101
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Qian Z, Jia Y, Wei G. Binding Orientations and Lipid Interactions of Human Amylin at Zwitterionic and Anionic Lipid Bilayers. J Diabetes Res 2016; 2016:1749196. [PMID: 26649316 PMCID: PMC4663351 DOI: 10.1155/2016/1749196] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2014] [Revised: 03/22/2015] [Accepted: 04/15/2015] [Indexed: 11/17/2022] Open
Abstract
Increasing evidence suggests that the interaction of human islet amyloid polypeptide (hIAPP) with lipids may facilitate hIAPP aggregation and cause the death of pancreatic islet β-cells. However, the detailed hIAPP-membrane interactions and the influences of lipid compositions are unclear. In this study, as a first step to understand the mechanism of membrane-mediated hIAPP aggregation, we investigate the binding behaviors of hIAPP monomer at zwitterionic palmitoyloleoyl-phosphatidylcholine (POPC) bilayer by performing atomistic molecular dynamics simulations. The results are compared with those of hIAPP at anionic palmitoyloleoyl-phosphatidylglycerol (POPG) bilayers. We find that the adsorption of hIAPP to POPC bilayer is mainly initiated from the C-terminal region and the peptide adopts a helical structure with multiple binding orientations, while the adsorption to POPG bilayer is mostly initiated from the N-terminal region and hIAPP displays one preferential binding orientation, with its hydrophobic residues exposed to water. hIAPP monomer inserts into POPC lipid bilayers more readily than into POPG bilayers. Peptide-lipid interaction analyses show that the different binding features of hIAPP at POPC and POPG bilayers are attributed to different magnitudes of electrostatic and hydrogen-bonding interactions with lipids. This study provides mechanistic insights into the different interaction behaviors of hIAPP with zwitterionic and anionic lipid bilayers.
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Affiliation(s)
- Zhenyu Qian
- State Key Laboratory of Surface Physics, Key Laboratory for Computational Physical Sciences (Ministry of Education), and Department of Physics, Fudan University, Shanghai 200433, China
| | - Yan Jia
- State Key Laboratory of Surface Physics, Key Laboratory for Computational Physical Sciences (Ministry of Education), and Department of Physics, Fudan University, Shanghai 200433, China
| | - Guanghong Wei
- State Key Laboratory of Surface Physics, Key Laboratory for Computational Physical Sciences (Ministry of Education), and Department of Physics, Fudan University, Shanghai 200433, China
- *Guanghong Wei:
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102
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Young LM, Mahood RA, Saunders JC, Tu LH, Raleigh DP, Radford SE, Ashcroft AE. Insights into the consequences of co-polymerisation in the early stages of IAPP and Aβ peptide assembly from mass spectrometry. Analyst 2015; 140:6990-9. [PMID: 26193839 PMCID: PMC4626081 DOI: 10.1039/c5an00865d] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The precise molecular mechanisms by which different peptides and proteins assemble into highly ordered amyloid deposits remain elusive. The fibrillation of human amylin (also known as islet amyloid polypeptide, hIAPP) and the amyloid-beta peptide (Aβ-40) are thought to be pathogenic factors in Type 2 diabetes mellitus (T2DM) and Alzheimer's disease (AD), respectively. Amyloid diseases may involve co-aggregation of different protein species, in addition to the self-assembly of single precursor sequences. Here we investigate the formation of heterogeneous pre-fibrillar, oligomeric species produced by the co-incubation of hIAPP and Aβ-40 using electrospray ionisation-ion mobility spectrometry-mass spectrometry (ESI-IMS-MS)-based methods. Conformational properties and gas-phase stabilities of amyloid oligomers formed from hIAPP or Aβ40 alone, and from a 1 : 1 mixture of hIAPP and Aβ40 monomers, were determined and compared. We show that co-assembly of the two sequences results in hetero-oligomers with distinct properties and aggregation kinetics properties compared with the homo-oligomers present in solution. The observations may be of key significance to unravelling the mechanisms of amyloid formation in vivo and elucidating how different sequences and/or assembly conditions can result in different fibril structures and/or pathogenic outcomes.
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Affiliation(s)
- Lydia M. Young
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds, LS2 9JT, UK
| | - Rachel A. Mahood
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds, LS2 9JT, UK
| | - Janet C. Saunders
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds, LS2 9JT, UK
| | - Ling-Hsien Tu
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, USA
| | - Daniel P. Raleigh
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, USA
- Research Department of Structural and Molecule Biology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Sheena E. Radford
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds, LS2 9JT, UK
| | - Alison E. Ashcroft
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds, LS2 9JT, UK
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103
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Cole H, Porrini M, Morris R, Smith T, Kalapothakis J, Weidt S, Mackay CL, MacPhee CE, Barran PE. Early stages of insulin fibrillogenesis examined with ion mobility mass spectrometry and molecular modelling. Analyst 2015; 140:7000-11. [PMID: 26369607 PMCID: PMC11226345 DOI: 10.1039/c5an01253h] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 09/09/2015] [Indexed: 07/07/2024]
Abstract
A prevalent type of protein misfolding causes the formation of β-sheet-rich structures known as amyloid fibrils. Research into the mechanisms of fibril formation has implications for both disease prevention and nanoscale templating technologies. This investigation into the aggregation of insulin utilises ion mobility mass spectrometry coupled with molecular modelling to identify and characterise oligomers formed during the 'lag' phase that precedes fibril growth. High resolution mass spectrometry and collision induced dissociation is used to unequivocally assign species as m/z coincident multimers or confomers, providing a robust analytical approach that supports the use of molecular dynamics to atomistically resolve the observed oligomers. We show that insulin oligomerises to form species In where 2 ≤ n ≤ 12 and within this set of oligomers we delineate over 60 distinct conformations, the most dominant of which are compact species. Modelling trained with experimental data suggests that the dominant compact dimers are enriched in β-sheet secondary structure and dominated by hydrophobic interactions, and provides a linear relationship between Rg and collision cross section. This approach provides detailed insight to the early stages of assembly of this much studied amyloidogenic protein, and can be used to inform models of nucleation and growth.
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Affiliation(s)
- Harriet Cole
- EastChem School of ChemistryJoseph Black BuildingThe King's BuildingsWest Mains RdEdinburgh EH9 3JJUK
- SUPA, School of Physics and AstronomyJames Clark Maxwell BuildingThe King's BuildingsWest Mains RdEdinburgh EH9 3JZUK
| | - Massimiliano Porrini
- SUPA, School of Physics and AstronomyJames Clark Maxwell BuildingThe King's BuildingsWest Mains RdEdinburgh EH9 3JZUK
| | - Ryan Morris
- SUPA, School of Physics and AstronomyJames Clark Maxwell BuildingThe King's BuildingsWest Mains RdEdinburgh EH9 3JZUK
| | - Tom Smith
- EastChem School of ChemistryJoseph Black BuildingThe King's BuildingsWest Mains RdEdinburgh EH9 3JJUK
| | - Jason Kalapothakis
- EastChem School of ChemistryJoseph Black BuildingThe King's BuildingsWest Mains RdEdinburgh EH9 3JJUK
- SUPA, School of Physics and AstronomyJames Clark Maxwell BuildingThe King's BuildingsWest Mains RdEdinburgh EH9 3JZUK
| | - Stefan Weidt
- EastChem School of ChemistryJoseph Black BuildingThe King's BuildingsWest Mains RdEdinburgh EH9 3JJUK
| | - C. Logan Mackay
- EastChem School of ChemistryJoseph Black BuildingThe King's BuildingsWest Mains RdEdinburgh EH9 3JJUK
| | - Cait E. MacPhee
- SUPA, School of Physics and AstronomyJames Clark Maxwell BuildingThe King's BuildingsWest Mains RdEdinburgh EH9 3JZUK
| | - Perdita E. Barran
- Michael Barber Centre for Collaborative Mass Spectrometry, School of Chemistry, Manchester Institute of Mass Spectrometry, The University of ManchesterManchesterM1 7DNUK+44(0) 161 275 0256
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104
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De Carufel CA, Quittot N, Nguyen PT, Bourgault S. Delineating the Role of Helical Intermediates in Natively Unfolded Polypeptide Amyloid Assembly and Cytotoxicity. Angew Chem Int Ed Engl 2015; 54:14383-7. [DOI: 10.1002/anie.201507092] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Revised: 09/04/2015] [Indexed: 11/10/2022]
Affiliation(s)
- Carole Anne De Carufel
- Department of Chemistry, Université du Québec à Montréal, Quebec Network for Research on Protein Function, Structure and Engineering (PROTEO), C.P. 8888, Montréal (Canada)
| | - Noé Quittot
- Department of Chemistry, Université du Québec à Montréal, Quebec Network for Research on Protein Function, Structure and Engineering (PROTEO), C.P. 8888, Montréal (Canada)
| | - Phuong Trang Nguyen
- Department of Chemistry, Université du Québec à Montréal, Quebec Network for Research on Protein Function, Structure and Engineering (PROTEO), C.P. 8888, Montréal (Canada)
| | - Steve Bourgault
- Department of Chemistry, Université du Québec à Montréal, Quebec Network for Research on Protein Function, Structure and Engineering (PROTEO), C.P. 8888, Montréal (Canada)
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105
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De Carufel CA, Quittot N, Nguyen PT, Bourgault S. Delineating the Role of Helical Intermediates in Natively Unfolded Polypeptide Amyloid Assembly and Cytotoxicity. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201507092] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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106
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He J, Dai J, Li J, Peng X, Niemi AJ. Aspects of structural landscape of human islet amyloid polypeptide. J Chem Phys 2015; 142:045102. [PMID: 25638009 DOI: 10.1063/1.4905586] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The human islet amyloid polypeptide (hIAPP) co-operates with insulin to maintain glycemic balance. It also constitutes the amyloid plaques that aggregate in the pancreas of type-II diabetic patients. We have performed extensive in silico investigations to analyse the structural landscape of monomeric hIAPP, which is presumed to be intrinsically disordered. For this, we construct from first principles a highly predictive energy function that describes a monomeric hIAPP observed in a nuclear magnetic resonance experiment, as a local energy minimum. We subject our theoretical model of hIAPP to repeated heating and cooling simulations, back and forth between a high temperature regime where the conformation resembles a random walker and a low temperature limit where no thermal motions prevail. We find that the final low temperature conformations display a high level of degeneracy, in a manner which is fully in line with the presumed intrinsically disordered character of hIAPP. In particular, we identify an isolated family of α-helical conformations that might cause the transition to amyloidosis, by nucleation.
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Affiliation(s)
- Jianfeng He
- School of Physics, Beijing Institute of Technology, Beijing 100081, People's Republic of China
| | - Jin Dai
- School of Physics, Beijing Institute of Technology, Beijing 100081, People's Republic of China
| | - Jing Li
- Institute of Biopharmaceutical Research, Yangtze River Pharmaceutical Group Beijing Haiyan Pharmaceutical Co., Ltd, Beijing 102206, China
| | - Xubiao Peng
- Department of Physics and Astronomy, Uppsala University, P.O. Box 803, S-75108 Uppsala, Sweden
| | - Antti J Niemi
- School of Physics, Beijing Institute of Technology, Beijing 100081, People's Republic of China
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107
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Zhou X, Cao C, Chen Q, Yu Q, Liu Y, Yin T, Liu J. PEG modified graphene oxide loaded with EALYLV peptides for inhibiting the aggregation of hIAPP associated with type-2 diabetes. J Mater Chem B 2015; 3:7055-7067. [PMID: 32262708 DOI: 10.1039/c5tb00487j] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Human islet amyloid polypeptide (hIAPP) was found as amyloid aggregate deposits in the pancreatic islets of patients with type-2 diabetes and studies showed that insulin and its derivatives were the potent inhibitors of hIAPP aggregation. However, several emerging therapies with this goal showed limited success due to the instability and inefficiency of insulin derivatives. Nanosized graphene oxide (nGO) possesses high stability and affinity toward aromatic rings. In this study, an insulin-derived peptide, EALYLV, was stabilized by loading on nGO@PEG to inhibit aggregation and hIAPP-induced cytotoxicity. The results showed that nGO@PEG@EALYLV (abbreviated as nGO@PEG@E) can effectively inhibit the aggregation of hIAPP via electrostatic adsorption and specific binding to the active sites of hIAPP. We further evaluated the protective effect of nGO@PEG@E on INS-1 cells in the presence of hIAPP. Treatment with nGO@PEG@E could significantly elevate the viability of INS-1 cells, decrease the level of intracellular reactive oxygen species, and stabilize mitochondrial membrane potential. All the results indicated that nGO@PEG@E could inhibit the aggregation of hIAPP, which reduces its cytotoxicity.
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Affiliation(s)
- Xianbo Zhou
- Department of Chemistry, Jinan University, Guangzhou 510632, China.
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108
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Abstract
The aggregation of human amylin has been strongly implicated in the progression of Type II diabetes. This 37-residue peptide forms a variety of secondary structures, including random coils, α-helices, and β-hairpins. The balance between these structures depends on the chemical environment, making amylin an ideal candidate to examine inherent biases in force fields. Rat amylin differs from human amylin by only 6 residues; however, it does not form fibrils. Therefore it provides a useful complement to human amylin in studies of the key events along the aggregation pathway. In this work, the free energy of rat and human amylin was determined as a function of α-helix and β-hairpin content for the Gromos96 53a6, OPLS-AA/L, CHARMM22/CMAP, CHARMM22*, Amberff99sb*-ILDN, and Amberff03w force fields using advanced sampling techniques, specifically bias exchange metadynamics. This work represents a first systematic attempt to evaluate the conformations and the corresponding free energy of a large, clinically relevant disordered peptide in solution across force fields. The NMR chemical shifts of rIAPP were calculated for each of the force fields using their respective free energy maps, allowing us to quantitatively assess their predictions. We show that the predicted distribution of secondary structures is sensitive to the choice of force-field: Gromos53a6 is biased towards β-hairpins, while CHARMM22/CMAP predicts structures that are overly α-helical. OPLS-AA/L favors disordered structures. Amberff99sb*-ILDN, AmberFF03w and CHARMM22* provide the balance between secondary structures that is most consistent with available experimental data. In contrast to previous reports, our findings suggest that the equilibrium conformations of human and rat amylin are remarkably similar, but that subtle differences arise in transient alpha-helical and beta-strand containing structures that the human peptide can more readily adopt. We hypothesize that these transient states enable dynamic pathways that facilitate the formation of aggregates and, eventually, amyloid fibrils.
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109
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Ashraf GM, Greig NH, Khan TA, Hassan I, Tabrez S, Shakil S, Sheikh IA, Zaidi SK, Akram M, Jabir NR, Firoz CK, Naeem A, Alhazza IM, Damanhouri GA, Kamal MA. Protein misfolding and aggregation in Alzheimer's disease and type 2 diabetes mellitus. CNS & NEUROLOGICAL DISORDERS-DRUG TARGETS 2015; 13:1280-93. [PMID: 25230234 DOI: 10.2174/1871527313666140917095514] [Citation(s) in RCA: 108] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2014] [Revised: 05/11/2014] [Accepted: 05/12/2014] [Indexed: 12/27/2022]
Abstract
In general, proteins can only execute their various biological functions when they are appropriately folded. Their amino acid sequence encodes the relevant information required for correct three-dimensional folding, with or without the assistance of chaperones. The challenge associated with understanding protein folding is currently one of the most important aspects of the biological sciences. Misfolded protein intermediates form large polymers of unwanted aggregates and are involved in the pathogenesis of many human diseases, including Alzheimer's disease (AD) and Type 2 diabetes mellitus (T2DM). AD is one of the most prevalent neurological disorders and has worldwide impact; whereas T2DM is considered a metabolic disease that detrementally influences numerous organs, afflicts some 8% of the adult population, and shares many risk factors with AD. Research data indicates that there is a widespread conformational change in the proteins involved in AD and T2DM that form β-sheet like motifs. Although conformation of these β-sheets is common to many functional proteins, the transition from α-helix to β-sheet is a typical characteristic of amyloid deposits. Any abnormality in this transition results in protein aggregation and generation of insoluble fibrils. The abnormal and toxic proteins can interact with other native proteins and consequently catalyze their transition into the toxic state. Both AD and T2DM are prevalent in the aged population. AD is characterized by the accumulation of amyloid-β (Aβ) in brain, while T2DM is characterized by the deposition of islet amyloid polypeptide (IAPP, also known as amylin) within beta-cells of the pancreas. T2DM increases pathological angiogenesis and immature vascularisation. This also leads to chronic cerebral hypoperfusion, which results in dysfunction and degeneration of neuroglial cells. With an abundance of common mechanisms underpinning both disorders, a significant question that can be posed is whether T2DM leads to AD in aged individuals and the associations between other protein misfolding diseases.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | - Mohammad A Kamal
- King Fahd Medical Research Center, King Abdulaziz University, P. O. Box 80216, Jeddah 21589, Kingdom of Saudi Arabia.
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110
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Do TD, Chamas A, Zheng X, Barnes A, Chang D, Veldstra T, Takhar H, Dressler N, Trapp B, Miller K, McMahon A, Meredith SC, Shea JE, Lazar Cantrell K, Bowers MT. Elucidation of the Aggregation Pathways of Helix-Turn-Helix Peptides: Stabilization at the Turn Region Is Critical for Fibril Formation. Biochemistry 2015; 54:4050-62. [PMID: 26070092 DOI: 10.1021/acs.biochem.5b00414] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Aggregation of proteins to fiberlike aggregates often involves a transformation of native monomers to β-sheet-rich oligomers. This general observation underestimates the importance of α-helical segments in the aggregation cascade. Here, using a combination of experimental techniques and accelerated molecular dynamics simulations, we investigate the aggregation of a 43-residue, apolipoprotein A-I mimetic peptide and its E21Q and D26N mutants. Our study indicates a strong propensity of helical segments not to adopt cross-β-fibrils. The helix-turn-helix monomeric conformation of the peptides is preserved in the mature fibrils. Furthermore, we reveal opposite effects of mutations on and near the turn region in the self-assembly of these peptides. We show that the E21-R24 salt bridge is a major contributor to helix-turn-helix folding, subsequently leading to abundant fibril formation. On the other hand, the K19-D26 interaction is not required to fold the native helix-turn-helix peptide. However, removal of the charged D26 residue decreases the stability of the helix-turn-helix monomer and consequently reduces the level of aggregation. Finally, we provide a more refined assembly model for the helix-turn-helix peptides from apolipoprotein A-I based on the parallel stacking of helix-turn-helix dimers.
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Affiliation(s)
| | | | | | - Aaron Barnes
- §Department of Chemistry, Westmont College, Santa Barbara, California 93108, United States
| | - Dayna Chang
- §Department of Chemistry, Westmont College, Santa Barbara, California 93108, United States
| | - Tjitske Veldstra
- §Department of Chemistry, Westmont College, Santa Barbara, California 93108, United States
| | - Harmeet Takhar
- §Department of Chemistry, Westmont College, Santa Barbara, California 93108, United States
| | - Nicolette Dressler
- §Department of Chemistry, Westmont College, Santa Barbara, California 93108, United States
| | - Benjamin Trapp
- §Department of Chemistry, Westmont College, Santa Barbara, California 93108, United States
| | - Kylie Miller
- §Department of Chemistry, Westmont College, Santa Barbara, California 93108, United States
| | - Audrene McMahon
- §Department of Chemistry, Westmont College, Santa Barbara, California 93108, United States
| | | | | | - Kristi Lazar Cantrell
- §Department of Chemistry, Westmont College, Santa Barbara, California 93108, United States
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111
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Lopes DHJ, Attar A, Nair G, Hayden EY, Du Z, McDaniel K, Dutt S, Bandmann H, Bravo-Rodriguez K, Mittal S, Klärner FG, Wang C, Sanchez-Garcia E, Schrader T, Bitan G. Molecular tweezers inhibit islet amyloid polypeptide assembly and toxicity by a new mechanism. ACS Chem Biol 2015; 10:1555-69. [PMID: 25844890 DOI: 10.1021/acschembio.5b00146] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
In type-2 diabetes (T2D), islet amyloid polypeptide (IAPP) self-associates into toxic assemblies causing islet β-cell death. Therefore, preventing IAPP toxicity is a promising therapeutic strategy for T2D. The molecular tweezer CLR01 is a supramolecular tool for selective complexation of K residues in (poly)peptides. Surprisingly, it inhibits IAPP aggregation at substoichiometric concentrations even though IAPP has only one K residue at position 1, whereas efficient inhibition of IAPP toxicity requires excess CLR01. The basis for this peculiar behavior is not clear. Here, a combination of biochemical, biophysical, spectroscopic, and computational methods reveals a detailed mechanistic picture of the unique dual inhibition mechanism for CLR01. At low concentrations, CLR01 binds to K1, presumably nucleating nonamyloidogenic, yet toxic, structures, whereas excess CLR01 binds also to R11, leading to nontoxic structures. Encouragingly, the CLR01 concentrations needed for inhibition of IAPP toxicity are safe in vivo, supporting its development toward disease-modifying therapy for T2D.
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Affiliation(s)
| | | | | | | | - Zhenming Du
- Department of Biology, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | | | - Som Dutt
- Institute of Organic Chemistry, University of Duisburg-Essen, 45141 Essen, Germany
| | - Heinz Bandmann
- Institute of Organic Chemistry, University of Duisburg-Essen, 45141 Essen, Germany
| | | | - Sumit Mittal
- Max-Planck-Institut für Kohlenforschung, 45470 Mülheim an der Ruhr, Germany
| | - Frank-Gerrit Klärner
- Institute of Organic Chemistry, University of Duisburg-Essen, 45141 Essen, Germany
| | - Chunyu Wang
- Department of Biology, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | | | - Thomas Schrader
- Institute of Organic Chemistry, University of Duisburg-Essen, 45141 Essen, Germany
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112
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Politis A, Borysik AJ. Assembling the pieces of macromolecular complexes: Hybrid structural biology approaches. Proteomics 2015; 15:2792-803. [DOI: 10.1002/pmic.201400507] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 01/26/2015] [Accepted: 02/24/2015] [Indexed: 01/14/2023]
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113
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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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114
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Guo C, Côté S, Mousseau N, Wei G. Distinct helix propensities and membrane interactions of human and rat IAPP(1-19) monomers in anionic lipid bilayers. J Phys Chem B 2015; 119:3366-76. [PMID: 25646717 DOI: 10.1021/jp5111357] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Islet amyloid polypeptide, IAPP or amylin, is a 37-residue peptide hormone coexpressed with insulin by pancreatic β-cells. The aggregation of human IAPP (hIAPP) into amyloid deposits is associated with type II diabetes. Substantial evidence suggests that the interaction of anionic membranes with hIAPP may facilitate peptide aggregation and the N-terminal 1-19 fragment (IAPP(1-19)) plays an important role in peptide-membrane interaction. As a first step to understand how structural differences between human and rat IAPP peptides in membranes may influence the later oligomerization process, we have investigated the structures and orientations of hIAPP(1-19) and the less toxic rIAPP(1-19) (i.e., the H18R mutant of hIAPP(1-19)) monomers in anionic POPG bilayers by performing replica exchange molecular dynamics (REMD) simulations. On the basis of ∼20 μs REMD simulations started from a random coil conformation of the peptide placed in water, we find that unfolded h(r)IAPP(1-19) can insert into the bilayers and the membrane-bound peptide stays mainly at the lipid head-tail interface. hIAPP(1-19) displays higher helix propensity than rIAPP(1-19), especially in the L12-L16 region. The helix is oriented parallel to the bilayer surface and buried in the membrane 0.3-0.8 nm below the phosphorus atoms, consistent with previous electron paramagnetic resonance data. The helical conformation is an amphiphilic helix with its hydrophilic and hydrophobic faces pointing, respectively, to the lipid head and tail regions. The H18R substitution enhances the electrostatic interactions of IAPP(1-19) with the membrane, while it weakens the intrapeptide interactions crucial for helix formation, thus leading to lower helix propensity of rIAPP(1-19). Implications of our simulation results on the membrane-mediated IAPP(1-19) oligomerization are discussed.
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Affiliation(s)
- Cong Guo
- State Key Laboratory of Surface Physics, Key Laboratory for Computational Physical Sciences (MOE), and Department of Physics, Fudan University , 220 Handan Road, Shanghai 200433, China
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115
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Zhao DS, Chen YX, Li YM. Rational design of an orthosteric regulator of hIAPP aggregation. Chem Commun (Camb) 2015; 51:2095-8. [DOI: 10.1039/c4cc06739h] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Compounds that can block hIAPP toxic oligomer but not fibril formation have been rationally designed based on the helix aggregation mechanism.
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Affiliation(s)
- De-Sheng Zhao
- Department of Chemistry
- Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology (Ministry of Education)
- Tsinghua University
- Beijing 10084
- P. R. China
| | - Yong-Xiang Chen
- Department of Chemistry
- Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology (Ministry of Education)
- Tsinghua University
- Beijing 10084
- P. R. China
| | - Yan-Mei Li
- Department of Chemistry
- Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology (Ministry of Education)
- Tsinghua University
- Beijing 10084
- P. R. China
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116
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Bleiholder C. A local collision probability approximation for predicting momentum transfer cross sections. Analyst 2015; 140:6804-13. [DOI: 10.1039/c5an00712g] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The local collision probability approximation (LCPA) method is introduced to compute molecular momentum transfer cross sections for comparison to ion mobility experiments.
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Affiliation(s)
- Christian Bleiholder
- Department of Chemistry and Biochemistry
- Florida State University
- Florida State University
- Tallahassee
- USA
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117
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Phillips AS, Gomes AF, Kalapothakis JMD, Gillam JE, Gasparavicius J, Gozzo FC, Kunath T, MacPhee C, Barran PE. Conformational dynamics of α-synuclein: insights from mass spectrometry. Analyst 2015; 140:3070-81. [DOI: 10.1039/c4an02306d] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Different mass spectrometry approaches are combined to investigate the conformational flexibility of α-synuclein.
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Affiliation(s)
- Ashley S. Phillips
- Manchester Institute of Biotechnology
- University of Manchester
- Manchester
- UK
| | - Alexandre F. Gomes
- Dalton Mass Spectrometry Laboratory
- University of Campinas – UNICAMP
- Brazil
| | | | - Jay E. Gillam
- School of Physics and Astronomy
- University of Edinburgh
- Edinburgh
- UK
| | | | - Fabio C. Gozzo
- Dalton Mass Spectrometry Laboratory
- University of Campinas – UNICAMP
- Brazil
| | - Tilo Kunath
- MRC Centre for Regenerative Medicine
- University of Edinburgh
- Edinburgh
- UK
| | - Cait MacPhee
- School of Physics and Astronomy
- University of Edinburgh
- Edinburgh
- UK
| | - Perdita E. Barran
- Manchester Institute of Biotechnology
- University of Manchester
- Manchester
- UK
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118
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Nguyen PT, Andraka N, De Carufel CA, Bourgault S. Mechanistic Contributions of Biological Cofactors in Islet Amyloid Polypeptide Amyloidogenesis. J Diabetes Res 2015; 2015:515307. [PMID: 26576436 PMCID: PMC4630397 DOI: 10.1155/2015/515307] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Revised: 01/26/2015] [Accepted: 02/09/2015] [Indexed: 01/24/2023] Open
Abstract
Type II diabetes mellitus is associated with the deposition of fibrillar aggregates in pancreatic islets. The major protein component of islet amyloids is the glucomodulatory hormone islet amyloid polypeptide (IAPP). Islet amyloid fibrils are virtually always associated with several biomolecules, including apolipoprotein E, metals, glycosaminoglycans, and various lipids. IAPP amyloidogenesis has been originally perceived as a self-assembly homogeneous process in which the inherent aggregation propensity of the peptide and its local concentration constitute the major driving forces to fibrillization. However, over the last two decades, numerous studies have shown a prominent role of amyloid cofactors in IAPP fibrillogenesis associated with the etiology of type II diabetes. It is increasingly evident that the biochemical microenvironment in which IAPP amyloid formation occurs and the interactions of the polypeptide with various biomolecules not only modulate the rate and extent of aggregation, but could also remodel the amyloidogenesis process as well as the structure, toxicity, and stability of the resulting fibrils.
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Affiliation(s)
- Phuong Trang Nguyen
- Department of Chemistry, Pharmaqam, University of Quebec in Montreal, Montreal, QC, Canada H3C 3P8
- Quebec Network for Research on Protein Function, Structure, and Engineering (PROTEO), Canada
| | - Nagore Andraka
- Department of Chemistry, Pharmaqam, University of Quebec in Montreal, Montreal, QC, Canada H3C 3P8
- Quebec Network for Research on Protein Function, Structure, and Engineering (PROTEO), Canada
- Biophysics Unit (CSIC, UPV/EHU) and Department of Biochemistry and Molecular Biology, Faculty of Science and Technology, University of the Basque Country, 48080 Bilbao, Spain
| | - Carole Anne De Carufel
- Department of Chemistry, Pharmaqam, University of Quebec in Montreal, Montreal, QC, Canada H3C 3P8
- Quebec Network for Research on Protein Function, Structure, and Engineering (PROTEO), Canada
| | - Steve Bourgault
- Department of Chemistry, Pharmaqam, University of Quebec in Montreal, Montreal, QC, Canada H3C 3P8
- Quebec Network for Research on Protein Function, Structure, and Engineering (PROTEO), Canada
- *Steve Bourgault:
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119
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Wei L, Jiang P, Manimekalai MSS, Hunke C, Grüber G, Pervushin K, Mu Y. Extended structure of rat islet amyloid polypeptide in solution. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 827:85-92. [PMID: 25387961 DOI: 10.1007/978-94-017-9245-5_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The process of islet amyloid polypeptide (IAPP) formation and the prefibrillar oligomers are supposed to be one of the pathogenic agents causing pancreatic β-cell dysfunction. The human IAPP (hIAPP) aggregates easily and therefore, it is difficult to characterize its structural features by standard biophysical tools. The rat version of IAPP (rIAPP) that differs by six amino acids when compared with hIAPP, is not prone to aggregation and does not form amyloid fibrils. Similar to hIAPP it also demonstrates random-coiled nature in solution. The structural propensity of rIAPP has been studied as a hIAPP mimic in recent works. However, the overall shape of it in solution still remains elusive. Using small angle X-ray scattering (SAXS) measurements combined with nuclear magnetic resonance (NMR) and molecular dynamics simulations (MD) the solution structure of rIAPP was studied. An unambiguously extended structural model with a radius of gyration of 1.83 nm was determined from SAXS data. Consistent with previous studies, an overall random-coiled feature with residual helical propensity in the N-terminus was confirmed. Combined efforts are necessary to unambiguously resolve the structural features of intrinsic disordered proteins.
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Affiliation(s)
- Lei Wei
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, Singapore
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120
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Shaykhalishahi H, Mirecka EA, Gauhar A, Grüning CSR, Willbold D, Härd T, Stoldt M, Hoyer W. A β-Hairpin-Binding Protein for Three Different Disease-Related Amyloidogenic Proteins. Chembiochem 2014; 16:411-4. [DOI: 10.1002/cbic.201402552] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2014] [Indexed: 12/12/2022]
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121
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Young LM, Saunders JC, Mahood RA, Revill CH, Foster RJ, Tu LH, Raleigh DP, Radford SE, Ashcroft AE. Screening and classifying small-molecule inhibitors of amyloid formation using ion mobility spectrometry-mass spectrometry. Nat Chem 2014; 7:73-81. [PMID: 25515893 PMCID: PMC4280571 DOI: 10.1038/nchem.2129] [Citation(s) in RCA: 223] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Accepted: 11/05/2014] [Indexed: 12/28/2022]
Abstract
The search for therapeutic agents which bind specifically to precursor protein conformations and inhibit amyloid assembly is an important challenge. Identifying such inhibitors is difficult since many protein precursors of aggregation are partially folded or intrinsically disordered, ruling out structure-based design. Furthermore, inhibitors can act by a variety of mechanisms, including specific or non-specific binding, as well as colloidal inhibition. Here we report a high throughput method based on ion mobility spectrometry-mass spectrometry (IMS-MS) that is capable of rapidly detecting small molecules that bind to amyloid precursors, identifying the interacting protein species, and defining the mode of inhibition. Using this method we have classified a variety of small molecules that are potential inhibitors of human islet amyloid polypeptide (hIAPP) aggregation or amyloid-beta 1-40 (Aβ40) aggregation as either specific, non-specific, colloidal or non-interacting. We also demonstrate the ability of IMS-MS to screen for inhibitory small molecules in a 96-well plate format and use this to discover a new inhibitor of hIAPP amyloid assembly.
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Affiliation(s)
- Lydia M Young
- Astbury Centre for Structural Molecular Biology, University of Leeds, LS2 9JT, UK.,School of Molecular and Cellular Biology, University of Leeds, LS2 9JT, UK
| | - Janet C Saunders
- Astbury Centre for Structural Molecular Biology, University of Leeds, LS2 9JT, UK.,School of Molecular and Cellular Biology, University of Leeds, LS2 9JT, UK
| | - Rachel A Mahood
- Astbury Centre for Structural Molecular Biology, University of Leeds, LS2 9JT, UK.,School of Molecular and Cellular Biology, University of Leeds, LS2 9JT, UK
| | - Charlotte H Revill
- Astbury Centre for Structural Molecular Biology, University of Leeds, LS2 9JT, UK.,School of Chemistry, University of Leeds, LS2 9JT, UK
| | - Richard J Foster
- Astbury Centre for Structural Molecular Biology, University of Leeds, LS2 9JT, UK.,School of Chemistry, University of Leeds, LS2 9JT, UK
| | - Ling-Hsien Tu
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
| | - Daniel P Raleigh
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
| | - Sheena E Radford
- Astbury Centre for Structural Molecular Biology, University of Leeds, LS2 9JT, UK.,School of Molecular and Cellular Biology, University of Leeds, LS2 9JT, UK
| | - Alison E Ashcroft
- Astbury Centre for Structural Molecular Biology, University of Leeds, LS2 9JT, UK.,School of Molecular and Cellular Biology, University of Leeds, LS2 9JT, UK
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122
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Stow SM, Goodwin CR, Kliman M, Bachmann BO, McLean JA, Lybrand TP. Distance geometry protocol to generate conformations of natural products to structurally interpret ion mobility-mass spectrometry collision cross sections. J Phys Chem B 2014; 118:13812-20. [PMID: 25360896 PMCID: PMC4259499 DOI: 10.1021/jp509398e] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
Ion mobility-mass spectrometry (IM-MS)
allows the separation of
ionized molecules based on their charge-to-surface area (IM) and mass-to-charge
ratio (MS), respectively. The IM drift time data that is obtained
is used to calculate the ion-neutral collision cross section (CCS)
of the ionized molecule with the neutral drift gas, which is directly
related to the ion conformation and hence molecular size and shape.
Studying the conformational landscape of these ionized molecules computationally
provides interpretation to delineate the potential structures that
these CCS values could represent, or conversely, structural motifs
not consistent with the IM data. A challenge in the IM-MS community
is the ability to rapidly compute conformations to interpret natural
product data, a class of molecules exhibiting a broad range of biological
activity. The diversity of biological activity is, in part, related
to the unique structural characteristics often observed for natural
products. Contemporary approaches to structurally interpret IM-MS
data for peptides and proteins typically utilize molecular dynamics
(MD) simulations to sample conformational space. However, MD calculations
are computationally expensive, they require a force field that accurately
describes the molecule of interest, and there is no simple metric
that indicates when sufficient conformational sampling has been achieved.
Distance geometry is a computationally inexpensive approach that creates
conformations based on sampling different pairwise distances between
the atoms within the molecule and therefore does not require a force
field. Progressively larger distance bounds can be used in distance
geometry calculations, providing in principle a strategy to assess
when all plausible conformations have been sampled. Our results suggest
that distance geometry is a computationally efficient and potentially
superior strategy for conformational analysis of natural products
to interpret gas-phase CCS data.
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Affiliation(s)
- Sarah M Stow
- Department of Chemistry, ‡Department of Pharmacology, §Vanderbilt Institute of Chemical Biology, ∥Vanderbilt Institute of Integrative Biosystems Research and Education, ⊥Center for Structural Biology, Vanderbilt University , Nashville, Tennessee 37235, United States
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123
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Zhang M, Zhao J, Zheng J. Molecular understanding of a potential functional link between antimicrobial and amyloid peptides. SOFT MATTER 2014; 10:7425-7451. [PMID: 25105988 DOI: 10.1039/c4sm00907j] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Antimicrobial and amyloid peptides do not share common sequences, typical secondary structures, or normal biological activity but both the classes of peptides exhibit membrane-disruption ability to induce cell toxicity. Different membrane-disruption mechanisms have been proposed for antimicrobial and amyloid peptides, individually, some of which are not exclusive to either peptide type, implying that certain common principles may govern the folding and functions of different cytolytic peptides and associated membrane disruption mechanisms. Particularly, some antimicrobial and amyloid peptides have been identified to have dual complementary amyloid and antimicrobial properties, suggesting a potential functional link between amyloid and antimicrobial peptides. Given that some similar structural and membrane-disruption characteristics exist between the two classes of peptides, this review summarizes major findings, recent advances, and future challenges related to antimicrobial and amyloid peptides and strives to illustrate the similarities, differences, and relationships in the sequences, structures, and membrane interaction modes between amyloid and antimicrobial peptides, with a special focus on direct interactions of the peptides with the membranes. We hope that this review will stimulate further research at the interface of antimicrobial and amyloid peptides - which has been studied less intensively than either type of peptides - to decipher a possible link between both amyloid pathology and antimicrobial activity, which can guide drug design and peptide engineering to influence peptide-membrane interactions important in human health and diseases.
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Affiliation(s)
- Mingzhen Zhang
- Department of Chemical and Biomolecular Engineering, The University of Akron, Akron, Ohio 44325, USA.
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124
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Susa AC, Wu C, Bernstein SL, Dupuis NF, Wang H, Raleigh DP, Shea JE, Bowers MT. Defining the molecular basis of amyloid inhibitors: human islet amyloid polypeptide-insulin interactions. J Am Chem Soc 2014; 136:12912-9. [PMID: 25144879 PMCID: PMC4183647 DOI: 10.1021/ja504031d] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Indexed: 11/28/2022]
Abstract
Human islet amyloid polypeptide (hIAPP or Amylin) is a 37 residue hormone that is cosecreted with insulin from the pancreatic islets. The aggregation of hIAPP plays a role in the progression of type 2 diabetes and contributes to the failure of islet cell grafts. Despite considerable effort, little is known about the mode of action of IAPP amyloid inhibitors, and this has limited rational drug design. Insulin is one of the most potent inhibitors of hIAPP fibril formation, but its inhibition mechanism is not understood. In this study, the aggregation of mixtures of hIAPP with insulin, as well as with the separate A and B chains of insulin, were characterized using ion mobility spectrometry-based mass spectrometry and atomic force microscopy. Insulin and the insulin B chain target the hIAPP monomer in its compact isoform and shift the equilibrium away from its extended isoform, an aggregation-prone conformation, and thus inhibit hIAPP from forming β-sheets and subsequently amyloid fibrils. All-atom molecular modeling supports these conclusions.
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Affiliation(s)
- Anna C. Susa
- Department
of Chemistry and Biochemistry, University
of California, Santa Barbara, California 93106, United States
| | - Chun Wu
- Department
of Chemistry and Biochemistry, University
of California, Santa Barbara, California 93106, United States
| | - Summer L. Bernstein
- Department
of Chemistry and Biochemistry, University
of California, Santa Barbara, California 93106, United States
| | - Nicholas F. Dupuis
- Department
of Chemistry and Biochemistry, University
of California, Santa Barbara, California 93106, United States
| | - Hui Wang
- Department
of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States
| | - Daniel P. Raleigh
- Department
of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States
| | - Joan-Emma Shea
- Department
of Chemistry and Biochemistry, University
of California, Santa Barbara, California 93106, United States
| | - Michael T. Bowers
- Department
of Chemistry and Biochemistry, University
of California, Santa Barbara, California 93106, United States
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125
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Chen SH, Chen L, Russell DH. Metal-induced conformational changes of human metallothionein-2A: a combined theoretical and experimental study of metal-free and partially metalated intermediates. J Am Chem Soc 2014; 136:9499-508. [PMID: 24918957 DOI: 10.1021/ja5047878] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Electrospray ionization ion mobility mass spectrometry (ESI IM-MS) and molecular dynamics (MD) simulations reveal new insights into metal-induced conformational changes and the mechanism for metalation of human metallothionein-2A (MT), an intrinsically disordered protein. ESI of solutions containing apoMT yields multiple charge states of apoMT; following addition of Cd(2+) to the solution, ESI yields a range of CdiMT (i = 1-7) product ions (see Chen et al. Anal. Chem. 2013, 85, 7826-33). Ion mobility arrival-time distributions (ATDs) for the CdiMT (i = 0-7) ions reveal a diverse population of ion conformations. The ion mobility data clearly show that the conformational diversity for apoMT and partially metalated ions converges toward ordered, compact conformations as the number of bound Cd(2+) ions increase. MD simulations provide additional information on conformation candidates of CdiMT (i = 0-7) that supports the convergence of distinct conformational populations upon metal binding. Integrating the IM-MS and MD data provides a global view that shows stepwise conformational transition of an ensemble as a function of metal ion bound. ApoMT is comprised of a wide range of conformational states that populate between globular-like compact and coil-rich extended conformations. During the initial stepwise metal addition (number of metal ions bound i = 1-3), the metal ions bind to different sites to yield distinct conformations, whereas for i > 4, the conformational changes appear to be domain-specific, attributed to different degrees of disorder of the β domain; the β domain becomes more ordered as additional metal ions are added, promoting convergences to the dumbbell-shaped conformation.
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Affiliation(s)
- Shu-Hua Chen
- Department of Chemistry, Texas A&M University , College Station, Texas 77843, United States
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126
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Zhang M, Hu R, Liang G, Chang Y, Sun Y, Peng Z, Zheng J. Structural and Energetic Insight into the Cross-Seeding Amyloid Assemblies of Human IAPP and Rat IAPP. J Phys Chem B 2014; 118:7026-36. [DOI: 10.1021/jp5022246] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Mingzhen Zhang
- Department
of Chemical and Biomolecular Engineering, The University of Akron, Akron, Ohio 44325, United States
| | - Rundong Hu
- Department
of Chemical and Biomolecular Engineering, The University of Akron, Akron, Ohio 44325, United States
| | - Guizhao Liang
- Key
Laboratory of Biorheological Science and Technology, Ministry of Education,
Bioengineering College, Chongqing University, Chongqing 400044, China
| | - Yung Chang
- R&D Center for Membrane Technology and Department of Chemical Engineering, Chung Yuan University, Chung Li, Taoyuan 320, Taiwan
| | - Yan Sun
- Department
of Biochemical Engineering and Key Laboratory of Systems Bioengineering
of the Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
- Collaborative
Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, China
| | - Zhenmeng Peng
- Department
of Chemical and Biomolecular Engineering, The University of Akron, Akron, Ohio 44325, United States
| | - Jie Zheng
- Department
of Chemical and Biomolecular Engineering, The University of Akron, Akron, Ohio 44325, United States
- Collaborative
Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, China
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127
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Morriss-Andrews A, Shea JE. Simulations of Protein Aggregation: Insights from Atomistic and Coarse-Grained Models. J Phys Chem Lett 2014; 5:1899-908. [PMID: 26273871 DOI: 10.1021/jz5006847] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
This Perspective highlights recent computational approaches to protein aggregation, from coarse-grained models to atomistic simulations, using the islet amyloid polypeptide (IAPP) as a case study. We review salient open questions where simulations can make an impact, discuss the successes and challenges met by simulations, and explore new directions.
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Affiliation(s)
- Alex Morriss-Andrews
- Department of Chemistry and Biochemistry and Department of Physics, University of California, Santa Barbara, California 93106-9510, United States
| | - Joan-Emma Shea
- Department of Chemistry and Biochemistry and Department of Physics, University of California, Santa Barbara, California 93106-9510, United States
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128
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Hu R, Zhang M, Patel K, Wang Q, Chang Y, Gong X, Zhang G, Zheng J. Cross-sequence interactions between human and rat islet amyloid polypeptides. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:5193-5201. [PMID: 24754490 DOI: 10.1021/la500632d] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Human islet amyloid polypeptide (hIAPP) can assemble into toxic oligomers and fibrils, which are associated with cell degeneration and the pathogenesis of type 2 diabetes. Cross-interaction of hIAPP with rat IAPP (rIAPP)--a non-amyloidogenic peptide with high sequence similarity to hIAPP--might influence the aggregation and toxicity of hIAPP. However, the exact role of rIAPP in hIAPP aggregation and toxicity still remains unclear. In this work, we investigated the effect of cross-sequence interactions between full-length hIAPP(1-37) and rIAPP(1-37) on hybrid amyloid structures, aggregation kinetics, and cell toxicity using combined computational and experimental approaches. Experimental results indicate a contrasting role of rIAPP in hIAPP aggregation, in which rIAPP initially inhibits the early aggregation and nuclei formation of hIAPP, but hIAPP seeds can also recruit both hIAPP and rIAPP to form more hybrid fibrils, thus promoting amyloid fibrillation ultimately. The coincubation of hIAPP and rIAPP also decreases cell viability, presumably due to the formation of more toxic hybrid oligomers at the prolonged lag phase. Comparative MD simulations confirm that the cross-sequence interactions between hIAPP and rIAPP stabilize β-sheet structure and thus likely promote their fibrillization. This work provides valuable insights into a critical role of cross-amyloid interactions in protein aggregation.
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Affiliation(s)
- Rundong Hu
- Department of Chemical and Biomolecular Engineering, The University of Akron , Akron, Ohio 44325, United States
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129
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Paslawski W, Mysling S, Thomsen K, Jørgensen TJD, Otzen DE. Co-existence of Two Different α-Synuclein Oligomers with Different Core Structures Determined by Hydrogen/Deuterium Exchange Mass Spectrometry. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201400491] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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130
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Paslawski W, Mysling S, Thomsen K, Jørgensen TJD, Otzen DE. Co-existence of Two Different α-Synuclein Oligomers with Different Core Structures Determined by Hydrogen/Deuterium Exchange Mass Spectrometry. Angew Chem Int Ed Engl 2014; 53:7560-3. [DOI: 10.1002/anie.201400491] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Revised: 03/06/2014] [Indexed: 12/24/2022]
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131
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Zhou M, Politis A, Davies R, Liko I, Wu KJ, Stewart AG, Stock D, Robinson CV. Ion mobility-mass spectrometry of a rotary ATPase reveals ATP-induced reduction in conformational flexibility. Nat Chem 2014; 6:208-215. [PMID: 24557135 PMCID: PMC4067995 DOI: 10.1038/nchem.1868] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Accepted: 01/08/2014] [Indexed: 12/20/2022]
Abstract
Rotary ATPases play fundamental roles in energy conversion as their catalytic rotation is associated with interdomain fluctuations and heterogeneity of conformational states. Using ion mobility mass spectrometry we compared the conformational dynamics of the intact ATPase from Thermus thermophilus with those of its membrane and soluble subcomplexes. Our results define regions with enhanced flexibility assigned to distinct subunits within the overall assembly. To provide a structural context for our experimental data we performed molecular dynamics simulations and observed conformational changes of the peripheral stalks that reflect their intrinsic flexibility. By isolating complexes at different phases of cell growth and manipulating nucleotides, metal ions and pH during isolation, we reveal differences that can be related to conformational changes in the Vo complex triggered by ATP binding. Together these results implicate nucleotides in modulating flexibility of the stator components and uncover mechanistic detail that underlies operation and regulation in the context of the holoenzyme.
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Affiliation(s)
- Min Zhou
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford OX1 3QZ, UK
| | - Argyris Politis
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford OX1 3QZ, UK
| | - Roberta Davies
- The Victor Chang Cardiac Research Institute, Darlinghurst NSW 2010, Australia
- The University of New South Wales, Sydney NSW 2052, Australia
| | - Idlir Liko
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford OX1 3QZ, UK
| | - Kuan-Jung Wu
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford OX1 3QZ, UK
| | - Alastair G Stewart
- The Victor Chang Cardiac Research Institute, Darlinghurst NSW 2010, Australia
- The University of New South Wales, Sydney NSW 2052, Australia
| | - Daniela Stock
- The Victor Chang Cardiac Research Institute, Darlinghurst NSW 2010, Australia
- The University of New South Wales, Sydney NSW 2052, Australia
| | - Carol V Robinson
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford OX1 3QZ, UK
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132
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Gill AC. β-hairpin-mediated formation of structurally distinct multimers of neurotoxic prion peptides. PLoS One 2014; 9:e87354. [PMID: 24498083 PMCID: PMC3909104 DOI: 10.1371/journal.pone.0087354] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Accepted: 12/19/2013] [Indexed: 01/09/2023] Open
Abstract
Protein misfolding disorders are associated with conformational changes in specific proteins, leading to the formation of potentially neurotoxic amyloid fibrils. During pathogenesis of prion disease, the prion protein misfolds into β-sheet rich, protease-resistant isoforms. A key, hydrophobic domain within the prion protein, comprising residues 109-122, recapitulates many properties of the full protein, such as helix-to-sheet structural transition, formation of fibrils and cytotoxicity of the misfolded isoform. Using all-atom, molecular simulations, it is demonstrated that the monomeric 109-122 peptide has a preference for α-helical conformations, but that this peptide can also form β-hairpin structures resulting from turns around specific glycine residues of the peptide. Altering a single amino acid within the 109-122 peptide (A117V, associated with familial prion disease) increases the prevalence of β-hairpin formation and these observations are replicated in a longer peptide, comprising residues 106-126. Multi-molecule simulations of aggregation yield different assemblies of peptide molecules composed of conformationally-distinct monomer units. Small molecular assemblies, consistent with oligomers, comprise peptide monomers in a β-hairpin-like conformation and in many simulations appear to exist only transiently. Conversely, larger assemblies are comprised of extended peptides in predominately antiparallel β-sheets and are stable relative to the length of the simulations. These larger assemblies are consistent with amyloid fibrils, show cross-β structure and can form through elongation of monomer units within pre-existing oligomers. In some simulations, assemblies containing both β-hairpin and linear peptides are evident. Thus, in this work oligomers are on pathway to fibril formation and a preference for β-hairpin structure should enhance oligomer formation whilst inhibiting maturation into fibrils. These simulations provide an important new atomic-level model for the formation of oligomers and fibrils of the prion protein and suggest that stabilization of β-hairpin structure may enhance cellular toxicity by altering the balance between oligomeric and fibrillar protein assemblies.
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Affiliation(s)
- Andrew C. Gill
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, Easter Bush Campus, University of Edinburgh, Roslin, Edinburgh, United Kingdom
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133
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Landreh M, Alvelius G, Johansson J, Jörnvall H. Insulin, islet amyloid polypeptide and C-peptide interactions evaluated by mass spectrometric analysis. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2014; 28:178-184. [PMID: 24338965 DOI: 10.1002/rcm.6772] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Revised: 10/13/2013] [Accepted: 10/20/2013] [Indexed: 06/03/2023]
Abstract
RATIONALE Insulin, islet amyloid polypeptide (IAPP), and the C-peptide part of proinsulin are co-secreted from the pancreatic beta cell granules. IAPP aggregation can be inhibited by insulin and insulin aggregation by C-peptide, but different binding and disaggregating interactions may apply for the peptide complexes. A more detailed knowledge of these interactions is necessary for the development strategies against diabetic complications that stem from peptide aggregations. METHODS Mass spectrometry (MS) is utilized to investigate pH-dependencies, sequence determinants and association strengths of interactions between pairs of all three peptides. Electrospray ionization (ESI)-MS was used to monitor complex formation and interaction stoichiometries at different pH values. Collision-induced dissociation (CID) was employed to probe relative association strengths and complex dissociation pathways. RESULTS IAPP, like C-peptide, removes insulin oligomers observable by ESI-MS. Both C-peptide and IAPP form stable 1:1 heterodimers with insulin. Complexes of the negatively charged C-peptide with the positively charged IAPP, on the other hand, are easily dissociated. Replacement of the conserved glutamic acid residues in C-peptide with alanine residues increases the stability, indicating that net charge alone does not predict association strength. Binding to insulin has been suggested to stabilize a helical fold in IAPP via charge and hydrophobic interactions, which is in agreement with the now observed high gas-phase stability and sensitivity to low pH. CONCLUSIONS Combined, these results suggest that the C-peptide-insulin and IAPP-insulin interactions are mediated by a defined binding site, while such a feature is not apparent in the IAPP-C-peptide association. Hence, IAPP and C-peptide are interacting in similar manners and with similar monomerizing effects on insulin, suggesting that both peptides can prevent insulin aggregation. Simultaneous interactions of all three peptides cannot be excluded but appear unlikely from the uneven pairwise binding strengths.
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Affiliation(s)
- Michael Landreh
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-171 77, Stockholm, Sweden
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134
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Young LM, Cao P, Raleigh DP, Ashcroft AE, Radford SE. Ion mobility spectrometry-mass spectrometry defines the oligomeric intermediates in amylin amyloid formation and the mode of action of inhibitors. J Am Chem Soc 2014; 136:660-70. [PMID: 24372466 PMCID: PMC3928500 DOI: 10.1021/ja406831n] [Citation(s) in RCA: 149] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Indexed: 12/31/2022]
Abstract
The molecular mechanisms by which different proteins assemble into highly ordered fibrillar deposits and cause disease remain topics of debate. Human amylin (also known as islet amyloid polypeptide/hIAPP) is found in vivo as amyloid deposits in the pancreatic islets of sufferers of type II diabetes mellitus, and its self-aggregation is thought to be a pathogenic factor in disease and to contribute to the failure of islet transplants. Here, electrospray ionization-ion mobility spectrometry-mass spectrometry (ESI-IMS-MS) has been used to monitor oligomer formation from IAPP. The detection, identification and characterization of oligomers from both human and rat amylin (rIAPP) are described. Oligomers up to and including hexamers have been detected for both peptides. From ESI-IMS-MS derived collision cross sections (CCS), these species are shown to be elongated in conformation. Collision-induced dissociation (CID-MS/MS) revealed differences in the gas-phase stability of the oligomers formed from hIAPP and rIAPP, which may contribute to their differences in amyloid propensity. Using ESI-IMS-MS, the mode of inhibition of amyloid formation from hIAPP using small molecules or co-incubation with rIAPP was also investigated. We show that the polyphenolic compounds epigallocatechin gallate (EGCG) and silibinin bind to specific conformers within a dynamic ensemble of hIAPP monomers, altering the progress of oligomerization and fibril assembly. Hetero-oligomer formation also occurs with rIAPP but leads only to inefficient inhibition. The results indicate that although different small molecules can be effective inhibitors of hIAPP self-assembly, their modes of action are distinct and can be distinguished using ESI-IMS-MS.
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Affiliation(s)
- Lydia M Young
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds , Leeds LS2 9JT, U.K
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135
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Qi R, Luo Y, Ma B, Nussinov R, Wei G. Conformational distribution and α-helix to β-sheet transition of human amylin fragment dimer. Biomacromolecules 2014; 15:122-31. [PMID: 24313776 PMCID: PMC6429924 DOI: 10.1021/bm401406e] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Experiments suggested that the fibrillation of the 11-25 fragment (hIAPP(11-25)) of human islet amyloid polypeptide (hIAPP or amylin) involves the formation of transient α-helical intermediates, followed by conversion to β-sheet-rich structure. However, atomic details of α-helical intermediates and the transition mechanism are mostly unknown. We investigated the structural properties of the monomer and dimer in atomistic detail by replica exchange molecular dynamics (REMD) simulations. Transient α-helical monomers and dimers were both observed in the REMD trajectories. Our calculated H(α) chemical shifts based on the monomer REMD run are in agreement with the solution-state NMR experimental observations. Multiple 300 ns MD simulations at 310 K show that α-helix-to-β-sheet transition follows two mechanisms: the first involved direct transition of the random coil part of the helical conformation into antiparallel β-sheet, and in the second, the α-helical conformation unfolded and converted into antiparallel β-sheet. In both mechanisms, the α-helix-to-β-sheet transition occurred via random coil, and the transition was accompanied by an increase of interpeptide contacts. In addition, our REMD simulations revealed different temperature dependencies of helical and β-structures. Comparison with experimental data suggests that the propensity for hIAPP(11-25) to form α-helices and amyloid structures is concentration- and temperature-dependent.
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Affiliation(s)
- Ruxi Qi
- State Key Laboratory of Surface Physics, Key Laboratory for Computational Physical Sciences (MOE), and Department of Physics, Fudan University , Shanghai, China
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136
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Lee SJC, Lee JW, Choi TS, Jin KS, Lee S, Ban C, Kim HI. Probing Conformational Change of Intrinsically Disordered α-Synuclein to Helical Structures by Distinctive Regional Interactions with Lipid Membranes. Anal Chem 2014; 86:1909-16. [DOI: 10.1021/ac404132g] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Shin Jung C. Lee
- Department of Chemistry, ‡Pohang Accelerator
Laboratory, §Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH), Pohang, North Gyeongsang 790-784, South Korea
| | - Jong Wha Lee
- Department of Chemistry, ‡Pohang Accelerator
Laboratory, §Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH), Pohang, North Gyeongsang 790-784, South Korea
| | - Tae Su Choi
- Department of Chemistry, ‡Pohang Accelerator
Laboratory, §Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH), Pohang, North Gyeongsang 790-784, South Korea
| | - Kyeong Sik Jin
- Department of Chemistry, ‡Pohang Accelerator
Laboratory, §Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH), Pohang, North Gyeongsang 790-784, South Korea
| | - Seonghwan Lee
- Department of Chemistry, ‡Pohang Accelerator
Laboratory, §Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH), Pohang, North Gyeongsang 790-784, South Korea
| | - Changill Ban
- Department of Chemistry, ‡Pohang Accelerator
Laboratory, §Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH), Pohang, North Gyeongsang 790-784, South Korea
| | - Hugh I. Kim
- Department of Chemistry, ‡Pohang Accelerator
Laboratory, §Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH), Pohang, North Gyeongsang 790-784, South Korea
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137
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Ruzafa D, Varela L, Azuaga AI, Conejero-Lara F, Morel B. Mapping the structure of amyloid nucleation precursors by protein engineering kinetic analysis. Phys Chem Chem Phys 2014; 16:2989-3000. [PMID: 24394436 DOI: 10.1039/c3cp54383h] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Understanding the early molecular mechanisms governing amyloid aggregation is crucial to learn how to prevent it. Here, we used a site-directed mutagenesis approach to explore the molecular mechanism of nucleation of amyloid structure in the N47A Spc-SH3 domain. The changes in the native state stability produced by a series of mutations on each structural element of the domain were uncorrelated with the changes in the aggregation rates, although the overall aggregation mechanism was not altered. Analysis of the thioflavin T initial rates based on a simple kinetic model allowed us to extract thermodynamic magnitudes of the precursor states of nucleation and map the regions of the protein participating in the structure of the amyloidogenic precursors. This structure differs from that of the folding transition state of the SH3 domains, strongly suggesting that the regions of the conformational landscape leading to amyloid formation are divergent from those leading to the native fold.
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Affiliation(s)
- David Ruzafa
- Departamento de Química Física e Instituto de Biotecnología, Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain.
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138
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Coskuner O, Wise-Scira O. Arginine and disordered amyloid-β peptide structures: molecular level insights into the toxicity in Alzheimer's disease. ACS Chem Neurosci 2013; 4:1549-58. [PMID: 24041422 DOI: 10.1021/cn4001389] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Recent studies present that the single arginine (R) residue in the sequence of Aβ42 adopts abundant β-sheet structure and forms stable salt bridges with various residues. Furthermore, experiments proposed that R stimulates the Aβ assembly and arginine (R) to alanine (A) mutation (R5A) decreases both aggregate formation tendency and the degree of its toxicity. However, the exact roles of R and R5A mutation in the structures of Aβ42 are poorly understood. Extensive molecular dynamics simulations along with thermodynamic calculations present that R5A mutation impacts the structures and free energy landscapes of the aqueous Aβ42 peptide. The β-sheet structure almost disappears in the Ala21-Ala30 region but is more abundant in parts of the central hydrophobic core and C-terminal regions of Aβ42 upon R5A mutation. More abundant α-helix is adopted in parts of the N-terminal and mid-domain regions and less prominent α-helix formation occurs in the central hydrophobic core region of Aβ42 upon R5A mutation. Interestingly, intramolecular interactions between N- and C-terminal or mid-domain regions disappear upon R5A mutation. The structures of Aβ42 are thermodynamically less stable and retain reduced compactness upon R5A mutation. R5A mutant-type structure stability increases with more prominent central hydrophobic core and mid-domain or C-terminal region interactions. Based on our results reported in this work, small organic molecules and antibodies that avoid β-sheet formation in the Ala21-Ala30 region and hinder the intramolecular interactions occurring between the N-terminal and mid-domain or C-terminal regions of Aβ42 may help to reduce Aβ42 toxicity in Alzheimer's disease.
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Affiliation(s)
- Orkid Coskuner
- Department of Chemistry and ‡Neurosciences
Institute, The University of Texas at San Antonio, One UTSA Circle, San Antonio, Texas 78249, United States
| | - Olivia Wise-Scira
- Department of Chemistry and ‡Neurosciences
Institute, The University of Texas at San Antonio, One UTSA Circle, San Antonio, Texas 78249, United States
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139
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Miller C, Zerze GH, Mittal J. Molecular simulations indicate marked differences in the structure of amylin mutants, correlated with known aggregation propensity. J Phys Chem B 2013; 117:16066-75. [PMID: 24245879 DOI: 10.1021/jp409755y] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Human islet amyloid polypeptide (hIAPP), a 37-residue protein cosecreted with insulin by β-cells in the pancreas, is known to form amyloid fibrils in type II diabetes patients. This fibril formation is also associated with β-cell death. However, rat IAPP (rIAPP) does not aggregate into fibrils, nor is it associated with β-cell toxicity. Determining solution properties of hIAPP experimentally is difficult because it aggregates quickly. Our study uses molecular dynamics simulation to explore and compare in-solution characteristics of hIAPP and rIAPP, as well as two single-point hIAPP mutants, hIAPP I26P and hIAPP S20G, which exhibit observed differences from hIAPP in aggregation propensities. We find that all four polypeptide monomers sample structured states in solution. More importantly, differences in the helicity over residues 7-16 may play an important role in early aggregation, although this region is outside of commonly assumed amyloidogenic region 20-29. The long-range contacts, though unexpected of IDPs, cause variation in sampled conformations among four polypeptides within same amino acid sequence. Our results also yield evidence that previously determined structures bound to micelles are also transiently sampled in the solution state. In particular, similarities found in region 8-17 together with the helical differences that we observe in region 7-16 lead us to suggest that the region 7-16 is potentially responsible for amyloidogenic behavior of amylin peptides. Our results also provide support for the proposed mechanism of fibril formation based on experimentally observed transient helices in amyloidogenic peptides.
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Affiliation(s)
- Cayla Miller
- Department of Chemical Engineering, Lehigh University , Bethlehem, Pennsylvania 18015, United States
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140
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Bleiholder C, Do TD, Wu C, Economou NJ, Bernstein SS, Buratto SK, Shea JE, Bowers MT. Ion mobility spectrometry reveals the mechanism of amyloid formation of Aβ(25-35) and its modulation by inhibitors at the molecular level: epigallocatechin gallate and scyllo-inositol. J Am Chem Soc 2013; 135:16926-37. [PMID: 24131107 DOI: 10.1021/ja406197f] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Amyloid cascades leading to peptide β-sheet fibrils and plaques are central to many important diseases. Recently, intermediate assemblies of these cascades were identified as the toxic agents that interact with the cellular machinery. The relationship between the transformation from natively unstructured assembly to the β-sheet oligomers to disease is important in understanding disease onset and the development of therapeutic agents. Research on this early oligomeric region has largely been unsuccessful since traditional techniques measure only ensemble average oligomer properties. Here, ion mobility methods are utilized to deduce the modulation of peptide self-assembly pathways in the amyloid-β protein fragment Aβ(25-35) by two amyloid inhibitors (epigallocatechin gallate and scyllo-inositol) that are currently in clinical trials for Alzheimer's Disease. We provide evidence that suppression of β-extended oligomers from the onset of the conversion into β-oligomer conformations is essential for effective attenuation of β-structured amyloid oligomeric species often associated with oligomer toxicity. Furthermore, we demonstrate the ease with which ion mobility spectrometry-mass spectrometry can guide the development of therapeutic agents and drug evaluation by providing molecular level insight into the amyloid formation process and its modulation by small molecule assembly modulators.
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Affiliation(s)
- Christian Bleiholder
- Department of Chemistry and Biochemistry, University of California , Santa Barbara, California 93106-9510, United States
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141
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Qiao Q, Bowman GR, Huang X. Dynamics of an intrinsically disordered protein reveal metastable conformations that potentially seed aggregation. J Am Chem Soc 2013; 135:16092-101. [PMID: 24021023 DOI: 10.1021/ja403147m] [Citation(s) in RCA: 141] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Amyloid fibril deposits of the intrinsically disordered hIAPP peptide are found in 95% of type II diabetes patients, and the aggregation of this peptide is suggested to induce apoptotic cell-death in insulin-producing β-cells. Understanding the structure and dynamics of the hIAPP monomer in solution is thus important for understanding the nucleation of aggregation and the formation of oligomers. In this study, we identify the metastable conformational states of the hIAPP monomer and the dynamics of transitioning between them using Markov state models constructed from extensive molecular dynamics simulations. We show that the overall structure of the hIAPP peptide is random coil-like and lacks a dominant folded structure. Despite this fact, our model reveals a large number of reasonably well-populated metastable conformational states (or local free energy minima) having populations of a few percent or less. The time scales for transitioning between these states range from several microseconds to milliseconds. In contrast to folded proteins, there is no kinetic hub. More strikingly, a few states contain significant amounts of β-hairpin secondary structure and extended hydrophobic surfaces that are exposed to the solvent. We propose that these states may facilitate the nucleation of hIAPP aggregation through a significant component of the conformational selection mechanism, because they may increase their populations upon aggregation by promoting hydrophobic interactions and at the same time provide a flat geometry to seed the ordered β-strand packing of the fibrils.
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Affiliation(s)
- Qin Qiao
- Bioengineering Graduate Program, Division of Biomedical Engineering, ‡Department of Chemistry, §Center of Systems Biology and Human Health, School of Science and Institute for Advance Study, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong
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142
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Palmieri LC, Melo-Ferreira B, Braga CA, Fontes GN, Mattos LJ, Lima LMT. Stepwise oligomerization of murine amylin and assembly of amyloid fibrils. Biophys Chem 2013; 180-181:135-44. [DOI: 10.1016/j.bpc.2013.07.013] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 07/26/2013] [Accepted: 07/27/2013] [Indexed: 01/15/2023]
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143
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α-helical structures drive early stages of self-assembly of amyloidogenic amyloid polypeptide aggregate formation in membranes. Sci Rep 2013; 3:2781. [PMID: 24071712 PMCID: PMC3784961 DOI: 10.1038/srep02781] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Accepted: 09/03/2013] [Indexed: 12/17/2022] Open
Abstract
The human islet amyloid polypeptide (hIAPP) is the primary component in the toxic islet amyloid deposits in type-2 diabetes. hIAPP self-assembles to aggregates that permeabilize membranes and constitutes amyloid plaques. Uncovering the mechanisms of amyloid self-assembly is the key to understanding amyloid toxicity and treatment. Although structurally similar, hIAPP's rat counterpart, the rat islet amyloid polypeptide (rIAPP), is non-toxic. It has been a puzzle why these peptides behave so differently. We combined multiscale modelling and theory to explain the drastically different dynamics of hIAPP and rIAPP: The differences stem from electrostatic dipolar interactions. hIAPP forms pentameric aggregates with the hydrophobic residues facing the membrane core and stabilizing water-conducting pores. We give predictions for pore sizes, the number of hIAPP peptides, and aggregate morphology. We show the importance of curvature-induced stress at the early stages of hIAPP assembly and the α-helical structures over β-sheets. This agrees with recent fluorescence spectroscopy experiments.
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144
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Chiu CC, Singh S, de Pablo J. Effect of proline mutations on the monomer conformations of amylin. Biophys J 2013; 105:1227-35. [PMID: 24010666 PMCID: PMC3762349 DOI: 10.1016/j.bpj.2013.07.029] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2013] [Revised: 07/11/2013] [Accepted: 07/19/2013] [Indexed: 12/11/2022] Open
Abstract
The formation of human islet amyloid polypeptide (hIAPP) is implicated in the loss of pancreatic β-cells in type II diabetes. Rat amylin, which differs from human amylin at six residues, does not lead to formation of amyloid fibrils. Pramlintide is a synthetic analog of human amylin that shares three proline substitutions with rat amylin. Pramlintide has a much smaller propensity to form amyloid aggregates and has been widely prescribed in amylin replacement treatment. It is known that the three prolines attenuate β-sheet formation. However, the detailed effects of these proline substitutions on full-length hIAPP remain poorly understood. In this work, we use molecular simulations and bias-exchange metadynamics to investigate the effect of proline substitutions on the conformation of the hIAPP monomer. Our results demonstrate that hIAPP can adopt various β-sheet conformations, some of which have been reported in experiments. The proline substitutions perturb the formation of long β-sheets and reduce their stability. More importantly, we find that all three proline substitutions of pramlintide are required to inhibit β conformations and stabilize the α-helical conformation. Fewer substitutions do not have a significant inhibiting effect.
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Affiliation(s)
- Chi-cheng Chiu
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois
- Institute for Molecular Engineering, University of Chicago, Chicago, Illinois
| | - Sadanand Singh
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin
| | - Juan J. de Pablo
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois
- Institute for Molecular Engineering, University of Chicago, Chicago, Illinois
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145
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Structural similarities and differences between amyloidogenic and non-amyloidogenic islet amyloid polypeptide (IAPP) sequences and implications for the dual physiological and pathological activities of these peptides. PLoS Comput Biol 2013; 9:e1003211. [PMID: 24009497 PMCID: PMC3757079 DOI: 10.1371/journal.pcbi.1003211] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Accepted: 07/20/2013] [Indexed: 12/22/2022] Open
Abstract
IAPP, a 37 amino-acid peptide hormone belonging to the calcitonin family, is an intrinsically disordered protein that is coexpressed and cosecreted along with insulin by pancreatic islet β-cells in response to meals. IAPP plays a physiological role in glucose regulation; however, in certain species, IAPP can aggregate and this process is linked to β-cell death and Type II Diabetes. Using replica exchange molecular dynamics with extensive sampling (16 replicas per sequence and 600 ns per replica), we investigate the structure of the monomeric state of two species of aggregating peptides (human and cat IAPP) and two species of non-aggregating peptides (pig and rat IAPP). Our simulations reveal that the pig and rat conformations are very similar, and consist of helix-coil and helix-hairpin conformations. The aggregating sequences, on the other hand, populate the same helix-coil and helix-hairpin conformations as the non-aggregating sequence, but, in addition, populate a hairpin structure. Our exhaustive simulations, coupled with available peptide-activity data, leads us to a structure-activity relationship (SAR) in which we propose that the functional role of IAPP is carried out by the helix-coil conformation, a structure common to both aggregating and non-aggregating species. The pathological role of this peptide may have multiple origins, including the interaction of the helical elements with membranes. Nonetheless, our simulations suggest that the hairpin structure, only observed in the aggregating species, might be linked to the pathological role of this peptide, either as a direct precursor to amyloid fibrils, or as part of a cylindrin type of toxic oligomer. We further propose that the helix-hairpin fold is also a possible aggregation prone conformation that would lead normally non-aggregating variants of IAPP to form fibrils under conditions where an external perturbation is applied. The SAR relationship is used to suggest the rational design of therapeutics for treating diabetes. IAPP, a 37 amino-acid peptide hormone belonging to the calcitonin family, is an intrinsically disordered peptide produced along with insulin by pancreatic islet β-cells in response to meals. In its functional form, IAPP acts as a synergic partner of insulin to reduce blood glucose. IAPP can, however, also play a pathological role, contributing to Type II diabetes (T2D). Knowledge of the structural nature of the physiological and pathological forms of IAPP will facilitate the rational design of novel drugs for therapeutic treatment of T2D. However, because IAPP does not fold to a single structure, but rather co-exists between multiple functional (and toxic) structures, it is extremely challenging for experimental methods to gain detailed structural information. Using a computational approach, we were able to obtain detailed structures of four IAPP variants and propose a novel structural hypothesis for the two opposing roles of this peptide.
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146
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Sarkar N, Dubey VK. Exploring critical determinants of protein amyloidogenesis: a review. J Pept Sci 2013; 19:529-36. [DOI: 10.1002/psc.2539] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2013] [Revised: 06/03/2013] [Accepted: 06/17/2013] [Indexed: 11/12/2022]
Affiliation(s)
- Nandini Sarkar
- Department of Biotechnology and Medical Engineering; National Institute of Technology Rourkela; Rourkela Odisha 769008 India
| | - Vikash Kumar Dubey
- Department of Biotechnology; Indian Institute of Technology Guwahati; Guwahati Assam 781039 India
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147
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Woods L, Radford S, Ashcroft A. Advances in ion mobility spectrometry-mass spectrometry reveal key insights into amyloid assembly. BIOCHIMICA ET BIOPHYSICA ACTA 2013; 1834:1257-68. [PMID: 23063533 PMCID: PMC3787735 DOI: 10.1016/j.bbapap.2012.10.002] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Revised: 09/27/2012] [Accepted: 10/02/2012] [Indexed: 10/28/2022]
Abstract
Interfacing ion mobility spectrometry to mass spectrometry (IMS-MS) has enabled mass spectrometric analyses to extend into an extra dimension, providing unrivalled separation and structural characterization of lowly populated species in heterogeneous mixtures. One biological system that has benefitted significantly from such advances is that of amyloid formation. Using IMS-MS, progress has been made into identifying transiently populated monomeric and oligomeric species for a number of different amyloid systems and has led to an enhanced understanding of the mechanism by which small molecules modulate amyloid formation. This review highlights recent advances in this field, which have been accelerated by the commercial availability of IMS-MS instruments. This article is part of a Special Issue entitled: Mass spectrometry in structural biology.
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Affiliation(s)
| | - S.E. Radford
- Astbury Centre for Structural Molecular Biology & School of Molecular and Cellular Biology, University of Leeds, LS2 9JT, UK
| | - A.E. Ashcroft
- Astbury Centre for Structural Molecular Biology & School of Molecular and Cellular Biology, University of Leeds, LS2 9JT, UK
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148
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Williams DM, Pukala TL. Novel insights into protein misfolding diseases revealed by ion mobility-mass spectrometry. MASS SPECTROMETRY REVIEWS 2013; 32:169-187. [PMID: 23345084 DOI: 10.1002/mas.21358] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2012] [Revised: 05/23/2012] [Accepted: 05/29/2012] [Indexed: 06/01/2023]
Abstract
Amyloid disorders incorporate a wide range of human diseases arising from the failure of a specific peptide or protein to adopt, or remain in, its native functional conformational state. These pathological conditions, such as Parkinson's disease, Alzheimer's disease and Huntington's disease are highly debilitating, exact enormous costs on both individuals and society, and are predicted to increase in prevalence. Consequently, they form the focus of a topical and rich area of current scientific research. A major goal in attempts to understand and treat protein misfolding diseases is to define the structures and interactions of protein species intermediate between fully folded and aggregated, and extract a description of the aggregation process. This has proven a difficult task due to the inability of traditional structural biology approaches to analyze structurally heterogeneous systems. Continued developments in instrumentation and analytical approaches have seen ion mobility-mass spectrometry (IM-MS) emerge as a complementary approach for protein structure determination, and in some cases, a structural biology tool in its own right. IM-MS is well suited to the study of protein misfolding, and has already yielded significant structural information for selected amyloidogenic systems during the aggregation process. This review describes IM-MS for protein structure investigation, and provides a summary of current research highlighting how this methodology has unequivocally and unprecedentedly provided structural and mechanistic detail pertaining to the oligomerization of a variety of disease related proteins.
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Affiliation(s)
- Danielle M Williams
- School of Chemistry and Physics, The University of Adelaide, North Terrace, Adelaide, South Australia 5005, Australia
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149
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Singh S, Chiu CC, Reddy AS, de Pablo JJ. α-helix to β-hairpin transition of human amylin monomer. J Chem Phys 2013; 138:155101. [PMID: 23614446 PMCID: PMC3643982 DOI: 10.1063/1.4798460] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Accepted: 03/13/2013] [Indexed: 12/20/2022] Open
Abstract
The human islet amylin polypeptide is produced along with insulin by pancreatic islets. Under some circumstances, amylin can aggregate to form amyloid fibrils, whose presence in pancreatic cells is a common pathological feature of Type II diabetes. A growing body of evidence indicates that small, early stage aggregates of amylin are cytotoxic. A better understanding of the early stages of the amylin aggregation process and, in particular, of the nucleation events leading to fibril growth could help identify therapeutic strategies. Recent studies have shown that, in dilute solution, human amylin can adopt an α-helical conformation, a β-hairpin conformation, or an unstructured coil conformation. While such states have comparable free energies, the β-hairpin state exhibits a large propensity towards aggregation. In this work, we present a detailed computational analysis of the folding pathways that arise between the various conformational states of human amylin in water. A free energy surface for amylin in explicit water is first constructed by resorting to advanced sampling techniques. Extensive transition path sampling simulations are then employed to identify the preferred folding mechanisms between distinct minima on that surface. Our results reveal that the α-helical conformer of amylin undergoes a transformation into the β-hairpin monomer through one of two mechanisms. In the first, misfolding begins through formation of specific contacts near the turn region, and proceeds via a zipping mechanism. In the second, misfolding occurs through an unstructured coil intermediate. The transition states for these processes are identified. Taken together, the findings presented in this work suggest that the inter-conversion of amylin between an α-helix and a β-hairpin is an activated process and could constitute the nucleation event for fibril growth.
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Affiliation(s)
- Sadanand Singh
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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150
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Cao P, Marek P, Noor H, Patsalo V, Tu LH, Wang H, Abedini A, Raleigh DP. Islet amyloid: from fundamental biophysics to mechanisms of cytotoxicity. FEBS Lett 2013; 587:1106-18. [PMID: 23380070 DOI: 10.1016/j.febslet.2013.01.046] [Citation(s) in RCA: 150] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Revised: 01/22/2013] [Accepted: 01/23/2013] [Indexed: 12/21/2022]
Abstract
Pancreatic islet amyloid is a characteristic feature of type 2 diabetes. The major protein component of islet amyloid is the polypeptide hormone known as islet amyloid polypeptide (IAPP, or amylin). IAPP is stored with insulin in the β-cell secretory granules and is released in response to the stimuli that lead to insulin secretion. IAPP is normally soluble and is natively unfolded in its monomeric state, but forms islet amyloid in type 2 diabetes. Islet amyloid is not the cause of type 2 diabetes, but it leads to β-cell dysfunction and cell death, and contributes to the failure of islet cell transplantation. The mechanism of IAPP amyloid formation is not understood and the mechanisms of cytotoxicity are not fully defined.
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Affiliation(s)
- Ping Cao
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
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