1
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Jacob MH, D’Souza RN, Lazar AI, Nau WM. Diffusion-Enhanced Förster Resonance Energy Transfer in Flexible Peptides: From the Haas-Steinberg Partial Differential Equation to a Closed Analytical Expression. Polymers (Basel) 2023; 15:polym15030705. [PMID: 36772006 PMCID: PMC9919848 DOI: 10.3390/polym15030705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 01/20/2023] [Accepted: 01/23/2023] [Indexed: 01/31/2023] Open
Abstract
In the huge field of polymer structure and dynamics, including intrinsically disordered peptides, protein folding, and enzyme activity, many questions remain that cannot be answered by methodology based on artificial intelligence, X-ray, or NMR spectroscopy but maybe by fluorescence spectroscopy. The theory of Förster resonance energy transfer (FRET) describes how an optically excited fluorophore transfers its excitation energy through space to an acceptor moiety-with a rate that depends on the distance between donor and acceptor. When the donor and acceptor moiety are conjugated to different sites of a flexible peptide chain or any other linear polymer, the pair could in principle report on chain structure and dynamics, on the site-to-site distance distribution, and on the diffusion coefficient of mutual site-to-site motion of the peptide chain. However, the dependence of FRET on distance distribution and diffusion is not defined by a closed analytical expression but by a partial differential equation (PDE), by the Haas-Steinberg equation (HSE), which can only be solved by time-consuming numerical methods. As a second complication, time-resolved FRET measurements have thus far been deemed necessary. As a third complication, the evaluation requires a computationally demanding but indispensable global analysis of an extended experimental data set. These requirements have made the method accessible to only a few experts. Here, we show how the Haas-Steinberg equation leads to a closed analytical expression (CAE), the Haas-Steinberg-Jacob equation (HSJE), which relates a diffusion-diagnosing parameter, the effective donor-acceptor distance, to the augmented diffusion coefficient, J, composed of the diffusion coefficient, D, and the photophysical parameters that characterize the used FRET method. The effective donor-acceptor distance is easily retrieved either through time-resolved or steady-state fluorescence measurements. Any global fit can now be performed in seconds and minimizes the sum-of-square difference between the experimental values of the effective distance and the values obtained from the HSJE. In summary, the HSJE can give a decisive advantage in applying the speed and sensitivity of FRET spectroscopy to standing questions of polymer structure and dynamics.
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2
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Giampà M, Amundarain MJ, Herrera MG, Tonali N, Dodero VI. Implementing Complementary Approaches to Shape the Mechanism of α-Synuclein Oligomerization as a Model of Amyloid Aggregation. Molecules 2021; 27:88. [PMID: 35011320 PMCID: PMC8747028 DOI: 10.3390/molecules27010088] [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: 11/30/2021] [Revised: 12/17/2021] [Accepted: 12/21/2021] [Indexed: 11/17/2022] Open
Abstract
The aggregation of proteins into amyloid fibers is linked to more than forty still incurable cellular and neurodegenerative diseases such as Parkinson's disease (PD), multiple system atrophy, Alzheimer's disease and type 2 diabetes, among others. The process of amyloid formation is a main feature of cell degeneration and disease pathogenesis. Despite being methodologically challenging, a complete understanding of the molecular mechanism of aggregation, especially in the early stages, is essential to find new biological targets for innovative therapies. Here, we reviewed selected examples on α-syn showing how complementary approaches, which employ different biophysical techniques and models, can better deal with a comprehensive study of amyloid aggregation. In addition to the monomer aggregation and conformational transition hypothesis, we reported new emerging theories regarding the self-aggregation of α-syn, such as the alpha-helix rich tetramer hypothesis, whose destabilization induce monomer aggregation; and the liquid-liquid phase separation hypothesis, which considers a phase separation of α-syn into liquid droplets as a primary event towards the evolution to aggregates. The final aim of this review is to show how multimodal methodologies provide a complete portrait of α-syn oligomerization and can be successfully extended to other protein aggregation diseases.
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Affiliation(s)
- Marco Giampà
- Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, Olav Kyrres Gate 9, 7491 Trondheim, Norway;
| | - María J. Amundarain
- Instituto de Física del Sur (IFISUR), Departamento de Física, Universidad Nacional del Sur (UNS), CONICET, Av. L. N. Alem 1253, Bahía Blanca B8000CPB, Argentina;
| | - Maria Georgina Herrera
- Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, 44801 Bochum, Germany;
| | - Nicolò Tonali
- BioCIS, CNRS, Faculté de Pharmacie, Université Paris-Saclay, 92290 Châtenay-Malabry, France
| | - Veronica I. Dodero
- Organic and Bioorganic Chemistry, Chemistry Department, Bielefeld University, Universitätstr. 25, 33615 Bielefeld, Germany
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3
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Chen J, Zaer S, Drori P, Zamel J, Joron K, Kalisman N, Lerner E, Dokholyan NV. The structural heterogeneity of α-synuclein is governed by several distinct subpopulations with interconversion times slower than milliseconds. Structure 2021; 29:1048-1064.e6. [PMID: 34015255 PMCID: PMC8419013 DOI: 10.1016/j.str.2021.05.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 03/12/2021] [Accepted: 04/30/2021] [Indexed: 11/22/2022]
Abstract
α-Synuclein plays an important role in synaptic functions by interacting with synaptic vesicle membrane, while its oligomers and fibrils are associated with several neurodegenerative diseases. The specific monomer structures that promote its membrane binding and self-association remain elusive due to its transient nature as an intrinsically disordered protein. Here, we use inter-dye distance distributions from bulk time-resolved Förster resonance energy transfer as restraints in discrete molecular dynamics simulations to map the conformational space of the α-synuclein monomer. We further confirm the generated conformational ensemble in orthogonal experiments utilizing far-UV circular dichroism and cross-linking mass spectrometry. Single-molecule protein-induced fluorescence enhancement measurements show that within this conformational ensemble, some of the conformations of α-synuclein are surprisingly stable, exhibiting conformational transitions slower than milliseconds. Our comprehensive analysis of the conformational ensemble reveals essential structural properties and potential conformations that promote its various functions in membrane interaction or oligomer and fibril formation.
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Affiliation(s)
- Jiaxing Chen
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA 17033, USA
| | - Sofia Zaer
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, Faculty of Mathematics & Science, The Edmond J. Safra Campus, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Paz Drori
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, Faculty of Mathematics & Science, The Edmond J. Safra Campus, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Joanna Zamel
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, Faculty of Mathematics & Science, The Edmond J. Safra Campus, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Khalil Joron
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, Faculty of Mathematics & Science, The Edmond J. Safra Campus, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Nir Kalisman
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, Faculty of Mathematics & Science, The Edmond J. Safra Campus, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Eitan Lerner
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, Faculty of Mathematics & Science, The Edmond J. Safra Campus, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel; The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel.
| | - Nikolay V Dokholyan
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA 17033, USA; Department of Biochemistry & Molecular Biology, Penn State College of Medicine, Hershey, PA 17033, USA; Departments of Chemistry and Biomedical Engineering, Pennsylvania State University, University Park, PA 16802, USA.
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4
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Abstract
Intrinsically disordered proteins play vital roles in biology, and their dysfunction contributes to many major disease states. These proteins remain challenging targets for rational ligand discovery or drug design because they are highly dynamic and fluctuate through a diverse set of conformations, frustrating structure-based approaches. To meet this challenge, we have developed protocols to efficiently identify active small molecule ligands of disordered proteins. Our approach utilizes enhanced sampling molecular dynamics and conformational analysis approaches optimized for disordered targets, coupled with computational docking and machine learning-based screens of compound libraries. By applying this protocol to an amyloid-forming segment of microtubule-associated protein tau, we successfully identified novel, chemically diverse tau ligands, including an inhibitor that delays the aggregation reaction in vitro without affecting the amount of aggregate formed at the steady state. Our results indicate that we have expanded the toolkit of protein aggregation inhibitors into new areas of chemical space and demonstrate the feasibility of our ligand discovery strategy.
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Affiliation(s)
- David W Baggett
- Department of Medicinal Chemistry , University of Washington , 1959 Northeast Pacific Street , Box 357610, Seattle , Washington 98195 , United States
| | - Abhinav Nath
- Department of Medicinal Chemistry , University of Washington , 1959 Northeast Pacific Street , Box 357610, Seattle , Washington 98195 , United States
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5
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Jacob MH, Ghosh I, D'Souza RN, Nau WM. Two Orders of Magnitude Variation of Diffusion-Enhanced Förster Resonance Energy Transfer in Polypeptide Chains. Polymers (Basel) 2018; 10:E1079. [PMID: 30961004 PMCID: PMC6403563 DOI: 10.3390/polym10101079] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 09/20/2018] [Accepted: 09/26/2018] [Indexed: 11/17/2022] Open
Abstract
A flexible peptide chain displays structural and dynamic properties that correspond to its folding and biological activity. These properties are mirrored in intrachain site-to-site distances and diffusion coefficients of mutual site-to-site motion. Both distance distribution and diffusion determine the extent of Förster resonance energy transfer (FRET) between two sites labeled with a FRET donor and acceptor. The relatively large Förster radii of traditional FRET methods (R₀ > 20 Å) lead to a fairly low contribution of diffusion. We introduced short-distance FRET (sdFRET) where Dbo, an asparagine residue conjugated to 2,3-diazabicyclo[2.2.2]octane, acts as acceptor paired with donors, such as naphtylalanine (NAla), tryptophan, 5-l-fluorotryptophan, or tyrosine. The Förster radii are always close to 10 Å, which makes sdFRET highly sensitive to diffusional motion. We recently found indications that the FRET enhancement caused by diffusion depends symmetrically on the product of the radiative fluorescence lifetime of the donor and the diffusion coefficient. In this study, we varied this product by two orders of magnitude, using both donors of different lifetime, NAla and FTrp, as well as a varying viscogen concentration, to corroborate this statement. We demonstrate the consequences of this relationship in evaluating the impact of viscogenic coadditives on peptide dimensions.
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Affiliation(s)
- Maik H Jacob
- Department of Life Sciences and Chemistry, Jacobs University Bremen, 28759 Bremen, Germany.
| | - Indrajit Ghosh
- Department of Life Sciences and Chemistry, Jacobs University Bremen, 28759 Bremen, Germany.
| | - Roy N D'Souza
- Department of Life Sciences and Chemistry, Jacobs University Bremen, 28759 Bremen, Germany.
| | - Werner M Nau
- Department of Life Sciences and Chemistry, Jacobs University Bremen, 28759 Bremen, Germany.
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6
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Teunissen AJP, Pérez-Medina C, Meijerink A, Mulder WJM. Investigating supramolecular systems using Förster resonance energy transfer. Chem Soc Rev 2018; 47:7027-7044. [PMID: 30091770 PMCID: PMC6441672 DOI: 10.1039/c8cs00278a] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Supramolecular systems have applications in areas as diverse as materials science, biochemistry, analytical chemistry, and nanomedicine. However, analyzing such systems can be challenging due to the wide range of time scales, binding strengths, distances, and concentrations at which non-covalent phenomena take place. Due to their versatility and sensitivity, Förster resonance energy transfer (FRET)-based techniques are excellently suited to meet such challenges. Here, we detail the ways in which FRET has been used to study non-covalent interactions in both synthetic and biological supramolecular systems. Among other topics, we examine methods to measure molecular forces, determine protein conformations, monitor assembly kinetics, and visualize in vivo drug release from nanoparticles. Furthermore, we highlight multiplex FRET techniques, discuss the field's limitations, and provide a perspective on new developments.
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Affiliation(s)
- Abraham J. P. Teunissen
- Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, 1470 Madison Avenue, New York, NY 10029, USA
| | - Carlos Pérez-Medina
- Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, 1470 Madison Avenue, New York, NY 10029, USA
| | - Andries Meijerink
- Department of Chemistry, Utrecht University, Princetonplein 1, 3584 CC Utrecht, The Netherlands
| | - Willem J. M. Mulder
- Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, 1470 Madison Avenue, New York, NY 10029, USA
- Department of Medical Biochemistry, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
- Laboratory of Chemical biology, Department of Biomedical Engineering and Institute for Complex Molecular systems, Eindhoven University of Technology, P.O. Box 513, 5600 MB, The Netherlands
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7
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Woodard J, Srivastava KR, Rahamim G, Grupi A, Hogan S, Witalka DJ, Nawrocki G, Haas E, Feig M, Lapidus LJ. Intramolecular Diffusion in α-Synuclein: It Depends on How You Measure It. Biophys J 2018; 115:1190-1199. [PMID: 30224053 DOI: 10.1016/j.bpj.2018.08.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Revised: 08/09/2018] [Accepted: 08/21/2018] [Indexed: 10/28/2022] Open
Abstract
Intramolecular protein diffusion, the motion of one part of the polypeptide chain relative to another part, is a fundamental aspect of protein folding and may modulate amyloidogenesis of disease-associated intrinsically disordered proteins. Much work has determined such diffusion coefficients using a variety of probes, but there has been an apparent discrepancy between measurements using long-range probes, such as fluorescence resonance energy transfer, and short-range probes, such as Trp-Cys quenching. In this work, we make both such measurements on the same protein, α-synuclein, and confirm that such discrepancy exists. Molecular dynamics simulations suggest that such differences result from a diffusion coefficient that depends on the spatial distance between probes. Diffusional estimates in good quantitative agreement with experiment are obtained by accounting for the distinct distance ranges probed by fluorescence resonance energy transfer and Trp-Cys quenching.
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Affiliation(s)
- Jaie Woodard
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan
| | - Kinshuk R Srivastava
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan
| | - Gil Rahamim
- The Goodman Faculty of Life Science, Bar-Ilan University, Ramat Gan, Israel
| | - Asaf Grupi
- The Goodman Faculty of Life Science, Bar-Ilan University, Ramat Gan, Israel
| | - Steven Hogan
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan
| | - David J Witalka
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan
| | - Grzegorz Nawrocki
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan
| | - Elisha Haas
- The Goodman Faculty of Life Science, Bar-Ilan University, Ramat Gan, Israel
| | - Michael Feig
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan
| | - Lisa J Lapidus
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan; Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan.
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8
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Graen T, Klement R, Grupi A, Haas E, Grubmüller H. Transient Secondary and Tertiary Structure Formation Kinetics in the Intrinsically Disordered State ofα-Synuclein from Atomistic Simulations. Chemphyschem 2018; 19:2507-2511. [DOI: 10.1002/cphc.201800504] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Indexed: 12/24/2022]
Affiliation(s)
- Timo Graen
- Theoretical and Computational Biophysics Department; Max Planck Institute for Biophysical Chemistry; 37077 Göttingen Germany
| | - Reinhard Klement
- Theoretical and Computational Biophysics Department; Max Planck Institute for Biophysical Chemistry; 37077 Göttingen Germany
| | - Asaf Grupi
- Physics Department; Bar-Ilan University; Ramat Gan 52900 Israel
| | - Elisha Haas
- The Goodman Faculty of Life Sciences; Bar-Ilan University; Ramat Gan 52900 Israel
| | - Helmut Grubmüller
- Theoretical and Computational Biophysics Department; Max Planck Institute for Biophysical Chemistry; 37077 Göttingen Germany
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9
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Jacob MH, D'Souza RN, Schwarzlose T, Wang X, Huang F, Haas E, Nau WM. Method-Unifying View of Loop-Formation Kinetics in Peptide and Protein Folding. J Phys Chem B 2018; 122:4445-4456. [PMID: 29617564 DOI: 10.1021/acs.jpcb.8b00879] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Protein folding can be described as a probabilistic succession of events in which the peptide chain forms loops closed by specific amino acid residue contacts, herein referred to as loop nodes. To measure loop rates, several photophysical methods have been introduced where a pair of optically active probes is incorporated at selected chain positions and the excited probe undergoes contact quenching (CQ) upon collision with the second probe. The quenching mechanisms involved triplet-triplet energy transfer, photoinduced electron transfer, and collision-induced fluorescence quenching, where the fluorescence of Dbo, an asparagine residue conjugated to 2,3-diazabicyclo[2.2.2]octane, is quenched by tryptophan. The discrepancy between the loop rates afforded from these three CQ techniques has, however, remained unresolved. In analyzing this discrepancy, we now report two short-distance FRET methods where Dbo acts as an energy acceptor in combination with tryptophan and naphtylalanine, two donors with largely different fluorescence lifetimes of 1.3 and 33 ns, respectively. Despite the different quenching mechanisms, the rates from FRET and CQ methods were, surprisingly, of comparable magnitude. This combination of FRET and CQ data led to a unifying physical model and to the conclusion that the rate of loop formation in folding reactions varies not only with the kind and number of residues that constitute the chain but also in particular with the size and properties of the residues that constitute the loop node.
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Affiliation(s)
- Maik H Jacob
- Department of Life Sciences and Chemistry , Jacobs University Bremen , Bremen 28759 , Germany
| | - Roy N D'Souza
- Department of Life Sciences and Chemistry , Jacobs University Bremen , Bremen 28759 , Germany
| | - Thomas Schwarzlose
- Department of Life Sciences and Chemistry , Jacobs University Bremen , Bremen 28759 , Germany
| | - Xiaojuan Wang
- Center for Biotechnology and Bioengineering , China University of Petroleum , Qingdao , Shandong , China 266580
| | - Fang Huang
- Center for Biotechnology and Bioengineering , China University of Petroleum , Qingdao , Shandong , China 266580
| | - Elisha Haas
- Department of Life Science , Bar Ilan University , Ramat Gan 5290002 , Israel
| | - Werner M Nau
- Department of Life Sciences and Chemistry , Jacobs University Bremen , Bremen 28759 , Germany.,Center for Biotechnology and Bioengineering , China University of Petroleum , Qingdao , Shandong , China 266580
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10
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Sahay S, Krishnamoorthy G, Maji SK. Site-specific structural dynamics ofα-Synuclein revealed by time-resolved fluorescence spectroscopy: a review. Methods Appl Fluoresc 2016; 4:042002. [DOI: 10.1088/2050-6120/4/4/042002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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11
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Haney CM, Wissner RF, Warner JB, Wang YJ, Ferrie JJ, J Covell D, Karpowicz RJ, Lee VMY, Petersson EJ. Comparison of strategies for non-perturbing labeling of α-synuclein to study amyloidogenesis. Org Biomol Chem 2016; 14:1584-92. [PMID: 26695131 PMCID: PMC4733880 DOI: 10.1039/c5ob02329g] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Characterization of the amyloidogenic Parkinson's disease protein α-synuclein (αS) has proven difficult due to its structural plasticity. Here, we present a number of complementary methods to site-specifically introduce fluorescent probes to examine αS fibril formation and cellular uptake. By using various combinations of conventional Cys modification, amber codon suppression, transferase mediated N-terminal modification, and native chemical ligation, several variants of singly- and doubly-labeled αS were produced. We validated the nonperturbative nature of the label by a combination of in vitro aggregation kinetics measurements and imaging of the resulting fibrils. The labeled αS can then be used to monitor conformational changes during fibril formation or cellular uptake of αS fibrils in models of disease propagation.
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Affiliation(s)
- Conor M Haney
- Department of Chemistry, University of Pennsylvania, 213 South 34th Street, Philadelphia, PA 19104, USA.
| | - Rebecca F Wissner
- Department of Chemistry, University of Pennsylvania, 213 South 34th Street, Philadelphia, PA 19104, USA.
| | - John B Warner
- Department of Chemistry, University of Pennsylvania, 213 South 34th Street, Philadelphia, PA 19104, USA.
| | - Yanxin J Wang
- Department of Chemistry, University of Pennsylvania, 213 South 34th Street, Philadelphia, PA 19104, USA.
| | - John J Ferrie
- Department of Chemistry, University of Pennsylvania, 213 South 34th Street, Philadelphia, PA 19104, USA.
| | - Dustin J Covell
- Center for Neurodegenerative Disease Research, University of Pennsylvania, 3600 Spruce Street, Philadelphia, PA 19104, USA
| | - Richard J Karpowicz
- Center for Neurodegenerative Disease Research, University of Pennsylvania, 3600 Spruce Street, Philadelphia, PA 19104, USA
| | - Virginia M-Y Lee
- Center for Neurodegenerative Disease Research, University of Pennsylvania, 3600 Spruce Street, Philadelphia, PA 19104, USA
| | - E James Petersson
- Department of Chemistry, University of Pennsylvania, 213 South 34th Street, Philadelphia, PA 19104, USA.
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12
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Rahamim G, Chemerovski-Glikman M, Rahimipour S, Amir D, Haas E. Resolution of Two Sub-Populations of Conformers and Their Individual Dynamics by Time Resolved Ensemble Level FRET Measurements. PLoS One 2015; 10:e0143732. [PMID: 26699718 PMCID: PMC4689530 DOI: 10.1371/journal.pone.0143732] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 11/08/2015] [Indexed: 11/19/2022] Open
Abstract
Most active biopolymers are dynamic structures; thus, ensembles of such molecules should be characterized by distributions of intra- or intermolecular distances and their fast fluctuations. A method of choice to determine intramolecular distances is based on Förster resonance energy transfer (FRET) measurements. Major advances in such measurements were achieved by single molecule FRET measurements. Here, we show that by global analysis of the decay of the emission of both the donor and the acceptor it is also possible to resolve two sub-populations in a mixture of two ensembles of biopolymers by time resolved FRET (trFRET) measurements at the ensemble level. We show that two individual intramolecular distance distributions can be determined and characterized in terms of their individual means, full width at half maximum (FWHM), and two corresponding diffusion coefficients which reflect the rates of fast ns fluctuations within each sub-population. An important advantage of the ensemble level trFRET measurements is the ability to use low molecular weight small-sized probes and to determine nanosecond fluctuations of the distance between the probes. The limits of the possible resolution were first tested by simulation and then by preparation of mixtures of two model peptides. The first labeled polypeptide was a relatively rigid Pro7 and the second polypeptide was a flexible molecule consisting of (Gly-Ser)7 repeats. The end to end distance distributions and the diffusion coefficients of each peptide were determined. Global analysis of trFRET measurements of a series of mixtures of polypeptides recovered two end-to-end distance distributions and associated intramolecular diffusion coefficients, which were very close to those determined from each of the pure samples. This study is a proof of concept study demonstrating the power of ensemble level trFRET based methods in resolution of subpopulations in ensembles of flexible macromolecules.
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Affiliation(s)
- Gil Rahamim
- The Goodman Faculty of Life Sciences Bar Ilan University, Ramat Gan Israel 52900
| | | | - Shai Rahimipour
- Department of Chemistry, Bar-Ilan University, Ramat Gan Israel 52900
| | - Dan Amir
- The Goodman Faculty of Life Sciences Bar Ilan University, Ramat Gan Israel 52900
| | - Elisha Haas
- The Goodman Faculty of Life Sciences Bar Ilan University, Ramat Gan Israel 52900
- * E-mail:
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13
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Reif MM, Oostenbrink C. Molecular dynamics simulation of configurational ensembles compatible with experimental FRET efficiency data through a restraint on instantaneous FRET efficiencies. J Comput Chem 2014; 35:2319-32. [PMID: 25338770 DOI: 10.1002/jcc.23756] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2014] [Revised: 09/02/2014] [Accepted: 09/21/2014] [Indexed: 01/19/2023]
Abstract
Förster resonance energy transfer (FRET) measurements are widely used to investigate (bio)molecular interactions or/and association. FRET efficiencies, the primary data obtained from this method, give, in combination with the common assumption of isotropic chromophore orientation, detailed insight into the lengthscale of molecular phenomena. This study illustrates the application of a FRET efficiency restraint during classical atomistic molecular dynamics simulations of a mutant mastoparan X peptide in either water or 7 M aqueous urea. The restraint forces acting on the donor and acceptor chromophores ensure that the sampled peptide configurational ensemble satisfies the experimental primary data by modifying interchromophore separation and chromophore transition dipole moment orientations. By means of a conformational cluster analysis, it is seen that indeed different configurational ensembles may be sampled without and with application of the restraint. In particular, while the FRET efficiency and interchromophore distances monitored in an unrestrained simulation may differ from the experimentally-determined values, they can be brought in agreement with experimental data through usage of the FRET efficiency restraining potential. Furthermore, the present results suggest that the assumption of isotropic chromophore orientation is not always justified. The FRET efficiency restraint allows the generation of configurational ensembles that may not be accessible with unrestrained simulations, and thereby supports a meaningful interpretation of experimental FRET results in terms of the underlying molecular degrees of freedom. Thus, it offers an additional tool to connect the realms of computer and wet-lab experimentation.
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Affiliation(s)
- Maria M Reif
- Department of Material Sciences and Process Engineering, Institute for Molecular Modeling and Simulation, University of Natural Resources and Life Sciences, Vienna
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14
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Nath A, Sammalkorpi M, DeWitt DC, Trexler AJ, Elbaum-Garfinkle S, O'Hern CS, Rhoades E. The conformational ensembles of α-synuclein and tau: combining single-molecule FRET and simulations. Biophys J 2013. [PMID: 23199922 DOI: 10.1016/j.bpj.2012.09.032] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
Intrinsically disordered proteins (IDPs) are increasingly recognized for their important roles in a range of biological contexts, both in normal physiological function and in a variety of devastating human diseases. However, their structural characterization by traditional biophysical methods, for the purposes of understanding their function and dysfunction, has proved challenging. Here, we investigate the model IDPs α-Synuclein (αS) and tau, that are involved in major neurodegenerative conditions including Parkinson's and Alzheimer's diseases, using excluded volume Monte Carlo simulations constrained by pairwise distance distributions from single-molecule fluorescence measurements. Using this, to our knowledge, novel approach we find that a relatively small number of intermolecular distance constraints are sufficient to accurately determine the dimensions and polymer conformational statistics of αS and tau in solution. Moreover, this method can detect local changes in αS and tau conformations that correlate with enhanced aggregation. Constrained Monte Carlo simulations produce ensembles that are in excellent agreement both with experimental measurements on αS and tau and with all-atom, explicit solvent molecular dynamics simulations of αS, with much lower configurational sampling requirements and computational expense.
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Affiliation(s)
- Abhinav Nath
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA.
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15
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Perera AS, Wang H, Shrestha TB, Troyer DL, Bossmann SH. Nanoscopic surfactant behavior of the porin MspA in aqueous media. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2013; 4:278-284. [PMID: 23766950 PMCID: PMC3678404 DOI: 10.3762/bjnano.4.30] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Accepted: 04/12/2013] [Indexed: 06/02/2023]
Abstract
The mycobacterial porin MspA is one of the most stable channel proteins known to date. MspA forms vesicles at low concentrations in aqueous buffers. Evidence from dynamic light scattering, transmission electron microscopy and zeta-potential measurements by electrophoretic light scattering indicate that MspA behaves like a nanoscale surfactant. The extreme thermostability of MspA allows these investigations to be carried out at temperatures as high as 343 K, at which most other proteins would quickly denature. The principles of vesicle formation of MspA as a function of temperature and the underlying thermodynamic factors are discussed here. The results obtained provide crucial evidence in support of the hypothesis that, during vesicle formation, nanoscopic surfactant molecules, such as MspA, deviate from the principles underlined in classical surface chemistry.
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Affiliation(s)
- Ayomi S Perera
- Kansas State University, Department of Chemistry, CBC Building 201, Manhattan, KS 66506, USA
| | - Hongwang Wang
- Kansas State University, Department of Chemistry, CBC Building 201, Manhattan, KS 66506, USA
| | - Tej B Shrestha
- Kansas State University, Department of Anatomy & Physiology, Coles 130, Manhattan, KS 66506, USA
| | - Deryl L Troyer
- Kansas State University, Department of Anatomy & Physiology, Coles 130, Manhattan, KS 66506, USA
| | - Stefan H Bossmann
- Kansas State University, Department of Chemistry, CBC Building 201, Manhattan, KS 66506, USA
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16
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Nath A, Rhoades E. A flash in the pan: dissecting dynamic amyloid intermediates using fluorescence. FEBS Lett 2013; 587:1096-105. [PMID: 23458258 DOI: 10.1016/j.febslet.2013.02.044] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Revised: 02/21/2013] [Accepted: 02/22/2013] [Indexed: 12/15/2022]
Abstract
Several widespread and severe degenerative diseases are characterized by the deposition of amyloid protein aggregates in affected tissues. While there is great interest in the complete description of the aggregation pathway of the proteins involved, a molecular level understanding is hindered by the complexity of the self-assembly process. In particular, the early stages of aggregation, where dynamic, heterogeneous and often toxic intermediates are populated, are resistant to high-resolution structural characterization. Fluorescence spectroscopy is a powerful and versatile tool for such analysis. In this review, we survey its application to provide residue-specific information about amyloid intermediate states for three selected proteins: IAPP, α-synuclein, and tau.
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Affiliation(s)
- Abhinav Nath
- Department of Molecular Biophysics & Biochemistry, Yale University, New Haven, CT, USA
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17
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Jacob MH, Dsouza RN, Ghosh I, Norouzy A, Schwarzlose T, Nau WM. Diffusion-Enhanced Förster Resonance Energy Transfer and the Effects of External Quenchers and the Donor Quantum Yield. J Phys Chem B 2012; 117:185-98. [DOI: 10.1021/jp310381f] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Maik H. Jacob
- School of Engineering and Science, Jacobs University Bremen, Campus Ring 1, D-28759, Bremen, Germany
| | - Roy N. Dsouza
- School of Engineering and Science, Jacobs University Bremen, Campus Ring 1, D-28759, Bremen, Germany
| | - Indrajit Ghosh
- School of Engineering and Science, Jacobs University Bremen, Campus Ring 1, D-28759, Bremen, Germany
| | - Amir Norouzy
- School of Engineering and Science, Jacobs University Bremen, Campus Ring 1, D-28759, Bremen, Germany
| | - Thomas Schwarzlose
- School of Engineering and Science, Jacobs University Bremen, Campus Ring 1, D-28759, Bremen, Germany
| | - Werner M. Nau
- School of Engineering and Science, Jacobs University Bremen, Campus Ring 1, D-28759, Bremen, Germany
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18
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Drescher M, Huber M, Subramaniam V. Hunting the Chameleon: Structural Conformations of the Intrinsically Disordered Protein Alpha-Synuclein. Chembiochem 2012; 13:761-8. [DOI: 10.1002/cbic.201200059] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Indexed: 12/14/2022]
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Aggregation of α-synuclein is kinetically controlled by intramolecular diffusion. Proc Natl Acad Sci U S A 2012; 109:2336-41. [PMID: 22308332 DOI: 10.1073/pnas.1109526109] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We hypothesize that the first step of aggregation of disordered proteins, such as α-synuclein, is controlled by the rate of backbone reconfiguration. When reconfiguration is fast, bimolecular association is not stable, but as reconfiguration slows, association is more stable and subsequent aggregation is faster. To investigate this hypothesis, we have measured the rate of intramolecular diffusion in α-synuclein, a protein involved in Parkinson's disease, under solvent conditions that accelerate or decelerate aggregation. Using the method of tryptophan-cysteine (Trp-Cys) quenching, the rate of intramolecular contact is measured in four different loops along the chain length. This intrinsically disordered protein is highly diffusive at low temperature at neutral pH, when aggregation is slow, and compacts and diffuses more slowly at high temperature or low pH, when aggregation is rapid. Diffusion also slows with the disease mutation A30P. This work provides unique insights into the earliest steps of α-synuclein aggregation pathway and should provide the basis for the development of drugs that can prevent aggregation at the initial stage.
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20
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Abstract
The main structural characteristic of intrinsically disordered proteins (IDPs) or intrinsically disordered regions of globular proteins is that they exist as ensembles of multiple conformers which can continuously interconvert, and at times, form ensembles of a more restricted number of conformers. Characterization of the disordered state and transitions to partially or fully ordered states of such ensembles must be expressed in statistical terms, i.e., determination of probability distributions of the various conformers. This can be achieved by measurements of time-resolved dynamic non-radiative excitation energy transfer within ensembles of site-specifically labeled IDP molecules. Distributions of intramolecular segmental end-to-end distances and their fast fluctuations can be determined and fast and slow conformational transitions within selected sections of the molecule can be monitored and analyzed.
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Affiliation(s)
- Elisha Haas
- The Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel.
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