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Lipid bilayer disruption by oligomeric alpha-synuclein depends on bilayer charge and accessibility of the hydrophobic core. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:1271-8. [PMID: 19328772 DOI: 10.1016/j.bbamem.2009.03.010] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2008] [Revised: 02/27/2009] [Accepted: 03/13/2009] [Indexed: 11/22/2022]
Abstract
Soluble oligomeric aggregates of alpha-synuclein have been implicated to play a central role in the pathogenesis of Parkinson's disease. Disruption and permeabilization of lipid bilayers by alpha-synuclein oligomers is postulated as a toxic mechanism, but the molecular details controlling the oligomer-membrane interaction are still unknown. Here we show that membrane disruption strongly depends on the accessibility of the hydrophobic membrane core and that charge interactions play an important but complex role. We systematically studied the influence of the physical membrane properties and solution conditions on lipid bilayer disruption by oligomers using a dye release assay. Varying the lipid headgroup composition revealed that membrane disruption only occurs for negatively charged bilayers. Furthermore, the electrostatic repulsion between the negatively charged alpha-synuclein and the negative surface charge of the bilayer inhibits vesicle disruption at low ionic strength. The disruption of negatively charged vesicles further depends on lipid packing parameters. Bilayer composition changes that result in an increased lipid headgroup spacing make vesicles more prone to disruption, suggesting that the accessibility of the bilayer hydrocarbon core modulates oligomer-membrane interaction. These data shed important new insights into the driving forces governing the highly debated process of oligomer-membrane interactions.
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102
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Abstract
Interactions between the synaptic protein alpha-Synuclein and cellular membranes may be relevant both to its native function as well as its role in Parkinson's disease. We use single molecule Forster resonance energy transfer to probe the structure of alpha-Synuclein bound to detergent micelles and lipid vesicles. We find evidence that it forms a bent-helix when bound to highly curved detergent micelles, whereas it binds more physiological 100 nm diameter lipid vesicles as an elongated helix. Our results highlight the influence of membrane curvature in determining alpha-Synuclein conformation, which may be important for both its normal and disease-associated functions.
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Affiliation(s)
- Adam J. Trexler
- Department of Molecular Biophysics and Biochemistry, Yale University, P.O. Box 208114, New Haven, CT 06520
| | - Elizabeth Rhoades
- Department of Molecular Biophysics and Biochemistry, Yale University, P.O. Box 208114, New Haven, CT 06520
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103
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Pandey AP, Haque F, Rochet JC, Hovis JS. Clustering of alpha-synuclein on supported lipid bilayers: role of anionic lipid, protein, and divalent ion concentration. Biophys J 2009; 96:540-51. [PMID: 19167303 DOI: 10.1016/j.bpj.2008.10.011] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2008] [Accepted: 10/09/2008] [Indexed: 10/21/2022] Open
Abstract
Alpha-synuclein is the major component of Lewy body inclusions found in the brains of patients with Parkinson's disease. Several studies indicate that alpha-synuclein binds to negatively charged phospholipid bilayers. We examined the binding of alpha-synuclein to membranes containing different amounts of negatively charged lipids using supported lipid bilayers, epifluorescence microscopy, fluorescence recovery after photobleaching, and bulk fluorescence techniques. The membranes contained phosphatidylcholine and phosphatidylglycerol. In the absence of protein, these lipids mix uniformly. Our results show that the propensity of alpha-synuclein to cluster on the membrane increases as the concentration of anionic lipid and/or protein increases. Regions on the lipid bilayer where alpha-synuclein is clustered are enriched in phosphatidylglycerol. We also observe divalent metal ions stimulate protein cluster formation, primarily by promoting lipid demixing. The importance of protein structure, lipid demixing, and divalent ions, as well as the physiological implications, will be discussed. Because membrane-bound alpha-synuclein assemblies may play a role in neurotoxicity, it is of interest to determine how membranes can be used to tune the propensity of alpha-synuclein to aggregate.
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Affiliation(s)
- Anjan P Pandey
- Department of Chemistry, Purdue University, West Lafayette, Indiana, USA
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104
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Rochet JC, Liu F. Inhibition of α-Synuclein Aggregation by Antioxidants and Chaperones in Parkinson’s Disease. PROTEIN FOLDING AND MISFOLDING: NEURODEGENERATIVE DISEASES 2008. [DOI: 10.1007/978-1-4020-9434-7_8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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105
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Dunker AK, Silman I, Uversky VN, Sussman JL. Function and structure of inherently disordered proteins. Curr Opin Struct Biol 2008; 18:756-64. [PMID: 18952168 DOI: 10.1016/j.sbi.2008.10.002] [Citation(s) in RCA: 733] [Impact Index Per Article: 45.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2008] [Accepted: 10/14/2008] [Indexed: 12/15/2022]
Abstract
The application of bioinformatics methodologies to proteins inherently lacking 3D structure has brought increased attention to these macromolecules. Here topics concerning these proteins are discussed, including their prediction from amino acid sequence, their enrichment in eukaryotes compared to prokaryotes, their more rapid evolution compared to structured proteins, their organization into specific groups, their structural preferences, their half-lives in cells, their contributions to signaling diversity (via high contents of multiple-partner binding sites, post-translational modifications, and alternative splicing), their distinct functional repertoire compared to that of structured proteins, and their involvement in diseases.
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Affiliation(s)
- A Keith Dunker
- Center for Computational Biology and Bioinformatics, Institute for Intrinsically Disordered Protein Research, Indiana University Schools of Medicine and Informatics, Indianapolis, IN 46202, USA
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106
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Bisaglia M, Mammi S, Bubacco L. Structural insights on physiological functions and pathological effects of alpha-synuclein. FASEB J 2008; 23:329-40. [PMID: 18948383 DOI: 10.1096/fj.08-119784] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Alpha-synuclein is an intrinsically unfolded protein that can adopt a partially helical structure when it interacts with different lipid membranes. Its pathological relevance is linked to its involvement in several neurodegenerative disorders including Parkinson's disease, Alzheimer's disease, and dementia with Lewy bodies. Typical of such ailments is the presence of alpha-synuclein aggregates in a beta-structure that can be soluble or precipitate. This review focuses on the structural knowledge acquired in recent years on the various conformations accessible to alpha-synuclein and to its pathologically relevant mutants. Furthermore, the role of the different variables of the chemical environments that govern the equilibria among the accessible conformations is also reviewed. The hypotheses that rationalize the relevance of the individual structural features and conformations for the physiological function of the protein or for its purported pathological role are described and compared.
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Affiliation(s)
- Marco Bisaglia
- Department of Biology, University of Padova, Via U. Bassi 58B, 35121, Padova, Italy
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107
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Waxman EA, Giasson BI. Molecular mechanisms of alpha-synuclein neurodegeneration. Biochim Biophys Acta Mol Basis Dis 2008; 1792:616-24. [PMID: 18955133 DOI: 10.1016/j.bbadis.2008.09.013] [Citation(s) in RCA: 146] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2008] [Revised: 09/18/2008] [Accepted: 09/24/2008] [Indexed: 12/31/2022]
Abstract
alpha-Synuclein is an abundant highly charged protein that is normally predominantly localized around synaptic vesicles in presynaptic terminals. Although the function of this protein is still ill-defined, genetic studies have demonstrated that point mutations or genetic alteration (duplications or triplications) that increase the number of copies of the alpha-synuclein (SCNA) gene can cause Parkinson's disease or the related disorder dementia with Lewy bodies. alpha-Synuclein can aberrantly polymerize into fibrils with typical amyloid properties, and these fibrils are the major component of many types of pathological inclusions, including Lewy bodies, which are associated with neurodegenerative diseases, such as Parkinson's disease. Although there is substantial evidence supporting the toxic nature of alpha-synuclein inclusions, other modes of toxicity such as oligomers have been proposed. In this review, some of the evidence for the different mechanisms of alpha-synuclein toxicity is presented and discussed.
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Affiliation(s)
- Elisa A Waxman
- Department of Pharmacology, University of Pennsylvania School of Medicine, 125 John Morgan Building, Philadelphia, PA 19104-6084, USA
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108
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Perevoshchikova I, Zorov D, Antonenko Y. Peak intensity analysis as a method for estimation of fluorescent probe binding to artificial and natural nanoparticles: Tetramethylrhodamine uptake by isolated mitochondria. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1778:2182-90. [DOI: 10.1016/j.bbamem.2008.04.008] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2007] [Revised: 04/22/2008] [Accepted: 04/23/2008] [Indexed: 10/22/2022]
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109
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Tsigelny IF, Crews L, Desplats P, Shaked GM, Sharikov Y, Mizuno H, Spencer B, Rockenstein E, Trejo M, Platoshyn O, Yuan JXJ, Masliah E. Mechanisms of hybrid oligomer formation in the pathogenesis of combined Alzheimer's and Parkinson's diseases. PLoS One 2008; 3:e3135. [PMID: 18769546 PMCID: PMC2519786 DOI: 10.1371/journal.pone.0003135] [Citation(s) in RCA: 223] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2008] [Accepted: 08/08/2008] [Indexed: 11/29/2022] Open
Abstract
Background Misfolding and pathological aggregation of neuronal proteins has been proposed to play a critical role in the pathogenesis of neurodegenerative disorders. Alzheimer's disease (AD) and Parkinson's disease (PD) are frequent neurodegenerative diseases of the aging population. While progressive accumulation of amyloid β protein (Aβ) oligomers has been identified as one of the central toxic events in AD, accumulation of α-synuclein (α-syn) resulting in the formation of oligomers and protofibrils has been linked to PD and Lewy body Disease (LBD). We have recently shown that Aβ promotes α-syn aggregation and toxic conversion in vivo, suggesting that abnormal interactions between misfolded proteins might contribute to disease pathogenesis. However the molecular characteristics and consequences of these interactions are not completely clear. Methodology/Principal Findings In order to understand the molecular mechanisms involved in potential Aβ/α-syn interactions, immunoblot, molecular modeling, and in vitro studies with α-syn and Aβ were performed. We showed in vivo in the brains of patients with AD/PD and in transgenic mice, Aβ and α-synuclein co-immunoprecipitate and form complexes. Molecular modeling and simulations showed that Aβ binds α-syn monomers, homodimers, and trimers, forming hybrid ring-like pentamers. Interactions occurred between the N-terminus of Aβ and the N-terminus and C-terminus of α-syn. Interacting α-syn and Aβ dimers that dock on the membrane incorporated additional α-syn molecules, leading to the formation of more stable pentamers and hexamers that adopt a ring-like structure. Consistent with the simulations, under in vitro cell-free conditions, Aβ interacted with α-syn, forming hybrid pore-like oligomers. Moreover, cells expressing α-syn and treated with Aβ displayed increased current amplitudes and calcium influx consistent with the formation of cation channels. Conclusion/Significance These results support the contention that Aβ directly interacts with α-syn and stabilized the formation of hybrid nanopores that alter neuronal activity and might contribute to the mechanisms of neurodegeneration in AD and PD. The broader implications of such hybrid interactions might be important to the pathogenesis of other disorders of protein misfolding.
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Affiliation(s)
- Igor F. Tsigelny
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California, United States of America
- San Diego Super Computer Center, University of California San Diego, La Jolla, California, United States of America
| | - Leslie Crews
- Department of Pathology, University of California San Diego, La Jolla, California, United States of America
| | - Paula Desplats
- Department of Neurosciences, University of California San Diego, La Jolla, California, United States of America
| | - Gideon M. Shaked
- Department of Neurosciences, University of California San Diego, La Jolla, California, United States of America
| | - Yuriy Sharikov
- San Diego Super Computer Center, University of California San Diego, La Jolla, California, United States of America
| | - Hideya Mizuno
- Department of Neurosciences, University of California San Diego, La Jolla, California, United States of America
| | - Brian Spencer
- Department of Neurosciences, University of California San Diego, La Jolla, California, United States of America
| | - Edward Rockenstein
- Department of Neurosciences, University of California San Diego, La Jolla, California, United States of America
| | - Margarita Trejo
- Department of Neurosciences, University of California San Diego, La Jolla, California, United States of America
| | - Oleksandr Platoshyn
- Department of Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Jason X.-J. Yuan
- Department of Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Eliezer Masliah
- Department of Neurosciences, University of California San Diego, La Jolla, California, United States of America
- Department of Pathology, University of California San Diego, La Jolla, California, United States of America
- * E-mail:
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