51
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Sasmal S, Lincoff J, Head-Gordon T. Effect of a Paramagnetic Spin Label on the Intrinsically Disordered Peptide Ensemble of Amyloid-β. Biophys J 2017; 113:1002-1011. [PMID: 28877484 DOI: 10.1016/j.bpj.2017.06.067] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 06/16/2017] [Accepted: 06/30/2017] [Indexed: 10/18/2022] Open
Abstract
Paramagnetic relaxation enhancement is an NMR technique that has yielded important insight into the structure of folded proteins, although the perturbation introduced by the large spin probe might be thought to diminish its usefulness when applied to characterizing the structural ensembles of intrinsically disordered proteins (IDPs). We compare the computationally generated structural ensembles of the IDP amyloid-β42 (Aβ42) to an alternative sequence in which a nitroxide spin label attached to cysteine has been introduced at its N-terminus. Based on this internally consistent computational comparison, we find that the spin label does not perturb the signature population of the β-hairpin formed by residues 16-21 and 29-36 that is dominant in the Aβ42 reference ensemble. However, the presence of the tag induces a strong population shift in a subset of the original Aβ42 structural sub-populations, including a sevenfold enhancement of the β-hairpin formed by residues 27-31 and 33-38. Through back-calculation of NMR observables from the computational structural ensembles, we show that the structural differences between the labeled and unlabeled peptide would be evident in local residual dipolar couplings, and possibly differences in homonuclear 1H-1H nuclear Overhauser effects (NOEs) and heteronuclear 1H-15N NOEs if the paramagnetic contribution to the longitudinal relaxation does not suppress the NOE intensities in the real experiment. This work shows that molecular simulation provides a complementary approach to resolving the potential structural perturbations introduced by reporter tags that can aid in the interpretation of paramagnetic relaxation enhancement, double electron-electron resonance, and fluorescence resonance energy transfer experiments applied to IDPs.
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Affiliation(s)
- Sukanya Sasmal
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California
| | - James Lincoff
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California
| | - Teresa Head-Gordon
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California; Department of Chemistry, University of California, Berkeley, Berkeley, California; Department of Bioengineering, University of California, Berkeley, Berkeley, California; Pitzer Center for Theoretical Chemistry, University of California, Berkeley, Berkeley, California.
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52
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Zheng W, Tsai MY, Wolynes PG. Comparing the Aggregation Free Energy Landscapes of Amyloid Beta(1-42) and Amyloid Beta(1-40). J Am Chem Soc 2017; 139:16666-16676. [PMID: 29057654 PMCID: PMC5805378 DOI: 10.1021/jacs.7b08089] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Using a predictive coarse-grained protein force field, we compute and compare the free energy landscapes and relative stabilities of amyloid-β protein (1-42) and amyloid-β protein (1-40) in their monomeric and oligomeric forms up to the octamer. At the same concentration, the aggregation free energy profile of Aβ42 is more downhill, with a computed solubility that is about 10 times smaller than that of Aβ40. At a concentration of 40 μM, the clear free energy barrier between the pre-fibrillar tetramer form and the fibrillar pentamer in the Aβ40 aggregation landscape disappears for Aβ42, suggesting that the Aβ42 tetramer has a more diverse structural range. To further compare the landscapes, we develop a cluster analysis based on the structural similarity between configurations and use it to construct an oligomerization map that captures the paths of easy interconversion between different but structurally similar states of oligomers for both species. A taxonomy of the oligomer species based on β-sheet stacking topologies is proposed. The comparison of the two oligomerization maps highlights several key differences in the landscapes that can be attributed to the two additional C-terminal residues that Aβ40 lacks. In general, the two terminal residues strongly stabilize the oligomeric structures for Aβ42 relative to Aβ40, and greatly facilitate the conversion from pre-fibrillar trimers to fibrillar tetramers.
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Affiliation(s)
- Weihua Zheng
- Department of Chemistry, and Center for Theoretical Biological Physics, Rice University, Houston, Texas 77005, United States
| | - Min-Yeh Tsai
- Department of Chemistry, and Center for Theoretical Biological Physics, Rice University, Houston, Texas 77005, United States
| | - Peter G. Wolynes
- Department of Chemistry, and Center for Theoretical Biological Physics, Rice University, Houston, Texas 77005, United States
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53
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Cao Y, Jiang X, Han W. Self-Assembly Pathways of β-Sheet-Rich Amyloid-β(1-40) Dimers: Markov State Model Analysis on Millisecond Hybrid-Resolution Simulations. J Chem Theory Comput 2017; 13:5731-5744. [PMID: 29019683 DOI: 10.1021/acs.jctc.7b00803] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Early oligomerization during amyloid-β (Aβ) aggregation is essential for Aβ neurotoxicity. Understanding how unstructured Aβs assemble into oligomers, especially those rich in β-sheets, is essential but remains challenging as the assembly process is too transient for experimental characterization and too slow for molecular dynamics simulations. So far, atomic simulations are limited only to studies of either oligomer structures or assembly pathways for short Aβ segments. To overcome the computational challenge, we combine in this study a hybrid-resolution model and adaptive sampling techniques to perform over 2.7 ms of simulations of formation of full-length Aβ40 dimers that are the earliest toxic oligomeric species. The Markov state model is further employed to characterize the transition pathways and associated kinetics. Our results show that for two major forms of β-sheet-rich structures reported experimentally, the corresponding assembly mechanisms are markedly different. Hairpin-containing structures are formed by direct binding of soluble Aβ in β-hairpin-like conformations. Formation of parallel, in-register structures resembling fibrils occurs ∼100-fold more slowly and involves a rapid encounter of Aβ in arbitrary conformations followed by a slow structural conversion. The structural conversion proceeds via diverse pathways but always requires transient unfolding of encounter complexes. We find that the transition kinetics could be affected differently by intra-/intermolecular interactions involving individual residues in a conformation-dependent manner. In particular, the interactions involving Aβ's N-terminal part promote the assembly into hairpin-containing structures but delay the formation of fibril-like structures, thus explaining puzzling observations reported previously regarding the roles of this region in the early assembly process.
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Affiliation(s)
- Yang Cao
- Key Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School , Shenzhen, 518055, China
| | - Xuehan Jiang
- Key Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School , Shenzhen, 518055, China
| | - Wei Han
- Key Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School , Shenzhen, 518055, China
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54
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Huy PDQ, Thai NQ, Bednarikova Z, Phuc LH, Linh HQ, Gazova Z, Li MS. Bexarotene Does Not Clear Amyloid Beta Plaques but Delays Fibril Growth: Molecular Mechanisms. ACS Chem Neurosci 2017; 8:1960-1969. [PMID: 28689412 DOI: 10.1021/acschemneuro.7b00107] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
In 2012, it was reported that anticancer drug bexarotene reduced amyloid plaque and improved mental functioning in a small sample of mice engineered to exhibit Alzheimer's like symptoms. It has been suggested that bexarotene stimulates expression of apolipoprotein E (ApoE) leading to intracellular clearance of amyloid beta (Aβ). However, the effect of bexarotene on clearance of plaques has not been seen in some mouse models. Two interesting questions include whether bexarotene can destroy Aβ fibrils via direct interaction with them and how this compound impacts the lag phase in the fibril growth process. By the Thioflavin T fluorescence assay and atomic force microscopy, we have shown that bexarotene prolongs the lag phase, but it does not degrade Aβ fibrils. The impotence of bexarotene in destroying fibrils means that this compound is weakly bound to Aβ. On the other hand, the weak binding would prevent bexarotene from prolonging the lag phase. Thus, our two main in vitro observations seem to contradict each other. In order to settle this problem at the atomic level, we have performed all-atom molecular dynamics simulations in explicit water. We have demonstrated that bexarotene is not capable to reduce amyloid deposits due to weak binding to Aβ fibrils. However, it delays the self-assembly through reduction of the β-content of Aβ monomers at high enough ligand concentrations. Bexarotene is the first compound which displays such an unusual behavior. We have also shown that bexarotene has a low binding propensity to Aβ monomer and dimer.
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Affiliation(s)
- Pham Dinh Quoc Huy
- Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw, Poland
- Institute for Computational Science and Technology, Quang Trung Software City, Tan Chanh Hiep Ward,
District 12, Ho Chi Minh City, Vietnam
| | - Nguyen Quoc Thai
- Division of Theoretical Physics, Dong Thap University, 783 Pham Huu Lau Street, Ward 6, Cao Lanh
City, Dong Thap, Vietnam
- Biomedical Engineering Department, University of Technology, VNU HCM
268 Ly Thuong Kiet Street, District 10, Ho
Chi Minh City, Vietnam
| | - Zuzana Bednarikova
- Department of Theoretical
Physics, University of Natural Sciences, VNU, 227 Nguyen Van Cu,
District 5, Ho Chi Minh City, Vietnam
| | - Le Huu Phuc
- Department of Biophysics Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, 040
01 Kosice, Slovakia
| | - Huynh Quang Linh
- Biomedical Engineering Department, University of Technology, VNU HCM
268 Ly Thuong Kiet Street, District 10, Ho
Chi Minh City, Vietnam
| | - Zuzana Gazova
- Department of Theoretical
Physics, University of Natural Sciences, VNU, 227 Nguyen Van Cu,
District 5, Ho Chi Minh City, Vietnam
| | - Mai Suan Li
- Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw, Poland
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55
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Cieplak AS. Protein folding, misfolding and aggregation: The importance of two-electron stabilizing interactions. PLoS One 2017; 12:e0180905. [PMID: 28922400 PMCID: PMC5603215 DOI: 10.1371/journal.pone.0180905] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2017] [Accepted: 06/22/2017] [Indexed: 12/17/2022] Open
Abstract
Proteins associated with neurodegenerative diseases are highly pleiomorphic and may adopt an all-α-helical fold in one environment, assemble into all-β-sheet or collapse into a coil in another, and rapidly polymerize in yet another one via divergent aggregation pathways that yield broad diversity of aggregates’ morphology. A thorough understanding of this behaviour may be necessary to develop a treatment for Alzheimer’s and related disorders. Unfortunately, our present comprehension of folding and misfolding is limited for want of a physicochemical theory of protein secondary and tertiary structure. Here we demonstrate that electronic configuration and hyperconjugation of the peptide amide bonds ought to be taken into account to advance such a theory. To capture the effect of polarization of peptide linkages on conformational and H-bonding propensity of the polypeptide backbone, we introduce a function of shielding tensors of the Cα atoms. Carrying no information about side chain-side chain interactions, this function nonetheless identifies basic features of the secondary and tertiary structure, establishes sequence correlates of the metamorphic and pH-driven equilibria, relates binding affinities and folding rate constants to secondary structure preferences, and manifests common patterns of backbone density distribution in amyloidogenic regions of Alzheimer’s amyloid β and tau, Parkinson’s α-synuclein and prions. Based on those findings, a split-intein like mechanism of molecular recognition is proposed to underlie dimerization of Aβ, tau, αS and PrPC, and divergent pathways for subsequent association of dimers are outlined; a related mechanism is proposed to underlie formation of PrPSc fibrils. The model does account for: (i) structural features of paranuclei, off-pathway oligomers, non-fibrillar aggregates and fibrils; (ii) effects of incubation conditions, point mutations, isoform lengths, small-molecule assembly modulators and chirality of solid-liquid interface on the rate and morphology of aggregation; (iii) fibril-surface catalysis of secondary nucleation; and (iv) self-propagation of infectious strains of mammalian prions.
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Affiliation(s)
- Andrzej Stanisław Cieplak
- Department of Chemistry, Bilkent University, Ankara, Turkey
- Department of Chemistry, Yale University, New Haven, Connecticut, United States of America
- Department of Chemistry, Brandeis University, Waltham, Massachusetts, United States of America
- * E-mail:
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56
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Chakraborty S, Das P. Emergence of Alternative Structures in Amyloid Beta 1-42 Monomeric Landscape by N-terminal Hexapeptide Amyloid Inhibitors. Sci Rep 2017; 7:9941. [PMID: 28855598 PMCID: PMC5577341 DOI: 10.1038/s41598-017-10212-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 08/04/2017] [Indexed: 02/01/2023] Open
Abstract
Alzheimer’s disease (AD) is characterized by deposition of amyloid beta (Aβ) peptides into senile plaques in the brain. While most familial mutations are associated with early-onset AD, recent studies report the AD-protective nature of two genetic human Aβ variants, i.e. A2T and A2V, in the heterozygous state. The mixture of A2V Aβ1-6 (Aβ6) hexapeptide and WT Aβ1–42 (Αβ42) is also found neuroprotective. Motivated by these findings, in this study we investigate the effects of WT, A2V, and A2T Aβ6 hexapeptide binding on the monomeric WT Aβ42 landscape. For this purpose, we have performed extensive atomistic Replica Exchange Molecular Dynamics simulations, elucidating preferential binding of Aβ42 with the A2V and A2T hexapeptides compared to WT Aβ6. A notable reorganization of the Aβ42 landscape is revealed due to hexapeptide association, as manifested by lowering of transient interactions between the central and C-terminal hydrophobic patches. Concurrently, Aβ6-bound Aβ42 monomer exhibits alternative structural features that are strongly dependent on the hexapeptide sequence. For example, a central helix is more frequently populated within the A2T-bound monomer, while A2V-bound Aβ42 is often enhanced in overall disorder. Taken together, the present simulations offer novel molecular insights onto the effect of the N-terminal hexapeptide binding on the Aβ42 monomer structure, which might help in explaining their reported amyloid inhibition properties.
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Affiliation(s)
| | - Payel Das
- IBM Thomas J. Watson Research Center, Yorktown Heights, NY, 10598, USA.
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57
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Voelker MJ, Barz B, Urbanc B. Fully Atomistic Aβ40 and Aβ42 Oligomers in Water: Observation of Porelike Conformations. J Chem Theory Comput 2017; 13:4567-4583. [DOI: 10.1021/acs.jctc.7b00495] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Matthew J. Voelker
- Department
of Physics, Drexel University, Philadelphia, Pennsylvania 19104, United States
| | - Bogdan Barz
- Institute
of Complex Systems, Structural Biochemistry ICS-6: Structural Biochemistry, Forschungzentrum Jülich GmbH, Jülich 52425, Germany
- Institute
of Theoretical and Computational Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf 40225, Germany
| | - Brigita Urbanc
- Department
of Physics, Drexel University, Philadelphia, Pennsylvania 19104, United States
- Faculty
of Mathematics and Physics, University of Ljubljana, Ljubljana 1000, Slovenia
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58
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Study of structural stability and damaging effect on membrane for four Aβ42 dimers. PLoS One 2017; 12:e0179147. [PMID: 28594887 PMCID: PMC5464659 DOI: 10.1371/journal.pone.0179147] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 05/24/2017] [Indexed: 11/19/2022] Open
Abstract
Increasing evidence shows that Aβ oligomers are key pathogenic molecules in Alzheimer’s disease. Among Aβ oligomers, dimer is the smallest aggregate and toxic unit. Therefore, understanding its structural and dynamic properties is quite useful to prevent the formation and toxicity of the Aβ oligomers. In this study, we performed molecular dynamic simulations on four Aβ42 dimers, 2NCb, CNNC, NCNC and NCCN, within the hydrated DPPC membrane. Four Aβ42 dimers differ in the arrangements of two Aβ42 peptides. This study aims to investigate the impact of aggregation pattern of two Aβ peptides on the structural stability of the Aβ42 dimer and its disruption to the biological membrane. The MD results demonstrate that the NCCN, CNNC and NCNC have the larger structural fluctuation at the N-terminus of Aβ42 peptide, where the β-strand structure converts into the coil structure. The loss of the N-terminal β-strand further impairs the aggregate ability of Aβ42 dimer. In addition, inserting Aβ42 dimer into the membrane can considerably decrease the average APL of DPPC membrane. Moreover this decrease effect is largely dependent on the distance to the location of Aβ42 dimer and its secondary structure forms. Based on the results, the 2NCb is considered as a stable dimeric unit for aggregating the larger Aβ42 oligomer, and has a potent ability to disrupt the membrane.
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59
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Linh NH, Thu TTM, Tu L, Hu CK, Li MS. Impact of Mutations at C-Terminus on Structures and Dynamics of Aβ40 and Aβ42: A Molecular Simulation Study. J Phys Chem B 2017; 121:4341-4354. [DOI: 10.1021/acs.jpcb.6b12888] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Nguyen Hoang Linh
- Institute for Computational Science and Technology
, SBI Building, Quang Trung Software City, Tan Chanh Hiep Ward, District 12, Ho Chi Minh City, Vietnam
- Biomedical
Engineering Department, University of Technology - VNU HCM
, 268 Ly Thuong
Kiet Street, District 10, Ho Chi Minh City, Vietnam
| | - 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, Vietnam
- Biomedical
Engineering Department, University of Technology - VNU HCM
, 268 Ly Thuong
Kiet Street, District 10, Ho Chi Minh City, Vietnam
| | - LyAnh Tu
- Institute for Computational Science and Technology
, SBI Building, Quang Trung Software City, Tan Chanh Hiep Ward, District 12, Ho Chi Minh City, Vietnam
- Biomedical
Engineering Department, University of Technology - VNU HCM
, 268 Ly Thuong
Kiet Street, District 10, Ho Chi Minh City, Vietnam
| | - Chin-Kun Hu
- Institute
of Physics, Academia Sinica
, 128 Academia Road Section 2, Taipei
11529, Taiwan
- National
Center for Theoretical Sciences, National Tsing Hua University
, 101 Kuang-Fu Road Section 2, Hsinch
30013, Taiwan
- Business
School, University of Shanghai for Science and Technology
, 334 Jun
Gong Road, Shanghai
200093, China
| | - 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, Vietnam
- Institute of Physics Polish Academy of Sciences
, Al. Lotnikow 32/46, 02-668
Warsaw, Poland
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60
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Lucato CM, Lupton CJ, Halls ML, Ellisdon AM. Amyloidogenicity at a Distance: How Distal Protein Regions Modulate Aggregation in Disease. J Mol Biol 2017; 429:1289-1304. [PMID: 28342736 DOI: 10.1016/j.jmb.2017.03.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 03/12/2017] [Accepted: 03/14/2017] [Indexed: 12/14/2022]
Abstract
The misfolding of proteins to form amyloid is a key pathological feature of several progressive, and currently incurable, diseases. A mechanistic understanding of the pathway from soluble, native protein to insoluble amyloid is crucial for therapeutic design, and recent efforts have helped to elucidate the key molecular events that trigger protein misfolding. Generally, either global or local structural perturbations occur early in amyloidogenesis to expose aggregation-prone regions of the protein that can then self-associate to form toxic oligomers. Surprisingly, these initiating structural changes are often caused or influenced by protein regions distal to the classically amyloidogenic sequences. Understanding the importance of these distal regions in the pathogenic process has highlighted many remaining knowledge gaps regarding the precise molecular events that occur in classic aggregation pathways. In this review, we discuss how these distal regions can influence aggregation in disease and the recent technical and conceptual advances that have allowed this insight.
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Affiliation(s)
- Christina M Lucato
- Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia; Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Monash University, Clayton, Victoria 3800, Australia
| | - Christopher J Lupton
- Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia; Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Monash University, Clayton, Victoria 3800, Australia
| | - Michelle L Halls
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Andrew M Ellisdon
- Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia; Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Monash University, Clayton, Victoria 3800, Australia.
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61
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Das P, Chacko AR, Belfort G. Alzheimer's Protective Cross-Interaction between Wild-Type and A2T Variants Alters Aβ 42 Dimer Structure. ACS Chem Neurosci 2017; 8:606-618. [PMID: 28292185 DOI: 10.1021/acschemneuro.6b00357] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Whole genome sequencing has recently revealed the protective effect of a single A2T mutation in heterozygous carriers against Alzheimer's disease (AD) and age-related cognitive decline. The impact of the protective cross-interaction between the wild-type (WT) and A2T variants on the dimer structure is therefore of high interest, as the Aβ dimers are the smallest known neurotoxic species. Toward this goal, extensive atomistic replica exchange molecular dynamics simulations of the solvated WT homo- and A2T hetero- Aβ1-42 dimers have been performed, resulting into a total of 51 μs of sampling for each system. Weakening of a set of transient, intrachain contacts formed between the central and C-terminal hydrophobic residues is observed in the heterodimeric system. The majority of the heterodimers with reduced interaction between central and C-terminal regions lack any significant secondary structure and display a weak interchain interface. Interestingly, the A2T N-terminus, particularly residue F4, is frequently engaged in tertiary and quaternary interactions with central and C-terminal hydrophobic residues in those distinct structures, leading to hydrophobic burial. This atypical involvement of the N-terminus within A2T heterodimer revealed in our simulations implies possible interference on Aβ42 aggregation and toxic oligomer formation, which is consistent with experiments. In conclusion, the present study provides detailed structural insights onto A2T Aβ42 heterodimer, which might provide molecular insights onto the AD protective effect of the A2T mutation in the heterozygous state.
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Affiliation(s)
- Payel Das
- IBM Thomas J. Watson Research Center, Yorktown Heights, New York 10598, United States
| | - Anita R. Chacko
- IBM Thomas J. Watson Research Center, Yorktown Heights, New York 10598, United States
| | - Georges Belfort
- Howard
P. Isermann Department of Chemical and Biological Engineering, and
Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York 12180-3590, United States
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62
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Bellucci L, Bussi G, Di Felice R, Corni S. Fibrillation-prone conformations of the amyloid-β-42 peptide at the gold/water interface. NANOSCALE 2017; 9:2279-2290. [PMID: 28124697 DOI: 10.1039/c6nr06010b] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Proteins in the proximity of inorganic surfaces and nanoparticles may undergo profound adjustments that trigger biomedically relevant processes, such as protein fibrillation. The mechanisms that govern protein-surface interactions at the molecular level are still poorly understood. In this work, we investigate the adsorption onto a gold surface, in water, of an amyloid-β (Aβ) peptide, which is the amyloidogenic peptide involved in Alzheimer's disease. The entire adsorption process, from the peptide in bulk water to its conformational relaxation on the surface, is explored by large-scale atomistic molecular dynamics (MD) simulations. We start by providing a description of the conformational ensemble of Aβ in solution by a 22 μs temperature replica exchange MD simulation, which is consistent with previous results. Then, we obtain a statistical description of how the peptide approaches the gold surface by multiple MD simulations, identifying the preferential gold-binding sites and giving a kinetic picture of the association process. Finally, relaxation of the Aβ conformations at the gold/water interface is performed by a 19 μs Hamiltonian-temperature replica exchange MD simulation. We find that the conformational ensemble of Aβ is strongly perturbed by the presence of the surface. In particular, at the gold/water interface the population of the conformers akin to amyloid fibrils is significantly enriched, suggesting that this extended contact geometry may promote fibrillation.
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Affiliation(s)
- Luca Bellucci
- Center S3, CNR Institute of Nanoscience, via Campi 213/A, 41125 Modena, Italy.
| | - Giovanni Bussi
- SISSA-Scuola Internazionale Superiore di Studi Avanzati, via Bonomea 265, 34136 Trieste, Italy
| | - Rosa Di Felice
- Center S3, CNR Institute of Nanoscience, via Campi 213/A, 41125 Modena, Italy. and Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089, USA
| | - Stefano Corni
- Center S3, CNR Institute of Nanoscience, via Campi 213/A, 41125 Modena, Italy.
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63
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Abstract
The investigation of intrinsically disordered proteins (IDPs) is a new frontier in structural and molecular biology that requires a new paradigm to connect structural disorder to function. Molecular dynamics simulations and statistical thermodynamics potentially offer ideal tools for atomic-level characterizations and thermodynamic descriptions of this fascinating class of proteins that will complement experimental studies. However, IDPs display sensitivity to inaccuracies in the underlying molecular mechanics force fields. Thus, achieving an accurate structural characterization of IDPs via simulations is a challenge. It is also daunting to perform a configuration-space integration over heterogeneous structural ensembles sampled by IDPs to extract, in particular, protein configurational entropy. In this review, we summarize recent efforts devoted to the development of force fields and the critical evaluations of their performance when applied to IDPs. We also survey recent advances in computational methods for protein configurational entropy that aim to provide a thermodynamic link between structural disorder and protein activity.
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Affiliation(s)
- Song-Ho Chong
- Department of Chemistry, Sookmyung Women's University, Yongsan-Ku, Seoul 04310, Korea;
| | - Prathit Chatterjee
- Department of Chemistry, Sookmyung Women's University, Yongsan-Ku, Seoul 04310, Korea;
| | - Sihyun Ham
- Department of Chemistry, Sookmyung Women's University, Yongsan-Ku, Seoul 04310, Korea;
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64
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Urbanc B. Flexible N‐Termini of Amyloid β‐Protein Oligomers: A Link between Structure and Activity? Isr J Chem 2017. [DOI: 10.1002/ijch.201600097] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Brigita Urbanc
- Department of Physics Drexel University Philadelphia, PA 19104 USA
- Faculty of Mathematics and Physics Jadranska ulica 19 1000 Ljubljana Slovenia
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65
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Carballo‐Pacheco M, Strodel B. Comparison of force fields for Alzheimer's A β42: A case study for intrinsically disordered proteins. Protein Sci 2017; 26:174-185. [PMID: 27727496 PMCID: PMC5275744 DOI: 10.1002/pro.3064] [Citation(s) in RCA: 104] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2016] [Revised: 10/02/2016] [Accepted: 10/09/2016] [Indexed: 01/06/2023]
Abstract
Intrinsically disordered proteins are essential for biological processes such as cell signalling, but are also associated to devastating diseases including Alzheimer's disease, Parkinson's disease or type II diabetes. Because of their lack of a stable three-dimensional structure, molecular dynamics simulations are often used to obtain atomistic details that cannot be observed experimentally. The applicability of molecular dynamics simulations depends on the accuracy of the force field chosen to represent the underlying free energy surface of the system. Here, we use replica exchange molecular dynamics simulations to test five modern force fields, OPLS, AMBER99SB, AMBER99SB*ILDN, AMBER99SBILDN-NMR and CHARMM22*, in their ability to model Aβ42 , an intrinsically disordered peptide associated with Alzheimer's disease, and compare our results to nuclear magnetic resonance (NMR) experimental data. We observe that all force fields except AMBER99SBILDN-NMR successfully reproduce local NMR observables, with CHARMM22* being slightly better than the other force fields.
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Affiliation(s)
- Martín Carballo‐Pacheco
- Institute of Complex Systems, Structural Biochemistry (ICS‐6), Forschungszentrum Jülich GmbHJülich52425Germany
- AICES Graduate School, RWTH Aachen UniversitySchinkelstraße 2Aachen52062Germany
| | - Birgit Strodel
- Institute of Complex Systems, Structural Biochemistry (ICS‐6), Forschungszentrum Jülich GmbHJülich52425Germany
- Institute of Theoretical and Computational Chemistry, Heinrich Heine University DüsseldorfUniversitätstraße 1Düsseldorf40225Germany
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66
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Siwy CM, Lockhart C, Klimov DK. Is the Conformational Ensemble of Alzheimer's Aβ10-40 Peptide Force Field Dependent? PLoS Comput Biol 2017; 13:e1005314. [PMID: 28085875 PMCID: PMC5279813 DOI: 10.1371/journal.pcbi.1005314] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2016] [Revised: 01/30/2017] [Accepted: 12/16/2016] [Indexed: 11/21/2022] Open
Abstract
By applying REMD simulations we have performed comparative analysis of the conformational ensembles of amino-truncated Aβ10-40 peptide produced with five force fields, which combine four protein parameterizations (CHARMM36, CHARMM22*, CHARMM22/cmap, and OPLS-AA) and two water models (standard and modified TIP3P). Aβ10-40 conformations were analyzed by computing secondary structure, backbone fluctuations, tertiary interactions, and radius of gyration. We have also calculated Aβ10-40 3JHNHα-coupling and RDC constants and compared them with their experimental counterparts obtained for the full-length Aβ1-40 peptide. Our study led us to several conclusions. First, all force fields predict that Aβ adopts unfolded structure dominated by turn and random coil conformations. Second, specific TIP3P water model does not dramatically affect secondary or tertiary Aβ10-40 structure, albeit standard TIP3P model favors slightly more compact states. Third, although the secondary structures observed in CHARMM36 and CHARMM22/cmap simulations are qualitatively similar, their tertiary interactions show little consistency. Fourth, two force fields, OPLS-AA and CHARMM22* have unique features setting them apart from CHARMM36 or CHARMM22/cmap. OPLS-AA reveals moderate β-structure propensity coupled with extensive, but weak long-range tertiary interactions leading to Aβ collapsed conformations. CHARMM22* exhibits moderate helix propensity and generates multiple exceptionally stable long- and short-range interactions. Our investigation suggests that among all force fields CHARMM22* differs the most from CHARMM36. Fifth, the analysis of 3JHNHα-coupling and RDC constants based on CHARMM36 force field with standard TIP3P model led us to an unexpected finding that in silico Aβ10-40 and experimental Aβ1-40 constants are generally in better agreement than these quantities computed and measured for identical peptides, such as Aβ1-40 or Aβ1-42. This observation suggests that the differences in the conformational ensembles of Aβ10-40 and Aβ1-40 are small and the former can be used as proxy of the full-length peptide. Based on this argument, we concluded that CHARMM36 force field with standard TIP3P model produces the most accurate representation of Aβ10-40 conformational ensemble. Dependence of protein conformational ensembles on force field parameterizations limits the predictive power of molecular dynamics simulations. To address this problem, we evaluated five all-atom force fields for their consistency in reproducing the conformational ensemble of Alzheimer’s Aβ10-40 peptide. To generate conformational ensembles, we have used replica exchange molecular dynamics and computed Aβ10-40 secondary and tertiary structures. We found that, although all force fields predict Aβ10-40 unfolded structure, they strongly disagree on helix and β propensities and tertiary structure distributions. We have also calculated Aβ10-40 J-coupling and residual dipolar coupling constants and compared them with the experimental data for the full-length Aβ1-40 peptide. Unexpectedly, we determined that in silico Aβ10-40 and experimental Aβ1-40 constants are in better agreement than these quantities computed and measured previously for identical peptides, such as Aβ1-40 or Aβ1-42. We then concluded that the conformational ensembles of Aβ10-40 and Aβ1-40 are similar and on this basis argue that CHARMM36 force field with standard TIP3P water model provides the most accurate description of Aβ10-40. Although our objective was not to evaluate the biomolecular force fields in general, our study is expected to facilitate their proper selection for the simulations of Alzheimer’s peptides.
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Affiliation(s)
- Christopher M. Siwy
- School of Systems Biology, George Mason University, Manassas, Virginia, United States of America
| | - Christopher Lockhart
- School of Systems Biology, George Mason University, Manassas, Virginia, United States of America
| | - Dmitri K. Klimov
- School of Systems Biology, George Mason University, Manassas, Virginia, United States of America
- * E-mail:
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67
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Gandhi NS, Kukic P, Lippens G, Mancera RL. Molecular Dynamics Simulation of Tau Peptides for the Investigation of Conformational Changes Induced by Specific Phosphorylation Patterns. Methods Mol Biol 2017; 1523:33-59. [PMID: 27975243 DOI: 10.1007/978-1-4939-6598-4_3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The Tau protein plays an important role due to its biomolecular interactions in neurodegenerative diseases. The lack of stable structure and various posttranslational modifications such as phosphorylation at various sites in the Tau protein pose a challenge for many experimental methods that are traditionally used to study protein folding and aggregation. Atomistic molecular dynamics (MD) simulations can help around deciphering relationship between phosphorylation and various intermediate and stable conformations of the Tau protein which occur on longer timescales. This chapter outlines protocols for the preparation, execution, and analysis of all-atom MD simulations of a 21-amino acid-long phosphorylated Tau peptide with the aim of generating biologically relevant structural and dynamic information. The simulations are done in explicit solvent and starting from nearly extended configurations of the peptide. The scaled MD method implemented in AMBER14 was chosen to achieve enhanced conformational sampling in addition to a conventional MD approach, thereby allowing the characterization of folding for such an intrinsically disordered peptide at 293 K. Emphasis is placed on the analysis of the simulation trajectories to establish correlations with NMR data (i.e., chemical shifts and NOEs). Finally, in-depth discussions are provided for commonly encountered problems.
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Affiliation(s)
- Neha S Gandhi
- School of Biomedical Sciences, CHIRI Biosciences and Curtin Institute for Computation, Curtin University, G.P.O. Box U1987, Perth, WA, 6845, Australia.
| | - Predrag Kukic
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - Guy Lippens
- Laboratoire d'Ingénierie des Systèmes Biologiques et des Procédés, Université de Toulouse, CNRS, INRA, INSA Toulouse, 135Avenue de Rangueil, 31077, Toulouse, France
- Université de Lille, CNRS, UMR 8576, UGSF-Unité de Glycobiologie Structurale et Fonctionnelle, 59000 Lille, France
| | - Ricardo L Mancera
- School of Biomedical Sciences, CHIRI Biosciences and Curtin Institute for Computation, Curtin University, G.P.O. Box U1987, Perth, WA, 6845, Australia.
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68
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Brown AM, Bevan DR. Influence of sequence and lipid type on membrane perturbation by human and rat amyloid β-peptide (1–42). Arch Biochem Biophys 2017; 614:1-13. [DOI: 10.1016/j.abb.2016.11.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 11/17/2016] [Accepted: 11/20/2016] [Indexed: 12/20/2022]
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69
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Sasmal S, Schwierz N, Head-Gordon T. Mechanism of Nucleation and Growth of Aβ40 Fibrils from All-Atom and Coarse-Grained Simulations. J Phys Chem B 2016; 120:12088-12097. [PMID: 27806205 DOI: 10.1021/acs.jpcb.6b09655] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this work, we characterize the nucleation and elongation mechanisms of the "diseased" polymorph of the amyloid-β 40 (Aβ40) fibril using an off-lattice coarse-grained (CG) protein model. After determining the nucleation size and subsequent stable protofibrillar structure from the CG model, validated with all-atom simulations, we consider the "lock and dock" and "activated monomer" fibril elongation mechanisms for the protofibril by statistical additions of a monomer drawn from four different ensembles of the free Aβ40 peptide to grow the fibril. Our CG model shows that the dominant mechanism for fibril elongation is the lock and dock mechanism across all monomer ensembles, even when the monomer is in the activated form. Although our CG model finds no thermodynamic difference between the two fibril elongation mechanisms, the activated monomer is found to be kinetically faster by a factor of 2 for the "locking" step compared with all other structured or unstructured monomer ensembles.
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Affiliation(s)
- Sukanya Sasmal
- Department of Chemical and Biomolecular Engineering, ‡Department of Chemistry, §Department of Bioengineering, ∥Kenneth S. Pitzer Center for Theoretical Chemistry, University of California , Berkeley, California 94720, United States
| | - Nadine Schwierz
- Department of Chemical and Biomolecular Engineering, ‡Department of Chemistry, §Department of Bioengineering, ∥Kenneth S. Pitzer Center for Theoretical Chemistry, University of California , Berkeley, California 94720, United States
| | - Teresa Head-Gordon
- Department of Chemical and Biomolecular Engineering, ‡Department of Chemistry, §Department of Bioengineering, ∥Kenneth S. Pitzer Center for Theoretical Chemistry, University of California , Berkeley, California 94720, United States
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70
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Lincoff J, Sasmal S, Head-Gordon T. Comparing generalized ensemble methods for sampling of systems with many degrees of freedom. J Chem Phys 2016; 145:174107. [PMID: 27825215 PMCID: PMC5097048 DOI: 10.1063/1.4965439] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 10/05/2016] [Indexed: 11/14/2022] Open
Abstract
We compare two standard replica exchange methods using temperature and dielectric constant as the scaling variables for independent replicas against two new corresponding enhanced sampling methods based on non-equilibrium statistical cooling (temperature) or descreening (dielectric). We test the four methods on a rough 1D potential as well as for alanine dipeptide in water, for which their relatively small phase space allows for the ability to define quantitative convergence metrics. We show that both dielectric methods are inferior to the temperature enhanced sampling methods, and in turn show that temperature cool walking (TCW) systematically outperforms the standard temperature replica exchange (TREx) method. We extend our comparisons of the TCW and TREx methods to the 5 residue met-enkephalin peptide, in which we evaluate the Kullback-Leibler divergence metric to show that the rate of convergence between two independent trajectories is faster for TCW compared to TREx. Finally we apply the temperature methods to the 42 residue amyloid-β peptide in which we find non-negligible differences in the disordered ensemble using TCW compared to the standard TREx. All four methods have been made available as software through the OpenMM Omnia software consortium (http://www.omnia.md/).
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Affiliation(s)
- James Lincoff
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, USA
| | - Sukanya Sasmal
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, USA
| | - Teresa Head-Gordon
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, USA
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71
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Hayden EY, Conovaloff JL, Mason A, Bitan G, Teplow DB. Preparation of pure populations of covalently stabilized amyloid β-protein oligomers of specific sizes. Anal Biochem 2016; 518:78-85. [PMID: 27810329 DOI: 10.1016/j.ab.2016.10.026] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 10/25/2016] [Accepted: 10/30/2016] [Indexed: 12/23/2022]
Abstract
Evidence suggests that amyloid β-protein (Aβ) oligomers may be seminal pathogenic agents in Alzheimer's disease (AD). If so, developing oligomer-targeted therapeutics requires an understanding of oligomer structure. This has been difficult due to the instability of these non-covalently associated Aβ assemblies. We previously used rapid, zero-length, in situ chemical cross-linking to stabilize oligomers of Aβ40. These enabled us to isolate pure, stable populations of dimers, trimers, and tetramers and to determine their structure-activity relationships. However, equivalent methods applied to Aβ42 did not produce stable oligomers. We report here that the use of an Aβ42 homologue, [F10, Y42]Aβ42, coupled with sequential denaturation/dissociation and gel electrophoresis procedures, provides the means to produce highly pure, stable populations of oligomers of sizes ranging from dimer through dodecamer that are suitable for structure-activity relationship determination.
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Affiliation(s)
- Eric Y Hayden
- Department of Neurology, David Geffen School of Medicine, and Molecular Biology Institute and Brain Research Institute, University of California, Los Angeles, CA 90095, United States
| | - Joseph L Conovaloff
- Department of Neurology, David Geffen School of Medicine, and Molecular Biology Institute and Brain Research Institute, University of California, Los Angeles, CA 90095, United States
| | - Ashley Mason
- Department of Neurology, David Geffen School of Medicine, and Molecular Biology Institute and Brain Research Institute, University of California, Los Angeles, CA 90095, United States
| | - Gal Bitan
- Department of Neurology, David Geffen School of Medicine, and Molecular Biology Institute and Brain Research Institute, University of California, Los Angeles, CA 90095, United States
| | - David B Teplow
- Department of Neurology, David Geffen School of Medicine, and Molecular Biology Institute and Brain Research Institute, University of California, Los Angeles, CA 90095, United States.
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72
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Shi H, Kang B, Lee JY. Tautomeric Effect of Histidine on the Monomeric Structure of Amyloid β-Peptide(1–40). J Phys Chem B 2016; 120:11405-11411. [DOI: 10.1021/acs.jpcb.6b08685] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Hu Shi
- Department
of Chemistry, Sungkyunkwan University, Suwon 440-746, Korea
| | - Baotao Kang
- Department
of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, P. R. China
| | - Jin Yong Lee
- Department
of Chemistry, Sungkyunkwan University, Suwon 440-746, Korea
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73
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Musiani F, Giorgetti A. Protein Aggregation and Molecular Crowding: Perspectives From Multiscale Simulations. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2016; 329:49-77. [PMID: 28109331 DOI: 10.1016/bs.ircmb.2016.08.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Cells are extremely crowded environments, thus the use of diluted salted aqueous solutions containing a single protein is too simplistic to mimic the real situation. Macromolecular crowding might affect protein structure, folding, shape, conformational stability, binding of small molecules, enzymatic activity, interactions with cognate biomolecules, and pathological aggregation. The latter phenomenon typically leads to the formation of amyloid fibrils that are linked to several lethal neurodegenerative diseases, but that can also play a functional role in certain organisms. The majority of molecular simulations performed before the last few years were conducted in diluted solutions and were restricted both in the timescales and in the system dimensions by the available computational resources. In recent years, several computational solutions were developed to get close to physiological conditions. In this review we summarize the main computational techniques used to tackle the issue of protein aggregation both in a diluted and in a crowded environment.
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Affiliation(s)
- F Musiani
- Laboratory of Bioinorganic Chemistry, University of Bologna, Bologna, Italy.
| | - A Giorgetti
- Applied Bioinformatics Group, University of Verona, Verona, Italy.
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74
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Huy PDQ, Vuong QV, La Penna G, Faller P, Li MS. Impact of Cu(II) Binding on Structures and Dynamics of Aβ 42 Monomer and Dimer: Molecular Dynamics Study. ACS Chem Neurosci 2016; 7:1348-1363. [PMID: 27454036 DOI: 10.1021/acschemneuro.6b00109] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The classical force field, which is compatible with the Amber force field 99SB, has been obtained for the interaction of Cu(II) with monomer and dimers of amyloid-β peptides using the coordination where Cu(II) is bound to His6, His13 (or His14), and Asp1 with distorted planar geometry. The newly developed force field and molecular dynamics simulation were employed to study the impact of Cu(II) binding on structures and dynamics of Aβ42 monomer and dimers. It was shown that in the presence of Cu(II) the β content of monomer is reduced substantially compared with the wild-type Aβ42 suggesting that, in accord with experiments, metal ions facilitate formation of amorphous aggregates rather than amyloid fibrils with cross-β structures. In addition, one possible mechanism for amorphous assembly is that the Asp23-Lys28 salt bridge, which plays a crucial role in β sheet formation, becomes more flexible upon copper ion binding to the Aβ N-terminus. The simulation of dimers was conducted with the Cu(II)/Aβ stoichiometric ratios of 1:1 and 1:2. For the 1:1 ratio Cu(II) delays the Aβ dimerization process as observed in a number of experiments. The mechanism underlying this phenomenon is associated with slow formation of interchain salt bridges in dimer as well as with decreased hydrophobicity of monomer upon Cu-binding.
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Affiliation(s)
- Pham Dinh Quoc Huy
- Institute
of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw, Poland
- Institute
for Computational Science and Technology, Quang Trung Software City, Tan Chanh Hiep Ward, District 12, Ho Chi
Minh City, Vietnam
| | - Quan Van Vuong
- Institute
for Computational Science and Technology, Quang Trung Software City, Tan Chanh Hiep Ward, District 12, Ho Chi
Minh City, Vietnam
- Department
of Chemistry, Nagoya University, Nagoya 464-8602, Japan
| | - Giovanni La Penna
- National Research Council of Italy CNR, Institute
for Chemistry of Organometallic Compounds ICCOM, 50019 Florence, Italy
- Italian Institute for Nuclear Physics INFN, Section
of Roma-Tor Vergata, 50019 Florence, Italy
| | - Peter Faller
- Biometals
and Biological Chemistry, Institute of Chemistry, University of Strasbourg, 4 rue B. Pascal, 67081 Strasbourg, France
| | - Mai Suan Li
- Institute
of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw, Poland
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75
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Truex NL, Wang Y, Nowick JS. Assembly of Peptides Derived from β-Sheet Regions of β-Amyloid. J Am Chem Soc 2016; 138:13882-13890. [PMID: 27642651 PMCID: PMC5089065 DOI: 10.1021/jacs.6b06000] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
![]()
In
Alzheimer’s disease, aggregation of the β-amyloid
peptide (Aβ) results in the formation of oligomers and fibrils
that are associated with neurodegeneration. Aggregation of Aβ
occurs through interactions between different regions of the peptide.
This paper and the accompanying paper constitute a two-part investigation
of two key regions of Aβ: the central region and the C-terminal
region. These two regions promote aggregation and adopt β-sheet
structure in the fibrils, and may also do so in the oligomers. In
this paper, we study the assembly of macrocyclic β-sheet peptides
that contain residues 17–23 (LVFFAED) from the central region
and residues 30–36 (AIIGLMV) from the C-terminal region. These
peptides assemble to form tetramers. Each tetramer consists of two
hydrogen-bonded dimers that pack through hydrophobic interactions
in a sandwich-like fashion. Incorporation of a single 15N isotopic label into each peptide provides a spectroscopic probe
with which to elucidate the β-sheet assembly and interaction: 1H,15N HSQC studies facilitate the identification
of the monomers and tetramers; 15N-edited NOESY studies
corroborate the pairing of the dimers within the tetramers. In the
following paper, J. Am. Chem. Soc.2016, DOI: 10.1021/jacs.6b06001, we will extend these studies to elucidate the coassembly of the
peptides to form heterotetramers.
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Affiliation(s)
- Nicholas L Truex
- Department of Chemistry, University of California, Irvine , Irvine, California 92697-2025, United States
| | - Yilin Wang
- Department of Chemistry, University of California, Irvine , Irvine, California 92697-2025, United States
| | - James S Nowick
- Department of Chemistry, University of California, Irvine , Irvine, California 92697-2025, United States
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76
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Exploring the aggregation free energy landscape of the amyloid-β protein (1-40). Proc Natl Acad Sci U S A 2016; 113:11835-11840. [PMID: 27698130 DOI: 10.1073/pnas.1612362113] [Citation(s) in RCA: 100] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
A predictive coarse-grained protein force field [associative memory, water-mediated, structure, and energy model for molecular dynamics (AWSEM)-MD] is used to study the energy landscapes and relative stabilities of amyloid-β protein (1-40) in the monomer and all of its oligomeric forms up to an octamer. We find that an isolated monomer is mainly disordered with a short α-helix formed at the central hydrophobic core region (L17-D23). A less stable hairpin structure, however, becomes increasingly more stable in oligomers, where hydrogen bonds can form between neighboring monomers. We explore the structure and stability of both prefibrillar oligomers that consist of mainly antiparallel β-sheets and fibrillar oligomers with only parallel β-sheets. Prefibrillar oligomers are polymorphic but typically take on a cylindrin-like shape composed of mostly antiparallel β-strands. At the concentration of the simulation, the aggregation free energy landscape is nearly downhill. We use umbrella sampling along a structural progress coordinate for interconversion between prefibrillar and fibrillar forms to identify a conversion pathway between these forms. The fibrillar oligomer only becomes favored over its prefibrillar counterpart in the pentamer where an interconversion bottleneck appears. The structural characterization of the pathway along with statistical mechanical perturbation theory allow us to evaluate the effects of concentration on the free energy landscape of aggregation as well as the effects of the Dutch and Arctic mutations associated with early onset of Alzheimer's disease.
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77
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Acharya S, Srivastava KR, Nagarajan S, Lapidus LJ. Monomer Dynamics of Alzheimer Peptides and Kinetic Control of Early Aggregation in Alzheimer's Disease. Chemphyschem 2016; 17:3470-3479. [PMID: 27490673 DOI: 10.1002/cphc.201600706] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Indexed: 12/20/2022]
Abstract
The rate of reconfiguration-or intramolecular diffusion-of monomeric Alzheimer (Aβ) peptides is measured and, under conditions that aggregation is more likely, peptide diffusion slows down significantly, which allows bimolecular associations to be initiated. By using the method of Trp-Cys contact quenching, the rate of reconfiguration is observed to be about five times faster for Aβ40 , which aggregates slowly, than that for Aβ42 , which aggregates quickly. Furthermore, the rate of reconfiguration for Aβ42 speeds up at higher pH, which slows aggregation, and in the presence of the aggregation inhibitor curcumin. The measured reconfiguration rates are able to predict the early aggregation behavior of the Aβ peptide and provide a kinetic basis for why Aβ42 is more prone to aggregation than Aβ40 , despite a difference of only two amino acids.
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Affiliation(s)
- Srabasti Acharya
- Department of Physics and Astronomy, Michigan State University, 567 Wilson Rd. Rm 4227, East Lansing, MI, 48824, USA
| | - Kinshuk R Srivastava
- Department of Physics and Astronomy, Michigan State University, 567 Wilson Rd. Rm 4227, East Lansing, MI, 48824, USA
| | - Sureshbabu Nagarajan
- Department of Physics and Astronomy, Michigan State University, 567 Wilson Rd. Rm 4227, East Lansing, MI, 48824, USA
| | - Lisa J Lapidus
- Department of Physics and Astronomy, Michigan State University, 567 Wilson Rd. Rm 4227, East Lansing, MI, 48824, USA.,Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA
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78
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Gibbs EB, Showalter SA. Quantification of Compactness and Local Order in the Ensemble of the Intrinsically Disordered Protein FCP1. J Phys Chem B 2016; 120:8960-9. [DOI: 10.1021/acs.jpcb.6b06934] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Eric B. Gibbs
- Department
of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Scott A. Showalter
- Department
of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department
of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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79
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Bhowmick A, Brookes DH, Yost SR, Dyson HJ, Forman-Kay JD, Gunter D, Head-Gordon M, Hura GL, Pande VS, Wemmer DE, Wright PE, Head-Gordon T. Finding Our Way in the Dark Proteome. J Am Chem Soc 2016; 138:9730-42. [PMID: 27387657 PMCID: PMC5051545 DOI: 10.1021/jacs.6b06543] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The traditional structure-function paradigm has provided significant insights for well-folded proteins in which structures can be easily and rapidly revealed by X-ray crystallography beamlines. However, approximately one-third of the human proteome is comprised of intrinsically disordered proteins and regions (IDPs/IDRs) that do not adopt a dominant well-folded structure, and therefore remain "unseen" by traditional structural biology methods. This Perspective considers the challenges raised by the "Dark Proteome", in which determining the diverse conformational substates of IDPs in their free states, in encounter complexes of bound states, and in complexes retaining significant disorder requires an unprecedented level of integration of multiple and complementary solution-based experiments that are analyzed with state-of-the art molecular simulation, Bayesian probabilistic models, and high-throughput computation. We envision how these diverse experimental and computational tools can work together through formation of a "computational beamline" that will allow key functional features to be identified in IDP structural ensembles.
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Affiliation(s)
- Asmit Bhowmick
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA 94720
| | - David H. Brookes
- Department of Chemistry, University of California, Berkeley, CA 94720
| | - Shane R. Yost
- Department of Chemistry, University of California, Berkeley, CA 94720
| | - H. Jane Dyson
- Department of Integrative Structural and Computational Biology, Scripps Research Institute, La Jolla, California 92037
| | - Julie D. Forman-Kay
- Molecular Structure and Function Program, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Daniel Gunter
- Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley CA, 94720
| | | | - Gregory L. Hura
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley CA, 94720
| | - Vijay S. Pande
- Department of Chemistry, Stanford University, Stanford, CA 94305
| | - David E. Wemmer
- Department of Chemistry, University of California, Berkeley, CA 94720
| | - Peter E. Wright
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Teresa Head-Gordon
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA 94720
- Department of Chemistry, University of California, Berkeley, CA 94720
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley CA, 94720
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80
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Nguyen HL, Thi Minh Thu T, Truong PM, Lan PD, Man VH, Nguyen PH, Tu LA, Chen YC, Li MS. Aβ41 Aggregates More Like Aβ40 than Like Aβ42: In Silico and in Vitro Study. J Phys Chem B 2016; 120:7371-9. [DOI: 10.1021/acs.jpcb.6b06368] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Hoang Linh Nguyen
- Institute for Computational Science and Technology, SBI Building, Quang Trung Software City, Tan Chanh
Hiep Ward, District 12, Ho Chi Minh City, Vietnam
- 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, Vietnam
| | - 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, Vietnam
- 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, Vietnam
| | - Phan Minh Truong
- Institute for Computational Science and Technology, SBI Building, Quang Trung Software City, Tan Chanh
Hiep Ward, District 12, Ho Chi Minh City, Vietnam
| | - Pham Dang Lan
- Institute for Computational Science and Technology, SBI Building, Quang Trung Software City, Tan Chanh
Hiep Ward, District 12, Ho Chi Minh City, Vietnam
| | - Viet Hoang Man
- Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw, Poland
| | - Phuong H. Nguyen
- Laboratoire
de
Biochimie Theorique, UPR 9080 CNRS, IBPC, Universite Paris 7, 13 rue Pierre et Marie Curie, 75005 Paris, France
| | - 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, Vietnam
| | - Yi-Cheng Chen
- Department
of Medicine, MacKay Medical College, New Taipei City 252, Taiwan
| | - Mai Suan Li
- Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw, Poland
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81
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Garvey M, Baumann M, Wulff M, Kumar ST, Markx D, Morgado I, Knüpfer U, Horn U, Mawrin C, Fändrich M, Balbach J. Molecular architecture of Aβ fibrils grown in cerebrospinal fluid solution and in a cell culture model of Aβ plaque formation. Amyloid 2016; 23:76-85. [PMID: 26972581 DOI: 10.3109/13506129.2016.1146989] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVES The detailed structure of brain-derived Aβ amyloid fibrils is unknown. To approach this issue, we investigate the molecular architecture of Aβ(1-40) fibrils grown in either human cerebrospinal fluid solution, in chemically simple phosphate buffer in vitro or extracted from a cell culture model of Aβ amyloid plaque formation. METHODS We have used hydrogen-deuterium exchange (HX) combined with nuclear magnetic resonance, transmission electron microscopy, seeding experiments both in vitro and in cell culture as well as several other spectroscopic measurements to compare the morphology and residue-specific conformation of these different Aβ fibrils. RESULTS AND CONCLUSIONS Our data reveal that, despite considerable variations in morphology, the spectroscopic properties and the pattern of slowly exchanging backbone amides are closely similar in the fibrils investigated. This finding implies that a fundamentally conserved molecular architecture of Aβ peptide fold is common to Aβ fibrils.
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Affiliation(s)
- Megan Garvey
- a School of Medicine, Deakin University , East Geelong , VIC , Australia
| | - Monika Baumann
- b Institute for Physics, Biophysics, Martin-Luther-University Halle-Wittenberg , Halle (Saale) , Germany
| | - Melanie Wulff
- c Institute for Pharmaceutical Biotechnology, Ulm University , Ulm , Germany
| | - Senthil T Kumar
- c Institute for Pharmaceutical Biotechnology, Ulm University , Ulm , Germany
| | - Daniel Markx
- c Institute for Pharmaceutical Biotechnology, Ulm University , Ulm , Germany
| | - Isabel Morgado
- d Boston University School of Medicine , Boston , MA , USA
| | - Uwe Knüpfer
- e Leibniz-Institute for Infection Biology and Natural Product Research, Hans-Knöll-Institut (HKI) , Jena , Germany , and
| | - Uwe Horn
- e Leibniz-Institute for Infection Biology and Natural Product Research, Hans-Knöll-Institut (HKI) , Jena , Germany , and
| | - Christian Mawrin
- f Institute for Neuropathology, Otto-von-Guericke University , Magdeburg , Germany
| | - Marcus Fändrich
- c Institute for Pharmaceutical Biotechnology, Ulm University , Ulm , Germany
| | - Jochen Balbach
- b Institute for Physics, Biophysics, Martin-Luther-University Halle-Wittenberg , Halle (Saale) , Germany
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82
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Slide-and-exchange mechanism for rapid and selective transport through the nuclear pore complex. Proc Natl Acad Sci U S A 2016; 113:E2489-97. [PMID: 27091992 DOI: 10.1073/pnas.1522663113] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Nucleocytoplasmic transport is mediated by the interaction of transport factors (TFs) with disordered phenylalanine-glycine (FG) repeats that fill the central channel of the nuclear pore complex (NPC). However, the mechanism by which TFs rapidly diffuse through multiple FG repeats without compromising NPC selectivity is not yet fully understood. In this study, we build on our recent NMR investigations showing that FG repeats are highly dynamic, flexible, and rapidly exchanging among TF interaction sites. We use unbiased long timescale all-atom simulations on the Anton supercomputer, combined with extensive enhanced sampling simulations and NMR experiments, to characterize the thermodynamic and kinetic properties of FG repeats and their interaction with a model transport factor. Both the simulations and experimental data indicate that FG repeats are highly dynamic random coils, lack intrachain interactions, and exhibit significant entropically driven resistance to spatial confinement. We show that the FG motifs reversibly slide in and out of multiple TF interaction sites, transitioning rapidly between a strongly interacting state and a weakly interacting state, rather than undergoing a much slower transition between strongly interacting and completely noninteracting (unbound) states. In the weakly interacting state, FG motifs can be more easily displaced by other competing FG motifs, providing a simple mechanism for rapid exchange of TF/FG motif contacts during transport. This slide-and-exchange mechanism highlights the direct role of the disorder within FG repeats in nucleocytoplasmic transport, and resolves the apparent conflict between the selectivity and speed of transport.
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83
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Brookes DH, Head-Gordon T. Experimental Inferential Structure Determination of Ensembles for Intrinsically Disordered Proteins. J Am Chem Soc 2016; 138:4530-8. [PMID: 26967199 DOI: 10.1021/jacs.6b00351] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
We develop a Bayesian approach to determine the most probable structural ensemble model from candidate structures for intrinsically disordered proteins (IDPs) that takes full advantage of NMR chemical shifts and J-coupling data, their known errors and variances, and the quality of the theoretical back-calculation from structure to experimental observables. Our approach differs from previous formulations in the optimization of experimental and back-calculation nuisance parameters that are treated as random variables with known distributions, as opposed to structural or ensemble weight optimization or use of a reference ensemble. The resulting experimental inferential structure determination (EISD) method is size extensive with O(N) scaling, with N = number of structures, that allows for the rapid ranking of large ensemble data comprising tens of thousands of conformations. We apply the EISD approach on singular folded proteins and a corresponding set of ∼25 000 misfolded states to illustrate the problems that can arise using Boltzmann weighted priors. We then apply the EISD method to rank IDP ensembles most consistent with the NMR data and show that the primary error for ranking or creating good IDP ensembles resides in the poor back-calculation from structure to simulated experimental observable. We show that a reduction by a factor of 3 in the uncertainty of the back-calculation error can improve the discrimination among qualitatively different IDP ensembles for the amyloid-beta peptide.
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Affiliation(s)
- David H Brookes
- Department of Chemistry, ‡Department of Bioengineering, §Department of Chemical and Biomolecular Engineering, ∥Chemical Sciences Division, Lawrence Berkeley National Laboratory, University of California , Berkeley, California 94720, United States
| | - Teresa Head-Gordon
- Department of Chemistry, ‡Department of Bioengineering, §Department of Chemical and Biomolecular Engineering, ∥Chemical Sciences Division, Lawrence Berkeley National Laboratory, University of California , Berkeley, California 94720, United States
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84
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Carballo-Pacheco M, Strodel B. Advances in the Simulation of Protein Aggregation at the Atomistic Scale. J Phys Chem B 2016; 120:2991-9. [PMID: 26965454 DOI: 10.1021/acs.jpcb.6b00059] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Protein aggregation into highly structured amyloid fibrils is associated with various diseases including Alzheimer's disease, Parkinson's disease, and type II diabetes. Amyloids can also have normal biological functions and, in the future, could be used as the basis for novel nanoscale materials. However, a full understanding of the physicochemical forces that drive protein aggregation is still lacking. Such understanding is crucial for the development of drugs that can effectively inhibit aberrant amyloid aggregation and for the directed design of functional amyloids. Atomistic simulations can help understand protein aggregation. In particular, atomistic simulations can be used to study the initial formation of toxic oligomers which are hard to characterize experimentally and to understand the difference in aggregation behavior between different amyloidogenic peptides. Here, we review the latest atomistic simulations of protein aggregation, concentrating on amyloidogenic protein fragments, and provide an outlook for the future in this field.
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Affiliation(s)
- Martín Carballo-Pacheco
- Institute of Complex Systems: Structural Biochemistry , Forschungszentrum Jülich, 52425 Jülich, Germany.,AICES Graduate School, RWTH Aachen University , Schinkelstraße 2, 52062 Aachen, Germany
| | - Birgit Strodel
- Institute of Complex Systems: Structural Biochemistry , Forschungszentrum Jülich, 52425 Jülich, Germany.,Institute of Theoretical and Computational Chemistry, Heinrich Heine University Düsseldorf , Universitätsstrasse 1, 40225 Düsseldorf, Germany
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85
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Roche J, Shen Y, Lee JH, Ying J, Bax A. Monomeric Aβ(1-40) and Aβ(1-42) Peptides in Solution Adopt Very Similar Ramachandran Map Distributions That Closely Resemble Random Coil. Biochemistry 2016; 55:762-75. [PMID: 26780756 PMCID: PMC4750080 DOI: 10.1021/acs.biochem.5b01259] [Citation(s) in RCA: 139] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
![]()
The
pathogenesis of Alzheimer’s disease is characterized
by the aggregation and fibrillation of amyloid peptides Aβ1–40 and Aβ1–42 into amyloid
plaques. Despite strong potential therapeutic interest, the structural
pathways associated with the conversion of monomeric Aβ peptides
into oligomeric species remain largely unknown. In particular, the
higher aggregation propensity and associated toxicity of Aβ1–42 compared to that of Aβ1–40 are poorly understood. To explore in detail the structural propensity
of the monomeric Aβ1–40 and Aβ1–42 peptides in solution, we recorded a large set of nuclear magnetic
resonance (NMR) parameters, including chemical shifts, nuclear Overhauser
effects (NOEs), and J couplings. Systematic comparisons
show that at neutral pH the Aβ1–40 and Aβ1–42 peptides populate almost indistinguishable coil-like
conformations. Nuclear Overhauser effect spectra collected at very
high resolution remove assignment ambiguities and show no long-range
NOE contacts. Six sets of backbone J couplings (3JHNHα, 3JC′C′, 3JC′Hα, 1JHαCα, 2JNCα, and 1JNCα) recorded
for Aβ1–40 were used as input for the recently
developed MERA Ramachandran map analysis, yielding residue-specific
backbone ϕ/ψ torsion angle distributions that closely
resemble random coil distributions, the absence of a significantly
elevated propensity for β-conformations in the C-terminal region
of the peptide, and a small but distinct propensity for αL at K28. Our results suggest that the self-association of
Aβ peptides into toxic oligomers is not driven by elevated propensities
of the monomeric species to adopt β-strand-like conformations.
Instead, the accelerated disappearance of Aβ NMR signals in
D2O over H2O, particularly pronounced for Aβ1–42, suggests that intermolecular interactions between
the hydrophobic regions of the peptide dominate the aggregation process.
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Affiliation(s)
- Julien Roche
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health , Bethesda, Maryland 20892-0510, United States
| | - Yang Shen
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health , Bethesda, Maryland 20892-0510, United States
| | - Jung Ho Lee
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health , Bethesda, Maryland 20892-0510, United States
| | - Jinfa Ying
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health , Bethesda, Maryland 20892-0510, United States
| | - Ad Bax
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health , Bethesda, Maryland 20892-0510, United States
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86
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Roche J, Ying J, Bax A. Accurate measurement of (3)J(HNHα) couplings in small or disordered proteins from WATERGATE-optimized TROSY spectra. JOURNAL OF BIOMOLECULAR NMR 2016; 64:1-7. [PMID: 26660434 PMCID: PMC4744140 DOI: 10.1007/s10858-015-0004-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2015] [Accepted: 11/30/2015] [Indexed: 06/05/2023]
Abstract
Provided that care is taken in adjusting the WATERGATE element of a (1)H-(15)N TROSY-HSQC experiment, such that neither the water magnetization nor the (1)H(α) protons are inverted by its final 180° pulse, (3)JHNHα couplings can be measured directly from splittings in the (1)H dimension of the spectrum. With band-selective (1)H decoupling, very high (15)N resolution can be achieved. A complete set of (3)JHNHα values, ranging from 3.4 to 10.1 Hz was measured for the 56-residue third domain of IgG-binding protein G (GB3). Using the H-N-C(α)-H(α) dihedral angles extracted from a RDC-refined structure of GB3, (3)JHNHα values predicted by a previously parameterized Karplus equation agree to within a root-mean-square deviation (rmsd) of 0.37 Hz with the experimental data. Values measured for the Alzheimer's implicated Aβ(1-40) peptide fit to within an rmsd of 0.45 Hz to random coil (3)JHNHα values.
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Affiliation(s)
- Julien Roche
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jinfa Ying
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ad Bax
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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87
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Yu H, Han W, Ma W, Schulten K. Transient β-hairpin formation in α-synuclein monomer revealed by coarse-grained molecular dynamics simulation. J Chem Phys 2015; 143:243142. [PMID: 26723627 PMCID: PMC4684271 DOI: 10.1063/1.4936910] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 11/18/2015] [Indexed: 12/18/2022] Open
Abstract
Parkinson's disease, originating from the intrinsically disordered peptide α-synuclein, is a common neurodegenerative disorder that affects more than 5% of the population above age 85. It remains unclear how α-synuclein monomers undergo conformational changes leading to aggregation and formation of fibrils characteristic for the disease. In the present study, we perform molecular dynamics simulations (over 180 μs in aggregated time) using a hybrid-resolution model, Proteins with Atomic details in Coarse-grained Environment (PACE), to characterize in atomic detail structural ensembles of wild type and mutant monomeric α-synuclein in aqueous solution. The simulations reproduce structural properties of α-synuclein characterized in experiments, such as secondary structure content, long-range contacts, chemical shifts, and (3)J(HNHCα )-coupling constants. Most notably, the simulations reveal that a short fragment encompassing region 38-53, adjacent to the non-amyloid-β component region, exhibits a high probability of forming a β-hairpin; this fragment, when isolated from the remainder of α-synuclein, fluctuates frequently into its β-hairpin conformation. Two disease-prone mutations, namely, A30P and A53T, significantly accelerate the formation of a β-hairpin in the stated fragment. We conclude that the formation of a β-hairpin in region 38-53 is a key event during α-synuclein aggregation. We predict further that the G47V mutation impedes the formation of a turn in the β-hairpin and slows down β-hairpin formation, thereby retarding α-synuclein aggregation.
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Affiliation(s)
- Hang Yu
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Wei Han
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Wen Ma
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Klaus Schulten
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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88
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Rosenman DJ, Wang C, García AE. Characterization of Aβ Monomers through the Convergence of Ensemble Properties among Simulations with Multiple Force Fields. J Phys Chem B 2015; 120:259-77. [PMID: 26562747 DOI: 10.1021/acs.jpcb.5b09379] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Amyloid β (Aβ) monomers represent a base state in the pathways of aggregation that result in the fibrils and oligomers implicated in the pathogenesis of Alzheimer's disease (AD). The structural properties of these intrinsically disordered peptides remain unclear despite extensive experimental and computational investigations. Further, there are mutations within Aβ that change the way the peptide aggregates and are known to cause familial AD (FAD). Here, we analyze the ensembles of different isoforms (Aβ42 and Aβ40) and mutants (E22Δ, D23N, E22K, E22G, and A2T in Aβ40) of Aβ generated with all-atom replica exchange molecular dynamics (REMD) simulations on the μs/replica time scale. These were run using three different force field/water model combinations: OPLS-AA/L and TIP3P ("OPLS"), AMBER99sb-ILDN and TIP4P-Ew ("ILDN"), as well as CHARMM22* and TIP3SP ("CHARMM"). Despite fundamental changes in simulation parameters, we find that the resulting ensembles demonstrate a strong convergence in structural properties. In particular, antiparallel contacts between L17-A21 and A30-L34 are prevalent in ensembles of Aβ40, directly forming β sheets in the OPLS and ILDN combinations. A21-A30 commonly forms an interceding region that rarely interacts with the rest of the peptide. Further, Aβ42 contributes new β hairpin motifs involving V40-I41 in both OPLS and ILDN. However, the structural flexibility of the central region and the electrostatic interactions that characterize it are notably different between the different conditions. Further, for OPLS, each of the FAD mutations disrupts central bend character and increases the polymorphism of antiparallel contacts across the central region. However, the studied mutations in the ILDN set primarily encourage more global contacts involving the N-terminus and the central region, and promote the formation of new β topologies that may seed different aggregates involved in disease phenotypes. These differences aside, the large degree of agreement between simulation sets across multiple force fields provides a generalizable characterization of Aβ that is also consistent with experimental data and models.
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Affiliation(s)
- David J Rosenman
- Department of Biology, Rensselaer Polytechnic Institute , 110 Eighth Street, Troy, New York 12180, United States.,Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute , 110 Eighth Street, Troy, New York 12180, United States
| | - Chunyu Wang
- Department of Biology, Rensselaer Polytechnic Institute , 110 Eighth Street, Troy, New York 12180, United States.,Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute , 110 Eighth Street, Troy, New York 12180, United States.,Graduate Program in Biochemistry and Biophysics, Rensselaer Polytechnic Institute , 110 Eighth Street, Troy, New York 12180, United States
| | - Angel E García
- Department of Biology, Rensselaer Polytechnic Institute , 110 Eighth Street, Troy, New York 12180, United States.,Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute , 110 Eighth Street, Troy, New York 12180, United States.,Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute , 110 Eighth Street, Troy, New York 12180, United States.,Center for Non Linear Studies, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
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89
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Salmon L, Blackledge M. Investigating protein conformational energy landscapes and atomic resolution dynamics from NMR dipolar couplings: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2015; 78:126601. [PMID: 26517337 DOI: 10.1088/0034-4885/78/12/126601] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Nuclear magnetic resonance spectroscopy is exquisitely sensitive to protein dynamics. In particular inter-nuclear dipolar couplings, that become measurable in solution when the protein is dissolved in a dilute liquid crystalline solution, report on all conformations sampled up to millisecond timescales. As such they provide the opportunity to describe the Boltzmann distribution present in solution at atomic resolution, and thereby to map the conformational energy landscape in unprecedented detail. The development of analytical methods and approaches based on numerical simulation and their application to numerous biologically important systems is presented.
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Affiliation(s)
- Loïc Salmon
- Université Grenoble Alpes, Institut de Biologie Structurale (IBS), F-38027 Grenoble, France. CEA, DSV, IBS, F-38027 Grenoble, France. CNRS, IBS, F-38027 Grenoble, France
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90
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Sharma SC, Armand T, Ball KA, Chen A, Pelton JG, Wemmer DE, Head-Gordon T. A facile method for expression and purification of (15)N isotope-labeled human Alzheimer's β-amyloid peptides from E. coli for NMR-based structural analysis. Protein Expr Purif 2015; 116:82-9. [PMID: 26231074 PMCID: PMC5161032 DOI: 10.1016/j.pep.2015.07.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 07/20/2015] [Accepted: 07/26/2015] [Indexed: 01/16/2023]
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disease affecting millions of people worldwide. AD is characterized by the presence of extracellular plaques composed of aggregated/oligomerized β-amyloid peptides with Aβ42 peptide representing a major isoform in the senile plaques. Given the pathological significance of Aβ42 in the progression of AD, there is considerable interest in understanding the structural ensembles for soluble monomer and oligomeric forms of Aβ42. This report describes an efficient method to express and purify high quality (15)N isotope-labeled Aβ42 for structural studies by NMR. The protocol involves utilization of an auto induction system with (15)N isotope labeled medium, for high-level expression of Aβ42 as a fusion with IFABP. After the over-expression of the (15)N isotope-labeled IFABP-Aβ42 fusion protein in the inclusion bodies, pure (15)N isotope-labeled Aβ42 peptide is obtained following a purification method that is streamlined and improved from the method originally developed for the isolation of unlabeled Aβ42 peptide (Garai et al., 2009). We obtain a final yield of ∼ 6 mg/L culture for (15)N isotope-labeled Aβ42 peptide. Mass spectrometry and (1)H-(15)N HSQC spectra of monomeric Aβ42 peptide validate the uniform incorporation of the isotopic label. The method described here is equally applicable for the uniform isotope labeling with (15)N and (13)C in Aβ42 peptide as well as its other variants including any Aβ42 peptide mutants.
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Affiliation(s)
- Sudhir C Sharma
- Department of Chemistry, University of California, Berkeley, CA 94720, USA.
| | - Tara Armand
- Department of Bioengineering, University of California, Berkeley, CA 94720, USA
| | - K Aurelia Ball
- Pharmaceutical Chemistry, University of California, San Francisco, CA, USA
| | - Anna Chen
- Committee on Molecular Metabolism and Nutrition, University of Chicago, 1027 E. 57th Street, Chicago, IL 60637, USA
| | - Jeffrey G Pelton
- QB3 Institute, University of California, Berkeley, CA 94720, USA
| | - David E Wemmer
- Department of Chemistry, University of California, Berkeley, CA 94720, USA; QB3 Institute, University of California, Berkeley, CA 94720, USA
| | - Teresa Head-Gordon
- Department of Chemistry, University of California, Berkeley, CA 94720, USA; Department of Bioengineering, University of California, Berkeley, CA 94720, USA; Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA 94720, USA; QB3 Institute, University of California, Berkeley, CA 94720, USA; Chemical Sciences Division, Lawrence Berkeley National Labs, Berkeley, CA 94720, USA
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91
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Rauscher S, Gapsys V, Gajda MJ, Zweckstetter M, de Groot BL, Grubmüller H. Structural Ensembles of Intrinsically Disordered Proteins Depend Strongly on Force Field: A Comparison to Experiment. J Chem Theory Comput 2015; 11:5513-24. [PMID: 26574339 DOI: 10.1021/acs.jctc.5b00736] [Citation(s) in RCA: 305] [Impact Index Per Article: 33.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Intrinsically disordered proteins (IDPs) are notoriously challenging to study both experimentally and computationally. The structure of IDPs cannot be described by a single conformation but must instead be described as an ensemble of interconverting conformations. Atomistic simulations are increasingly used to obtain such IDP conformational ensembles. Here, we have compared the IDP ensembles generated by eight all-atom empirical force fields against primary small-angle X-ray scattering (SAXS) and NMR data. Ensembles obtained with different force fields exhibit marked differences in chain dimensions, hydrogen bonding, and secondary structure content. These differences are unexpectedly large: changing the force field is found to have a stronger effect on secondary structure content than changing the entire peptide sequence. The CHARMM 22* ensemble performs best in this force field comparison: it has the lowest error in chemical shifts and J-couplings and agrees well with the SAXS data. A high population of left-handed α-helix is present in the CHARMM 36 ensemble, which is inconsistent with measured scalar couplings. To eliminate inadequate sampling as a reason for differences between force fields, extensive simulations were carried out (0.964 ms in total); the remaining small sampling uncertainty is shown to be much smaller than the observed differences. Our findings highlight how IDPs, with their rugged energy landscapes, are highly sensitive test systems that are capable of revealing force field deficiencies and, therefore, contributing to force field development.
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Affiliation(s)
- Sarah Rauscher
- Department of Theoretical and Computational Biophysics, Max Planck Institute for Biophysical Chemistry , Göttingen 37077, Germany
| | - Vytautas Gapsys
- Department of Theoretical and Computational Biophysics, Max Planck Institute for Biophysical Chemistry , Göttingen 37077, Germany
| | - Michal J Gajda
- Department of NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry , Göttingen 37077, Germany
| | - Markus Zweckstetter
- Department of NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry , Göttingen 37077, Germany.,German Center for Neurodegenerative Diseases (DZNE) , Göttingen 37077, Germany.,Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), University Medical Center , Göttingen 37073, Germany
| | - Bert L de Groot
- Department of Theoretical and Computational Biophysics, Max Planck Institute for Biophysical Chemistry , Göttingen 37077, Germany
| | - Helmut Grubmüller
- Department of Theoretical and Computational Biophysics, Max Planck Institute for Biophysical Chemistry , Göttingen 37077, Germany
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92
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Tarus B, Tran TT, Nasica-Labouze J, Sterpone F, Nguyen PH, Derreumaux P. Structures of the Alzheimer's Wild-Type Aβ1-40 Dimer from Atomistic Simulations. J Phys Chem B 2015; 119:10478-87. [PMID: 26228450 DOI: 10.1021/acs.jpcb.5b05593] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have studied the dimer of amyloid beta peptide Aβ of 40 residues by means of all-atom replica exchange molecular dynamics. The Aβ-dimers have been found to be the smallest toxic species in Alzheimer's disease, but their inherent flexibilities have precluded structural characterization by experimental methods. Though the 24-μs-scale simulation reveals a mean secondary structure of 18% β-strand and 10% α helix, we find transient configurations with an unstructured N-terminus and multiple β-hairpins spanning residues 17-21 and 30-36, but the antiparallel and perpendicular peptide orientations are preferred over the parallel organization. Short-lived conformational states also consist of all α topologies, and one compact peptide with β-sheet structure stabilized by a rather extended peptide with α-helical content. Overall, this first all-atom study provides insights into the equilibrium structure of the Aβ1-40 dimer in aqueous solution, opening a new avenue for a comprehensive understanding of the impact of pathogenic and protective mutations in early-stage Alzheimer's disease on a molecular level.
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Affiliation(s)
- Bogdan Tarus
- Laboratoire de Biochimie Théorique, UPR 9080 CNRS, IBPC, Université Paris Diderot, Sorbonne Paris Cité, 13 Rue Pierre et Marie Curie, 75005 Paris, France
| | - Thanh T Tran
- Laboratoire de Biochimie Théorique, UPR 9080 CNRS, IBPC, Université Paris Diderot, Sorbonne Paris Cité, 13 Rue Pierre et Marie Curie, 75005 Paris, France
| | - Jessica Nasica-Labouze
- Laboratoire de Biochimie Théorique, UPR 9080 CNRS, IBPC, Université Paris Diderot, Sorbonne Paris Cité, 13 Rue Pierre et Marie Curie, 75005 Paris, France
| | - Fabio Sterpone
- Laboratoire de Biochimie Théorique, UPR 9080 CNRS, IBPC, Université Paris Diderot, Sorbonne Paris Cité, 13 Rue Pierre et Marie Curie, 75005 Paris, France
| | - Phuong H Nguyen
- Laboratoire de Biochimie Théorique, UPR 9080 CNRS, IBPC, Université Paris Diderot, Sorbonne Paris Cité, 13 Rue Pierre et Marie Curie, 75005 Paris, France
| | - Philippe Derreumaux
- Laboratoire de Biochimie Théorique, UPR 9080 CNRS, IBPC, Université Paris Diderot, Sorbonne Paris Cité, 13 Rue Pierre et Marie Curie, 75005 Paris, France
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93
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Ahalawat N, Arora S, Murarka RK. Structural Ensemble of CD4 Cytoplasmic Tail (402–419) Reveals a Nearly Flat Free-Energy Landscape with Local α-Helical Order in Aqueous Solution. J Phys Chem B 2015; 119:11229-42. [DOI: 10.1021/acs.jpcb.5b03092] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Navjeet Ahalawat
- Department
of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal By-pass Road, Bhauri, Bhopal 462066, Madhya Pradesh, India
| | - Simran Arora
- Department
of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal By-pass Road, Bhauri, Bhopal 462066, Madhya Pradesh, India
| | - Rajesh K. Murarka
- Department
of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal By-pass Road, Bhauri, Bhopal 462066, Madhya Pradesh, India
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94
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Kotler SA, Brender JR, Vivekanandan S, Suzuki Y, Yamamoto K, Monette M, Krishnamoorthy J, Walsh P, Cauble M, Holl MMB, Marsh ENG, Ramamoorthy A. High-resolution NMR characterization of low abundance oligomers of amyloid-β without purification. Sci Rep 2015; 5:11811. [PMID: 26138908 PMCID: PMC4490348 DOI: 10.1038/srep11811] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 05/21/2015] [Indexed: 01/30/2023] Open
Abstract
Alzheimer's disease is characterized by the misfolding and self-assembly of the amyloidogenic protein amyloid-β (Aβ). The aggregation of Aβ leads to diverse oligomeric states, each of which may be potential targets for intervention. Obtaining insight into Aβ oligomers at the atomic level has been a major challenge to most techniques. Here, we use magic angle spinning recoupling (1)H-(1)H NMR experiments to overcome many of these limitations. Using (1)H-(1)H dipolar couplings as a NMR spectral filter to remove both high and low molecular weight species, we provide atomic-level characterization of a non-fibrillar aggregation product of the Aβ1-40 peptide using non-frozen samples without isotopic labeling. Importantly, this spectral filter allows the detection of the specific oligomer signal without a separate purification procedure. In comparison to other solid-state NMR techniques, the experiment is extraordinarily selective and sensitive. A resolved 2D spectra could be acquired of a small population of oligomers (6 micrograms, 7% of the total) amongst a much larger population of monomers and fibers (93% of the total). By coupling real-time (1)H-(1)H NMR experiments with other biophysical measurements, we show that a stable, primarily disordered Aβ1-40 oligomer 5-15 nm in diameter can form and coexist in parallel with the well-known cross-β-sheet fibrils.
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Affiliation(s)
- Samuel A. Kotler
- Biophysics, University of Michigan-Ann Arbor, Ann Arbor, Michigan 48109, U.S.A
| | - Jeffrey R. Brender
- Biophysics, University of Michigan-Ann Arbor, Ann Arbor, Michigan 48109, U.S.A
- Department of Chemistry, University of Michigan-Ann Arbor, Ann Arbor, Michigan 48109, U.S.A
| | | | - Yuta Suzuki
- Department of Chemistry, University of Michigan-Ann Arbor, Ann Arbor, Michigan 48109, U.S.A
| | - Kazutoshi Yamamoto
- Biophysics, University of Michigan-Ann Arbor, Ann Arbor, Michigan 48109, U.S.A
- Department of Chemistry, University of Michigan-Ann Arbor, Ann Arbor, Michigan 48109, U.S.A
| | - Martine Monette
- Bruker BioSpin Ltd., Bruker Corporation, 555 E Steeles Ave, Milton, ON, Canada
| | - Janarthanan Krishnamoorthy
- Biophysics, University of Michigan-Ann Arbor, Ann Arbor, Michigan 48109, U.S.A
- Department of Chemistry, University of Michigan-Ann Arbor, Ann Arbor, Michigan 48109, U.S.A
| | - Patrick Walsh
- Biophysics, University of Michigan-Ann Arbor, Ann Arbor, Michigan 48109, U.S.A
- Department of Chemistry, University of Michigan-Ann Arbor, Ann Arbor, Michigan 48109, U.S.A
| | - Meagan Cauble
- Department of Chemistry, University of Michigan-Ann Arbor, Ann Arbor, Michigan 48109, U.S.A
| | - Mark M. Banaszak Holl
- Department of Chemistry, University of Michigan-Ann Arbor, Ann Arbor, Michigan 48109, U.S.A
- Michigan Nanotechnology Institute for Medicine and Biological Sciences, University of Michigan-Ann Arbor, Ann Arbor, Michigan 48109, U.S.A
| | - E. Neil. G. Marsh
- Department of Chemistry, University of Michigan-Ann Arbor, Ann Arbor, Michigan 48109, U.S.A
| | - Ayyalusamy Ramamoorthy
- Biophysics, University of Michigan-Ann Arbor, Ann Arbor, Michigan 48109, U.S.A
- Department of Chemistry, University of Michigan-Ann Arbor, Ann Arbor, Michigan 48109, U.S.A
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95
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Tran L, Ha-Duong T. Exploring the Alzheimer amyloid-β peptide conformational ensemble: A review of molecular dynamics approaches. Peptides 2015; 69:86-91. [PMID: 25908410 DOI: 10.1016/j.peptides.2015.04.009] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Revised: 04/02/2015] [Accepted: 04/07/2015] [Indexed: 12/22/2022]
Abstract
Alzheimer's disease is one of the most common dementia among elderly worldwide. There is no therapeutic drugs until now to treat effectively this disease. One main reason is due to the poorly understood mechanism of Aβ peptide aggregation, which plays a crucial role in the development of Alzheimer's disease. It remains challenging to experimentally or theoretically characterize the secondary and tertiary structures of the Aβ monomer because of its high flexibility and aggregation propensity, and its conformations that lead to the aggregation are not fully identified. In this review, we highlight various structural ensembles of Aβ peptide revealed and characterized by computational approaches in order to find converging structures of Aβ monomer. Understanding how Aβ peptide forms transiently stable structures prior to aggregation will contribute to the design of new therapeutic molecules against the Alzheimer's disease.
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Affiliation(s)
- Linh Tran
- BioCIS, UMR CNRS 8076, LabEx LERMIT, Faculty of Pharmacy, University Paris Sud, 5 Rue Jean-Baptiste Clément, 92296 Châtenay-Malabry, France
| | - Tâp Ha-Duong
- BioCIS, UMR CNRS 8076, LabEx LERMIT, Faculty of Pharmacy, University Paris Sud, 5 Rue Jean-Baptiste Clément, 92296 Châtenay-Malabry, France.
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96
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Xu L, Shan S, Chen Y, Wang X, Nussinov R, Ma B. Coupling of Zinc-Binding and Secondary Structure in Nonfibrillar Aβ40 Peptide Oligomerization. J Chem Inf Model 2015; 55:1218-30. [PMID: 26017140 PMCID: PMC6407634 DOI: 10.1021/acs.jcim.5b00063] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Nonfibrillar neurotoxic amyloid β (Aβ) oligomer structures are typically rich in β-sheets, which could be promoted by metal ions like Zn(2+). Here, using molecular dynamics (MD) simulations, we systematically examined combinations of Aβ40 peptide conformations and Zn(2+) binding modes to probe the effects of secondary structure on Aβ dimerization energies and kinetics. We found that random conformations do not contribute to dimerization either thermodynamically or kinetically. Zn(2+) couples with preformed secondary structures (α-helix and β-hairpin) to speed dimerization and stabilize the resulting dimer. Partial α-helices increase the dimerization speed, and dimers with α-helix rich conformations have the lowest energy. When Zn(2+) coordinates with residues D1, H6, H13, and H14, Aβ40 β-hairpin monomers have the fastest dimerization speed. Dimers with experimentally observed zinc coordination (E11, H6, H13, and H14) form with slower rate but have lower energy. Zn(2+) cannot stabilize fibril-like β-arch dimers. However, Zn(2+)-bound β-arch tetramers have the lowest energy. Collectively, zinc-stabilized β-hairpin oligomers could be important in the nucleation-polymerization of cross-β structures. Our results are consistent with experimental findings that α-helix to β-structural transition should accompany Aβ aggregation in the presence of zinc ions and that Zn(2+) stabilizes nonfibrillar Aβ oligomers and, thus, inhibits formation of less toxic Aβ fibrils.
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Affiliation(s)
- Liang Xu
- School of Chemistry, Dalian University of Technology, Dalian, China
| | - Shengsheng Shan
- School of Chemistry, Dalian University of Technology, Dalian, China
| | - Yonggang Chen
- Network and Information Center, Dalian University of Technology, Dalian, China
| | - Xiaojuan Wang
- School of Chemical Machinery, Dalian University of Technology, Dalian, China
| | - Ruth Nussinov
- Sackler Inst. of Molecular Medicine Department of Human Genetics and Molecular Medicine Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
- Basic Science Program, Leidos Biomedical Research, Inc. Cancer and Inflammation Program, National Cancer Institute, Frederick, Maryland 21702
| | - Buyong Ma
- Basic Science Program, Leidos Biomedical Research, Inc. Cancer and Inflammation Program, National Cancer Institute, Frederick, Maryland 21702
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97
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Song W, Wang Y, Colletier JP, Yang H, Xu Y. Varied Probability of Staying Collapsed/Extended at the Conformational Equilibrium of Monomeric Aβ40 and Aβ42. Sci Rep 2015; 5:11024. [PMID: 26046578 PMCID: PMC4603783 DOI: 10.1038/srep11024] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Accepted: 05/12/2015] [Indexed: 01/02/2023] Open
Abstract
In present study, we set out to investigate the conformation dynamics of Aβ40 and Aβ42 through exploring the impact of intra-molecular interactions on conformation dynamics using equilibrium molecular dynamics simulations. Our 40 microsecond-scale simulations reveal heterogeneous conformation ensembles of Aβ40 and Aβ42 that encompass ~35% β-strand and ~60% unstructured coils. Two conformational states were identified in both alloforms: a collapsed state (CS) that resembles the structural motif of face-to-face hydrophobic clustering in amyloid fibrils, and an extended state (ES) that features the structural characteristics of anti-parallel β-sheets in amyloid oligomers. In Aβ40, the C-terminus remains unstructured and rarely interacts with other parts, thereof the hydrophobic clustering is in loose contact and the peptide assumes ES with high probability. In contrast, the C-terminus of Aβ42 adopts a β-strand structure that strongly interacts with segments E3-R5 and V18-A21. The active association leads to a more compact hydrophobic collapse and refrain the alloform from ES. Based on the structural characterization, we propose that the fibril and oligomer assembly pathways could respectively take off from CS and ES, and their aggregation propensity may be governed by the probability of visiting the corresponding conformational states at the equilibrium.
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Affiliation(s)
- Wanling Song
- CAS Key Laboratory of Receptor Research, Drug Discovery and Design Center, Shanghai Institute of Materia Medica, Chinese Academy of Sciences (CAS), Shanghai 201203, China
| | - Yuanyuan Wang
- CAS Key Laboratory of Receptor Research, Drug Discovery and Design Center, Shanghai Institute of Materia Medica, Chinese Academy of Sciences (CAS), Shanghai 201203, China
| | - Jacques-Philippe Colletier
- Univ. Grenoble Alpes, IBS, F-38044 Grenoble, France
- CNRS, IBS, F-38044 Grenoble, France
- CEA, IBS, F-38044 Grenoble, France
| | - Huaiyu Yang
- CAS Key Laboratory of Receptor Research, Drug Discovery and Design Center, Shanghai Institute of Materia Medica, Chinese Academy of Sciences (CAS), Shanghai 201203, China
| | - Yechun Xu
- CAS Key Laboratory of Receptor Research, Drug Discovery and Design Center, Shanghai Institute of Materia Medica, Chinese Academy of Sciences (CAS), Shanghai 201203, China
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98
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Ning L, Pan D, Zhang Y, Wang S, Liu H, Yao X. Effects of the Pathogenic Mutation A117V and the Protective Mutation H111S on the Folding and Aggregation of PrP106-126: Insights from Replica Exchange Molecular Dynamics Simulations. PLoS One 2015; 10:e0125899. [PMID: 25993001 PMCID: PMC4439087 DOI: 10.1371/journal.pone.0125899] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 03/24/2015] [Indexed: 11/19/2022] Open
Abstract
The fragment 106-126 of prion protein exhibits similar properties to full-length prion. Experiments have shown that the A117V mutation enhances the aggregation of PrP106-126, while the H111S mutation abolishes the assembly. However, the mechanism of the change in the aggregation behavior of PrP106-126 upon the two mutations is not fully understood. In this study, replica exchange molecular dynamics simulations were performed to investigate the conformational ensemble of the WT PrP106-126 and its two mutants A117V and H111S. The obtained results indicate that the three species are all intrinsically disordered but they have distinct morphological differences. The A117V mutant has a higher propensity to form β-hairpin structures than the WT, while the H111S mutant has a higher population of helical structures. Furthermore, the A117V mutation increases the hydrophobic solvent accessible surface areas of PrP106-126 and the H111S mutation reduces the exposure of hydrophobic residues. It can be concluded that the difference in populations of β-hairpin structures and the change of hydrophobic solvent accessible areas may induce the different aggregation behaviors of the A117V and the H111S mutated PrP106-126. Understanding why the two mutations have contrary effects on the aggregation of PrP106-126 is very meaningful for further elucidation of the mechanism underlying aggregation and design of inhibitor against aggregation process.
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Affiliation(s)
- Lulu Ning
- State Key Laboratory of Applied Organic Chemistry and Department of Chemistry, Lanzhou University, Lanzhou, China
| | - Dabo Pan
- State Key Laboratory of Applied Organic Chemistry and Department of Chemistry, Lanzhou University, Lanzhou, China
- School of pharmaceutical technology, Qiandongnan National Polytechnic, Kaili, China
| | - Yan Zhang
- School of Pharmacy, Lanzhou University, Lanzhou, China
| | - Shaopeng Wang
- State Key Laboratory of Applied Organic Chemistry and Department of Chemistry, Lanzhou University, Lanzhou, China
| | - Huanxiang Liu
- School of Pharmacy, Lanzhou University, Lanzhou, China
- * E-mail: (HL); (XY)
| | - Xiaojun Yao
- State Key Laboratory of Applied Organic Chemistry and Department of Chemistry, Lanzhou University, Lanzhou, China
- State Key Laboratory of Quality Research in Chinese Medicine, Macau Institute for Applied Research in Medicine and Health, Macau University of Science and Technology, Taipa, Macau, China
- * E-mail: (HL); (XY)
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99
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Lyubchenko YL. Amyloid misfolding, aggregation, and the early onset of protein deposition diseases: insights from AFM experiments and computational analyses. AIMS MOLECULAR SCIENCE 2015; 2:190-210. [PMID: 27830177 PMCID: PMC5098429 DOI: 10.3934/molsci.2015.3.190] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The development of Alzheimer's disease is believed to be caused by the assembly of amyloid β proteins into aggregates and the formation of extracellular senile plaques. Similar models suggest that structural misfolding and aggregation of proteins are associated with the early onset of diseases such as Parkinson's, Huntington's, and other protein deposition diseases. Initially, the aggregates were structurally characterized by traditional techniques such as x-ray crystallography, NMR, electron microscopy, and AFM. However, data regarding the structures formed during the early stages of the aggregation process were unknown. Experimental models of protein deposition diseases have demonstrated that the small oligomeric species have significant neurotoxicity. This highlights the urgent need to discover the properties of these species, to enable the development of efficient diagnostic and therapeutic strategies. The oligomers exist transiently, making it impossible to use traditional structural techniques to study their characteristics. The recent implementation of single-molecule imaging and probing techniques that are capable of probing transient states have enabled the properties of these oligomers to be characterized. Additionally, powerful computational techniques capable of structurally analyzing oligomers at the atomic level advanced our understanding of the amyloid aggregation problem. This review outlines the progress in AFM experimental studies and computational analyses with a primary focus on understanding the very first stage of the aggregation process. Experimental approaches can aid in the development of novel sensitive diagnostic and preventive strategies for protein deposition diseases, and several examples of these approaches will be discussed.
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Affiliation(s)
- Yuri L Lyubchenko
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, NE 68198, USA
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100
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Morriss-Andrews A, Shea JE. Computational Studies of Protein Aggregation: Methods and Applications. Annu Rev Phys Chem 2015; 66:643-66. [DOI: 10.1146/annurev-physchem-040513-103738] [Citation(s) in RCA: 132] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
| | - Joan-Emma Shea
- Department of Physics and
- Department of Chemistry, University of California, Santa Barbara, California 93106;
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