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Wang C, Zhang K, Cai B, Haller JE, Carnazza KE, Hu J, Zhao C, Tian Z, Hu X, Hall D, Qiang J, Hou S, Liu Z, Gu J, Zhang Y, Seroogy KB, Burré J, Fang Y, Liu C, Brunger AT, Li D, Diao J. VAMP2 chaperones α-synuclein in synaptic vesicle co-condensates. Nat Cell Biol 2024:10.1038/s41556-024-01456-1. [PMID: 38951706 DOI: 10.1038/s41556-024-01456-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 06/05/2024] [Indexed: 07/03/2024]
Abstract
α-Synuclein (α-Syn) aggregation is closely associated with Parkinson's disease neuropathology. Physiologically, α-Syn promotes synaptic vesicle (SV) clustering and soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex assembly. However, the underlying structural and molecular mechanisms are uncertain and it is not known whether this function affects the pathological aggregation of α-Syn. Here we show that the juxtamembrane region of vesicle-associated membrane protein 2 (VAMP2)-a component of the SNARE complex that resides on SVs-directly interacts with the carboxy-terminal region of α-Syn through charged residues to regulate α-Syn's function in clustering SVs and promoting SNARE complex assembly by inducing a multi-component condensed phase of SVs, α-Syn and other components. Moreover, VAMP2 binding protects α-Syn against forming aggregation-prone oligomers and fibrils in these condensates. Our results suggest a molecular mechanism that maintains α-Syn's function and prevents its pathological amyloid aggregation, the failure of which may lead to Parkinson's disease.
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Affiliation(s)
- Chuchu Wang
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
- University of Chinese Academy of Sciences, Beijing, China
| | - Kai Zhang
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Bin Cai
- Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Jillian E Haller
- Helen and Robert Appel Alzheimer's Disease Research Institute, Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY, USA
| | - Kathryn E Carnazza
- Helen and Robert Appel Alzheimer's Disease Research Institute, Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY, USA
| | - Jiaojiao Hu
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Chunyu Zhao
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Zhiqi Tian
- Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Xiao Hu
- Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Daniel Hall
- Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Jiali Qiang
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Shouqiao Hou
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Zhenying Liu
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Jinge Gu
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yaoyang Zhang
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
- State Key Laboratory of Chemical Biology, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
| | - Kim B Seroogy
- Department of Neurology, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Jacqueline Burré
- Helen and Robert Appel Alzheimer's Disease Research Institute, Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY, USA
| | - Yanshan Fang
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
- State Key Laboratory of Chemical Biology, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
| | - Cong Liu
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
- State Key Laboratory of Chemical Biology, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
| | - Axel T Brunger
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
| | - Dan Li
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Shanghai Jiao Tong University, Shanghai, China.
- Zhangjiang Institute for Advanced Study, Shanghai Jiao Tong University, Shanghai, China.
| | - Jiajie Diao
- Department of Cancer Biology, University of Cincinnati College of Medicine, Cincinnati, OH, USA.
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2
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Semerdzhiev SA, Segers-Nolten I, van der Schoot P, Blum C, Claessens MMAE. SARS-CoV-2 N-protein induces the formation of composite α-synuclein/N-protein fibrils that transform into a strain of α-synuclein fibrils. NANOSCALE 2023; 15:18337-18346. [PMID: 37921451 DOI: 10.1039/d3nr03556e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/04/2023]
Abstract
The presence of deposits of alpha-synuclein (αS) fibrils in the cells of the brain is a hallmark of several α-synucleinopathies, including Parkinson's disease. As most disease cases are not familial, it is likely that external factors play a role in the disease onset. One of the external factors that may influence the disease onset is viral infection. It has recently been shown in in vitro assays that in the presence of SARS-Cov-2 N-protein, αS fibril formation is faster and proceeds in an unusual two-step aggregation process. Here, we show that faster fibril formation is not due to the SARS-CoV-2 N-protein-catalysed formation of an aggregation-prone nucleus. Instead, aggregation starts with the formation of a population of mixed αS/N-protein fibrils with low affinity for αS. Mixed amyloid fibrils, composed of two different proteins, have not been observed before. After the depletion of N-protein, fibril formation comes to a halt, until a slow transformation into fibrils with characteristics of a pure αS fibril strain occurs. This transformation into a strain of αS fibrils subsequently results in a second phase of fibril growth until a new equilibrium is reached. We hypothesize that this fibril strain transformation may be of relevance in the cell-to-cell spread of the αS pathology and disease onset.
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Affiliation(s)
- Slav A Semerdzhiev
- Nanobiophysics, Faculty of Science and Technology, MESA + Institute for Nanotechnology and, Technical Medical Centre, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
| | - Ine Segers-Nolten
- Nanobiophysics, Faculty of Science and Technology, MESA + Institute for Nanotechnology and, Technical Medical Centre, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
| | - Paul van der Schoot
- Soft Matter and Biological Physics, Department of Applied Physics and Science Education, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Christian Blum
- Nanobiophysics, Faculty of Science and Technology, MESA + Institute for Nanotechnology and, Technical Medical Centre, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
| | - Mireille M A E Claessens
- Nanobiophysics, Faculty of Science and Technology, MESA + Institute for Nanotechnology and, Technical Medical Centre, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
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3
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Heesink G, Marseille MJ, Fakhree MAA, Driver MD, van Leijenhorst-Groener KA, Onck PR, Blum C, Claessens MM. Exploring Intra- and Inter-Regional Interactions in the IDP α-Synuclein Using smFRET and MD Simulations. Biomacromolecules 2023; 24:3680-3688. [PMID: 37407505 PMCID: PMC10428166 DOI: 10.1021/acs.biomac.3c00404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 06/23/2023] [Indexed: 07/07/2023]
Abstract
Theoretical concepts from polymer physics are often used to describe intrinsically disordered proteins (IDPs). However, amino acid interactions within and between regions of the protein can lead to deviations from typical polymer scaling behavior and even to short-lived secondary structures. To investigate the key interactions in the dynamic IDP α-synuclein (αS) at the amino acid level, we conducted single-molecule fluorescence resonance energy transfer (smFRET) experiments and coarse-grained molecular dynamics (CG-MD) simulations. We find excellent agreement between experiments and simulations. Our results show that a physiological salt solution is a good solvent for αS and that the protein is highly dynamic throughout its entire chain, with local intra- and inter-regional interactions leading to deviations from global scaling. Specifically, we observe expansion in the C-terminal region, compaction in the NAC region, and a slightly smaller distance between the C- and N-termini than expected. Our simulations indicate that the compaction in the NAC region results from hydrophobic aliphatic contacts, mostly between valine and alanine residues, and cation-π interactions between lysine and tyrosine. In addition, hydrogen bonds also seem to contribute to the compaction of the NAC region. The expansion of the C-terminal region is due to intraregional electrostatic repulsion and increased chain stiffness from several prolines. Overall, our study demonstrates the effectiveness of combining smFRET experiments with CG-MD simulations to investigate the key interactions in highly dynamic IDPs at the amino acid level.
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Affiliation(s)
- Gobert Heesink
- Nanobiophysics,
Faculty of Science and Technology, MESA + Institute for Nanotechnology
and Technical Medical Centre, University
of Twente, PO Box 217, 7500 AE Enschede, The Netherlands
| | - Mirjam J. Marseille
- Nanobiophysics,
Faculty of Science and Technology, MESA + Institute for Nanotechnology
and Technical Medical Centre, University
of Twente, PO Box 217, 7500 AE Enschede, The Netherlands
| | - Mohammad A. A. Fakhree
- Nanobiophysics,
Faculty of Science and Technology, MESA + Institute for Nanotechnology
and Technical Medical Centre, University
of Twente, PO Box 217, 7500 AE Enschede, The Netherlands
| | - Mark D. Driver
- Micromechanics,
Zernike Institute for Advanced Materials, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Kirsten A. van Leijenhorst-Groener
- Nanobiophysics,
Faculty of Science and Technology, MESA + Institute for Nanotechnology
and Technical Medical Centre, University
of Twente, PO Box 217, 7500 AE Enschede, The Netherlands
| | - Patrick R. Onck
- Micromechanics,
Zernike Institute for Advanced Materials, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Christian Blum
- Nanobiophysics,
Faculty of Science and Technology, MESA + Institute for Nanotechnology
and Technical Medical Centre, University
of Twente, PO Box 217, 7500 AE Enschede, The Netherlands
| | - Mireille M.A.E. Claessens
- Nanobiophysics,
Faculty of Science and Technology, MESA + Institute for Nanotechnology
and Technical Medical Centre, University
of Twente, PO Box 217, 7500 AE Enschede, The Netherlands
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4
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Vaneyck J, Yousif TA, Segers-Nolten I, Blum C, Claessens MMAE. Quantitative Seed Amplification Assay: A Proof-of-Principle Study. J Phys Chem B 2023; 127:1735-1743. [PMID: 36795058 PMCID: PMC9986870 DOI: 10.1021/acs.jpcb.2c08326] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
Amyloid fibrils of the protein α-synuclein (αS) have recently been identified as a biomarker for Parkinson's disease (PD). To detect the presence of these amyloid fibrils, seed amplification assays (SAAs) have been developed. SAAs allow for the detection of αS amyloid fibrils in biomatrices such as cerebral spinal fluid and are promising for PD diagnosis by providing a dichotomous (yes/no) response. The additional quantification of the number of αS amyloid fibrils may enable clinicians to evaluate and follow the disease progression and severity. Developing quantitative SAAs has been shown to be challenging. Here, we report on a proof-of-principle study on the quantification of αS fibrils in fibril-spiked model solutions of increasing compositional complexity including blood serum. We show that parameters derived from standard SAAs can be used for fibril quantification in these solutions. However, interactions between the monomeric αS reactant that is used for amplification and biomatrix components such as human serum albumin have to be taken into account. We demonstrate that quantification of fibrils is possible even down to the single fibril level in a model sample consisting of fibril-spiked diluted blood serum.
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Affiliation(s)
- Jonathan Vaneyck
- Nanobiophysics (NBP), Faculty of Science and Technology, MESA + Institute for Nanotechnology and Technical Medical Centre, University of Twente, PO Box 217, 7500 AE Enschede, Overijssel, The Netherlands
| | - Therese A Yousif
- Nanobiophysics (NBP), Faculty of Science and Technology, MESA + Institute for Nanotechnology and Technical Medical Centre, University of Twente, PO Box 217, 7500 AE Enschede, Overijssel, The Netherlands
| | - Ine Segers-Nolten
- Nanobiophysics (NBP), Faculty of Science and Technology, MESA + Institute for Nanotechnology and Technical Medical Centre, University of Twente, PO Box 217, 7500 AE Enschede, Overijssel, The Netherlands
| | - Christian Blum
- Nanobiophysics (NBP), Faculty of Science and Technology, MESA + Institute for Nanotechnology and Technical Medical Centre, University of Twente, PO Box 217, 7500 AE Enschede, Overijssel, The Netherlands
| | - Mireille M A E Claessens
- Nanobiophysics (NBP), Faculty of Science and Technology, MESA + Institute for Nanotechnology and Technical Medical Centre, University of Twente, PO Box 217, 7500 AE Enschede, Overijssel, The Netherlands
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5
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Sharma M, Burré J. α-Synuclein in synaptic function and dysfunction. Trends Neurosci 2023; 46:153-166. [PMID: 36567199 PMCID: PMC9877183 DOI: 10.1016/j.tins.2022.11.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 11/07/2022] [Accepted: 11/29/2022] [Indexed: 12/24/2022]
Abstract
α-Synuclein is a neuronal protein that is enriched in presynaptic terminals. Under physiological conditions, it binds to synaptic vesicle membranes and functions in neurotransmitter release, although the molecular details remain unclear, and it is controversial whether α-synuclein inhibits or facilitates neurotransmitter release. Pathologically, in synucleinopathies including Parkinson's disease (PD), α-synuclein forms aggregates that recruit monomeric α-synuclein and spread throughout the brain, which triggers neuronal dysfunction at molecular, cellular, and organ levels. Here, we present an overview of the effects of α-synuclein on SNARE-complex assembly, neurotransmitter release, and synaptic vesicle pool homeostasis, and discuss how the observed divergent effects of α-synuclein on neurotransmitter release can be reconciled. We also discuss how gain-of-function versus loss-of-function of α-synuclein may contribute to pathogenesis in synucleinopathies.
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Affiliation(s)
- Manu Sharma
- Appel Alzheimer's Disease Research Institute, Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY, USA.
| | - Jacqueline Burré
- Appel Alzheimer's Disease Research Institute, Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY, USA.
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6
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Gao V, Briano JA, Komer LE, Burré J. Functional and Pathological Effects of α-Synuclein on Synaptic SNARE Complexes. J Mol Biol 2023; 435:167714. [PMID: 35787839 PMCID: PMC10472340 DOI: 10.1016/j.jmb.2022.167714] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Revised: 06/24/2022] [Accepted: 06/27/2022] [Indexed: 02/07/2023]
Abstract
α-Synuclein is an abundant protein at the neuronal synapse that has been implicated in Parkinson's disease for over 25 years and characterizes the hallmark pathology of a group of neurodegenerative diseases now known as the synucleinopathies. Physiologically, α-synuclein exists in an equilibrium between a synaptic vesicle membrane-bound α-helical multimer and a cytosolic largely unstructured monomer. Through its membrane-bound state, α-synuclein functions in neurotransmitter release by modulating several steps in the synaptic vesicle cycle, including synaptic vesicle clustering and docking, SNARE complex assembly, and homeostasis of synaptic vesicle pools. These functions have been ascribed to α-synuclein's interactions with the synaptic vesicle SNARE protein VAMP2/synaptobrevin-2, the synaptic vesicle-attached synapsins, and the synaptic vesicle membrane itself. How α-synuclein affects these processes, and whether disease is due to loss-of-function or gain-of-toxic-function of α-synuclein remains unclear. In this review, we provide an in-depth summary of the existing literature, discuss possible reasons for the discrepancies in the field, and propose a working model that reconciles the findings in the literature.
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Affiliation(s)
- Virginia Gao
- Appel Alzheimer's Disease Research Institute & Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY, USA; Department of Neurology, New York Presbyterian/Weill Cornell Medicine, New York, NY, USA.
| | - Juan A Briano
- Appel Alzheimer's Disease Research Institute & Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY, USA
| | - Lauren E Komer
- Appel Alzheimer's Disease Research Institute & Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY, USA. https://www.twitter.com/lauren_komer
| | - Jacqueline Burré
- Appel Alzheimer's Disease Research Institute & Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY, USA.
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7
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A comprehensive mini-review on amyloidogenesis of different SARS-CoV-2 proteins and its effect on amyloid formation in various host proteins. 3 Biotech 2022; 12:322. [PMID: 36254263 PMCID: PMC9558030 DOI: 10.1007/s13205-022-03390-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2022] [Accepted: 09/30/2022] [Indexed: 11/21/2022] Open
Abstract
Amyloidogenesis is the inherent ability of proteins to change their conformation from native state to cross β-sheet rich fibrillar structures called amyloids which result in a wide range of diseases like Parkinson's disease, Alzheimer’s disease, Finnish familial amyloidosis, ATTR amyloidosis, British and Danish dementia, etc. COVID-19, on the other hand is seen to have many similarities in symptoms with other amyloidogenic diseases and the overlap of these morbidities and symptoms led to the proposition whether SARS-CoV-2 proteins are undergoing amyloidogenesis and whether it is resulting in or aggravating amyloidogenesis of any human host protein. Thus the SARS-CoV-2 proteins in infected cells, i.e., Spike (S) protein, Nucleocapsid (N) protein, and Envelope (E) protein were tested via different machinery and amyloidogenesis in them were proven. In this review, we will analyze the pathway of amyloid formation in S-protein, N-protein, E-protein along with the effect that SARS-CoV-2 is creating on various host proteins leading to the unexpected onset of many morbidities like COVID-induced Acute Respiratory Distress Syndrome (ARDS), Parkinsonism in young COVID patients, formation of fibrin microthrombi in heart, etc., and their future implications.
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8
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Semerdzhiev SA, Fakhree MAA, Segers-Nolten I, Blum C, Claessens MMAE. Interactions between SARS-CoV-2 N-Protein and α-Synuclein Accelerate Amyloid Formation. ACS Chem Neurosci 2022; 13:143-150. [PMID: 34860005 PMCID: PMC8739828 DOI: 10.1021/acschemneuro.1c00666] [Citation(s) in RCA: 78] [Impact Index Per Article: 39.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
![]()
First cases that
point at a correlation between SARS-CoV-2 infections
and the development of Parkinson’s disease (PD) have been reported.
Currently, it is unclear if there is also a direct causal link between
these diseases. To obtain first insights into a possible molecular
relation between viral infections and the aggregation of α-synuclein
protein into amyloid fibrils characteristic for PD, we investigated
the effect of the presence of SARS-CoV-2 proteins on α-synuclein
aggregation. We show, in test tube experiments, that SARS-CoV-2 spike
protein (S-protein) has no effect on α-synuclein aggregation,
while SARS-CoV-2 nucleocapsid protein (N-protein) considerably speeds
up the aggregation process. We observe the formation of multiprotein
complexes and eventually amyloid fibrils. Microinjection of N-protein
in SH-SY5Y cells disturbed the α-synuclein proteostasis and
increased cell death. Our results point toward direct interactions
between the N-protein of SARS-CoV-2 and α-synuclein as molecular
basis for the observed correlation between SARS-CoV-2 infections and
Parkinsonism.
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Affiliation(s)
- Slav A. Semerdzhiev
- Nanobiophysics, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Mohammad A. A. Fakhree
- Nanobiophysics, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Ine Segers-Nolten
- Nanobiophysics, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Christian Blum
- Nanobiophysics, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Mireille M. A. E. Claessens
- Nanobiophysics, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
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9
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Specht CG. A Quantitative Perspective of Alpha-Synuclein Dynamics - Why Numbers Matter. Front Synaptic Neurosci 2021; 13:753462. [PMID: 34744680 PMCID: PMC8569944 DOI: 10.3389/fnsyn.2021.753462] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 09/30/2021] [Indexed: 12/02/2022] Open
Abstract
The function of synapses depends on spatially and temporally controlled molecular interactions between synaptic components that can be described in terms of copy numbers, binding affinities, and diffusion properties. To understand the functional role of a given synaptic protein, it is therefore crucial to quantitatively characterise its biophysical behaviour in its native cellular environment. Single molecule localisation microscopy (SMLM) is ideally suited to obtain quantitative information about synaptic proteins on the nanometre scale. Molecule counting of recombinant proteins tagged with genetically encoded fluorophores offers a means to determine their absolute copy numbers at synapses due to the known stoichiometry of the labelling. As a consequence of its high spatial precision, SMLM also yields accurate quantitative measurements of molecule concentrations. In addition, live imaging of fluorescently tagged proteins at synapses can reveal diffusion dynamics and local binding properties of behaving proteins under normal conditions or during pathological processes. In this perspective, it is argued that the detailed structural information provided by super-resolution imaging can be harnessed to gain new quantitative information about the organisation and dynamics of synaptic components in cellula. To illustrate this point, I discuss the concentration-dependent aggregation of α-synuclein in the axon and the concomitant changes in the dynamic equilibrium of α-synuclein at synapses in quantitative terms.
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Affiliation(s)
- Christian G. Specht
- Diseases and Hormones of the Nervous System (DHNS), Inserm, Université Paris-Saclay, Paris, France
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10
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Exploiting Complex Fluorophore Interactions to Monitor Virus Capsid Disassembly. Molecules 2021; 26:molecules26195750. [PMID: 34641294 PMCID: PMC8510433 DOI: 10.3390/molecules26195750] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 09/14/2021] [Accepted: 09/16/2021] [Indexed: 02/06/2023] Open
Abstract
Supramolecular protein complexes are the corner stone of biological processes; they are essential for many biological functions. Unraveling the interactions responsible for the (dis)assembly of these complexes is required to understand nature and to exploit such systems in future applications. Virus capsids are well-defined assemblies of hundreds of proteins and form the outer shell of non-enveloped viruses. Due to their potential as a drug carriers or nano-reactors and the need for virus inactivation strategies, assessing the intactness of virus capsids is of great interest. Current methods to evaluate the (dis)assembly of these protein assemblies are experimentally demanding in terms of instrumentation, expertise and time. Here we investigate a new strategy to monitor the disassembly of fluorescently labeled virus capsids. To monitor surfactant-induced capsid disassembly, we exploit the complex photophysical interplay between multiple fluorophores conjugated to capsid proteins. The disassembly of the capsid changes the photophysical interactions between the fluorophores, and this can be spectrally monitored. The presented data show that this low complexity method can be used to study and monitor the disassembly of supramolecular protein complexes like virus capsids. However, the range of labeling densities that is suitable for this assay is surprisingly narrow.
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11
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Podder S, Ghosh A, Ghosh T. Mutations in membrane-fusion subunit of spike glycoprotein play crucial role in the recent outbreak of COVID-19. J Med Virol 2021; 93:2790-2798. [PMID: 33090493 PMCID: PMC7675664 DOI: 10.1002/jmv.26598] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 09/14/2020] [Accepted: 10/11/2020] [Indexed: 01/06/2023]
Abstract
Coronavirus disease‐2019 (COVID‐19), the ongoing pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) is a major threat to the entire human race. It is reported that SARS‐CoV‐2 seems to have relatively low pathogenicity and higher transmissibility than previously outbroke SARS‐CoV. To explore the reason of the increased transmissibility of SARS‐CoV‐2 compared with SARS‐CoV, we have performed a comparative analysis on the structural proteins (spike, envelope, membrane, and nucleoprotein) of two viruses. Our analysis revealed that extensive substitutions of hydrophobic to polar and charged amino acids in spike glycoproteins of SARS‐CoV2 creates an intrinsically disordered region (IDR) at the beginning of membrane‐fusion subunit and intrinsically disordered residues in fusion peptide. IDR provides a potential site for proteolysis by furin and enriched disordered residues facilitate prompt fusion of the SARS‐CoV2 with host membrane by recruiting molecular recognition features. Here, we have hypothesized that mutation‐driven accumulation of intrinsically disordered residues in spike glycoproteins play dual role in enhancing viral transmissibility than previous SARS‐coronavirus. These analyses may help in epidemic surveillance and preventive measures against COVID‐19. Spike glycoprotein of SARS‐CoV2 experiences higher synonymous and non‐synonymous substitution rates than other three structural (E, M, N) proteins. Extensive hydrophobic to polar and charged amino acid substitutions in S proteins during evolution from SARS‐CoV generate intrinsically disordered residues in the membrane fusion subunit (S2) of S protein. Intrinsically disordered region at the beginning of S2 offers cleavage site of furin protease and by virtue of their flexible nature, they provide sensitive site for efficient proteolysis to activate the fusion peptide. Enrichment of intrinsically disordered residues in fusion peptide prompts rapid fusion of viral envelop with host membrane by recruiting several MoRFs. Intrinsic disorderness in spike glycoproteins in SARS‐CoV2 play dual role in enhancing their transmissibility than previous SARS‐corona virus.
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Affiliation(s)
- Soumita Podder
- Department of Microbiology, Raiganj University, Uttar Dinajpur, West Bengal, India
| | - Avishek Ghosh
- Department of Microbiology, Maulana Azad College, Kolkata, West Bengal, India
| | - Tapash Ghosh
- Department of Microbiology, Raiganj University, Uttar Dinajpur, West Bengal, India.,Department of Bioinformatics, Bose Institute, Kolkata, West Bengal, India
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12
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Fakhree MAA, Konings IBM, Kole J, Cambi A, Blum C, Claessens MMAE. The Localization of Alpha-synuclein in the Endocytic Pathway. Neuroscience 2021; 457:186-195. [PMID: 33482328 DOI: 10.1016/j.neuroscience.2021.01.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 01/11/2021] [Accepted: 01/11/2021] [Indexed: 01/24/2023]
Abstract
Alpha-synuclein (αS) is an intrinsically disordered protein (IDP) that is abundantly present in the brain and is associated with Parkinson's disease (PD). In spite of its abundance and its contribution to PD pathogenesis, the exact cellular function of αS remains largely unknown. The ability of αS to remodel phospholipid model membranes combined with biochemical and cellular studies suggests that αS is involved in endocytosis. To unravel with which route(s) and stage(s) of the endocytic pathway αS is associated, we quantified the colocalization between αS and endocytic marker proteins in differentiated SH-SY5Y neuronal cells, using an object based colocalization analysis. Comparison with randomized data allowed us to discriminate between structural and coincidental colocalizations. A large fraction of the αS positive vesicles colocalizes with caveolin positive vesicles, a smaller fraction colocalizes with EEA1 and Rab7. We find no structural colocalization between αS and clathrin and Rab11 positive vesicles. We conclude that in a physiological context, αS is structurally associated with caveolin dependent membrane vesiculation and is found further along the endocytic pathway, in decreasing amounts, on early and late endosomes. Our results not only shed new light on the function of αS, they also provide a possible link between αS function and vesicle trafficking malfunction in PD.
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Affiliation(s)
- Mohammad A A Fakhree
- Nanobiophysics, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Irene B M Konings
- Nanobiophysics, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Jeroen Kole
- Nanobiophysics, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Alessandra Cambi
- Department of Cell Biology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Geert Grooteplein Zuid 26-28, 6525 GA Nijmegen, The Netherlands
| | - Christian Blum
- Nanobiophysics, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Mireille M A E Claessens
- Nanobiophysics, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
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13
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Fakhree MAA, Blum C, Claessens MMAE. Shaping membranes with disordered proteins. Arch Biochem Biophys 2019; 677:108163. [PMID: 31672499 DOI: 10.1016/j.abb.2019.108163] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 10/23/2019] [Accepted: 10/27/2019] [Indexed: 12/15/2022]
Abstract
Membrane proteins control and shape membrane trafficking processes. The role of protein structure in shaping cellular membranes is well established. However, a significant fraction of membrane proteins is disordered or contains long disordered regions. It becomes more and more clear that these disordered regions contribute to the function of membrane proteins. While the fold of a structured protein is essential for its function, being disordered seems to be a crucial feature of membrane bound intrinsically disordered proteins and protein regions. Here we outline the motifs that encode function in disordered proteins and discuss how these functional motifs enable disordered proteins to modulate membrane properties. These changes in membrane properties facilitate and regulate membrane trafficking processes which are highly abundant in eukaryotes.
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Affiliation(s)
| | - Christian Blum
- Nanobiophysics Group, University of Twente, 7522, NB, Enschede, the Netherlands
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14
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Yeboah F, Kim TE, Bill A, Dettmer U. Dynamic behaviors of α-synuclein and tau in the cellular context: New mechanistic insights and therapeutic opportunities in neurodegeneration. Neurobiol Dis 2019; 132:104543. [PMID: 31351173 DOI: 10.1016/j.nbd.2019.104543] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 07/18/2019] [Accepted: 07/22/2019] [Indexed: 10/26/2022] Open
Abstract
α-Synuclein (αS) and tau have a lot in common. Dyshomeostasis and aggregation of both proteins are central in the pathogenesis of neurodegenerative diseases: Parkinson's disease, dementia with Lewy bodies, multi-system atrophy and other 'synucleinopathies' in the case of αS; Alzheimer's disease, frontotemporal dementia, progressive supranuclear palsy and other 'tauopathies' in the case of tau. The aggregated states of αS and tau are found to be (hyper)phosphorylated, but the relevance of the phosphorylation in health or disease is not well understood. Both tau and αS are typically characterized as 'intrinsically disordered' proteins, while both engage in transient interactions with cellular components, thereby undergoing structural changes and context-specific folding. αS transiently binds to (synaptic) vesicles forming a membrane-induced amphipathic helix; tau transiently interacts with microtubules forming an 'extended structure'. The regulation and exact nature of the interactions are not fully understood. Here we review recent and previous insights into the dynamic, transient nature of αS and tau with regard to the mode of interaction with their targets, the dwell-time while bound, and the cis and trans factors underlying the frequent switching between bound and unbound states. These aspects are intimately linked to hypotheses on how subtle changes in the transient behaviors may trigger the earliest steps in the pathogenesis of the respective brain diseases. Based on a deeper understanding of transient αS and tau conformations in the cellular context, new therapeutic strategies may emerge, and it may become clearer why existing approaches have failed or how they could be optimized.
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Affiliation(s)
- Fred Yeboah
- Novartis Institute for Biomedical Research, Chemical Biology and Therapeutics, Cambridge, MA 02139, USA
| | - Tae-Eun Kim
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Anke Bill
- Novartis Institute for Biomedical Research, Chemical Biology and Therapeutics, Cambridge, MA 02139, USA.
| | - Ulf Dettmer
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA.
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15
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Chung PJ, Zhang Q, Hwang HL, Leong A, Maj P, Szczygiel R, Dufresne EM, Narayanan S, Adams EJ, Lee KYC. α-Synuclein Sterically Stabilizes Spherical Nanoparticle-Supported Lipid Bilayers. ACS APPLIED BIO MATERIALS 2019; 2:1413-1419. [DOI: 10.1021/acsabm.8b00774] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Peter J. Chung
- James Franck Institute, The University of Chicago, Chicago, Illinois 60637, United States
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
- Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, United States
| | - Qingteng Zhang
- X-ray Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Hyeondo Luke Hwang
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
| | - Alessandra Leong
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
| | - Piotr Maj
- Department of Measurement and Electronics, AGH University of Science and Technology, Kraków 30059, Poland
| | - Robert Szczygiel
- Department of Measurement and Electronics, AGH University of Science and Technology, Kraków 30059, Poland
| | - Eric M. Dufresne
- X-ray Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Suresh Narayanan
- X-ray Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Erin J. Adams
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois 60637, United States
| | - Ka Yee C. Lee
- James Franck Institute, The University of Chicago, Chicago, Illinois 60637, United States
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
- Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, United States
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16
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Fakhree MAA, Engelbertink SAJ, van Leijenhorst-Groener KA, Blum C, Claessens MMAE. Cooperation of Helix Insertion and Lateral Pressure to Remodel Membranes. Biomacromolecules 2019; 20:1217-1223. [PMID: 30653915 PMCID: PMC6581421 DOI: 10.1021/acs.biomac.8b01606] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
![]()
Nature
has developed different protein mediated mechanisms to remodel
cellular membranes. One of the proteins that is implicated in these
processes is α-synuclein (αS). Here we investigate if
besides αS’s membrane bound amphipathic helix the disordered,
solvent exposed tail of the protein contributes to membrane reshaping.
We produced αS variants with elongated or truncated disordered
solvent exposed domains. We observe a transformation of opaque multi
lamellar vesicle solutions into nonscattering solutions containing
smaller structures upon addition of all αS variants. Experimental
data combined with model calculations show that the cooperation of
helix insertion and lateral pressure exerted by the disordered domain
makes the full length protein decidedly more efficient in membrane
remodeling than the truncated version. Using disordered domains may
not only be cost-efficient, it may also add a new level of control
over vesicle fusion/fission by expansion or compaction of the domain.
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Affiliation(s)
- Mohammad A A Fakhree
- Nanobiophysics, MESA+ Institute for Nanotechnology, Faculty of Science and Technology , University of Twente , P.O. Box 217, 7500 AE Enschede , The Netherlands
| | - Sjoerd A J Engelbertink
- Nanobiophysics, MESA+ Institute for Nanotechnology, Faculty of Science and Technology , University of Twente , P.O. Box 217, 7500 AE Enschede , The Netherlands
| | - Kirsten A van Leijenhorst-Groener
- Nanobiophysics, MESA+ Institute for Nanotechnology, Faculty of Science and Technology , University of Twente , P.O. Box 217, 7500 AE Enschede , The Netherlands
| | - Christian Blum
- Nanobiophysics, MESA+ Institute for Nanotechnology, Faculty of Science and Technology , University of Twente , P.O. Box 217, 7500 AE Enschede , The Netherlands
| | - Mireille M A E Claessens
- Nanobiophysics, MESA+ Institute for Nanotechnology, Faculty of Science and Technology , University of Twente , P.O. Box 217, 7500 AE Enschede , The Netherlands
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Iyer A, Claessens MMAE. Disruptive membrane interactions of alpha-synuclein aggregates. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2018; 1867:468-482. [PMID: 30315896 DOI: 10.1016/j.bbapap.2018.10.006] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 08/14/2018] [Accepted: 10/04/2018] [Indexed: 12/17/2022]
Abstract
Alpha synuclein (αS) is a ~14 kDa intrinsically disordered protein. Decades of research have increased our knowledge on αS yet its physiological function remains largely elusive. The conversion of monomeric αS into oligomers and amyloid fibrils is believed to play a central role of the pathology of Parkinson's disease (PD). It is becoming increasingly clear that the interactions of αS with cellular membranes are important for both αS's functional and pathogenic actions. Therefore, understanding interactions of αS with membranes seems critical to uncover functional or pathological mechanisms. This review summarizes our current knowledge of how physicochemical properties of phospholipid membranes affect the binding and aggregation of αS species and gives an overview of how post-translational modifications and point mutations in αS affect phospholipid membrane binding and protein aggregation. We discuss the disruptive effects resulting from the interaction of αS aggregate species with membranes and highlight current approaches and hypotheses that seek to understand the pathogenic and/or protective role of αS in PD.
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Affiliation(s)
- Aditya Iyer
- Membrane Enzymology Group, University of Groningen, Groningen 9747 AG, The Netherlands
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18
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Choi TS, Han JY, Heo CE, Lee SW, Kim HI. Electrostatic and hydrophobic interactions of lipid-associated α-synuclein: The role of a water-limited interfaces in amyloid fibrillation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:1854-1862. [DOI: 10.1016/j.bbamem.2018.02.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 02/05/2018] [Accepted: 02/05/2018] [Indexed: 12/22/2022]
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19
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Fakhree MA, Nolten IS, Blum C, Claessens MMAE. Different Conformational Subensembles of the Intrinsically Disordered Protein α-Synuclein in Cells. J Phys Chem Lett 2018; 9:1249-1253. [PMID: 29474083 PMCID: PMC5857923 DOI: 10.1021/acs.jpclett.8b00092] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 02/23/2018] [Indexed: 05/27/2023]
Abstract
The intrinsically disordered protein α-synuclein (αS) is thought to play an important role in cellular membrane processes. Although in vitro experiments indicate that this initially disordered protein obtains structure upon membrane binding, NMR and EPR studies in cells could not single out any conformational subensemble. Here we microinjected small amounts of αS, labeled with a Förster resonance energy transfer (FRET) pair, into SH-SY5Y cells to investigate conformational changes upon membrane binding. Our FRET studies show a clear conformational difference between αS in the cytosol and when bound to small vesicles. The identification of these different conformational subensembles inside cells resolves the apparent contradiction between in vitro and in vivo experiments and shows that at least two different conformational subensembles of αS exist in cells. The existence of conformational subensembles supports the idea that αS can obtain different functions which can possibly be dynamically addressed with changing intracellular physicochemical conditions.
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20
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Chaudhary H, Subramaniam V, Claessens MMAE. Direct Visualization of Model Membrane Remodeling by α-Synuclein Fibrillization. Chemphyschem 2017; 18:1620-1626. [PMID: 28370874 PMCID: PMC5485007 DOI: 10.1002/cphc.201700050] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Indexed: 12/03/2022]
Abstract
The interaction of α‐synuclein (αS) with membranes is thought to be critical in the etiology of Parkinson's disease. Besides oligomeric αS aggregates that possibly form membrane pores, the aggregation of αS into amyloid fibrils has been reported to disrupt membranes. The mechanism by which aggregation affects the integrity of membranes is, however, unknown. Here, we show that whereas mature αS fibrils only weakly adhere to POPC/POPG giant unilamellar vesicles (GUVs), fibrillization of αS on the membrane results in large‐scale membrane remodeling. Fibrils that grow on the vesicle surface stiffen the membrane and make the initially spherical membrane become polyhedral. Additionally, membrane‐attached fibrils extract lipids. The lipid extraction and membrane remodeling of growing fibrils can consume the complete bilayer surface and results in loss of vesicle content. These observations suggest that there are several mechanisms by which growing fibrils can disrupt membrane function.
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Affiliation(s)
- Himanshu Chaudhary
- Nanobiophysics, MESA+ Institute for Nanotechnology and MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, 7500AE, Enschede, The Netherlands
| | - Vinod Subramaniam
- Vrije Universiteit Amsterdam, De Boelelaan 1104, 1081HV, Amsterdam, The Netherlands
| | - Mireille M A E Claessens
- Nanobiophysics, MESA+ Institute for Nanotechnology and MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, 7500AE, Enschede, The Netherlands
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21
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Uversky VN. Looking at the recent advances in understanding α-synuclein and its aggregation through the proteoform prism. F1000Res 2017; 6:525. [PMID: 28491292 PMCID: PMC5399969 DOI: 10.12688/f1000research.10536.1] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/13/2017] [Indexed: 12/31/2022] Open
Abstract
Despite attracting the close attention of multiple researchers for the past 25 years, α-synuclein continues to be an enigma, hiding sacred truth related to its structure, function, and dysfunction, concealing mechanisms of its pathological spread within the affected brain during disease progression, and, above all, covering up the molecular mechanisms of its multipathogenicity, i.e. the ability to be associated with the pathogenesis of various diseases. The goal of this article is to present the most recent advances in understanding of this protein and its aggregation and to show that the remarkable structural, functional, and dysfunctional multifaceted nature of α-synuclein can be understood using the proteoform concept.
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Affiliation(s)
- Vladimir N Uversky
- Department of Molecular Medicine and USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, 12901 Bruce B. Downs Blvd. MDC07, Tampa, FL, 33620, USA.,Laboratory of New Methods in Biology, Institute for Biological Instrumentation, Russian Academy of Sciences, 7 Institutskaya St., 142290 Pushchino, Moscow Region, Russian Federation.,Laboratory of Structural Dynamics, Stability and Folding Of Proteins, Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Av., 194064 St. Petersburg, Russian Federation
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22
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Abstract
Membrane fission, which facilitates compartmentalization of biological processes into discrete, membrane-bound volumes, is essential for cellular life. Proteins with specific structural features including constricting rings, helical scaffolds, and hydrophobic membrane insertions are thought to be the primary drivers of fission. In contrast, here we report a mechanism of fission that is independent of protein structure-steric pressure among membrane-bound proteins. In particular, random collisions among crowded proteins generate substantial pressure, which if unbalanced on the opposite membrane surface can dramatically increase membrane curvature, leading to fission. Using the endocytic protein epsin1 N-terminal homology domain (ENTH), previously thought to drive fission by hydrophobic insertion, our results show that membrane coverage correlates equally with fission regardless of the hydrophobicity of insertions. Specifically, combining FRET-based measurements of membrane coverage with multiple, independent measurements of membrane vesiculation revealed that fission became spontaneous as steric pressure increased. Further, fission efficiency remained equally potent when helices were replaced by synthetic membrane-binding motifs. These data challenge the view that hydrophobic insertions drive membrane fission, suggesting instead that the role of insertions is to anchor proteins strongly to membrane surfaces, amplifying steric pressure. In line with these conclusions, even green fluorescent protein (GFP) was able to drive fission efficiently when bound to the membrane at high coverage. Our conclusions are further strengthened by the finding that intrinsically disordered proteins, which have large hydrodynamic radii yet lack a defined structure, drove fission with substantially greater potency than smaller, structured proteins.
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