molecular assemblies). These hierarchal approaches can be combined with molecular dynamics (MD) simulation and/or integral equation theories for liquids, which cover all size hierarchies. SCOPE OF REVIEW We review the framework of quantum mechanical/molecular mechanical (QM/MM) calculations, AA MD simulations, CG modeling, and integral equation theories. Applications of these methods to the dynamical ordering of biomolecular systems are also exemplified. MAJOR CONCLUSIONS The QM/MM calculation enables the study of chemical reactions. The AA MD simulation, which omits the QM calculation, can follow longer time-scale phenomena. By reducing the number of degrees of freedom and the computational cost, CG modeling can follow much longer time-scale phenomena than AA modeling. Integral equation theories for liquids elucidate the liquid structure, for example, whether the liquid follows a radial distribution function. GENERAL SIGNIFICANCE These theoretical approaches can analyze the dynamic behaviors of biomolecular systems. They also provide useful tools for exploring the dynamic ordering systems of biomolecules, such as self-assembly. This article is part of a Special Issue entitled "Biophysical Exploration of Dynamical Ordering of Biomolecular Systems" edited by Dr. Koichi Kato.
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Affiliation(s)
- Hisashi Okumura
- Research Center for Computational Science, Institute for Molecular Science, Okazaki, Aichi 444-8585, Japan; Department of Structural Molecular Science, The Graduate University for Advanced Studies, Okazaki, Aichi 444-8585, Japan.
| | - Masahiro Higashi
- Department of Chemistry, Biology and Marine Science, University of the Ryukyus, Nishihara, Okinawa 903-0213, Japan
| | - Yuichiro Yoshida
- Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Hirofumi Sato
- Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan; Elements Strategy Initiative for Catalysts and Batteries, Kyoto University, Japan
| | - Ryo Akiyama
- Department of Chemistry, Kyushu University, Fukuoka 819-0395, Japan
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Wen J, Scoles DR, Facelli JC. Molecular dynamics analysis of the aggregation propensity of polyglutamine segments. PLoS One 2017; 12:e0178333. [PMID: 28542401 PMCID: PMC5444867 DOI: 10.1371/journal.pone.0178333] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Accepted: 05/11/2017] [Indexed: 01/09/2023] Open
Abstract
Protein misfolding and aggregation is a pathogenic feature shared among at least ten polyglutamine (polyQ) neurodegenerative diseases. While solvent-solution interaction is a key factor driving protein folding and aggregation, the solvation properties of expanded polyQ tracts are not well understood. By using GPU-enabled all-atom molecular dynamics simulations of polyQ monomers in an explicit solvent environment, this study shows that solvent-polyQ interaction propensity decreases as the lengths of polyQ tract increases. This study finds a predominance in long-distance interactions between residues far apart in polyQ sequences with longer polyQ segments, that leads to significant conformational differences. This study also indicates that large loops, comprised of parallel β-structures, appear in long polyQ tracts and present new aggregation building blocks with aggregation driven by long-distance intra-polyQ interactions. Finally, consistent with previous observations using coarse-grain simulations, this study demonstrates that there is a gain in the aggregation propensity with increased polyQ length, and that this gain is correlated with decreasing ability of solvent-polyQ interaction. These results suggest the modulation of solvent-polyQ interactions as a possible therapeutic strategy for treating polyQ diseases.
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Affiliation(s)
- Jingran Wen
- Department of Biomedical Informatics, University of Utah, Salt Lake City, Utah, United States of America
| | - Daniel R. Scoles
- Department of Neurology, University of Utah, Salt Lake City, Utah, United States of America
| | - Julio C. Facelli
- Department of Biomedical Informatics, University of Utah, Salt Lake City, Utah, United States of America
- * E-mail:
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Structural and fluctuational difference between two ends of Aβ amyloid fibril: MD simulations predict only one end has open conformations. Sci Rep 2016; 6:38422. [PMID: 27934893 PMCID: PMC5146922 DOI: 10.1038/srep38422] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 11/08/2016] [Indexed: 02/02/2023] Open
Abstract
Aβ amyloid fibrils, which are related to Alzheimer’s disease, have a cross-β structure consisting of two β-sheets: β1 and β2. The Aβ peptides are thought to be serially arranged in the same molecular conformation along the fibril axis. However, to understand the amyloid extension mechanism, we must understand the amyloid fibril structure and fluctuation at the fibril end, which has not been revealed to date. Here, we reveal these features by all-atom molecular dynamics (MD) simulations of Aβ42 and Aβ40 fibrils in explicit water. The structure and fluctuation were observed to differ between the two ends. At the even end, the Aβ peptide always took a closed form wherein β1 and β2 were closely spaced. The Aβ peptide fluctuated more at the odd end and took an open form wherein the two β-sheets were well separated. The differences are attributed to the stronger β-sheet formation by the β1 exposed at the even end than the β2 exposed at the odd end. Along with the small fluctuations at the even end, these results explain why the fibril extends from one end only, as observed in experiments. Our MD results agree well with recent observations by high-speed atomic force microscopy.
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Mori Y, Okumura H. Simulated tempering based on global balance or detailed balance conditions: Suwa-Todo, heat bath, and Metropolis algorithms. J Comput Chem 2015; 36:2344-9. [PMID: 26466561 DOI: 10.1002/jcc.24213] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Revised: 09/13/2015] [Accepted: 09/15/2015] [Indexed: 11/11/2022]
Abstract
Simulated tempering (ST) is a useful method to enhance sampling of molecular simulations. When ST is used, the Metropolis algorithm, which satisfies the detailed balance condition, is usually applied to calculate the transition probability. Recently, an alternative method that satisfies the global balance condition instead of the detailed balance condition has been proposed by Suwa and Todo. In this study, ST method with the Suwa-Todo algorithm is proposed. Molecular dynamics simulations with ST are performed with three algorithms (the Metropolis, heat bath, and Suwa-Todo algorithms) to calculate the transition probability. Among the three algorithms, the Suwa-Todo algorithm yields the highest acceptance ratio and the shortest autocorrelation time. These suggest that sampling by a ST simulation with the Suwa-Todo algorithm is most efficient. In addition, because the acceptance ratio of the Suwa-Todo algorithm is higher than that of the Metropolis algorithm, the number of temperature states can be reduced by 25% for the Suwa-Todo algorithm when compared with the Metropolis algorithm.
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Affiliation(s)
- Yoshiharu Mori
- Department of Theoretical and Computational Molecular Science, Institute for Molecular Science, Okazaki, Aichi, 444-8585, Japan
| | - Hisashi Okumura
- Research Center for Computational Science, Institute for Molecular Science, Okazaki, Aichi, 444-8585, Japan.,Department of Structural Molecular Science, The Graduate University for Advanced Studies, Okazaki, Aichi, 444-8585, Japan
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30
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Luitz M, Bomblies R, Ostermeir K, Zacharias M. Exploring biomolecular dynamics and interactions using advanced sampling methods. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:323101. [PMID: 26194626 DOI: 10.1088/0953-8984/27/32/323101] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Molecular dynamics (MD) and Monte Carlo (MC) simulations have emerged as a valuable tool to investigate statistical mechanics and kinetics of biomolecules and synthetic soft matter materials. However, major limitations for routine applications are due to the accuracy of the molecular mechanics force field and due to the maximum simulation time that can be achieved in current simulations studies. For improving the sampling a number of advanced sampling approaches have been designed in recent years. In particular, variants of the parallel tempering replica-exchange methodology are widely used in many simulation studies. Recent methodological advancements and a discussion of specific aims and advantages are given. This includes improved free energy simulation approaches and conformational search applications.
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Affiliation(s)
- Manuel Luitz
- Physik-Department T38, Technische Universität München, James Franck Str. 1, 85748 Garching, Germany
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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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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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