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Transthyretin Misfolding, A Fatal Structural Pathogenesis Mechanism. Int J Mol Sci 2021; 22:ijms22094429. [PMID: 33922648 PMCID: PMC8122960 DOI: 10.3390/ijms22094429] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 04/18/2021] [Accepted: 04/21/2021] [Indexed: 12/11/2022] Open
Abstract
Transthyretin (TTR) is an essential transporter of a thyroid hormone and a holo-retinol binding protein, found abundantly in human plasma and cerebrospinal fluid. In addition, this protein is infamous for its amyloidogenic propensity, causing various amyloidoses in humans, such as senile systemic amyloidosis, familial amyloid polyneuropathy, and familial amyloid cardiomyopathy. It has been known for over two decades that decreased stability of the native tetrameric conformation of TTR is the main cause of these diseases. Yet, mechanistic details on the amyloidogenic transformation of TTR were not clear until recent multidisciplinary investigations on various structural states of TTR. In this review, we discuss recent advancements in the structural understanding of TTR misfolding and amyloidosis processes. Special emphasis has been laid on the observations of novel structural features in various amyloidogenic species of TTR. In addition, proteolysis-induced fragmentation of TTR, a recently proposed mechanism facilitating TTR amyloidosis, has been discussed in light of its structural consequences and relevance to acknowledge the amyloidogenicity of TTR.
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Vivoli Vega M, Cascella R, Chen SW, Fusco G, De Simone A, Dobson CM, Cecchi C, Chiti F. The Toxicity of Misfolded Protein Oligomers Is Independent of Their Secondary Structure. ACS Chem Biol 2019; 14:1593-1600. [PMID: 31074957 DOI: 10.1021/acschembio.9b00324] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The self-assembly of proteins into structured fibrillar aggregates is associated with a range of neurodegenerative diseases, including Alzheimer's and Parkinson's diseases, in which an important cytotoxic role is thought to be played by small soluble oligomers accumulating during the aggregation process or released by mature fibrils. As the structural characteristics of such species and their links with toxicity are still not fully defined, we have compared six examples of preformed misfolded protein oligomers with different β-sheet content, as determined using Fourier transform infrared spectroscopy, and with different toxicity, as determined by three cellular readouts of cell viability. The results show the absence of any measurable correlation between the nature of their secondary structure and their cellular toxicity, both when comparing the six types of oligomers as a group and when comparing species in subgroups characterized by either the same size or the same exposure of hydrophobic moieties.
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Affiliation(s)
- Mirella Vivoli Vega
- Department of Experimental and Clinical Biomedical Sciences, Section of Biochemistry, University of Florence, 50134 Florence, Italy
| | - Roberta Cascella
- Department of Experimental and Clinical Biomedical Sciences, Section of Biochemistry, University of Florence, 50134 Florence, Italy
| | - Serene W Chen
- Department of Life Sciences, Imperial College London, London SW7 2AZ, U.K
| | - Giuliana Fusco
- Centre for Misfolding disease, Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, U.K
| | - Alfonso De Simone
- Department of Life Sciences, Imperial College London, London SW7 2AZ, U.K
| | - Christopher M. Dobson
- Centre for Misfolding disease, Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, U.K
| | - Cristina Cecchi
- Department of Experimental and Clinical Biomedical Sciences, Section of Biochemistry, University of Florence, 50134 Florence, Italy
| | - Fabrizio Chiti
- Department of Experimental and Clinical Biomedical Sciences, Section of Biochemistry, University of Florence, 50134 Florence, Italy
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3
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Oropesa-Nuñez R, Keshavan S, Dante S, Diaspro A, Mannini B, Capitini C, Cecchi C, Stefani M, Chiti F, Canale C. Toxic HypF-N Oligomers Selectively Bind the Plasma Membrane to Impair Cell Adhesion Capability. Biophys J 2019; 114:1357-1367. [PMID: 29590593 DOI: 10.1016/j.bpj.2018.02.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 01/27/2018] [Accepted: 02/02/2018] [Indexed: 12/29/2022] Open
Abstract
The deposition of fibrillar protein aggregates in human organs is the hallmark of several pathological states, including highly debilitating neurodegenerative disorders and systemic amyloidoses. It is widely accepted that small oligomers arising as intermediates in the aggregation process, released by fibrils, or growing in secondary nucleation steps are the cytotoxic entities in protein-misfolding diseases, notably neurodegenerative conditions. Increasing evidence indicates that cytotoxicity is triggered by the interaction between nanosized protein aggregates and cell membranes, even though little information on the molecular details of such interaction is presently available. In this work, we propose what is, to our knowledge, a new approach, based on the use of single-cell force spectroscopy applied to multifunctional substrates, to study the interaction between protein oligomers, cell membranes, and/or the extracellular matrix. We compared the interaction of single Chinese hamster ovary cells with two types of oligomers (toxic and nontoxic) grown from the N-terminal domain of the Escherichia coli protein HypF. We were able to quantify the affinity between both oligomer type and the cell membrane by measuring the mechanical work needed to detach the cells from the aggregates, and we could discriminate the contributions of the membrane lipid and protein fractions to such affinity. The fundamental role of the ganglioside GM1 in the membrane-oligomers interaction was also highlighted. Finally, we observed that the binding of toxic oligomers to the cell membrane significantly affects the functionality of adhesion molecules such as Arg-Gly-Asp binding integrins, and that this effect requires the presence of the negatively charged sialic acid moiety of GM1.
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Affiliation(s)
- Reinier Oropesa-Nuñez
- Department of Nanophysics, Istituto Italiano di Tecnologia, Genova, Italy; DIBRIS Department, University of Genova, Genova, Italy
| | - Sandeep Keshavan
- Department of Nanophysics, Istituto Italiano di Tecnologia, Genova, Italy; DIBRIS Department, University of Genova, Genova, Italy
| | - Silvia Dante
- Department of Nanophysics, Istituto Italiano di Tecnologia, Genova, Italy
| | - Alberto Diaspro
- Department of Nanophysics, Istituto Italiano di Tecnologia, Genova, Italy; Department of Physics, University of Genova, Genova, Italy.
| | - Benedetta Mannini
- Department of Chemistry, University of Cambridge, Cambridge, United Kingdom
| | - Claudia Capitini
- Section of Biochemistry, Department of Experimental and Clinical Biomedical Sciences, University of Florence, Firenze, Italy
| | - Cristina Cecchi
- Section of Biochemistry, Department of Experimental and Clinical Biomedical Sciences, University of Florence, Firenze, Italy
| | - Massimo Stefani
- Section of Biochemistry, Department of Experimental and Clinical Biomedical Sciences, University of Florence, Firenze, Italy
| | - Fabrizio Chiti
- Section of Biochemistry, Department of Experimental and Clinical Biomedical Sciences, University of Florence, Firenze, Italy
| | - Claudio Canale
- Department of Nanophysics, Istituto Italiano di Tecnologia, Genova, Italy; Department of Physics, University of Genova, Genova, Italy
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4
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Vibrational Approach to the Dynamics and Structure of Protein Amyloids. Molecules 2019; 24:molecules24010186. [PMID: 30621325 PMCID: PMC6337179 DOI: 10.3390/molecules24010186] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 12/31/2018] [Accepted: 01/02/2019] [Indexed: 02/06/2023] Open
Abstract
Amyloid diseases, including neurodegenerative diseases such as Alzheimer’s and Parkinson’s, are linked to a poorly understood progression of protein misfolding and aggregation events that culminate in tissue-selective deposition and human pathology. Elucidation of the mechanistic details of protein aggregation and the structural features of the aggregates is critical for a comprehensive understanding of the mechanisms of protein oligomerization and fibrillization. Vibrational spectroscopies, such as Fourier transform infrared (FTIR) and Raman, are powerful tools that are sensitive to the secondary structure of proteins and have been widely used to investigate protein misfolding and aggregation. We address the application of the vibrational approaches in recent studies of conformational dynamics and structural characteristics of protein oligomers and amyloid fibrils. In particular, introduction of isotope labelled carbonyl into a peptide backbone, and incorporation of the extrinsic unnatural amino acids with vibrational moieties on the side chain, have greatly expanded the ability of vibrational spectroscopy to obtain site-specific structural and dynamic information. The applications of these methods in recent studies of protein aggregation are also reviewed.
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Pellequer JL, Parot P, Navajas D, Kumar S, Svetličić V, Scheuring S, Hu J, Li B, Engler A, Sousa S, Lekka M, Szymoński M, Schillers H, Odorico M, Lafont F, Janel S, Rico F. Fifteen years of Servitude et Grandeur
to the application of a biophysical technique in medicine: The tale of AFMBioMed. J Mol Recognit 2018; 32:e2773. [DOI: 10.1002/jmr.2773] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
| | | | - Daniel Navajas
- Institute for Bioengineering of Catalonia and CIBER de Enfermedades Respiratorias; Universitat de Barcelona; Barcelona Spain
| | - Sanjay Kumar
- Departments of Bioengineering and Chemical & Biomolecular Engineering; University of California, Berkeley; Berkeley California USA
| | | | - Simon Scheuring
- Department of Anesthesiology, Department of Physiology and Biophysics; Weill Cornell Medicine; New York City New York USA
| | - Jun Hu
- Shanghai Advanced Research Institute; Chinese Academy of Sciences; Shanghai China
- Shanghai Institute of Applied Physics; Chinese Academy of Sciences; Shanghai China
| | - Bin Li
- Shanghai Advanced Research Institute; Chinese Academy of Sciences; Shanghai China
- Shanghai Institute of Applied Physics; Chinese Academy of Sciences; Shanghai China
| | - Adam Engler
- Department of Bioengineering; University of California San Diego; La Jolla California USA
| | - Susana Sousa
- i3S-Instituto de Investigação e Inovação em Saúde; Universidade do Porto; Porto Portugal
- INEB-Instituto de Engenharia Biomédica; Universidade do Porto; Porto Portugal
- ISEP-Instituto Superior de Engenharia; Politécnico do Porto; Portugal
| | - Małgorzata Lekka
- Institute of Nuclear Physics Polish Academy of Sciences; Kraków Poland
| | - Marek Szymoński
- Center for Nanometer-scale Science and Advanced Materials, NANOSAM, Faculty of Physics, Astronomy and Applied Computer Science; Jagiellonian University; Kraków Poland
| | | | - Michael Odorico
- Institut de Chimie Séparative de Marcoule (ICSM), CEA, CNRS, ENSCM, Univ Montpellier, Marcoule; Montpellier France
| | - Frank Lafont
- Center for Infection and Immunity of Lille, CNRS UMR 8204, INSERM U1019, CHU Lille, Institut Pasteur de Lille, Univ Lille; Lille France
| | - Sebastien Janel
- Center for Infection and Immunity of Lille, CNRS UMR 8204, INSERM U1019, CHU Lille, Institut Pasteur de Lille, Univ Lille; Lille France
| | - Felix Rico
- LAI, U1067, Aix-Marseille Univ, CNRS, INSERM; Marseille France
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Imaging and Manipulation of Extracellular Traps by Atomic Force Microscopy. Methods Mol Biol 2018. [PMID: 30374869 DOI: 10.1007/978-1-4939-8894-5_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Neutrophil extracellular traps (NETs) are part of an immunological response and one of the mechanisms by which neutrophils protect the host from pathogen invasion and proliferation. Notwithstanding their protective role, NETs have also been linked to the development of a variety of disorders, including cardiovascular and autoimmune diseases. Since the first reports on NETs in 2004 it has been possible to image NETs by a variety of imaging techniques. Despite this, such reports seldomly include contact probe methods, and therefore lack the unique insights such techniques typically provide. In fact, more than 10 years have passed since the discovery of NETs, and although their importance as part of a unique cellular response mechanism has become very clear, studies that attempt to address them by atomic force microscopy (AFM) remain very limited. Particularly striking is the almost absent information on the mechanical properties of NETs, and factors that may influence them. The fact that NETs are a particularly adhesive network of filaments poses a considerable technical challenge for contact probe methods and can limit advances involving either imaging or manipulation of NETs by AFM. The current set of protocols aims at aiding a knowledgeable AFM operator to obtain AFM images and to perform force spectroscopy experiments with such samples. A variety of different topics, including sample preparation and data analysis, are discussed.
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7
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Canale C, Oropesa-Nuñez R, Diaspro A, Dante S. Amyloid and membrane complexity: The toxic interplay revealed by AFM. Semin Cell Dev Biol 2017; 73:82-94. [PMID: 28860102 DOI: 10.1016/j.semcdb.2017.08.046] [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: 06/29/2017] [Revised: 08/21/2017] [Accepted: 08/25/2017] [Indexed: 01/05/2023]
Abstract
Lipid membranes play a fundamental role in the pathological development of protein misfolding diseases. Several pieces of evidence suggest that the lipid membrane could act as a catalytic surface for protein aggregation. Furthermore, a leading theory indicates the interaction between the cell membrane and misfolded oligomer species as the responsible for cytotoxicity, hence, for neurodegeneration in disorders such as Alzheimer's and Parkinson's disease. The definition of the mechanisms that drive the interaction between pathological protein aggregates and plasma membrane is fundamental for the development of effective therapies for a large class of diseases. Atomic force microscopy (AFM) has been employed to study how amyloid aggregates affect the cell physiological properties. Considerable efforts were spent to characterize the interaction with model systems, i.e., planar supported lipid bilayers, but some works also addressed the problem directly on living cells. Here, an overview of the main works involving the use of the AFM on both model system and living cells will be provided. Different kind of approaches will be presented, as well as the main results derived from the AFM analysis.
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Affiliation(s)
- Claudio Canale
- Department of Nanophysics. Istituto Italiano di Tecnologia. Via Morego 30, 16163 Genova, Italy; Department of Physics, University of Genova, via Dodecaneso 33, 16146 Genova, Italy.
| | - Reinier Oropesa-Nuñez
- Department of Nanophysics. Istituto Italiano di Tecnologia. Via Morego 30, 16163 Genova, Italy; DIBRIS Department, University of Genova, viale Causa 13, 16145, Genova, Italy
| | - Alberto Diaspro
- Department of Nanophysics. Istituto Italiano di Tecnologia. Via Morego 30, 16163 Genova, Italy; Department of Physics, University of Genova, via Dodecaneso 33, 16146 Genova, Italy
| | - Silvia Dante
- Department of Nanophysics. Istituto Italiano di Tecnologia. Via Morego 30, 16163 Genova, Italy
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Pires RH, Saraiva MJ, Damas AM, Kellermayer MSZ. Force spectroscopy reveals the presence of structurally modified dimers in transthyretin amyloid annular oligomers. J Mol Recognit 2016; 30. [PMID: 27808434 DOI: 10.1002/jmr.2587] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Revised: 09/21/2016] [Accepted: 09/30/2016] [Indexed: 12/17/2022]
Abstract
Toxicity in amyloidogenic protein misfolding disorders is thought to involve intermediate states of aggregation associated with the formation of amyloid fibrils. Despite their relevance, the heterogeneity and transience of these oligomers have placed great barriers in our understanding of their structural properties. Among amyloid intermediates, annular oligomers or annular protofibrils have raised considerable interest because they may contribute to a mechanism of cellular toxicity via membrane permeation. Here we investigated, by using AFM force spectroscopy, the structural detail of amyloid annular oligomers from transthyretin (TTR), a protein involved in systemic and neurodegenerative amyloidogenic disorders. Manipulation was performed in situ, in the absence of molecular handles and using persistence length-fit values to select relevant curves. Force curves reveal the presence of dimers in TTR annular oligomers that unfold via a series of structural intermediates. This is in contrast with the manipulation of native TTR that was more often manipulated over length scales compatible with a TTR monomer and without unfolding intermediates. Imaging and force spectroscopy data suggest that dimers are formed by the assembly of monomers in a head-to-head orientation with a nonnative interface along their β-strands. Furthermore, these dimers stack through nonnative contacts that may enhance the stability of the misfolded structure.
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Affiliation(s)
- Ricardo H Pires
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary.,Institute for Molecular and Cell Biology (IBMC), Porto, Portugal
| | - Maria J Saraiva
- Institute for Molecular and Cell Biology (IBMC), Porto, Portugal.,Instituto de Ciências Biomédicas de Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal
| | - Ana M Damas
- Institute for Molecular and Cell Biology (IBMC), Porto, Portugal.,Instituto de Ciências Biomédicas de Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal
| | - Miklós S Z Kellermayer
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary.,MTA-SE Molecular Biophysics Research Group, Budapest, Hungary
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9
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Influence of the Aqueous Environment on Protein Structure—A Plausible Hypothesis Concerning the Mechanism of Amyloidogenesis. ENTROPY 2016. [DOI: 10.3390/e18100351] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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10
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Taghavi F, Habibi-Rezaei M, Bohlooli M, Farhadi M, Goodarzi M, Movaghati S, Maghami P, Taghibiglou C, Amanlou M, Haertlé T, Moosavi-Movahedi A. Antiamyloidogenic Effects of Ellagic Acid on Human Serum Albumin Fibril Formation Induced by Potassium Sorbate and Glucose. J Mol Recognit 2016; 29:611-618. [DOI: 10.1002/jmr.2560] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Revised: 06/20/2016] [Accepted: 07/13/2016] [Indexed: 02/02/2023]
Affiliation(s)
- F. Taghavi
- Institute of Biochemistry and Biophysics; University of Tehran; Tehran Iran
- Faculty of Biological Science; Tarbiat Modares University; Tehran Iran
| | | | - M. Bohlooli
- Institute of Biochemistry and Biophysics; University of Tehran; Tehran Iran
- School of Science; University of Zabol; Zabol Iran
| | - M. Farhadi
- ENT-HNS Research Center; IRAN University of Medical Sciences (IUMS); Tehran Iran
| | - M. Goodarzi
- Institute of Biochemistry and Biophysics; University of Tehran; Tehran Iran
| | - S. Movaghati
- Institute of Biochemistry and Biophysics; University of Tehran; Tehran Iran
| | - P. Maghami
- Institute of Biochemistry and Biophysics; University of Tehran; Tehran Iran
| | - C. Taghibiglou
- Department of Pharmacology, College of Medicine; University of Saskatchewan; Saskatchewan Canada
| | - M. Amanlou
- Department of Medicinal Chemistry, Faculty of Pharmacy; Tehran University of Medical Sciences; Tehran Iran
| | - T. Haertlé
- UR 1268 Biopolymères Interactions Assemblages; INRA, équipe Fonctions et Interactions des Protéines; Nantes France
- Department of Animal Nutrition and Feed Management; Poznan University of Life Sciences; Poznań Poland
| | - A.A. Moosavi-Movahedi
- Institute of Biochemistry and Biophysics; University of Tehran; Tehran Iran
- Center of Excellence in Biothermodynamics; University of Tehran; Tehran Iran
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11
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Groenning M, Campos RI, Hirschberg D, Hammarström P, Vestergaard B. Considerably Unfolded Transthyretin Monomers Preceed and Exchange with Dynamically Structured Amyloid Protofibrils. Sci Rep 2015; 5:11443. [PMID: 26108284 PMCID: PMC4480009 DOI: 10.1038/srep11443] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Accepted: 04/23/2015] [Indexed: 11/09/2022] Open
Abstract
Despite numerous studies, a detailed description of the transthyretin (TTR) self-assembly mechanism and fibril structure in TTR amyloidoses remains unresolved. Here, using a combination of primarily small -angle X-ray scattering (SAXS) and hydrogen exchange mass spectrometry (HXMS) analysis, we describe an unexpectedly dynamic TTR protofibril structure which exchanges protomers with highly unfolded monomers in solution. The protofibrils only grow to an approximate final size of 2,900 kDa and a length of 70 nm and a comparative HXMS analysis of native and aggregated samples revealed a much higher average solvent exposure of TTR upon fibrillation. With SAXS, we reveal the continuous presence of a considerably unfolded TTR monomer throughout the fibrillation process, and show that a considerable fraction of the fibrillating protein remains in solution even at a late maturation state. Together, these data reveal that the fibrillar state interchanges with the solution state. Accordingly, we suggest that TTR fibrillation proceeds via addition of considerably unfolded monomers, and the continuous presence of amyloidogenic structures near the protofibril surface offers a plausible explanation for secondary nucleation. We argue that the presence of such dynamic structural equilibria must impact future therapeutic development strategies.
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Affiliation(s)
- Minna Groenning
- Department of Pharmacy and Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
- IFM – Department of Chemistry, Linköping University, Linköping, Sweden
| | - Raul I. Campos
- IFM – Department of Chemistry, Linköping University, Linköping, Sweden
| | - Daniel Hirschberg
- IFM – Department of Chemistry, Linköping University, Linköping, Sweden
| | - Per Hammarström
- IFM – Department of Chemistry, Linköping University, Linköping, Sweden
| | - Bente Vestergaard
- Department of Pharmacy and Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
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Mártonfalvi Z, Kellermayer M. Individual globular domains and domain unfolding visualized in overstretched titin molecules with atomic force microscopy. PLoS One 2014; 9:e85847. [PMID: 24465745 PMCID: PMC3896421 DOI: 10.1371/journal.pone.0085847] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Accepted: 12/03/2013] [Indexed: 01/29/2023] Open
Abstract
Titin is a giant elastomeric protein responsible for the generation of passive muscle force. Mechanical force unfolds titin's globular domains, but the exact structure of the overstretched titin molecule is not known. Here we analyzed, by using high-resolution atomic force microscopy, the structure of titin molecules overstretched with receding meniscus. The axial contour of the molecules was interrupted by topographical gaps with a mean width of 27.7 nm that corresponds well to the length of an unfolded globular (immunoglobulin and fibronectin) domain. The wide gap-width distribution suggests, however, that additional mechanisms such as partial domain unfolding and the unfolding of neighboring domain multimers may also be present. In the folded regions we resolved globules with an average spacing of 5.9 nm, which is consistent with a titin chain composed globular domains with extended interdomain linker regions. Topographical analysis allowed us to allocate the most distal unfolded titin region to the kinase domain, suggesting that this domain systematically unfolds when the molecule is exposed to overstretching forces. The observations support the prediction that upon the action of stretching forces the N-terminal ß-sheet of the titin kinase unfolds, thus exposing the enzyme's ATP-binding site and hence contributing to the molecule's mechanosensory function.
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Affiliation(s)
- Zsolt Mártonfalvi
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary
| | - Miklós Kellermayer
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary
- MTA-SE Molecular Biophysics Research Group, Semmelweis University, Budapest, Hungary
- * E-mail:
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13
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Relini A, Marano N, Gliozzi A. Misfolding of amyloidogenic proteins and their interactions with membranes. Biomolecules 2013; 4:20-55. [PMID: 24970204 PMCID: PMC4030986 DOI: 10.3390/biom4010020] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Revised: 12/13/2013] [Accepted: 12/17/2013] [Indexed: 01/07/2023] Open
Abstract
In this paper, we discuss amyloidogenic proteins, their misfolding, resulting structures, and interactions with membranes, which lead to membrane damage and subsequent cell death. Many of these proteins are implicated in serious illnesses such as Alzheimer’s disease and Parkinson’s disease. Misfolding of amyloidogenic proteins leads to the formation of polymorphic oligomers and fibrils. Oligomeric aggregates are widely thought to be the toxic species, however, fibrils also play a role in membrane damage. We focus on the structure of these aggregates and their interactions with model membranes. Study of interactions of amlyoidogenic proteins with model and natural membranes has shown the importance of the lipid bilayer in protein misfolding and aggregation and has led to the development of several models for membrane permeabilization by the resulting amyloid aggregates. We discuss several of these models: formation of structured pores by misfolded amyloidogenic proteins, extraction of lipids, interactions with receptors in biological membranes, and membrane destabilization by amyloid aggregates perhaps analogous to that caused by antimicrobial peptides.
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Affiliation(s)
- Annalisa Relini
- Department of Physics, University of Genoa, Genoa 16146, Italy.
| | - Nadia Marano
- Department of Physics, University of Genoa, Genoa 16146, Italy.
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Disulfide scrambling in superoxide dismutase 1 reduces its cytotoxic effect in cultured cells and promotes protein aggregation. PLoS One 2013; 8:e78060. [PMID: 24143259 PMCID: PMC3797058 DOI: 10.1371/journal.pone.0078060] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Accepted: 09/16/2013] [Indexed: 01/17/2023] Open
Abstract
Mutations in the gene coding for superoxide dismutase 1 (SOD1) are associated with familiar forms of the neurodegenerative disease amyotrophic lateral sclerosis (ALS). These mutations are believed to result in a “gain of toxic function”, leading to neuronal degeneration. The exact mechanism is still unknown, but misfolding/aggregation events are generally acknowledged as important pathological events in this process. Recently, we observed that demetallated apoSOD1, with cysteine 6 and 111 substituted for alanine, is toxic to cultured neuroblastoma cells. This toxicity depended on an intact, high affinity Zn2+ site. It was therefor contradictory to discover that wild-type apoSOD1 was not toxic, despite of its high affinity for Zn2+. This inconsistency was hypothesized to originate from erroneous disulfide formation involving C6 and C111. Using high resolution non-reducing SDS-PAGE, we have in this study demonstrated that the inability of wild-type apoSOD1 to cause cell death stems from formation of non-native intra-molecular disulfides. Moreover, monomeric apoSOD1 variants capable of such disulfide scrambling aggregated into ThT positive oligomers under physiological conditions without agitation. The oligomers were stabilized by inter-molecular disulfides and morphologically resembled what has in other neurodegenerative diseases been termed protofibrils. Disulfide scrambling thus appears to be an important event for misfolding and aggregation of SOD1, but may also be significant for protein function involving cysteines, e.g. mitochondrial import and copper loading.
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15
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Irwin JA, Wong HE, Kwon I. Different Fates of Alzheimer’s Disease Amyloid-β Fibrils Remodeled by Biocompatible Small Molecules. Biomacromolecules 2012; 14:264-74. [DOI: 10.1021/bm3016994] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Jacob A. Irwin
- Department
of Chemical Engineering and 2Institutes on Aging, University of Virginia, Charlottesville, Virginia 22904-4741, United
States
| | - H. Edward Wong
- Department
of Chemical Engineering and 2Institutes on Aging, University of Virginia, Charlottesville, Virginia 22904-4741, United
States
| | - Inchan Kwon
- Department
of Chemical Engineering and 2Institutes on Aging, University of Virginia, Charlottesville, Virginia 22904-4741, United
States
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16
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Adamcik J, Mezzenga R. Study of amyloid fibrils via atomic force microscopy. Curr Opin Colloid Interface Sci 2012. [DOI: 10.1016/j.cocis.2012.08.001] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Pires RH, Karsai Á, Saraiva MJ, Damas AM, Kellermayer MSZ. Distinct annular oligomers captured along the assembly and disassembly pathways of transthyretin amyloid protofibrils. PLoS One 2012; 7:e44992. [PMID: 22984597 PMCID: PMC3440338 DOI: 10.1371/journal.pone.0044992] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Accepted: 08/15/2012] [Indexed: 11/20/2022] Open
Abstract
Background Defects in protein folding may lead to severe degenerative diseases characterized by the appearance of amyloid fibril deposits. Cytotoxicity in amyloidoses has been linked to poration of the cell membrane that may involve interactions with amyloid intermediates of annular shape. Although annular oligomers have been detected in many amyloidogenic systems, their universality, function and molecular mechanisms of appearance are debated. Methodology/Principal Findings We investigated with high-resolution in situ atomic force microscopy the assembly and disassembly of transthyretin (TTR) amyloid protofibrils formed of the native protein by pH shift. Annular oligomers were the first morphologically distinct intermediates observed in the TTR aggregation pathway. Morphological analysis suggests that they can assemble into a double-stack of octameric rings with a 16±2 nm diameter, and displaying the tendency to form linear structures. According to light scattering data coupled to AFM imaging, annular oligomers appeared to undergo a collapse type of structural transition into spheroid oligomers containing 8–16 monomers. Disassembly of TTR amyloid protofibrils also resulted in the rapid appearance of annular oligomers but with a morphology quite distinct from that observed in the assembly pathway. Conclusions/Significance Our observations indicate that annular oligomers are key dynamic intermediates not only in the assembly but also in the disassembly of TTR protofibrils. The balance between annular and more compact forms of aggregation could be relevant for cytotoxicity in amyloidogenic disorders.
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Affiliation(s)
- Ricardo H. Pires
- Department of Biophysics and Radiation Biology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
- Institute for Molecular and Cell Biology, University of Porto, Porto, Portugal
- * E-mail: (RHP); (AMD); (MSZK)
| | - Árpád Karsai
- Department of Biophysics, University of Pécs, Pécs, Hungary
| | - Maria J. Saraiva
- Institute for Molecular and Cell Biology, University of Porto, Porto, Portugal
- Instituto de Ciências Biomédicas de Abel Salazar, University of Porto, Porto, Portugal
| | - Ana M. Damas
- Institute for Molecular and Cell Biology, University of Porto, Porto, Portugal
- Instituto de Ciências Biomédicas de Abel Salazar, University of Porto, Porto, Portugal
- * E-mail: (RHP); (AMD); (MSZK)
| | - Miklós S. Z. Kellermayer
- Department of Biophysics and Radiation Biology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
- * E-mail: (RHP); (AMD); (MSZK)
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Abstract
TTR (transthyretin) was found recently to possess proteolytic competency besides its well-known transport capabilities. It was described as a cryptic serine peptidase cleaving multiple natural substrates (including β-amyloid and apolipoprotein A-I) involved in diseases such as Alzheimer's disease and atherosclerosis. In the present study, we aimed to elucidate the catalytic machinery of TTR. All attempts to identify a catalytic serine residue were unsuccessful. However, metal chelators abolished TTR activity. Proteolytic inhibition by EDTA or 1,10-phenanthroline could be reversed with Zn2+ and Mn2+. These observations, supported by analysis of three-dimensional structures of TTR complexed with Zn2+, led to the hypothesis that TTR is a metallopeptidase. Site-directed mutagenesis of selected amino acids unambiguously confirmed this hypothesis. The TTR active site is inducible and constituted via a protein rearrangement resulting in ~7% of proteolytically active TTR at pH 7.4. The side chain of His88 is shifted near His90 and Glu92 establishing a Zn2+-chelating pattern HXHXE not found previously in any metallopeptidase and only conserved in TTR of humans and some other primates. Point mutations of these three residues yielded proteins devoid of proteolytic activity. Glu72 was identified as the general base involved in activation of the catalytic water. Our results unveil TTR as a metallopeptidase and define its catalytic machinery.
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