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Man WK, De Simone A, Barritt JD, Vendruscolo M, Dobson CM, Fusco G. A Role of Cholesterol in Modulating the Binding of α-Synuclein to Synaptic-Like Vesicles. Front Neurosci 2020; 14:18. [PMID: 32063829 PMCID: PMC7000551 DOI: 10.3389/fnins.2020.00018] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Accepted: 01/09/2020] [Indexed: 12/15/2022] Open
Abstract
α-Synuclein (αS) is a presynaptic protein whose aggregation is associated with Parkinson's disease (PD). Although the physiological function of αS is still unclear, several lines of evidence indicate that this protein may play a role in the trafficking of synaptic vesicles (SVs) during neurotransmitter release, a task associated with its ability to bind SVs and promote their clustering. It is therefore crucial to identify the cellular factors that modulate this process. To address this question, using nuclear magnetic resonance (NMR) spectroscopy we have characterized the role of cholesterol, a major component of the membrane of SVs, in the binding of αS with synaptic-like vesicles. Our results indicate that cholesterol can act as a modulator of the overall affinity of αS for SVs by reducing the local affinity of the region spanning residues 65-97 in the non-amyloid-β component (NAC) of the protein. The increased population of bound states that expose the region 65-97 to the solvent was found to induce stronger vesicle-vesicle interactions by αS. These results provide evidence that cholesterol modulates the clustering of synaptic vesicles induced by (α)S, and supports the role of the disorder-to-order equilibrium of the NAC region in the modulation of the biological properties of the membrane-bound state of αS.
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Affiliation(s)
- Wing K. Man
- Department of Chemistry, Centre for Misfolding Diseases, University of Cambridge, Cambridge, United Kingdom
| | - Alfonso De Simone
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Joseph D. Barritt
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Michele Vendruscolo
- Department of Chemistry, Centre for Misfolding Diseases, University of Cambridge, Cambridge, United Kingdom
| | - Christopher M. Dobson
- Department of Chemistry, Centre for Misfolding Diseases, University of Cambridge, Cambridge, United Kingdom
| | - Giuliana Fusco
- Department of Chemistry, Centre for Misfolding Diseases, University of Cambridge, Cambridge, United Kingdom
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Press-Sandler O, Miller Y. Molecular mechanisms of membrane-associated amyloid aggregation: Computational perspective and challenges. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:1889-1905. [DOI: 10.1016/j.bbamem.2018.03.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 03/07/2018] [Accepted: 03/12/2018] [Indexed: 01/02/2023]
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Rawat A, Langen R, Varkey J. Membranes as modulators of amyloid protein misfolding and target of toxicity. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:1863-1875. [PMID: 29702073 DOI: 10.1016/j.bbamem.2018.04.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 04/19/2018] [Accepted: 04/19/2018] [Indexed: 12/15/2022]
Abstract
Abnormal protein aggregation is a hallmark of various human diseases. α-Synuclein, a protein implicated in Parkinson's disease, is found in aggregated form within Lewy bodies that are characteristically observed in the brains of PD patients. Similarly, deposits of aggregated human islet amyloid polypeptide (IAPP) are found in the pancreatic islets in individuals with type 2 diabetes mellitus. Significant number of studies have focused on how monomeric, disaggregated proteins transition into various amyloid structures leading to identification of a vast number of aggregation promoting molecules and processes over the years. Inasmuch as these factors likely enhance the formation of toxic, misfolded species, they might act as risk factors in disease. Cellular membranes, and particularly certain lipids, are considered to be among the major players for aggregation of α-synuclein and IAPP, and membranes might also be the target of toxicity. Past studies have utilized an array of biophysical tools, both in vitro and in vivo, to expound the membrane-mediated aggregation. Here, we focus on membrane interaction of α-synuclein and IAPP, and how various kinds of membranes catalyze or modulate the aggregation of these proteins and how, in turn, these proteins disrupt membrane integrity, both in vitro and in vivo. The membrane interaction and subsequent aggregation has been briefly contrasted to aggregation of α-synuclein and IAPP in solution. This article is part of a Special Issue entitled: Protein Aggregation and Misfolding at the Cell Membrane Interface edited by Ayyalusamy Ramamoorthy.
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Affiliation(s)
- Anoop Rawat
- Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, CA 90033, United States
| | - Ralf Langen
- Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, CA 90033, United States.
| | - Jobin Varkey
- Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, CA 90033, United States.
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Fusco G, Sanz-Hernandez M, De Simone A. Order and disorder in the physiological membrane binding of α-synuclein. Curr Opin Struct Biol 2017; 48:49-57. [PMID: 29100107 DOI: 10.1016/j.sbi.2017.09.004] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 09/21/2017] [Accepted: 09/25/2017] [Indexed: 11/25/2022]
Abstract
α-Synuclein (αS) is a neuronal protein that localises predominantly at the presynaptic terminals, and whose fibrillar aggregates are the major constituents of Lewy bodies in Parkinson's disease. In vivo αS is partitioned between water-soluble and membrane-bound states, and this highly regulated equilibrium influences its biological behaviour under both physiological and pathological conditions. Here we discuss the sequence and structural determinants underlying the transition between the unstructured cytosolic and partially structured membrane-bound states of αS. The balance between order and disorder in this protein system is crucial for the overall regulation of the membrane affinity, the ability to induce the clustering of synaptic vesicles, and the tendency to self assemble into amyloid fibrils at the surface of biological membranes.
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Affiliation(s)
- Giuliana Fusco
- Department of Life Sciences, Imperial College London, South Kensington SW7 2AZ, London, UK
| | - Maximo Sanz-Hernandez
- Department of Life Sciences, Imperial College London, South Kensington SW7 2AZ, London, UK
| | - Alfonso De Simone
- Department of Life Sciences, Imperial College London, South Kensington SW7 2AZ, London, UK.
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Structural basis of synaptic vesicle assembly promoted by α-synuclein. Nat Commun 2016; 7:12563. [PMID: 27640673 PMCID: PMC5031799 DOI: 10.1038/ncomms12563] [Citation(s) in RCA: 179] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Accepted: 07/14/2016] [Indexed: 02/02/2023] Open
Abstract
α-synuclein (αS) is an intrinsically disordered protein whose fibrillar aggregates are the major constituents of Lewy bodies in Parkinson's disease. Although the specific function of αS is still unclear, a general consensus is forming that it has a key role in regulating the process of neurotransmitter release, which is associated with the mediation of synaptic vesicle interactions and assembly. Here we report the analysis of wild-type αS and two mutational variants linked to familial Parkinson's disease to describe the structural basis of a molecular mechanism enabling αS to induce the clustering of synaptic vesicles. We provide support for this 'double-anchor' mechanism by rationally designing and experimentally testing a further mutational variant of αS engineered to promote stronger interactions between synaptic vesicles. Our results characterize the nature of the active conformations of αS that mediate the clustering of synaptic vesicles, and indicate their relevance in both functional and pathological contexts.
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SALS-linked WT-SOD1 adopts a highly similar helical conformation as FALS-causing L126Z-SOD1 in a membrane environment. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:2223-2230. [PMID: 27378311 DOI: 10.1016/j.bbamem.2016.06.027] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 06/18/2016] [Accepted: 06/30/2016] [Indexed: 12/30/2022]
Abstract
So far >180 mutations have been identified within the 153-residue human SOD1 to cause familial amyotrophic lateral sclerosis (FALS), while wild-type (WT) SOD1 was intriguingly implicated in sporadic ALS (SALS). SOD1 mutations lead to ALS by a dominant gain of cytotoxicity but its mechanism still remains elusive. Previously functional studies have revealed that SOD1 mutants became unexpectedly associated with organelle membranes. Indeed we decoded that the ALS-causing truncation mutant L126Z-SOD1 with an elevated toxicity completely loses the ability to fold into the native β-barrel structure but acquire a novel capacity to interact with membranes by forming helices over hydrophobic/amphiphilic segments. Very recently, the abnormal insertion of SOD1 mutants into ER membrane has been functionally characterized to trigger ER stress, an initial event of a cascade of cell-specific damages in ALS pathogenesis. Here we attempted to understand the mechanism for gain of cytotoxicity of the WT SOD1. We obtained atomic-resolution evidence that the nascent WT SOD1 without metalation and disulfide bridge is also highly disordered as L126Z. Most importantly, it owns the same capacity in interacting with membranes by forming very similar helices over the first 125 residues identical to L126Z-SOD1, plus an additional hydrophobic helix over Leu144-Ala152. Our study thus implies that the WT and mutant SOD1 indeed converge on a common mechanism for gain of cytotoxicity by abnormally interacting with membranes. Moreover, any genetic/environmental factors which can delay or impair its maturation might act to transform SOD1 into cytotoxic forms with the acquired capacity to abnormally interact with membranes.
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Sengupta B, Yadav R, Sen P. Startling temperature effect on proteins when confined: single molecular level behaviour of human serum albumin in a reverse micelle. Phys Chem Chem Phys 2016; 18:14350-8. [DOI: 10.1039/c6cp00452k] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The present work reports the effect of confinement, and temperature therein, on the conformational fluctuation dynamics of domain-I of human serum albumin (HSA) by fluorescence correlation spectroscopy (FCS).
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Affiliation(s)
- Bhaswati Sengupta
- Department of Chemistry, Indian Institute of Technology Kanpur
- Kanpur
- India
| | - Rajeev Yadav
- Department of Chemistry, Indian Institute of Technology Kanpur
- Kanpur
- India
| | - Pratik Sen
- Department of Chemistry, Indian Institute of Technology Kanpur
- Kanpur
- India
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Ysselstein D, Joshi M, Mishra V, Griggs AM, Asiago JM, McCabe GP, Stanciu LA, Post CB, Rochet JC. Effects of impaired membrane interactions on α-synuclein aggregation and neurotoxicity. Neurobiol Dis 2015; 79:150-63. [PMID: 25931201 DOI: 10.1016/j.nbd.2015.04.007] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Revised: 04/20/2015] [Accepted: 04/21/2015] [Indexed: 01/08/2023] Open
Abstract
The post-mortem brains of individuals with Parkinson's disease (PD) and other synucleinopathy disorders are characterized by the presence of aggregated forms of the presynaptic protein α-synuclein (aSyn). Understanding the molecular mechanism of aSyn aggregation is essential for the development of neuroprotective strategies to treat these diseases. In this study, we examined how interactions between aSyn and phospholipid vesicles influence the protein's aggregation and toxicity to dopaminergic neurons. Two-dimensional NMR data revealed that two familial aSyn mutants, A30P and G51D, populated an exposed, membrane-bound conformer in which the central hydrophobic region was dissociated from the bilayer to a greater extent than in the case of wild-type aSyn. A30P and G51D had a greater propensity to undergo membrane-induced aggregation and elicited greater toxicity to primary dopaminergic neurons compared to the wild-type protein. In contrast, the non-familial aSyn mutant A29E exhibited a weak propensity to aggregate in the presence of phospholipid vesicles or to elicit neurotoxicity, despite adopting a relatively exposed membrane-bound conformation. Our findings suggest that the aggregation of exposed, membrane-bound aSyn conformers plays a key role in the protein's neurotoxicity in PD and other synucleinopathy disorders.
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Affiliation(s)
- Daniel Ysselstein
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA
| | - Mehul Joshi
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA
| | - Vartika Mishra
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA
| | - Amy M Griggs
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA
| | - Josephat M Asiago
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA
| | - George P McCabe
- Department of Statistics, Purdue University, West Lafayette, IN, USA
| | - Lia A Stanciu
- Schools of Materials Engineering and Biomedical Engineering, Purdue University, West Lafayette, IN, USA
| | - Carol Beth Post
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA
| | - Jean-Christophe Rochet
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA.
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DeForte S, Reddy KD, Uversky VN. Digested disorder, Quarterly intrinsic disorder digest (October-November-December, 2013). INTRINSICALLY DISORDERED PROTEINS 2015; 3:e984569. [PMID: 28293487 DOI: 10.4161/21690707.2014.984569] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Revised: 10/09/2014] [Accepted: 10/10/2014] [Indexed: 11/19/2022]
Abstract
This is the 4th issue of the Digested Disorder series that represents reader's digest of the scientific literature on intrinsically disordered proteins. The only 2 criteria for inclusion in this digest are the publication date (a paper should be published within the covered time frame) and topic (a paper should be dedicated to any aspect of protein intrinsic disorder). The current digest issue covers papers published during the fourth quarter of 2013; i.e. during the period of October, November, and December of 2013. Similar to previous issues, the papers are grouped hierarchically by topics they cover, and for each of the included paper a short description is given on its major findings.
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Affiliation(s)
- Shelly DeForte
- Department of Molecular Medicine; Morsani College of Medicine; University of South Florida; Tampa, FL USA; These authors contributed equally to this work
| | - Krishna D Reddy
- Department of Molecular Medicine; Morsani College of Medicine; University of South Florida; Tampa, FL USA; These authors contributed equally to this work
| | - Vladimir N Uversky
- Department of Molecular Medicine; Morsani College of Medicine; University of South Florida; Tampa, FL USA; USF Health Byrd Alzheimer Research Institute; Morsani College of Medicine; University of South Florida; Tampa, FL USA; Biology Department; Faculty of Science; King Abdulaziz University; Jeddah, Kingdom of Saudi Arabia; Laboratory of Structural Dynamics, Stability, and Folding of Proteins; Institute of Cytology; Russian Academy of Sciences; St. Petersburg, Russia; Institute for Biological Instrumentation; Russian Academy of Sciences; Moscow Region, Russia
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Lim L, Lee X, Song J. Mechanism for transforming cytosolic SOD1 into integral membrane proteins of organelles by ALS-causing mutations. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1848:1-7. [PMID: 25306968 DOI: 10.1016/j.bbamem.2014.10.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 09/07/2014] [Accepted: 10/02/2014] [Indexed: 02/06/2023]
Abstract
Mutations in superoxide dismutase 1 (SOD1) cause familial amyotrophic lateral sclerosis (FALS), while wild-type SOD1 has been implicated in sporadic ALS (SALS). SOD1 mutants are now recognized to acquire one or more toxicities that include their association with mitochondrial and endoplasmic reticulum membranes but the underlying structural mechanism remains unknown. Here we determine NMR conformations of both wild-type and a truncation mutant (L126Z) of SOD1 in aqueous solution and a membrane environment. The truncation mutant (which causes FALS at very low levels, indicating its elevated toxicity) is highly unstructured in solution, failing to adopt the β-barrel SOD1 native structure. Wild-type SOD1 is also highly unstructured upon reduction of disulfides and depletion of zinc. Most remarkably, both mutant and wild type adopt similar, highly-helical conformations in a membrane environment. Thus, either truncation or depletion of zinc is sufficient to eliminate the native β-barrel structure, and transform cytosolic SOD1 into membrane proteins energetically driven by forming amphiphilic helices in membranes. That zinc-deficiency is sufficient to produce a similar transformation in wild-type SOD1 implies that the wild-type and FALS-linked SOD1 mutants may trigger ALS by a common mechanism.
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Affiliation(s)
- Liangzhong Lim
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Republic of Singapore
| | - Xiaowen Lee
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Republic of Singapore
| | - Jianxing Song
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Republic of Singapore.
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Lokappa SB, Suk JE, Balasubramanian A, Samanta S, Situ AJ, Ulmer TS. Sequence and Membrane Determinants of the Random Coil–Helix Transition of α-Synuclein. J Mol Biol 2014; 426:2130-44. [DOI: 10.1016/j.jmb.2014.02.024] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Revised: 02/24/2014] [Accepted: 02/28/2014] [Indexed: 11/16/2022]
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