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Díaz-Salinas MA, Jain A, Durham ND, Munro JB. Single-molecule imaging reveals allosteric stimulation of SARS-CoV-2 spike receptor binding domain by host sialic acid. SCIENCE ADVANCES 2024; 10:eadk4920. [PMID: 39018397 PMCID: PMC466946 DOI: 10.1126/sciadv.adk4920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Accepted: 06/13/2024] [Indexed: 07/19/2024]
Abstract
Conformational dynamics of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike glycoprotein (S) mediate exposure of the binding site for the cellular receptor, angiotensin-converting enzyme 2 (ACE2). The N-terminal domain (NTD) of S binds terminal sialic acid (SA) moieties on the cell surface, but the functional role of this interaction in virus entry is unknown. Here, we report that NTD-SA interaction enhances both S-mediated virus attachment and ACE2 binding. Through single-molecule Förster resonance energy transfer imaging of individual S trimers, we demonstrate that SA binding to the NTD allosterically shifts the S conformational equilibrium, favoring enhanced exposure of the ACE2-binding site. Antibodies that target the NTD block SA binding, which contributes to their mechanism of neutralization. These findings inform on mechanisms of S activation at the cell surface.
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Affiliation(s)
- Marco A. Díaz-Salinas
- Department of Microbiology and Physiological Systems, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
| | - Aastha Jain
- Department of Microbiology and Physiological Systems, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
| | - Natasha D. Durham
- Department of Microbiology and Physiological Systems, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
| | - James B. Munro
- Department of Microbiology and Physiological Systems, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
- Department of Biochemistry and Molecular Biotechnology, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
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Vorobyov V, Deev A, Chaprov K, Ninkina N. Disruption of Electroencephalogram Coherence between Cortex/Striatum and Midbrain Dopaminergic Regions in the Knock-Out Mice with Combined Loss of Alpha, Beta, and Gamma Synucleins. Biomedicines 2024; 12:881. [PMID: 38672235 PMCID: PMC11048202 DOI: 10.3390/biomedicines12040881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 03/10/2024] [Accepted: 04/10/2024] [Indexed: 04/28/2024] Open
Abstract
The malfunctioning of the brain synucleins is associated with pathogenesis of Parkinson's disease. Synucleins' ability to modulate various pre-synaptic processes suggests their modifying effects on the electroencephalogram (EEG) recorded from different brain structures. Disturbances in interrelations between them are critical for the onset and evolution of neurodegenerative diseases. Recently, we have shown that, in mice lacking several synucleins, differences between the frequency spectra of EEG from different brain structures are correlated with specificity of synucleins' combinations. Given that EEG spectra are indirect characteristics of inter-structural relations, in this study, we analyzed a coherence of instantaneous values for EEGs recorded from different structures as a direct measure of "functional connectivity" between them. METHODS EEG data from seven groups of knock-out (KO) mice with combined deletions of alpha, beta, and gamma synucleins versus a group of wild-type (WT) mice were compared. EEG coherence was estimated between the cortex (MC), putamen (Pt), ventral tegmental area (VTA), and substantia nigra (SN) in all combinations. RESULTS EEG coherence suppression, predominantly in the beta frequency band, was observed in KO mice versus WT littermates. The suppression was minimal in MC-Pt and VTA-SN interrelations in all KO groups and in all inter-structural relations in mice lacking either all synucleins or only beta synuclein. In other combinations of deleted synucleins, significant EEG coherence suppression in KO mice was dominant in relations with VTA and SN. CONCLUSION Deletions of the synucleins produced significant attenuation of intra-cerebral EEG coherence depending on the imbalance of different types of synucleins.
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Affiliation(s)
- Vasily Vorobyov
- Institute of Cell Biophysics, Russian Academy of Sciences, 142290 Pushchino, Russia;
| | - Alexander Deev
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, 142290 Pushchino, Russia;
| | - Kirill Chaprov
- Institute of Physiologically Active Compounds at Federal Research Center of Problems of Chemical Physics and Medicinal Chemistry, Russian Academy of Sciences, 142432 Chernogolovka, Russia;
- School of Biosciences, Cardiff University, Sir Martin Evans Building, Museum Avenue, Cardiff CF10 3AX, UK
| | - Natalia Ninkina
- Institute of Physiologically Active Compounds at Federal Research Center of Problems of Chemical Physics and Medicinal Chemistry, Russian Academy of Sciences, 142432 Chernogolovka, Russia;
- School of Biosciences, Cardiff University, Sir Martin Evans Building, Museum Avenue, Cardiff CF10 3AX, UK
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3
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Jain A, Govindan R, Berkman AR, Luban J, Díaz-Salinas MA, Durham ND, Munro JB. Regulation of Ebola GP conformation and membrane binding by the chemical environment of the late endosome. PLoS Pathog 2023; 19:e1011848. [PMID: 38055723 PMCID: PMC10727438 DOI: 10.1371/journal.ppat.1011848] [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: 10/17/2023] [Revised: 12/18/2023] [Accepted: 11/20/2023] [Indexed: 12/08/2023] Open
Abstract
Interaction between the Ebola virus envelope glycoprotein (GP) and the endosomal membrane is an essential step during virus entry into the cell. Acidic pH and Ca2+ have been implicated in mediating the GP-membrane interaction. However, the molecular mechanism by which these environmental factors regulate the conformational changes that enable engagement of GP with the target membrane is unknown. Here, we apply fluorescence correlation spectroscopy (FCS) and single-molecule Förster resonance energy transfer (smFRET) imaging to elucidate how the acidic pH, Ca2+ and anionic phospholipids in the late endosome promote GP-membrane interaction, thereby facilitating virus entry. We find that bis(monoacylglycero)phosphate (BMP), which is specific to the late endosome, is especially critical in determining the Ca2+-dependence of the GP-membrane interaction. Molecular dynamics (MD) simulations suggested residues in GP that sense pH and induce conformational changes that make the fusion loop available for insertion into the membrane. We similarly confirm residues in the fusion loop that mediate GP's interaction with Ca2+, which likely promotes local conformational changes in the fusion loop and mediates electrostatic interactions with the anionic phospholipids. Collectively, our results provide a mechanistic understanding of how the environment of the late endosome regulates the timing and efficiency of virus entry.
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Affiliation(s)
- Aastha Jain
- Department of Microbiology and Physiological Systems, UMass Chan Medical School, Worcester, Massachusetts, United States of America
| | - Ramesh Govindan
- Department of Microbiology and Physiological Systems, UMass Chan Medical School, Worcester, Massachusetts, United States of America
- Medical Scientist Training Program, Tufts University School of Medicine, Boston, Massachusetts, United States of America
| | - Alex R. Berkman
- Department of Microbiology and Physiological Systems, UMass Chan Medical School, Worcester, Massachusetts, United States of America
| | - Jeremy Luban
- Program in Molecular Medicine, UMass Chan Medical School, Worcester, Massachusetts, United States of America
- Department of Biochemistry and Molecular Biotechnology, UMass Chan Medical School, Worcester, Massachusetts, United States of America
| | - Marco A. Díaz-Salinas
- Department of Microbiology and Physiological Systems, UMass Chan Medical School, Worcester, Massachusetts, United States of America
| | - Natasha D. Durham
- Department of Microbiology and Physiological Systems, UMass Chan Medical School, Worcester, Massachusetts, United States of America
| | - James B. Munro
- Department of Microbiology and Physiological Systems, UMass Chan Medical School, Worcester, Massachusetts, United States of America
- Department of Biochemistry and Molecular Biotechnology, UMass Chan Medical School, Worcester, Massachusetts, United States of America
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4
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Jain A, Govindan R, Berkman A, Luban J, Durham ND, Munro J. Regulation of Ebola GP conformation and membrane binding by the chemical environment of the late endosome. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.18.524651. [PMID: 36711925 PMCID: PMC9882366 DOI: 10.1101/2023.01.18.524651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Interaction between the Ebola virus envelope glycoprotein (GP) and the endosomal membrane is an essential step during virus entry into the cell. Acidic pH and Ca2+ have been implicated in mediating the GP-membrane interaction. However, the molecular mechanism by which these environmental factors regulate the conformational changes that enable engagement of GP with the target membrane is unknown. Here, we apply fluorescence correlation spectroscopy (FCS) and single-molecule Forster resonance energy transfer (smFRET) imaging to elucidate how the acidic pH, Ca2+ and anionic phospholipids in the late endosome promote GP-membrane interaction, thereby facilitating virus entry. We find that bis(monoacylglycero)phosphate (BMP), which is specific to the late endosome, is especially critical in determining the Ca2+-dependence of the GP-membrane interaction. Molecular dynamics (MD) simulations suggested residues in GP that sense pH and induce conformational changes that make the fusion loop available for insertion into the membrane. We similarly confirm residues in the fusion loop that mediate GPs interaction with Ca2+, which likely promotes local conformational changes in the fusion loop and mediates electrostatic interactions with the anionic phospholipids. Collectively, our results provide a mechanistic understanding of how the environment of the late endosome regulates the timing and efficiency of virus entry.
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5
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Loss of the Synuclein Family Members Differentially Affects Baseline- and Apomorphine-Associated EEG Determinants in Single-, Double- and Triple-Knockout Mice. Biomedicines 2022; 10:biomedicines10123128. [PMID: 36551884 PMCID: PMC9775760 DOI: 10.3390/biomedicines10123128] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 11/14/2022] [Accepted: 11/24/2022] [Indexed: 12/12/2022] Open
Abstract
Synucleins comprise a family of small proteins highly expressed in the nervous system of vertebrates and involved in various intraneuronal processes. The malfunction of alpha-synuclein is one of the key events in pathogenesis of Parkinson disease and certain other neurodegenerative diseases, and there is a growing body of evidence that malfunction of other two synucleins might be involved in pathological processes in the nervous system. The modulation of various presynaptic mechanisms of neurotransmission is an important function of synucleins, and therefore, it is feasible that their deficiency might affect global electrical activity detected of the brain. However, the effects of the loss of synucleins on the frequency spectra of electroencephalograms (EEGs) have not been systematically studied so far. In the current study, we assessed changes in such spectra in single-, double- and triple-knockout mice lacking alpha-, beta- and gamma-synucleins in all possible combinations. EEGs were recorded from the motor cortex, the putamen, the ventral tegmental area and the substantia nigra of 78 3-month-old male mice from seven knockout groups maintained on the C57BL/6J genetic background, and 10 wild-type C57BL/6J mice for 30 min before and for 60 min after the systemic injection of a DA receptor agonist, apomorphine (APO). We found that almost any variant of synuclein deficiency causes multiple changes in both basal and APO-induced EEG oscillation profiles. Therefore, it is not the absence of any particular synuclein but rather a disbalance of synucleins that causes widespread changes in EEG spectral profiles.
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Carnazza KE, Komer LE, Xie YX, Pineda A, Briano JA, Gao V, Na Y, Ramlall T, Buchman VL, Eliezer D, Sharma M, Burré J. Synaptic vesicle binding of α-synuclein is modulated by β- and γ-synucleins. Cell Rep 2022; 39:110675. [PMID: 35417693 PMCID: PMC9116446 DOI: 10.1016/j.celrep.2022.110675] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Revised: 01/23/2022] [Accepted: 03/22/2022] [Indexed: 12/16/2022] Open
Abstract
α-synuclein, β-synuclein, and γ-synuclein are abundantly expressed proteins in the vertebrate nervous system. α-synuclein functions in neurotransmitter release by binding to and clustering synaptic vesicles and chaperoning SNARE-complex assembly. Pathologically, aggregates originating from soluble pools of α-synuclein are deposited into Lewy bodies in Parkinson's disease and related synucleinopathies. The functions of β-synuclein and γ-synuclein in presynaptic terminals remain poorly studied. Using in vitro liposome binding studies, circular dichroism spectroscopy, immunoprecipitation, and fluorescence resonance energy transfer (FRET) experiments on isolated synaptic vesicles in combination with subcellular fractionation of brains from synuclein mouse models, we show that β-synuclein and γ-synuclein have a reduced affinity toward synaptic vesicles compared with α-synuclein, and that heteromerization of β-synuclein or γ-synuclein with α-synuclein results in reduced synaptic vesicle binding of α-synuclein in a concentration-dependent manner. Our data suggest that β-synuclein and γ-synuclein are modulators of synaptic vesicle binding of α-synuclein and thereby reduce α-synuclein's physiological activity at the neuronal synapse.
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Affiliation(s)
- Kathryn E Carnazza
- Helen and Robert Appel Alzheimer's Disease Research Institute, Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10021, USA
| | - Lauren E Komer
- Helen and Robert Appel Alzheimer's Disease Research Institute, Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10021, USA
| | - Ying Xue Xie
- Helen and Robert Appel Alzheimer's Disease Research Institute, Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10021, USA
| | - André Pineda
- Helen and Robert Appel Alzheimer's Disease Research Institute, Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10021, USA
| | - Juan Antonio Briano
- Helen and Robert Appel Alzheimer's Disease Research Institute, Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10021, USA
| | - Virginia Gao
- Helen and Robert Appel Alzheimer's Disease Research Institute, Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10021, USA
| | - Yoonmi Na
- Helen and Robert Appel Alzheimer's Disease Research Institute, Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10021, USA
| | - Trudy Ramlall
- Department of Biochemistry, Weill Cornell Medicine, New York, NY 10021, USA
| | - Vladimir L Buchman
- School of Biosciences, Cardiff University, Cardiff CF103AX, UK; Belgorod State National Research University, 85 Pobedy Street, Belgorod, Belgorod 308015, Russian Federation
| | - David Eliezer
- Department of Biochemistry, Weill Cornell Medicine, New York, NY 10021, USA
| | - Manu Sharma
- Helen and Robert Appel Alzheimer's Disease Research Institute, Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10021, USA
| | - Jacqueline Burré
- Helen and Robert Appel Alzheimer's Disease Research Institute, Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY 10021, USA.
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Diaz-Salinas MA, Li Q, Ejemel M, Yurkovetskiy L, Luban J, Shen K, Wang Y, Munro JB. Conformational dynamics and allosteric modulation of the SARS-CoV-2 spike. eLife 2022; 11:75433. [PMID: 35323111 PMCID: PMC8963877 DOI: 10.7554/elife.75433] [Citation(s) in RCA: 46] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 03/17/2022] [Indexed: 11/13/2022] Open
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infects cells through binding to angiotensin-converting enzyme 2 (ACE2). This interaction is mediated by the receptor-binding domain (RBD) of the viral spike (S) glycoprotein. Structural and dynamic data have shown that S can adopt multiple conformations, which controls the exposure of the ACE2-binding site in the RBD. Here, using single-molecule Förster resonance energy transfer (smFRET) imaging, we report the effects of ACE2 and antibody binding on the conformational dynamics of S from the Wuhan-1 strain and in the presence of the D614G mutation. We find that D614G modulates the energetics of the RBD position in a manner similar to ACE2 binding. We also find that antibodies that target diverse epitopes, including those distal to the RBD, stabilize the RBD in a position competent for ACE2 binding. Parallel solution-based binding experiments using fluorescence correlation spectroscopy (FCS) indicate antibody-mediated enhancement of ACE2 binding. These findings inform on novel strategies for therapeutic antibody cocktails.
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Affiliation(s)
- Marco A Diaz-Salinas
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, United States
| | - Qi Li
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, United States
| | - Monir Ejemel
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, United States
| | - Leonid Yurkovetskiy
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, United States
| | - Jeremy Luban
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, United States
| | - Kuang Shen
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, United States
| | - Yang Wang
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, United States
| | - James B Munro
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, United States
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Barba L, Paolini Paoletti F, Bellomo G, Gaetani L, Halbgebauer S, Oeckl P, Otto M, Parnetti L. Alpha and Beta Synucleins: From Pathophysiology to Clinical Application as Biomarkers. Mov Disord 2022; 37:669-683. [PMID: 35122299 PMCID: PMC9303453 DOI: 10.1002/mds.28941] [Citation(s) in RCA: 37] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 12/21/2021] [Accepted: 12/21/2021] [Indexed: 12/12/2022] Open
Abstract
The synuclein family includes three neuronal proteins, named α‐synuclein, β‐synuclein, and γ‐synuclein, that have peculiar structural features. α‐synuclein is largely known for being a key protein in the pathophysiology of Parkinson's disease (PD) and other synucleinopathies, namely, dementia with Lewy bodies and multisystem atrophy. The role of β‐synuclein and γ‐synuclein is less well understood in terms of physiological functions and potential contribution to human diseases. α‐synuclein has been investigated extensively in both cerebrospinal fluid (CSF) and blood as a potential biomarker for synucleinopathies. Recently, great attention has been also paid to β‐synuclein, whose CSF and blood levels seem to reflect synaptic damage and neurodegeneration independent of the presence of synucleinopathy. In this review, we aim to provide an overview on the pathophysiological roles of the synucleins. Because γ‐synuclein has been poorly investigated in the field of synucleinopathy and its pathophysiological roles are far from being clear, we focus on the interactions between α‐synuclein and β‐synuclein in PD. We also discuss the role of α‐synuclein and β‐synuclein as potential biomarkers to improve the diagnostic characterization of synucleinopathies, thus highlighting their potential application in clinical trials for disease‐modifying therapies. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society
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Affiliation(s)
- Lorenzo Barba
- Section of Neurology, Laboratory of Clinical Neurochemistry, Department of Medicine and Surgery University of Perugia Perugia Italy
- Department of Neurology University of Ulm Ulm Germany
- Department of Neurology Martin‐Luther‐University Halle‐Wittenberg Halle/Saale Germany
| | - Federico Paolini Paoletti
- Section of Neurology, Laboratory of Clinical Neurochemistry, Department of Medicine and Surgery University of Perugia Perugia Italy
| | - Giovanni Bellomo
- Section of Neurology, Laboratory of Clinical Neurochemistry, Department of Medicine and Surgery University of Perugia Perugia Italy
| | - Lorenzo Gaetani
- Section of Neurology, Laboratory of Clinical Neurochemistry, Department of Medicine and Surgery University of Perugia Perugia Italy
| | | | - Patrick Oeckl
- Department of Neurology University of Ulm Ulm Germany
- German Center for Neurodegenerative Disorders Ulm (DZNE e. V.) Ulm Germany
| | - Markus Otto
- Department of Neurology University of Ulm Ulm Germany
- Department of Neurology Martin‐Luther‐University Halle‐Wittenberg Halle/Saale Germany
| | - Lucilla Parnetti
- Section of Neurology, Laboratory of Clinical Neurochemistry, Department of Medicine and Surgery University of Perugia Perugia Italy
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Hayashi J, Carver JA. β-Synuclein: An Enigmatic Protein with Diverse Functionality. Biomolecules 2022; 12:142. [PMID: 35053291 PMCID: PMC8773819 DOI: 10.3390/biom12010142] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 01/09/2022] [Accepted: 01/12/2022] [Indexed: 12/24/2022] Open
Abstract
α-Synuclein (αS) is a small, unstructured, presynaptic protein expressed in the brain. Its aggregated form is a major component of Lewy bodies, the large proteinaceous deposits in Parkinson's disease. The closely related protein, β-Synuclein (βS), is co-expressed with αS. In vitro, βS acts as a molecular chaperone to inhibit αS aggregation. As a result of this assignation, βS has been largely understudied in comparison to αS. However, recent reports suggest that βS promotes neurotoxicity, implying that βS is involved in other cellular pathways with functions independent of αS. Here, we review the current literature pertaining to human βS in order to understand better the role of βS in homeostasis and pathology. Firstly, the structure of βS is discussed. Secondly, the ability of βS to (i) act as a molecular chaperone; (ii) regulate synaptic function, lipid binding, and the nigrostriatal dopaminergic system; (iii) mediate apoptosis; (iv) participate in protein degradation pathways; (v) modulate intracellular metal levels; and (vi) promote cellular toxicity and protein aggregation is explored. Thirdly, the P123H and V70M mutations of βS, which are associated with dementia with Lewy bodies, are discussed. Finally, the importance of post-translational modifications on the structure and function of βS is reviewed. Overall, it is concluded that βS has both synergistic and antagonistic interactions with αS, but it may also possess important cellular functions independent of αS.
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Affiliation(s)
| | - John A. Carver
- Research School of Chemistry, The Australian National University, Acton, ACT 2601, Australia;
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Díaz-Salinas MA, Li Q, Ejemel M, Yurkovetskiy L, Luban J, Shen K, Wang Y, Munro JB. Conformational dynamics and allosteric modulation of the SARS-CoV-2 spike. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2021. [PMID: 34790979 DOI: 10.1101/2021.10.29.466470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infects cells through binding to angiotensin-converting enzyme 2 (ACE2). This interaction is mediated by the receptor-binding domain (RBD) of the viral spike (S) glycoprotein. Structural and dynamic data have shown that S can adopt multiple conformations, which controls the exposure of the ACE2-binding site in the RBD. Here, using single-molecule Förster resonance energy transfer (smFRET) imaging we report the effects of ACE2 and antibody binding on the conformational dynamics of S from the Wuhan-1 strain and the B.1 variant (D614G). We find that D614G modulates the energetics of the RBD position in a manner similar to ACE2 binding. We also find that antibodies that target diverse epitopes, including those distal to the RBD, stabilize the RBD in a position competent for ACE2 binding. Parallel solution-based binding experiments using fluorescence correlation spectroscopy (FCS) indicate antibody-mediated enhancement of ACE2 binding. These findings inform on novel strategies for therapeutic antibody cocktails.
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11
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Scheibe C, Karreman C, Schildknecht S, Leist M, Hauser K. Synuclein Family Members Prevent Membrane Damage by Counteracting α-Synuclein Aggregation. Biomolecules 2021; 11:biom11081067. [PMID: 34439733 DOI: 10.3390/biom11081067] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 07/09/2021] [Accepted: 07/15/2021] [Indexed: 01/09/2023] Open
Abstract
The 140 amino acid protein α-synuclein (αS) is an intrinsically disordered protein (IDP) with various roles and locations in healthy neurons that plays a key role in Parkinson's disease (PD). Contact with biomembranes can lead to α-helical conformations, but can also act as s seeding event for aggregation and a predominant β-sheet conformation. In PD patients, αS is found to aggregate in various fibrillary structures, and the shift in aggregation and localization is associated with disease progression. Besides full-length αS, several related polypeptides are present in neurons. The role of many αS-related proteins in the aggregation of αS itself is not fully understood Two of these potential aggregation modifiers are the αS splicing variant αS Δexon3 (Δ3) and the paralog β-synuclein (βS). Here, polarized ATR-FTIR spectroscopy was used to study the membrane interaction of these proteins individually and in various combinations. The method allowed a continuous monitoring of both the lipid structure of biomimetic membranes and the aggregation state of αS and related proteins. The use of polarized light also revealed the orientation of secondary structure elements. While αS led to a destruction of the lipid membrane upon membrane-catalyzed aggregation, βS and Δ3 aggregated significantly less, and they did not harm the membrane. Moreover, the latter proteins reduced the membrane damage triggered by αS. There were no major differences in the membrane interaction for the different synuclein variants. In combination, these observations suggest that the formation of particular protein aggregates is the major driving force for αS-driven membrane damage. The misbalance of αS, βS, and Δ3 might therefore play a crucial role in neurodegenerative disease.
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Affiliation(s)
- Christian Scheibe
- Department of Chemistry, University of Konstanz, 78457 Konstanz, Germany
| | | | - Stefan Schildknecht
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany
- Department of Life Sciences, Albstadt-Sigmaringen University of Applied Sciences, 72488 Sigmaringen, Germany
| | - Marcel Leist
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany
| | - Karin Hauser
- Department of Chemistry, University of Konstanz, 78457 Konstanz, Germany
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12
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Guschina IA, Ninkina N, Roman A, Pokrovskiy MV, Buchman VL. Triple-Knockout, Synuclein-Free Mice Display Compromised Lipid Pattern. Molecules 2021; 26:3078. [PMID: 34064018 PMCID: PMC8196748 DOI: 10.3390/molecules26113078] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 05/05/2021] [Accepted: 05/11/2021] [Indexed: 11/29/2022] Open
Abstract
Recent studies have implicated synucleins in several reactions during the biosynthesis of lipids and fatty acids in addition to their recognised role in membrane lipid binding and synaptic functions. These are among aspects of decreased synuclein functions that are still poorly acknowledged especially in regard to pathogenesis in Parkinson's disease. Here, we aimed to add to existing knowledge of synuclein deficiency (i.e., the lack of all three family members), with respect to changes in fatty acids and lipids in plasma, liver, and two brain regions in triple synuclein-knockout (TKO) mice. We describe changes of long-chain polyunsaturated fatty acids (LCPUFA) and palmitic acid in liver and plasma, reduced triacylglycerol (TAG) accumulation in liver and non-esterified fatty acids in plasma of synuclein free mice. In midbrain, we observed counterbalanced changes in the relative concentrations of phosphatidylcholine (PC) and cerebrosides (CER). We also recorded a notable reduction in ethanolamine plasmalogens in the midbrain of synuclein free mice, which is an important finding since the abnormal ether lipid metabolism usually associated with neurological disorders. In summary, our data demonstrates that synuclein deficiency results in alterations of the PUFA synthesis, storage lipid accumulation in the liver, and the reduction of plasmalogens and CER, those polar lipids which are principal compounds of lipid rafts in many tissues. An ablation of all three synuclein family members causes more profound changes in lipid metabolism than changes previously shown to be associated with γ-synuclein deficiency alone. Possible mechanisms by which synuclein deficiency may govern the reported modifications of lipid metabolism in TKO mice are proposed and discussed.
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Affiliation(s)
- Irina A. Guschina
- School of Biosciences, Cardiff University, Cardiff CF10 3AX, UK; (N.N.); (A.R.); (V.L.B.)
| | - Natalia Ninkina
- School of Biosciences, Cardiff University, Cardiff CF10 3AX, UK; (N.N.); (A.R.); (V.L.B.)
- Institute of Physiologically Active Compounds Russian Academy of Sciences (IPAC RAS), 1 Severniy Proezd, Chernogolovka 142432, Moscow Region, Russia
| | - Andrei Roman
- School of Biosciences, Cardiff University, Cardiff CF10 3AX, UK; (N.N.); (A.R.); (V.L.B.)
- Institute of Physiologically Active Compounds Russian Academy of Sciences (IPAC RAS), 1 Severniy Proezd, Chernogolovka 142432, Moscow Region, Russia
| | - Mikhail V. Pokrovskiy
- Research Institute of Living Systems Pharmacology, Belgorod State National Research University, 85 Pobedy Street, Belgorod 308015, Belgorod Oblast, Russia;
| | - Vladimir L. Buchman
- School of Biosciences, Cardiff University, Cardiff CF10 3AX, UK; (N.N.); (A.R.); (V.L.B.)
- Institute of Physiologically Active Compounds Russian Academy of Sciences (IPAC RAS), 1 Severniy Proezd, Chernogolovka 142432, Moscow Region, Russia
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13
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He S, Zhong S, Liu G, Yang J. Alpha-Synuclein: The Interplay of Pathology, Neuroinflammation, and Environmental Factors in Parkinson's Disease. NEURODEGENER DIS 2021; 20:55-64. [PMID: 33465773 DOI: 10.1159/000511083] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 08/21/2020] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Parkinson's disease (PD) is a multifactorial, chronic, and progressive neurodegenerative disease. α-Synuclein (α-syn), which is the main protein component of Lewy bodies, plays an important role in the pathological hallmarks of PD. However, the pathological function of α-syn and the molecular mechanisms responsible for the degeneration of dopaminergic neurons are still elusive. SUMMARY Cumulative evidence implicates that abnormal processing of α-syn will be predicted to lead to pathological changes in PD. Key Messages: In this review, we summarize the structure and physiological function of α-syn, and further discuss the interplay of pathology, neuroinflammation, and environmental factors in PD. Additionally, we suggest future directions for understanding the toxicity of α-syn to neurons, which may ultimately encourage us to better design disease-modifying therapeutic strategies for PD.
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Affiliation(s)
- Songzhe He
- Clinic Laboratory Department, Affiliated Hospital of Guilin Medical University, Guilin, China.,Department of Neurology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Shan Zhong
- Department of Acupuncture, Guilin Hospital of Traditional Chinese Medicine, Guilin, China
| | - Gang Liu
- Department of Acupuncture, Guilin Hospital of Traditional Chinese Medicine, Guilin, China
| | - Jun Yang
- Clinic Laboratory Department, Affiliated Hospital of Guilin Medical University, Guilin, China,
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14
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Yang Y, Margam NN. Structural Insights into Membrane Fusion Mediated by Convergent Small Fusogens. Cells 2021; 10:cells10010160. [PMID: 33467484 PMCID: PMC7830690 DOI: 10.3390/cells10010160] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 01/07/2021] [Accepted: 01/13/2021] [Indexed: 12/30/2022] Open
Abstract
From lifeless viral particles to complex multicellular organisms, membrane fusion is inarguably the important fundamental biological phenomena. Sitting at the heart of membrane fusion are protein mediators known as fusogens. Despite the extensive functional and structural characterization of these proteins in recent years, scientists are still grappling with the fundamental mechanisms underlying membrane fusion. From an evolutionary perspective, fusogens follow divergent evolutionary principles in that they are functionally independent and do not share any sequence identity; however, they possess structural similarity, raising the possibility that membrane fusion is mediated by essential motifs ubiquitous to all. In this review, we particularly emphasize structural characteristics of small-molecular-weight fusogens in the hope of uncovering the most fundamental aspects mediating membrane–membrane interactions. By identifying and elucidating fusion-dependent functional domains, this review paves the way for future research exploring novel fusogens in health and disease.
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15
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Bhattacharyya D, Bhunia A. Gut-Brain axis in Parkinson's disease etiology: The role of lipopolysaccharide. Chem Phys Lipids 2020; 235:105029. [PMID: 33338469 DOI: 10.1016/j.chemphyslip.2020.105029] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Revised: 12/05/2020] [Accepted: 12/10/2020] [Indexed: 12/26/2022]
Abstract
Recent studies highlight the initiation of Parkinson's disease (PD) in the gastrointestinal tract, decades before the manifestations in the central nervous system (CNS). This gut-brain axis of neurodegenerative diseases defines the critical role played by the unique microbial composition of the "second brain" formed by the enteric nervous system (ENS). Compromise in the enteric wall can result in the translocation of gut-microbiota along with their metabolites into the system that can affect the homeostatic machinery. The released metabolites can associate with protein substrates affecting several biological pathways. Among these, the bacterial endotoxin from Gram-negative bacteria, i.e., Lipopolysaccharide (LPS), has been implicated to play a definite role in progressive neurodegeneration. The molecular interaction of the lipid metabolites can have a direct neuro-modulatory effect on homeostatic protein components that can be transported to the CNS via the vagus nerve. α-synuclein (α-syn) is one such partner protein, the molecular interactions with which modulate its overall fibrillation propensity in the system. LPS interaction has been shown to affect the protein's aggregation kinetics in an alternative inflammatory pathway of PD pathogenesis. Several other lipid contents from the bacterial membranes could also be responsible for the initiation of α-syn amyloidogenesis. The present review will focus on the intermolecular interactions of α-syn with bacterial lipid components, particularly LPS, with a definite clinical manifestation in PD pathogenesis. However, deconvolution of the sequence of interaction events from the ENS to its propagation in the CNS is not easy or obvious. Nevertheless, the characterization of these lipid-mediated structures is a step towards realizing the novel targets in the pre-emptive diagnoses of PD. This comprehensive description should prompt the correlation of potential risk of amyloidogenesis upon detection of specific paradigm shifts in the microbial composition of the gut.
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Affiliation(s)
- Dipita Bhattacharyya
- Department of Biophysics, Bose Institute, P-1/12 CIT Scheme VII (M), Kolkata, 700054, India
| | - Anirban Bhunia
- Department of Biophysics, Bose Institute, P-1/12 CIT Scheme VII (M), Kolkata, 700054, India.
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16
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Zhukovsky MA, Filograna A, Luini A, Corda D, Valente C. Protein Amphipathic Helix Insertion: A Mechanism to Induce Membrane Fission. Front Cell Dev Biol 2019; 7:291. [PMID: 31921835 PMCID: PMC6914677 DOI: 10.3389/fcell.2019.00291] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 11/06/2019] [Indexed: 12/19/2022] Open
Abstract
One of the fundamental features of biomembranes is the ability to fuse or to separate. These processes called respectively membrane fusion and fission are central in the homeostasis of events such as those related to intracellular membrane traffic. Proteins that contain amphipathic helices (AHs) were suggested to mediate membrane fission via shallow insertion of these helices into the lipid bilayer. Here we analyze the AH-containing proteins that have been identified as essential for membrane fission and categorize them in few subfamilies, including small GTPases, Atg proteins, and proteins containing either the ENTH/ANTH- or the BAR-domain. AH-containing fission-inducing proteins may require cofactors such as additional proteins (e.g., lipid-modifying enzymes), or lipids (e.g., phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2], phosphatidic acid [PA], or cardiolipin). Both PA and cardiolipin possess a cone shape and a negative charge (-2) that favor the recruitment of the AHs of fission-inducing proteins. Instead, PtdIns(4,5)P2 is characterized by an high negative charge able to recruit basic residues of the AHs of fission-inducing proteins. Here we propose that the AHs of fission-inducing proteins contain sequence motifs that bind lipid cofactors; accordingly (K/R/H)(K/R/H)xx(K/R/H) is a PtdIns(4,5)P2-binding motif, (K/R)x6(F/Y) is a cardiolipin-binding motif, whereas KxK is a PA-binding motif. Following our analysis, we show that the AHs of many fission-inducing proteins possess five properties: (a) at least three basic residues on the hydrophilic side, (b) ability to oligomerize, (c) optimal (shallow) depth of insertion into the membrane, (d) positive cooperativity in membrane curvature generation, and (e) specific interaction with one of the lipids mentioned above. These lipid cofactors favor correct conformation, oligomeric state and optimal insertion depth. The most abundant lipid in a given organelle possessing high negative charge (more negative than -1) is usually the lipid cofactor in the fission event. Interestingly, naturally occurring mutations have been reported in AH-containing fission-inducing proteins and related to diseases such as centronuclear myopathy (amphiphysin 2), Charcot-Marie-Tooth disease (GDAP1), Parkinson's disease (α-synuclein). These findings add to the interest of the membrane fission process whose complete understanding will be instrumental for the elucidation of the pathogenesis of diseases involving mutations in the protein AHs.
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Affiliation(s)
- Mikhail A. Zhukovsky
- Institute of Biochemistry and Cell Biology, National Research Council, Naples, Italy
| | | | | | - Daniela Corda
- Institute of Biochemistry and Cell Biology, National Research Council, Naples, Italy
| | - Carmen Valente
- Institute of Biochemistry and Cell Biology, National Research Council, Naples, Italy
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17
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Alza NP, Iglesias González PA, Conde MA, Uranga RM, Salvador GA. Lipids at the Crossroad of α-Synuclein Function and Dysfunction: Biological and Pathological Implications. Front Cell Neurosci 2019; 13:175. [PMID: 31118888 PMCID: PMC6504812 DOI: 10.3389/fncel.2019.00175] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 04/11/2019] [Indexed: 12/15/2022] Open
Abstract
Since its discovery, the study of the biological role of α-synuclein and its pathological implications has been the subject of increasing interest. The propensity to adopt different conformational states governing its aggregation and fibrillation makes this small 14-kDa cytosolic protein one of the main etiologic factors associated with degenerative disorders known as synucleinopathies. The structure, function, and toxicity of α-synuclein and the possibility of different therapeutic approaches to target the protein have been extensively investigated and reviewed. One intriguing characteristic of α-synuclein is the different ways in which it interacts with lipids. Though in-depth studies have been carried out in this field, the information they have produced is puzzling and the precise role of lipids in α-synuclein biology and pathology and vice versa is still largely unknown. Here we provide an overview and discussion of the main findings relating to α-synuclein/lipid interaction and its involvement in the modulation of lipid metabolism and signaling.
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Affiliation(s)
- Natalia P Alza
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional del Sur, Bahía Blanca, Argentina.,Departamento de Química, Universidad Nacional del Sur, Bahía Blanca, Argentina
| | - Pablo A Iglesias González
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional del Sur, Bahía Blanca, Argentina
| | - Melisa A Conde
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional del Sur, Bahía Blanca, Argentina.,Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina
| | - Romina M Uranga
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional del Sur, Bahía Blanca, Argentina.,Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina
| | - Gabriela A Salvador
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional del Sur, Bahía Blanca, Argentina.,Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina
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18
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Williams JK, Yang X, Baum J. Interactions between the Intrinsically Disordered Proteins β-Synuclein and α-Synuclein. Proteomics 2018; 18:e1800109. [PMID: 30142698 PMCID: PMC6447293 DOI: 10.1002/pmic.201800109] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 08/18/2018] [Indexed: 12/31/2022]
Abstract
Several intrinsically disordered proteins have been implicated in the process of amyloid fibril formation in neurodegenerative disease, and developing approaches to inhibit the aggregation of these intrinsically disordered proteins is critical for establishing effective therapies against disease progression. The aggregation pathway of the intrinsically disordered protein alpha-synuclein, which is implicated in several neurodegenerative diseases known as synucleinopathies, has been extensively characterized. Less attention has been leveraged on beta-synuclein, a homologous intrinsically disordered protein that co-localizes with alpha-synuclein and is known to delay alpha-synuclein fibril formation. In this review, we focus on beta-synuclein and the molecular-level interactions between alpha-synuclein and beta-synuclein that underlie the delay of fibril formation. We highlight studies that begin to define alpha-synuclein and beta-synuclein interactions at the monomer, oligomer, and surface levels, and suggest that beta-synuclein plays a role in regulation of inhibition at many different stages of alpha-synuclein aggregation.
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Affiliation(s)
- Jonathan K Williams
- Department of Chemistry and Chemical Biology, Rutgers University, 08854, Piscataway, New Jersey, USA
| | - Xue Yang
- Department of Chemistry and Chemical Biology, Rutgers University, 08854, Piscataway, New Jersey, USA
| | - Jean Baum
- Department of Chemistry and Chemical Biology, Rutgers University, 08854, Piscataway, New Jersey, USA
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19
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Snead D, Eliezer D. Spectroscopic Characterization of Structure-Function Relationships in the Intrinsically Disordered Protein Complexin. Methods Enzymol 2018; 611:227-286. [PMID: 30471689 DOI: 10.1016/bs.mie.2018.08.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Complexins play a critical role in the regulation of neurotransmission by regulating SNARE-mediated exocytosis of synaptic vesicles. Complexins can exert either a facilitatory or an inhibitory effect on neurotransmitter release, depending on the context, and different complexin domains contribute differently to these opposing roles. Structural characterization of the central helix domain of complexin bound to the assembled SNARE bundle provided key insights into the functional mechanism of this domain of complexin, which is critical for both complexin activities, but many questions remain, particularly regarding the roles and mechanisms of other complexin domains. Recent progress has clarified the structural properties of these additional domains, and has led to various proposals regarding how they contribute to complexin function. This chapter describes spectroscopic approaches used in our laboratory and others, primarily involving circular dichroism and solution-state NMR spectroscopy, to characterize structure within complexins when isolated or when bound to interaction partners. The ability to characterize complexin structure enables structure/function studies employing in vitro or in vivo assays of complexin function. More generally, these types of approaches can be used to study the binding of other intrinsically disordered proteins or protein regions to membrane surfaces or for that matter to other large physiological binding partners.
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Affiliation(s)
- David Snead
- Department of Biochemistry, Weill Cornell Medicine, New York, NY, United States
| | - David Eliezer
- Department of Biochemistry, Weill Cornell Medicine, New York, NY, United States.
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20
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Popova B, Kleinknecht A, Arendarski P, Mischke J, Wang D, Braus GH. Sumoylation Protects Against β-Synuclein Toxicity in Yeast. Front Mol Neurosci 2018; 11:94. [PMID: 29636661 PMCID: PMC5880895 DOI: 10.3389/fnmol.2018.00094] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 03/09/2018] [Indexed: 02/05/2023] Open
Abstract
Aggregation of α-synuclein (αSyn) plays a central role in the pathogenesis of Parkinson’s disease (PD). The budding yeast Saccharomyces cerevisiae serves as reference cell to study the interplay between αSyn misfolding, cytotoxicity and post-translational modifications (PTMs). The synuclein family includes α, β and γ isoforms. β-synuclein (βSyn) and αSyn are found at presynaptic terminals and both proteins are presumably involved in disease pathogenesis. Similar to αSyn, expression of βSyn leads to growth deficiency and formation of intracellular aggregates in yeast. Co-expression of αSyn and βSyn exacerbates the cytotoxicity. This suggests an important role of βSyn homeostasis in PD pathology. We show here that the small ubiquitin-like modifier SUMO is an important determinant of protein stability and βSyn-induced toxicity in eukaryotic cells. Downregulation of sumoylation in a yeast strain, defective for the SUMO-encoding gene resulted in reduced yeast growth, whereas upregulation of sumoylation rescued growth of yeast cell expressing βSyn. This corroborates a protective role of the cellular sumoylation machinery against βSyn-induced toxicity. Upregulation of sumoylation significantly reduced βSyn aggregate formation. This is an indirect molecular process, which is not directly linked to βSyn sumoylation because amino acid substitutions in the lysine residues required for βSyn sumoylation decreased aggregation without changing yeast cellular toxicity. αSyn aggregates are more predominantly degraded by the autophagy/vacuole than by the 26S ubiquitin proteasome system. We demonstrate a vice versa situation for βSyn, which is mainly degraded in the 26S proteasome. Downregulation of sumoylation significantly compromised the clearance of βSyn by the 26S proteasome and increased protein stability. This effect is specific, because depletion of functional SUMO did neither affect βSyn aggregate formation nor its degradation by the autophagy/vacuolar pathway. Our data support that cellular βSyn toxicity and aggregation do not correlate in their cellular impact as for αSyn but rather represent two distinct independent molecular functions and molecular mechanisms. These insights into the relationship between βSyn-induced toxicity, aggregate formation and degradation demonstrate a significant distinction between the impact of αSyn compared to βSyn on eukaryotic cells.
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Affiliation(s)
- Blagovesta Popova
- Department of Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Institute for Microbiology and Genetics, Universität Göttingen, Göttingen, Germany.,Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany
| | - Alexandra Kleinknecht
- Department of Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Institute for Microbiology and Genetics, Universität Göttingen, Göttingen, Germany.,Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany
| | - Patricia Arendarski
- Department of Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Institute for Microbiology and Genetics, Universität Göttingen, Göttingen, Germany
| | - Jasmin Mischke
- Department of Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Institute for Microbiology and Genetics, Universität Göttingen, Göttingen, Germany
| | - Dan Wang
- Department of Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Institute for Microbiology and Genetics, Universität Göttingen, Göttingen, Germany
| | - Gerhard H Braus
- Department of Molecular Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB), Institute for Microbiology and Genetics, Universität Göttingen, Göttingen, Germany.,Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany
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21
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Moriarty GM, Olson MP, Atieh TB, Janowska MK, Khare SD, Baum J. A pH-dependent switch promotes β-synuclein fibril formation via glutamate residues. J Biol Chem 2017; 292:16368-16379. [PMID: 28710275 DOI: 10.1074/jbc.m117.780528] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 07/11/2017] [Indexed: 01/10/2023] Open
Abstract
α-Synuclein (αS) is the primary protein associated with Parkinson's disease, and it undergoes aggregation from its intrinsically disordered monomeric form to a cross-β fibrillar form. The closely related homolog β-synuclein (βS) is essentially fibril-resistant under cytoplasmic physiological conditions. Toxic gain-of-function by βS has been linked to dysfunction, but the aggregation behavior of βS under altered pH is not well-understood. In this work, we compare fibril formation of αS and βS at pH 7.3 and mildly acidic pH 5.8, and we demonstrate that pH serves as an on/off switch for βS fibrillation. Using αS/βS domain-swapped chimera constructs and single residue substitutions in βS, we localized the switch to acidic residues in the N-terminal and non-amyloid component domains of βS. Computational models of βS fibril structures indicate that key glutamate residues (Glu-31 and Glu-61) in these domains may be sites of pH-sensitive interactions, and variants E31A and E61A show dramatically altered pH sensitivity for fibril formation supporting the importance of these charged side chains in fibril formation of βS. Our results demonstrate that relatively small changes in pH, which occur frequently in the cytoplasm and in secretory pathways, may induce the formation of βS fibrils and suggest a complex role for βS in synuclein cellular homeostasis and Parkinson's disease.
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Affiliation(s)
- Gina M Moriarty
- From the Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey 08854
| | - Michael P Olson
- From the Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey 08854
| | - Tamr B Atieh
- From the Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey 08854
| | - Maria K Janowska
- From the Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey 08854
| | - Sagar D Khare
- From the Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey 08854
| | - Jean Baum
- From the Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey 08854
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22
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Braun AR, Lacy MM, Ducas VC, Rhoades E, Sachs JN. α-Synuclein's Uniquely Long Amphipathic Helix Enhances its Membrane Binding and Remodeling Capacity. J Membr Biol 2017; 250:183-193. [PMID: 28239748 DOI: 10.1007/s00232-017-9946-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Accepted: 01/24/2017] [Indexed: 10/20/2022]
Abstract
α-Synuclein is the primary protein found in Lewy bodies, the protein and lipid aggregates associated with Parkinson's disease and Lewy body dementia. The protein folds into a uniquely long amphipathic α-helix (AH) when bound to a membrane, and at high enough concentrations, it induces large-scale remodeling of membranes (tubulation and vesiculation). By engineering a less hydrophobic variant of α-Synuclein, we previously showed that the energy associated with binding of α-Synuclein's AH correlates with the extent of membrane remodeling (Braun et al. in J Am Chem Soc 136:9962-9972, 2014). In this study, we combine fluorescence correlation spectroscopy, electron microscopy, and vesicle clearance assays with coarse-grained molecular dynamics simulations to test the impact of decreasing the length of the amphipathic helix on membrane binding energy and tubulation. We show that truncation of α-Synuclein's AH length by approximately 15% reduces both its membrane binding affinity (by fivefold) and membrane remodeling capacity (by nearly 50% on per mole of bound protein basis). Results from simulations correlate well with the experiments and lend support to the idea that at high protein density there is a stabilization of individual, protein-induced membrane curvature fields. The extent to which these curvature fields are stabilized, a function of binding energy, dictates the extent of tubulation. Somewhat surprisingly, we find that this stabilization does not correlate directly with the geometric distribution of the proteins on the membrane surface.
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Affiliation(s)
- Anthony R Braun
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Michael M Lacy
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA
| | - Vanessa C Ducas
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA
| | - Elizabeth Rhoades
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA
| | - Jonathan N Sachs
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, 55455, USA.
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23
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β-Synuclein suppresses both the initiation and amplification steps of α-synuclein aggregation via competitive binding to surfaces. Sci Rep 2016; 6:36010. [PMID: 27808107 PMCID: PMC5093550 DOI: 10.1038/srep36010] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 10/04/2016] [Indexed: 11/08/2022] Open
Abstract
α-Synuclein is an intrinsically disordered protein that is associated with the pathogenesis of Parkinson's disease through the processes involved in the formation of amyloid fibrils. α and β-synuclein are homologous proteins found at comparable levels in presynaptic terminals but β-synuclein has a greatly reduced propensity to aggregate and indeed has been found to inhibit α-synuclein aggregation. In this paper, we describe how sequence differences between α- and β-synuclein affect individual microscopic processes in amyloid formation. In particular, we show that β-synuclein strongly suppresses both lipid-induced aggregation and secondary nucleation of α-synuclein by competing for binding sites at the surfaces of lipid vesicles and fibrils, respectively. These results suggest that β-synuclein can act as a natural inhibitor of α-synuclein aggregation by reducing both the initiation of its self-assembly and the proliferation of its aggregates.
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24
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Yerramilli VS, Scarlata S. The Breast Cancer Susceptibility Gene Product (γ-Synuclein) Alters Cell Behavior through its [corrected] Interaction with Phospholipase Cβ. Cell Signal 2015; 28:91-9. [PMID: 26521046 DOI: 10.1016/j.cellsig.2015.10.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Revised: 10/19/2015] [Accepted: 10/27/2015] [Indexed: 12/23/2022]
Abstract
The breast cancer susceptibility gene protein, also known as γ-synuclein, is highly expressed in human breast cancer in a stage-specific manner, with highest expression in late stage cancer. In model systems, γ-synuclein binds phospholipase Cβ2 which is regulated by Gαq to generate intracellular Ca(2+) signals. PLCβ2, which is also absent in normal tissue but highly expressed in breast cancer, is additionally regulated by Rac to promote migration pathways. We have found that γ-synuclein binds to the same region of PLCβ2 as Gαq. Using cells that mimic stage 4 breast cancer (MDA MB 231), we show that down-regulation of γ-synuclein reduces the protein level of PLCβ but increases the transcript level over 40 fold. γ-Synuclein down-regulation also promotes the interaction between Gαq and PLCβ resulting in a stronger Ca(2+) response to Gαq agonists. The ability of γ-synuclein to interfere with Gαq-PLCβ interactions allows more PLCβ to colocalize with Rac impacting Rac-mediated pathways that may give rise to cancerous phenotypes.
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Affiliation(s)
- V Siddartha Yerramilli
- Dept of Physiology & Biophysics, Stony Brook University, Stony Brook, NY, 11794-8661, United States
| | - Suzanne Scarlata
- Dept of Physiology & Biophysics, Stony Brook University, Stony Brook, NY, 11794-8661, United States; Dept. of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, MA, 01609, United States.
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25
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Surgucheva I, He S, Rich MC, Sharma R, Ninkina NN, Stahel PF, Surguchov A. Role of synucleins in traumatic brain injury — an experimental in vitro and in vivo study in mice. Mol Cell Neurosci 2015; 63:114-23. [PMID: 25447944 DOI: 10.1016/j.mcn.2014.10.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 10/16/2014] [Accepted: 10/23/2014] [Indexed: 11/25/2022] Open
Abstract
Synucleins are small prone to aggregate proteins associated with several neurodegenerative diseases (NDDs), however their role in traumatic brain injury (TBI) is an emerging area of investigation. Using in vitro scratch injury model and in vivo mouse weight-drop model we have found that the injury causes alterations in the expression and localization of synucleins near the damaged area. Before injury, α-synuclein is diffused in the cytoplasm of neurons and γ-synuclein is both in the cytoplasm and nucleus of oligodendrocytes. After the scratch injury of the mixed neuronal and glial culture, α-synuclein forms punctate structures in the cytoplasm of neurons and γ-synuclein is almost completely localized to the nucleus of the oligodendrocytes. Furthermore, the amount of post-translationally modified Met38-oxidized γ-synuclein is increased 3.8 fold 24 h after the scratch. α- and γ-synuclein containing cells increased in the initially cell free scratch zone up to 24 h after the scratch.Intracellular expression and localization of synucleins are also changed in a mouse model of focal closed head injury, using a standardized weight drop device. γ-Synuclein goes from diffuse to punctate staining in a piriform cortex near the amygdala, which may reflect the first steps in the formation of deposits/inclusions. Surprisingly, oxidized γ-synuclein co-localizes with cofilin-actin rods in the thalamus, which are absent in all other regions of the brain. These structures reach their peak amounts 7 days after injury. The changes in γ-synuclein localization are accompanied by injury-induced alterations in the morphology of both astrocytes and neurons.
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Boon JY, Dusonchet J, Trengrove C, Wolozin B. Interaction of LRRK2 with kinase and GTPase signaling cascades. Front Mol Neurosci 2014; 7:64. [PMID: 25071441 PMCID: PMC4087324 DOI: 10.3389/fnmol.2014.00064] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Accepted: 06/19/2014] [Indexed: 02/04/2023] Open
Abstract
LRRK2 is a protein that interacts with a plethora of signaling molecules, but the complexity of LRRK2 function presents a challenge for understanding the role of LRRK2 in the pathophysiology of Parkinson's disease (PD). Studies of LRRK2 using over-expression in transgenic mice have been disappointing, however, studies using invertebrate systems have yielded a much clearer picture, with clear effects of LRRK2 expression, knockdown or deletion in Caenorhabditis elegans and Drosophila on modulation of survival of dopaminergic neurons. Recent studies have begun to focus attention on particular signaling cascades that are a target of LRRK2 function. LRRK2 interacts with members of the mitogen activated protein kinase (MAPK) pathway and might regulate the pathway action by acting as a scaffold that directs the location of MAPK pathway activity, without strongly affecting the amount of MAPK pathway activity. Binding to GTPases, GTPase-activating proteins and GTPase exchange factors are another strong theme in LRRK2 biology, with LRRK2 binding to rac1, cdc42, rab5, rab7L1, endoA, RGS2, ArfGAP1, and ArhGEF7. All of these molecules appear to feed into a function output for LRRK2 that modulates cytoskeletal outgrowth and vesicular dynamics, including autophagy. These functions likely impact modulation of α-synuclein aggregation and associated toxicity eliciting the disease processes that we term PD.
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Affiliation(s)
- Joon Y Boon
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine Boston, MA, USA
| | - Julien Dusonchet
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine Boston, MA, USA
| | - Chelsea Trengrove
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine Boston, MA, USA
| | - Benjamin Wolozin
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine Boston, MA, USA ; Neurology, Boston University School of Medicine Boston, MA, USA
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Ducas VC, Rhoades E. Investigation of intramolecular dynamics and conformations of α-, β- and γ-synuclein. PLoS One 2014; 9:e86983. [PMID: 24489820 PMCID: PMC3904966 DOI: 10.1371/journal.pone.0086983] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Accepted: 12/18/2013] [Indexed: 01/01/2023] Open
Abstract
The synucleins are a family of natively unstructured proteins consisting of α-, β-, and γ-synuclein which are primarily expressed in neurons. They have been linked to a wide variety of pathologies, including neurological disorders, such as Parkinson's disease (α-synuclein) and dementia with Lewy bodies (α- and β-synuclein), as well as various types of cancers (γ-synuclein). Self-association is a key pathological feature of many of these disorders, with α-synuclein having the highest propensity to form aggregates, while β-synuclein is the least prone. Here, we used a combination of fluorescence correlation spectroscopy and single molecule Förster resonance energy transfer to compare the intrinsic dynamics of different regions of all three synuclein proteins to investigate any correlation with putative functional or dysfunctional interactions. Despite a relatively high degree of sequence homology, we find that individual regions sample a broad range of diffusion coefficients, differing by almost a factor of four. At low pH, a condition that accelerates aggregation of α-synuclein, on average smaller diffusion coefficients are measured, supporting a hypothesis that slower intrachain dynamics may be correlated with self-association. Moreover, there is a surprising inverse correlation between dynamics and bulkiness of the segments. Aside from this observation, we could not discern any clear relationship between the physico-chemical properties of the constructs and their intrinsic dynamics. This work suggests that while protein dynamics may play a role in modulating self-association or interactions with other binding partners, other factors, particularly the local cellular environment, may be more important.
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Affiliation(s)
- Vanessa C Ducas
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, United States of America
| | - Elizabeth Rhoades
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, United States of America ; Department of Physics, Yale University, New Haven, Connecticut, United States of America
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Brucale M, Schuler B, Samorì B. Single-molecule studies of intrinsically disordered proteins. Chem Rev 2014; 114:3281-317. [PMID: 24432838 DOI: 10.1021/cr400297g] [Citation(s) in RCA: 112] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Marco Brucale
- Institute for the Study of Nanostructured Materials (ISMN), Italian National Council of Research (CNR) , Area della Ricerca Roma1, Via Salaria km 29.3 00015 Monterotondo (Rome), Italy
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Golebiewska U, Zurawsky C, Scarlata S. Defining the oligomerization state of γ-synuclein in solution and in cells. Biochemistry 2014; 53:293-9. [PMID: 24367999 DOI: 10.1021/bi401479a] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
γ-Synuclein is expressed at high levels in neuronal cells and in multiple invasive cancers. Like its family member α-synuclein, γ-synuclein is thought to be natively unfolded but does not readily form fibrils. The function of γ-synuclein is unknown, but we have found that it interacts strongly with the enzyme phospholipase Cβ (PLCβ), altering its interaction with G proteins. As a first step in determining its role, we have characterized its oligomerization using fluorescence homotransfer, photon-counting histogram analysis, and native gel electrophoresis. We found that when its expressed in Escherichia coli and purified, γ-synuclein appears monomeric on chromatographs under denaturing conditions, but under native conditions, it appears as oligomers of varying sizes. We followed the monomer-to-tetramer association by labeling the protein with fluorescein and following the concentration-dependent loss in fluorescence anisotropy resulting from fluorescence homotransfer. We also performed photon-counting histogram analysis at increasing concentrations of fluorescein-labeled γ-synuclein and found concentration-dependent oligomerization. Addition of PLCβ2, a strong γ-synuclein binding partner whose cellular expression is correlated with γ-synuclein, results in disruption of γ-synuclein oligomers. Similarly, its binding to lipid membranes promotes the monomer form. When we exogenously express γ-synuclein or microinject purified protein into cells, the protein appears monomeric. Our studies show that even though purified γ-synuclein form oligomers, when binding partners are present, as in cells, it dissociates to a monomer to bind these partners, which in turn may modify protein function and integrity.
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Affiliation(s)
- Urszula Golebiewska
- Department of Physiology & Biophysics, Stony Brook University , Stony Brook, New York 11794, United States
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