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Paul S, Paul S. Molecular dynamics simulation study on the inhibitory effects of choline-O-sulfate on hIAPP protofibrilation. J Comput Chem 2019; 40:1957-1968. [PMID: 31062393 DOI: 10.1002/jcc.25851] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2019] [Revised: 04/10/2019] [Accepted: 04/16/2019] [Indexed: 11/06/2022]
Abstract
Type 2 diabetes mellitus (T2Dm) is a neurodegenerative disease, which occurs due to the self-association of human islet amyloid polypeptide (hIAPP), also known as human amylin. It was reported experimentally that choline-O-sulfate (COS), a small organic molecule having a tertiary amino group and sulfate group, can prevent the aggregation of human amylin without providing the mechanism of the action of COS in the inhibition process. In this work, we investigate the influence of COS on the full-length hIAPP peptide by performing 500 ns classical molecular dynamics simulations. From pure water simulation (without COS), we have identified the residues 11-20 and 23-36 that mainly participate in the fibril formation, but in the presence of 1.07 M COS these residues become totally free of β-sheet conformation. Our results also show that the sulfate oxygen of COS directly interacts with the peptide backbone, which leads to the local disruption of peptide-peptide interaction. Moreover, the presence of favorable peptide-COS vdW interaction energy and high coordination number of COS molecules in the first solvation shell of the peptide indicates the hydrophobic solvation of the peptide residues by COS molecules, which also play a crucial role in the prevention of β-sheet formation. Finally, from the potential of mean force (PMFs) calculations, we observe that the free energy between two peptides is more negative in the absence of COS and with increasing concentration of COS, it becomes unfavorable significantly indicating that the peptide dimer formation is most stable in pure water, which becomes less favorable in the presence of COS. © 2019 Wiley Periodicals, Inc.
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Affiliation(s)
- Srijita Paul
- Department of Chemistry, Indian Institute of Technology, Guwahati, Assam, India 781039
| | - Sandip Paul
- Department of Chemistry, Indian Institute of Technology, Guwahati, Assam, India 781039
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2
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Yuan C, Li S, Zou Q, Ren Y, Yan X. Multiscale simulations for understanding the evolution and mechanism of hierarchical peptide self-assembly. Phys Chem Chem Phys 2017; 19:23614-23631. [DOI: 10.1039/c7cp01923h] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Multiscale molecular simulations that combine and systematically link several hierarchies can provide insights into the evolution and dynamics of hierarchical peptide self-assembly from the molecular level to the mesoscale.
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Affiliation(s)
- Chengqian Yuan
- State Key Laboratory of Biochemical Engineering
- Institute of Process Engineering
- Chinese Academy of Sciences
- Beijing 100190
- China
| | - Shukun Li
- State Key Laboratory of Biochemical Engineering
- Institute of Process Engineering
- Chinese Academy of Sciences
- Beijing 100190
- China
| | - Qianli Zou
- State Key Laboratory of Biochemical Engineering
- Institute of Process Engineering
- Chinese Academy of Sciences
- Beijing 100190
- China
| | - Ying Ren
- Center for Mesoscience
- Institute of Process Engineering
- Chinese Academy of Sciences
- Beijing 100190
- China
| | - Xuehai Yan
- State Key Laboratory of Biochemical Engineering
- Institute of Process Engineering
- Chinese Academy of Sciences
- Beijing 100190
- China
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3
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Zhang M, Ren B, Chen H, Sun Y, Ma J, Jiang B, Zheng J. Molecular Simulations of Amyloid Structures, Toxicity, and Inhibition. Isr J Chem 2016. [DOI: 10.1002/ijch.201600075] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Mingzhen Zhang
- Department of Chemical and Biomolecular Engineering The University of Akron Akron OH 44325 USA
| | - Baiping Ren
- Department of Chemical and Biomolecular Engineering The University of Akron Akron OH 44325 USA
| | - Hong Chen
- Department of Chemical and Biomolecular Engineering The University of Akron Akron OH 44325 USA
| | - Yan Sun
- Department of Biochemical Engineering and Key Laboratory of Systems Bioengineering of the Ministry of Education, School of Chemical Engineering and Technology Tianjin University Tianjin 300072 P. R. China
| | - Jie Ma
- Department of Chemical and Biomolecular Engineering The University of Akron Akron OH 44325 USA
- State Key Laboratory of Pollution Control and Resource Reuse School of Environmental Science and Engineering Tongji University Shanghai 200092 P. R. China
| | - Binbo Jiang
- Department of Chemical and Biomolecular Engineering The University of Akron Akron OH 44325 USA
- College of Chemical and Biological Engineering Zhejiang University Hangzhou Zhejiang 310027 P. R. China
| | - Jie Zheng
- Department of Chemical and Biomolecular Engineering The University of Akron Akron OH 44325 USA
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Karmakar T, Roy S, Balaram H, Balasubramanian S. Structural and dynamical correlations in PfHGXPRT oligomers: A molecular dynamics simulation study. J Biomol Struct Dyn 2016; 34:1590-605. [PMID: 26441001 DOI: 10.1080/07391102.2015.1085441] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
PfHGXPRT is a key enzyme involved in purine nucleotide salvage pathway of the malarial parasite, Plasmodium falciparum. Atomistic molecular dynamics simulations have been performed on two types of PfHGXPRT dimers (D1 and D3) and its tetramer in their apo and ligand-bound states. A significant event in the catalytic cycle is the dynamics of a gate that provides access for the ligand molecules to the reaction center. The gate is formed by loops II and IV, the former being the most flexible. Large amplitude conformational changes have been observed in active site loop II. Upon complete occupancy of the active site, loop II gets stabilized due to specific interactions between its residues and the ligand molecules. Remote loop, X, is seen to be less fluxional in the D3 dimer than in D1 which is rationalized as due to the greater number of inter-subunit contacts in the former. The presence of ligand molecules in subunits of the tetramer further reduces the flexibility of loop X epitomizing a communication between this region and the active sites in the tetramer. These observations are in accordance with the outcomes of several experimental investigations. Participation of loop X in the oligomerization process has also been discerned. Between the two types of dimers in solution, D1 tetramerizes readily and thus would not be present as free dimers. We conjecture an equilibrium to exist between D3 and the tetramer in solution; upon binding of the ligand molecules to the D3 dimer, this equilibrium shifts toward the tetramer.
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Affiliation(s)
- Tarak Karmakar
- a Chemistry and Physics of Materials Unit , Jawaharlal Nehru Centre for Advanced Scientific Research , Bangalore , 560 064 India
| | - Sourav Roy
- b Molecular Biology and Genetics Unit , Jawaharlal Nehru Centre for Advanced Scientific Research , Bangalore , 560 064 India
| | - Hemalatha Balaram
- b Molecular Biology and Genetics Unit , Jawaharlal Nehru Centre for Advanced Scientific Research , Bangalore , 560 064 India
| | - Sundaram Balasubramanian
- a Chemistry and Physics of Materials Unit , Jawaharlal Nehru Centre for Advanced Scientific Research , Bangalore , 560 064 India
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5
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Free energy simulations of amylin I26P mutation in a lipid bilayer. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2014; 44:37-47. [DOI: 10.1007/s00249-014-0999-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2014] [Revised: 11/06/2014] [Accepted: 11/10/2014] [Indexed: 10/24/2022]
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6
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Li Y, Xu W, Mu Y, Zhang JZH. Acidic pH retards the fibrillization of human Islet Amyloid Polypeptide due to electrostatic repulsion of histidines. J Chem Phys 2014; 139:055102. [PMID: 23927287 DOI: 10.1063/1.4817000] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The human Islet Amyloid Polypeptide (hIAPP) is the major constituent of amyloid deposits in pancreatic islets of type-II diabetes. IAPP is secreted together with insulin from the acidic secretory granules at a low pH of approximately 5.5 to the extracellular environment at a neutral pH. The increased accumulation of extracellular hIAPP in diabetes indicates that changes in pH may promote amyloid formation. To gain insights and underlying mechanisms of the pH effect on hIAPP fibrillogenesis, all-atom molecular dynamics simulations in explicit solvent model were performed to study the structural properties of five hIAPP protofibrillar oligomers, under acidic and neutral pH, respectively. In consistent with experimental findings, simulation results show that acidic pH is not conducive to the structural stability of these oligomers. This provides a direct evidence for a recent experiment [L. Khemtemourian, E. Domenech, J. P. F. Doux, M. C. Koorengevel, and J. A. Killian, J. Am. Chem. Soc. 133, 15598 (2011)], which suggests that acidic pH inhibits the fibril formation of hIAPP. In addition, a complementary coarse-grained simulation shows the repulsive electrostatic interactions among charged His18 residues slow down the dimerization process of hIAPP by twofold. Besides, our all-atom simulations reveal acidic pH mainly affects the local structure around residue His18 by destroying the surrounding hydrogen-bonding network, due to the repulsive interactions between protonated interchain His18 residues at acidic pH. It is also disclosed that the local interactions nearby His18 operating between adjacent β-strands trigger the structural transition, which gives hints to the experimental findings that the rate of hIAPP fibril formation and the morphologies of the fibrillar structures are strongly pH-dependent.
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Affiliation(s)
- Yang Li
- State Key Laboratory of Precision Spectroscopy, Department of Physics, East China Normal University, Shanghai 200062, China
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Berhanu WM, Masunov AE. Full length amylin oligomer aggregation: insights from molecular dynamics simulations and implications for design of aggregation inhibitors. J Biomol Struct Dyn 2013; 32:1651-69. [PMID: 24028418 DOI: 10.1080/07391102.2013.832635] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Amyloid oligomers are considered to play essential roles in the pathogenesis of amyloid-related degenerative diseases including type 2 diabetes. Using an explicit solvent all atomic MD simulation, we explored the stability, conformational dynamics and association force of different single-layer models of the full-length wild-type and glycine mutants of amylin (pentamer) obtained from a recent high resolution fibril model. The RMSF profile shows enhanced flexibility in the disorder (Lys1-Cys7) and turn region (Ser19-Gly23), along with smallest fluctuation at the residues (Asn14-Phe15-Leu16-Val17-His18) of β1 region and (Ala25-Ile26-Leu27-Ser28-Ser29) of the β2 region. We obtained a significant difference in backbone RMSD between the wild-type and the mutants, indicating that mutations affected the stability of the peptide. The RMSD and RMSF profiles indicate the edge and loop residues are the primary contributors to the overall conformational changes. The degree of structural similarity between the oligomers in the simulation and the fibril conformation is proposed as the possible explanation for experimentally observed shortening of the nucleation lag phase of amylin with oligomer seeding. On the basis of structure-stability findings, the β1 and β2 portions are optimal target for further anti-amyloid drug design. The MM-PBSA binding energy calculation reveals the binding of amylin: amylin strands in single layer is dominated by contributions from van der Waals interactions. The non-polar solvation term is also found to be favorable. While the electrostatic interactions and polar solvation energy was found to be favorable for the interaction for the larger aggregate and unfavorable for the smaller aggregates. A per-residue decomposition of the binding free energy has been performed to identify the residues contributing most to the self-association free energy. Residues found in the β-sheet regions were found to be key residue making the largest favorable contributions to the single-layer association. The result from our simulation could be used in rational design of new amylinomimetic agent, amylin aggregation inhibitors and amylin-specific biomarkers.
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Affiliation(s)
- Workalemahu Mikre Berhanu
- a NanoScience Technology Center and Department of Chemistry , University of Central Florida , Orlando , FL , 32826 , USA
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8
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Adsorption and Orientation of Human Islet Amyloid Polypeptide (hIAPP) Monomer at Anionic Lipid Bilayers: Implications for Membrane-Mediated Aggregation. Int J Mol Sci 2013; 14:6241-58. [PMID: 23519103 PMCID: PMC3634446 DOI: 10.3390/ijms14036241] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Revised: 03/11/2013] [Accepted: 03/12/2013] [Indexed: 01/05/2023] Open
Abstract
Protein misfolding and aggregation cause serious degenerative diseases, such as Alzheimer's and type II diabetes. Human islet amyloid polypeptide (hIAPP) is the major component of amyloid deposits found in the pancreas of type II diabetic patients. Increasing evidence suggests that β-cell death is related to the interaction of hIAPP with the cellular membrane, which accelerates peptide aggregation. In this study, as a first step towards understanding the membrane-mediated hIAPP aggregation, we investigate the atomic details of the initial step of hIAPP-membrane interaction, including the adsorption orientation and conformation of hIAPP monomer at an anionic POPG lipid bilayer by performing all-atom molecular dynamics simulations. We found that hIAPP monomer is quickly adsorbed to bilayer surface, and the adsorption is initiated from the N-terminal residues driven by strong electrostatic interactions of the positively-charged residues K1 and R11 with negatively-charged lipid headgroups. hIAPP binds parallel to the lipid bilayer surface as a stable helix through residues 7-22, consistent with previous experimental study. Remarkably, different simulations lead to the same binding orientation stabilized by electrostatic and H-bonding interactions, with residues R11, F15 and S19 oriented towards membrane and hydrophobic residues L12, A13, L16 and V17 exposed to solvent. Implications for membrane-mediated hIAPP aggregation are discussed.
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9
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Morriss-Andrews A, Bellesia G, Shea JE. β-sheet propensity controls the kinetic pathways and morphologies of seeded peptide aggregation. J Chem Phys 2013; 137:145104. [PMID: 23061868 DOI: 10.1063/1.4755748] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The effect of seeds in templating the morphology of peptide aggregates is examined using molecular dynamics simulations and a coarse-grained peptide representation. Varying the nature of the aggregate seed between β-sheet, amorphous, and β-barrel seeds leads to different aggregation pathways and to morphologically different aggregates. Similar effects are seen by varying the β-sheet propensity of the free peptides. For a fibrillar seed and free peptides of high β-sheet propensity, fibrillar growth occurred by means of direct attachment (without structural rearrangement) of free individual peptides and small ordered oligomers onto the seed. For a fibrillar seed and free peptides of low β-sheet propensity, fibrillar growth occurred through a dock-lock mechanism, in which the free peptides first docked onto the seed, and then locked on, extending and aligning to join the fibril. Amorphous seeds absorbed free peptides into themselves indiscriminately, with any fibrillar rearrangement subsequent to this absorption by means of a condensation-ordering transition. Although the mechanisms observed by varying peptide β-sheet propensity are diverse, the initial pathways can always be broken down into the following steps: (i) the free peptides diffuse in the bulk and attach individually to the seed; (ii) the free peptides diffuse and aggregate among themselves; (iii) the free peptide oligomers collide with the seed; and (iv) the free oligomers merge with the seed and rearrange in a manner dependent on the backbone flexibility of both the free and seed peptides. Our simulations indicate that it is possible to sequester peptides from amorphous aggregates into fibrils, and also that aggregate morphology (and thus cytoxicity) can be controlled by introducing seeds of aggregate-compatible peptides with differing β-sheet propensities into the system.
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Affiliation(s)
- Alex Morriss-Andrews
- Department of Physics, University of California Santa Barbara, Santa Barbara, California 93106, USA
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10
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Liang G, Zhao J, Yu X, Zheng J. Comparative molecular dynamics study of human islet amyloid polypeptide (IAPP) and rat IAPP oligomers. Biochemistry 2013; 52:1089-100. [PMID: 23331123 DOI: 10.1021/bi301525e] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Human islet amyloid polypeptide (hIAPP or amylin) is a causative agent in pancreatic amyloid deposits found in patients with type 2 diabetes. The aggregation of full-length hIAPP(1-37) into small oligomeric species is increasingly believed to be responsible for cell dysfunction and death. However, rat IAPP (rIAPP(1-37)), which differs from hIAPP in only six of 37 residues, loses its aggregation ability to form toxic amyloid species. Atomic details of the effect of sequence on the structure and toxicity between the amyloidogenic, toxic hIAPP peptide and the nonamyloidogenic, nontoxic rIAPP peptide remain unclear. Here, we probe sequence-induced differences in structural stability, conformational dynamics, and driving forces between different hIAPP and rIAPP polymorphic forms from monomer to pentamer using molecular dynamics simulations. Simulations show that hIAPP forms from trimer to pentamer exhibit high structural stability with well-preserved in-register parallel β-sheet and the U-bend conformation. The hIAPP trimer appears to be a smallest minimal seed in solution. The stabilities of parallel hIAPP oligomers increase with the number of peptides. Conversely, replacement of hIAPP sequence by rIAPP sequence causes a significant loss of favorable interpeptide interactions in all rIAPP oligomers, destabilizing the C-terminal β-sheet, turn conformation, and overall stability. A less β-sheet-rich structure and a disturbed U-shaped topology exert a large energy penalty on the self-assemble of the rIAPP peptides into highly ordered, in-register β-sheet-rich protofibrils and fibrils, which explains the nonamyloidogenic activity of rIAPP. Moreover, the absence of interior water within the U-turn region in the well-packed higher-order hIAPP oligomers, not in the poorly packed rIAPP oligomers, also stabilizes peptide association. This work provides atomic details of the sequence-structure relationship between the amyloidogenic hIAPP and its analogues such as the nonamyloidogenic rIAPP and some mutants, which could help in the development of novel therapeutic agents to block the formation of toxic hIAPP oligomeric species for type 2 diabetes.
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Affiliation(s)
- Guizhao Liang
- Department of Chemical and Biomolecular Engineering, The University of Akron, Akron, OH 44325, USA
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11
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Xu W, Su H, Zhang JZH, Mu Y. Molecular dynamics simulation study on the molecular structures of the amylin fibril models. J Phys Chem B 2012; 116:13991-9. [PMID: 23145779 DOI: 10.1021/jp308708h] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The structural characterization of amyloid fibers is one of the most investigated areas in structural biology. Recently, protofibril models for amylin, i.e., the 37-residue human islet amyloid polypeptide or hIAPP were suggested by two groups based on NMR (Biochemistry 2007, 46, 13505-13522) and X-ray (Protein Sci. 2008, 17, 1467-1474) techniques. However, there are significant differences in the two models which maybe originate from the polymorphic nature of amylin fibrils. To obtain further insights into the packing and stability features of the different models, we performed a series of molecular dynamics simulations on them. Our analysis showed that even pairs of β-sheets composed of a limited number of β-strands are stable in the 100-ns simulations, which suggests that steric zipper interactions at a β-sheet-β-sheet interface strongly contribute to the stability of these amyloid aggregates. For both models, outer strands are more flexible, which might coincide with the dynamical requirement that outer strands act as growing sites facilitating conformational changes of new incoming chains. Moreover, simulation results showed that the X-ray models are structurally more compact than the NMR models and have more intimate patterns, which lead to more rigid amyloid models. As a result, the X-ray models are energetically more stable than the NMR models. Further modeling analyses verify the most likely amylin fibril model among both NMR and X-ray models. Upon further study of the force-induced dissociation of a single chain from the protofibrils, the binding energy and the mechanical stability of the fibril models are revealed. On these bases, it is possible to reconcile the crystallographic and the NMR data on the basic amylin fiber unit.
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Affiliation(s)
- Weixin Xu
- State Key Laboratory of Precision Spectroscopy, Department of Physics, Institute of Theoretical and Computational Science, East China Normal University, Shanghai, China.
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Li Y, Ji C, Xu W, Zhang JZH. Dynamical stability and assembly cooperativity of β-sheet amyloid oligomers--effect of polarization. J Phys Chem B 2012; 116:13368-73. [PMID: 23101885 DOI: 10.1021/jp3086599] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The soluble intermediate oligomers of amyloidogenic proteins are suspected to be more cytotoxic than the mature fibrils in neurodegenerative disorders. Here, the dynamic stability and assembly cooperativity of a model oligomer of human islet amyloid polypeptide (hIAPP) segments were explored by means of all-atom molecular dynamics (MD) simulations under different force fields including AMBER99SB, OPLS, and polarized protein-specific charge (PPC) model. Simulation results show that the dynamic stability of β-sheet oligomers is seriously impacted by electrostatic polarization. Without inclusion of polarization (simulation under standard AMBER and OPLS force field), the β-sheet oligomers are dynamically unstable during MD simulation. For comparison, simulation results under PPC give significantly more stable dynamical structures of the oligomers. Furthermore, calculation of electrostatic interaction energy between the neighboring β strands with an approximate polarizable method produces energetic evidence for cooperative assembly of β-strand oligomers. This result supports a picture of downhill-like cooperative assembly of β strands during fibrillation process. The present study demonstrates the critical role of polarization in dynamic stability and assembly cooperativity of β-sheet-rich amyloid oligomers.
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Affiliation(s)
- Yang Li
- State Key Laboratory of Precision Spectroscopy and Department of Physics, Institute of Theoretical and Computational Science, East China Normal University, Shanghai, China
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13
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Liu FF, Liu Z, Bai S, Dong XY, Sun Y. Exploring the inter-molecular interactions in amyloid-β protofibril with molecular dynamics simulations and molecular mechanics Poisson-Boltzmann surface area free energy calculations. J Chem Phys 2012; 136:145101. [PMID: 22502547 DOI: 10.1063/1.3702195] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Aggregation of amyloid-β (Aβ) peptides correlates with the pathology of Alzheimer's disease. However, the inter-molecular interactions between Aβ protofibril remain elusive. Herein, molecular mechanics Poisson-Boltzmann surface area analysis based on all-atom molecular dynamics simulations was performed to study the inter-molecular interactions in Aβ(17-42) protofibril. It is found that the nonpolar interactions are the important forces to stabilize the Aβ(17-42) protofibril, while electrostatic interactions play a minor role. Through free energy decomposition, 18 residues of the Aβ(17-42) are identified to provide interaction energy lower than -2.5 kcal/mol. The nonpolar interactions are mainly provided by the main chain of the peptide and the side chains of nine hydrophobic residues (Leu17, Phe19, Phe20, Leu32, Leu34, Met35, Val36, Val40, and Ile41). However, the electrostatic interactions are mainly supplied by the main chains of six hydrophobic residues (Phe19, Phe20, Val24, Met35, Val36, and Val40) and the side chains of the charged residues (Glu22, Asp23, and Lys28). In the electrostatic interactions, the overwhelming majority of hydrogen bonds involve the main chains of Aβ as well as the guanidinium group of the charged side chain of Lys28. The work has thus elucidated the molecular mechanism of the inter-molecular interactions between Aβ monomers in Aβ(17-42) protofibril, and the findings are considered critical for exploring effective agents for the inhibition of Aβ aggregation.
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Affiliation(s)
- Fu-Feng Liu
- Department of Biochemical Engineering and Key Laboratory of Systems Bioengineering of the Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
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Church MS, Ferry CE, van Giessen AE. Thermodynamics of peptide dimer formation. J Chem Phys 2012; 136:245102. [DOI: 10.1063/1.4730169] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Pohl G, Jákli I, Csizmadia IG, Papp D, Matías GF, Perczel A. The role of entropy in initializing the aggregation of peptides: a first principle study on oligopeptide oligomerization. Phys Chem Chem Phys 2012; 14:1507-16. [DOI: 10.1039/c2cp22821a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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16
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Cao Z, Liu L, Wang J. Why the OPLS-AA Force Field Cannot Produce the β-Hairpin Structure of H1 Peptide in Solution When Comparing with the GROMOS 43A1 Force Field? J Biomol Struct Dyn 2011; 29:527-39. [DOI: 10.1080/07391102.2011.10507403] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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17
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Xu W, Wei G, Su H, Nordenskiöld L, Mu Y. Effects of cholesterol on pore formation in lipid bilayers induced by human islet amyloid polypeptide fragments: a coarse-grained molecular dynamics study. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 84:051922. [PMID: 22181459 DOI: 10.1103/physreve.84.051922] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Indexed: 05/31/2023]
Abstract
Disruption of the cellular membrane by the amyloidogenic peptide, islet amyloid polypeptide (IAPP), has been considered as one of the mechanisms of β-cell death during type 2 diabetes. The N-terminal region (residues 1-19) of the human version of IAPP is suggested to be primarily responsible for the membrane-disrupting effect of the full-length hIAPP peptide. However, the detailed assembly mode of hIAPP1-19 with membrane remains unclear. To gain insight into the interactions of hIAPP1-19 oligomer with the model membrane, we have employed coarse-grained molecular dynamics self-assembly simulations to study the aggregation of hIAPP1-19 fragments in the binary lipid made of zwitterionic dipalmitoylphosphatidylcholine (DPPC) and anionic dipalmitoylphosphatidylserine (DPPS) in the presence and absence of different levels of cholesterol content. The membrane-destabilizing effect of hIAPP1-19 is found to be modulated by the presence of cholesterol. In the absence of cholesterol, hIAPP1-19 aggregates prefer to locate inside the bilayer, forming pore-like assemblies. While in the presence of cholesterol molecules, the lipid bilayer becomes more ordered and stiff, and the hIAPP1-19 aggregates are dominantly positioned at the bilayer-water interface. The action of cholesterol may suggest a possible way to maintain the membrane integrity by small molecule interference.
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Affiliation(s)
- Weixin Xu
- State Key Laboratory of Precision Spectroscopy, Institutes for Advanced Interdisciplinary Research, East China Normal University, Shanghai, China
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18
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Xu W, Zhang C, Derreumaux P, Gräslund A, Morozova-Roche L, Mu Y. Intrinsic determinants of Aβ(12-24) pH-dependent self-assembly revealed by combined computational and experimental studies. PLoS One 2011; 6:e24329. [PMID: 21957446 PMCID: PMC3177821 DOI: 10.1371/journal.pone.0024329] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2011] [Accepted: 08/04/2011] [Indexed: 11/19/2022] Open
Abstract
The propensity of amyloid- (A) peptide to self-assemble into highly ordered amyloid structures lies at the core of their accumulation in the brain during Alzheimer's disease. By using all-atom explicit solvent replica exchange molecular dynamics simulations, we elucidated at the atomic level the intrinsic determinants of the pH-dependent dimerization of the central hydrophobic segment A and related these with the propensity to form amyloid fibrils measured by experimental tools such as atomic force microscopy and fluorescence. The process of A dimerization was evaluated in terms of free energy landscape, side-chain two-dimensional contact probability maps, -sheet registries, potential mean force as a function of inter-chain distances, secondary structure development and radial solvation distributions. We showed that dimerization is a key event in A amyloid formation; it is highly prompted in the order of pH 5.02.98.4 and determines further amyloid growth. The dimerization is governed by a dynamic interplay of hydrophobic, electrostatic and solvation interactions permitting some variability of -sheets at each pH. These results provide atomistic insight into the complex process of molecular recognition detrimental for amyloid growth and pave the way for better understanding of the molecular basis of amyloid diseases.
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Affiliation(s)
- Weixin Xu
- State Key Laboratory of Precision Spectroscopy, Institute of Theoretical and Computational Science, East China Normal University, Shanghai, China
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Ce Zhang
- Departments of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Philippe Derreumaux
- Laboratoire de Biochimie Théorique, UPR9080 CNRS, Institut de Biologie Physico-Chimique, Paris, France
| | - Astrid Gräslund
- Department of Biophysics, Stockholm University, Stockholm, Sweden
| | - Ludmilla Morozova-Roche
- Departments of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
- * E-mail: (LM); (YM)
| | - Yuguang Mu
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
- * E-mail: (LM); (YM)
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19
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Unique example of amyloid aggregates stabilized by main chain H-bond instead of the steric zipper: molecular dynamics study of the amyloidogenic segment of amylin wild-type and mutants. J Mol Model 2011; 18:891-903. [PMID: 21625904 DOI: 10.1007/s00894-011-1030-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2010] [Accepted: 03/06/2011] [Indexed: 12/19/2022]
Abstract
Most proteins do not aggregate while in their native functional states. However, they may be disturbed from their native conformation by certain change in the environment, and form unwanted oligomeric or polymeric aggregates. Recent experimental data demonstrate that soluble oligomers of amyloidogenic proteins are responsible for amyloidosis and its cytotoxicity. Human islet amyloid polypeptide (IAPP or amylin) is a 37-residue hormone found as fibrillar deposits in pancreatic extracts of nearly all type II diabetics. In this study we performed in silico mutation analysis to examine the stability of the double layer five strand aggregates formed by heptapeptide NNFGAIL segment from amyline peptide. This segment is one of the shortest fragments that can form amyloid fibrils similar to those formed by the full length peptide. The mutants obtained by single glycine replacement were also studied to investigate the specificity of the dry self-complementary interface between the neighboring β-sheet layers. The molecular dynamics simulations of the aggregates run for 20 ns at 330 K, the degree of the aggregate disassembly was investigated using several geometry analysis tools: the root mean square deviations of the C(α) atoms, root mean square fluctuations per residue, twist angles, interstrand distances, fraction of the secondary structure elements, and number of H-bonds. The analysis shows that most mutations make the aggregates unstable, and their stabilities were dependent to a large extent on the position of replaced residues. Our mutational simulations are in agreement with the pervious experimental observations. We also used free binding energy calculations to determine the role of different components: nonpolar effects, electrostatics and entropy in binding. Nonpolar effects remained consistently more favorable in wild type and mutants reinforcing the importance of hydrophobic effects in protein-protein binding. While entropy systematically opposed binding in all cases, there was no clear trend in the entropy difference between wildtype and glycine mutants. Free energy decomposition shows residues situated at the interface were found to make favorable contributions to the peptide-peptide association. The study of the wild type and mutants in an explicit solvent could provide valuable insight into the future computer guided design efforts for the amyloid aggregation inhibitor.
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20
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Zhao J, Yu X, Liang G, Zheng J. Heterogeneous Triangular Structures of Human Islet Amyloid Polypeptide (Amylin) with Internal Hydrophobic Cavity and External Wrapping Morphology Reveal the Polymorphic Nature of Amyloid Fibrils. Biomacromolecules 2011; 12:1781-94. [DOI: 10.1021/bm2001507] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Jun Zhao
- Department of Chemical and Biomolecular Engineering, The University of Akron, Akron, Ohio 44325, United States
| | - Xiang Yu
- Department of Chemical and Biomolecular Engineering, The University of Akron, Akron, Ohio 44325, United States
| | - Guizhao Liang
- Department of Chemical and Biomolecular Engineering, The University of Akron, Akron, Ohio 44325, United States
- Key Laboratory of Biorheological Science and Technology Ministry of Education, Bioengineering College, Chongqing University, Chongqing 400044, P. R. China
| | - Jie Zheng
- Department of Chemical and Biomolecular Engineering, The University of Akron, Akron, Ohio 44325, United States
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21
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Wei L, Jiang P, Xu W, Li H, Zhang H, Yan L, Chan-Park MB, Liu XW, Tang K, Mu Y, Pervushin K. The molecular basis of distinct aggregation pathways of islet amyloid polypeptide. J Biol Chem 2011; 286:6291-300. [PMID: 21148563 PMCID: PMC3057848 DOI: 10.1074/jbc.m110.166678] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Revised: 12/09/2010] [Indexed: 11/06/2022] Open
Abstract
Abnormal aggregation of islet amyloid polypeptide (IAPP) into amyloid fibrils is a hallmark of type 2 diabetes. In this study, we investigated the initial oligomerization and subsequent addition of monomers to growing aggregates of human IAPP at the residue-specific level using NMR, atomic force microscopy, mass spectroscopy, and computational simulations. We found that in solution IAPPs rapidly associate into transient low-order oligomers such as dimers and trimers via interactions between histidine 18 and tyrosine 37. This initial event is proceeded by slow aggregation into higher-order spherical oligomers and elongated fibrils. In these two morphologically distinct types of aggregates IAPPs adopt structures with markedly different residual flexibility. Here we show that the anti-amyloidogenic compound resveratrol inhibits oligomerization and amyloid formation via binding to histidine 18, supporting the finding that this residue is crucial for on-pathway oligomer formation.
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Affiliation(s)
- Lei Wei
- From the Schools of Biological Sciences
| | | | - Weixin Xu
- From the Schools of Biological Sciences
| | - Hai Li
- Materials Science and Engineering
| | | | | | | | - Xue-Wei Liu
- Physical and Mathematical Sciences, Nanyang Technological University, Singapore 639798
| | - Kai Tang
- From the Schools of Biological Sciences
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22
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Zhao J, Yu X, Liang G, Zheng J. Structural Polymorphism of Human Islet Amyloid Polypeptide (hIAPP) Oligomers Highlights the Importance of Interfacial Residue Interactions. Biomacromolecules 2010; 12:210-20. [DOI: 10.1021/bm101159p] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Jun Zhao
- Department of Chemical and Biomolecular Engineering, University of Akron, Akron, Ohio 44325, United States, and Key Laboratory of Biorheological Science and Technology, Ministry of Education, Bioengineering College, Chongqing University, Chongqing 400044, P.R. China
| | - Xiang Yu
- Department of Chemical and Biomolecular Engineering, University of Akron, Akron, Ohio 44325, United States, and Key Laboratory of Biorheological Science and Technology, Ministry of Education, Bioengineering College, Chongqing University, Chongqing 400044, P.R. China
| | - Guizhao Liang
- Department of Chemical and Biomolecular Engineering, University of Akron, Akron, Ohio 44325, United States, and Key Laboratory of Biorheological Science and Technology, Ministry of Education, Bioengineering College, Chongqing University, Chongqing 400044, P.R. China
| | - Jie Zheng
- Department of Chemical and Biomolecular Engineering, University of Akron, Akron, Ohio 44325, United States, and Key Laboratory of Biorheological Science and Technology, Ministry of Education, Bioengineering College, Chongqing University, Chongqing 400044, P.R. China
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23
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Reddy AS, Wang L, Singh S, Ling YL, Buchanan L, Zanni MT, Skinner JL, de Pablo JJ. Stable and metastable states of human amylin in solution. Biophys J 2010; 99:2208-16. [PMID: 20923655 PMCID: PMC3042569 DOI: 10.1016/j.bpj.2010.07.014] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Revised: 06/28/2010] [Accepted: 07/06/2010] [Indexed: 11/26/2022] Open
Abstract
Patients with type II diabetes exhibit fibrillar deposits of human amylin protein in the pancreas. It has been proposed that amylin oligomers arising along the aggregation or fibril-formation pathways are important in the genesis of the disease. In a step toward understanding these aggregation pathways, in this work we report the conformational preferences of human amylin monomer in solution using molecular simulations and infrared experiments. In particular, we identify a stable conformer that could play a key role in aggregation. We find that amylin adopts three stable conformations: one with an α-helical segment comprising residues 9-17 and a short antiparallel β-sheet comprising residues 24-28 and 31-35; one with an extended antiparallel β-hairpin with the turn region comprising residues 20-23; and one with no particular structure. Using detailed calculations, we determine the relative stability of these various conformations, finding that the β-hairpin conformation is the most stable, followed by the α-helical conformation, and then the unstructured coil. To test our predicted structure, we calculate its infrared spectrum in the amide I stretch regime, which is sensitive to secondary structure through vibrational couplings and linewidths, and compare it to experiment. We find that theoretically predicted spectra are in good agreement with the experimental line shapes presented herein. The implications of the monomer secondary structures on its aggregation pathway and on its interaction with cell membranes are discussed.
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Affiliation(s)
- Allam S. Reddy
- Departments of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin
| | - Lu Wang
- Chemistry, University of Wisconsin-Madison, Madison, Wisconsin
| | - Sadanand Singh
- Departments of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin
| | - Yun L. Ling
- Chemistry, University of Wisconsin-Madison, Madison, Wisconsin
| | - Lauren Buchanan
- Chemistry, University of Wisconsin-Madison, Madison, Wisconsin
| | - Martin T. Zanni
- Chemistry, University of Wisconsin-Madison, Madison, Wisconsin
| | | | - Juan J. de Pablo
- Departments of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin
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24
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Thermodynamic selection of steric zipper patterns in the amyloid cross-beta spine. PLoS Comput Biol 2009; 5:e1000492. [PMID: 19730673 PMCID: PMC2723932 DOI: 10.1371/journal.pcbi.1000492] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2008] [Accepted: 07/28/2009] [Indexed: 11/19/2022] Open
Abstract
At the core of amyloid fibrils is the cross-beta spine, a long tape of beta-sheets formed by the constituent proteins. Recent high-resolution x-ray studies show that the unit of this filamentous structure is a beta-sheet bilayer with side chains within the bilayer forming a tightly interdigitating "steric zipper" interface. However, for a given peptide, different bilayer patterns are possible, and no quantitative explanation exists regarding which pattern is selected or under what condition there can be more than one pattern observed, exhibiting molecular polymorphism. We address the structural selection mechanism by performing molecular dynamics simulations to calculate the free energy of incorporating a peptide monomer into a beta-sheet bilayer. We test filaments formed by several types of peptides including GNNQQNY, NNQQ, VEALYL, KLVFFAE and STVIIE, and find that the patterns with the lowest binding free energy correspond to available atomistic structures with high accuracy. Molecular polymorphism, as exhibited by NNQQ, is likely because there are more than one most stable structures whose binding free energies differ by less than the thermal energy. Detailed analysis of individual energy terms reveals that these short peptides are not strained nor do they lose much conformational entropy upon incorporating into a beta-sheet bilayer. The selection of a bilayer pattern is determined mainly by the van der Waals and hydrophobic forces as a quantitative measure of shape complementarity among side chains between the beta-sheets. The requirement for self-complementary steric zipper formation supports that amyloid fibrils form more easily among similar or same sequences, and it also makes parallel beta-sheets generally preferred over anti-parallel ones. But the presence of charged side chains appears to kinetically drive anti-parallel beta-sheets to form at early stages of assembly, after which the bilayer formation is likely driven by energetics.
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