1
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Frommer J, Oppenheimer R, Allott BM, Núñez-Pertíñez S, Wilks TR, Cox LR, Bath J, O'Reilly RK, Turberfield AJ. A New Architecture for DNA-Templated Synthesis in Which Abasic Sites Protect Reactants from Degradation. Angew Chem Int Ed Engl 2024; 63:e202317482. [PMID: 38346169 DOI: 10.1002/anie.202317482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Indexed: 03/01/2024]
Abstract
The synthesis of artificial sequence-defined polymers that match and extend the functionality of proteins is an important goal in materials science. One way of achieving this is to program a sequence of chemical reactions between precursor building blocks by means of attached oligonucleotide adapters. However, hydrolysis of the reactive building blocks has so far limited the length and yield of product that can be obtained using DNA-templated reactions. Here, we report an architecture for DNA-templated synthesis in which reactants are tethered at internal abasic sites on opposite strands of a DNA duplex. We show that an abasic site within a DNA duplex can protect a nearby thioester from degradation, significantly increasing the yield of a DNA-templated reaction. This protective effect has the potential to overcome the challenges associated with programmable, sequence-controlled synthesis of long non-natural polymers by extending the lifetime of the reactive building blocks.
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Affiliation(s)
- Jennifer Frommer
- School of Chemistry, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom
| | - Robert Oppenheimer
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford, OX1 3PU, UK
| | - Benjamin M Allott
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford, OX1 3PU, UK
- Kavli Institute for Nanoscience Discovery, University of Oxford, Dorothy Crowfoot, Hodgkin Building, South Parks Road, Oxford, OX1 3QU, UK
| | - Samuel Núñez-Pertíñez
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford, OX1 3PU, UK
- Kavli Institute for Nanoscience Discovery, University of Oxford, Dorothy Crowfoot, Hodgkin Building, South Parks Road, Oxford, OX1 3QU, UK
| | - Thomas R Wilks
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford, OX1 3PU, UK
- Kavli Institute for Nanoscience Discovery, University of Oxford, Dorothy Crowfoot, Hodgkin Building, South Parks Road, Oxford, OX1 3QU, UK
| | - Liam R Cox
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford, OX1 3PU, UK
- Kavli Institute for Nanoscience Discovery, University of Oxford, Dorothy Crowfoot, Hodgkin Building, South Parks Road, Oxford, OX1 3QU, UK
| | - Jonathan Bath
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford, OX1 3PU, UK
- Kavli Institute for Nanoscience Discovery, University of Oxford, Dorothy Crowfoot, Hodgkin Building, South Parks Road, Oxford, OX1 3QU, UK
| | - Rachel K O'Reilly
- School of Chemistry, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom
| | - Andrew J Turberfield
- Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford, OX1 3PU, UK
- Kavli Institute for Nanoscience Discovery, University of Oxford, Dorothy Crowfoot, Hodgkin Building, South Parks Road, Oxford, OX1 3QU, UK
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2
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Clark BS, Silvernail I, Gordon K, Castaneda JF, Morgan AN, Rolband LA, LeBlanc SJ. A practical guide to time-resolved fluorescence microscopy and spectroscopy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.25.577300. [PMID: 38586000 PMCID: PMC10996486 DOI: 10.1101/2024.01.25.577300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Time-correlated single photon counting (TCSPC) coupled with confocal microscopy is a versatile biophysical tool that enables real-time monitoring of biomolecular dynamics across many timescales. With TCSPC, Fluorescence correlation spectroscopy (FCS) and pulsed interleaved excitation-Förster resonance energy transfer (PIE-FRET) are collected simultaneously on diffusing molecules to extract diffusion characteristics and proximity information. This article is a guide to calibrating FCS and PIE-FRET measurements with several biological samples including liposomes, streptavidin-coated quantum dots, proteins, and nucleic acids for reliable determination of diffusion coefficients and FRET efficiency. The FRET efficiency results are also compared to surface-attached single molecules using fluorescence lifetime imaging microscopy (FLIM-FRET). Combining the methods is a powerful approach to revealing mechanistic details of biological processes and pathways.
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3
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Das AK, Mandal AK, Mondal T. Probing Single-molecule Interfacial Electron Transfer Inside a Single Lipid Vesicle. J Fluoresc 2023; 33:2229-2239. [PMID: 37004622 DOI: 10.1007/s10895-023-03211-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 03/13/2023] [Indexed: 04/04/2023]
Abstract
Inhomogeneity in single molecule electron transfer at the surface of lipid in a single vesicle has been explored by single molecule spectroscopic technique. In our study we took Di-methyl aniline (DMA), as the electron donor (D) and three different organic dyes as acceptor. These dyes are C153, C480 and C152 and they reside in different regions in the vesicle depending upon their preference of residence. For each probe, we found fluctuations in the single-molecule fluorescence decay, which are attributed to the variation in the reactivity of interfacial electron transfer. We found a non-exponential auto-correlation fluctuation of the intensity of the probe, which is ascribed to the kinetic disorder in the rate of electron transfer. We have also shown the power law distribution of the dark state (off time), which obeys the levy's statistics. We found a shift in lifetime distribution for the probe (C153) from 3.9 ns to 3.5 ns. This observed quenching is due to the dynamic electron transfer. We observed the kinetic disorderness in the electron transfer reaction for each dye. This source of fluctuation in electron transfer rate may be ascribed to the inherent fluctuation, occurring on the time scale of ~ 1.1 ms (for C153) of the vesicle, containing lipids.
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Affiliation(s)
- Atanu Kumar Das
- Department of Physics, Kandi Raj College, Murshidabad, West Bengal, 742137, India
| | - Amit Kumar Mandal
- Department of Chemistry, Bankura University, Bankura, West Bengal, 722155, India
| | - Tridib Mondal
- Department of Chemistry, Sukanta Mahavidyalaya, Jalpaiguri, West Bengal, 735210, India.
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4
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Real-time single-molecule 3D tracking in E. coli based on cross-entropy minimization. Nat Commun 2023; 14:1336. [PMID: 36906676 PMCID: PMC10008558 DOI: 10.1038/s41467-023-36879-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 02/17/2023] [Indexed: 03/13/2023] Open
Abstract
Reaching sub-millisecond 3D tracking of individual molecules in living cells would enable direct measurements of diffusion-limited macromolecular interactions under physiological conditions. Here, we present a 3D tracking principle that approaches the relevant regime. The method is based on the true excitation point spread function and cross-entropy minimization for position localization of moving fluorescent reporters. Tests on beads moving on a stage reaches 67 nm lateral and 109 nm axial precision with a time resolution of 0.84 ms at a photon count rate of 60 kHz; the measurements agree with the theoretical and simulated predictions. Our implementation also features a method for microsecond 3D PSF positioning and an estimator for diffusion analysis of tracking data. Finally, we successfully apply these methods to track the Trigger Factor protein in living bacterial cells. Overall, our results show that while it is possible to reach sub-millisecond live-cell single-molecule tracking, it is still hard to resolve state transitions based on diffusivity at this time scale.
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5
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Shrinking gate fluorescence correlation spectroscopy yields equilibrium constants and separates photophysics from structural dynamics. Proc Natl Acad Sci U S A 2023; 120:e2211896120. [PMID: 36652471 PMCID: PMC9942831 DOI: 10.1073/pnas.2211896120] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Fluorescence correlation spectroscopy is a versatile tool for studying fast conformational changes of biomolecules especially when combined with Förster resonance energy transfer (FRET). Despite the many methods available for identifying structural dynamics in FRET experiments, the determination of the forward and backward transition rate constants and thereby also the equilibrium constant is difficult when two intensity levels are involved. Here, we combine intensity correlation analysis with fluorescence lifetime information by including only a subset of photons in the autocorrelation analysis based on their arrival time with respect to the excitation pulse (microtime). By fitting the correlation amplitude as a function of microtime gate, the transition rate constants from two fluorescence-intensity level systems and the corresponding equilibrium constants are obtained. This shrinking-gate fluorescence correlation spectroscopy (sg-FCS) approach is demonstrated using simulations and with a DNA origami-based model system in experiments on immobilized and freely diffusing molecules. We further show that sg-FCS can distinguish photophysics from dynamic intensity changes even if a dark quencher, in this case graphene, is involved. Finally, we unravel the mechanism of a FRET-based membrane charge sensor indicating the broad potential of the method. With sg-FCS, we present an algorithm that does not require prior knowledge and is therefore easily implemented when an autocorrelation analysis is carried out on time-correlated single-photon data.
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6
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Maus H, Hinze G, Hammerschmidt SJ, Basché T, Schirmeister T. A competition smFRET assay to study ligand-induced conformational changes of the dengue virus protease. Protein Sci 2023; 32:e4526. [PMID: 36461913 PMCID: PMC9793963 DOI: 10.1002/pro.4526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 11/07/2022] [Accepted: 11/29/2022] [Indexed: 12/05/2022]
Abstract
Ligand binding to proteins often is accompanied by conformational transitions. Here, we describe a competition assay based on single molecule Förster resonance energy transfer (smFRET) to investigate the ligand-induced conformational changes of the dengue virus (DENV) NS2B-NS3 protease, which can adopt at least two different conformations. First, a competitive ligand was used to stabilize the closed conformation of the protease. Subsequent addition of the allosteric inhibitor reduced the fraction of the closed conformation and simultaneously increased the fraction of the open conformation, demonstrating that the allosteric inhibitor stabilizes the open conformation. In addition, the proportions of open and closed conformations at different concentrations of the allosteric inhibitor were used to determine its binding affinity to the protease. The KD value observed is in accordance with the IC50 determined in the fluorometric assay. Our novel approach appears to be a valuable tool to study conformational transitions of other proteases and enzymes.
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Affiliation(s)
- Hannah Maus
- Institute for Pharmaceutical and Biomedical Sciences, Johannes Gutenberg‐UniversityMainzGermany
| | - Gerald Hinze
- Department of ChemistryJohannes Gutenberg‐UniversityMainzGermany
| | | | - Thomas Basché
- Department of ChemistryJohannes Gutenberg‐UniversityMainzGermany
| | - Tanja Schirmeister
- Institute for Pharmaceutical and Biomedical Sciences, Johannes Gutenberg‐UniversityMainzGermany
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7
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Fluorescence signal amplification by optical reflection in metal-coated nanowells. Mikrochim Acta 2022; 189:478. [DOI: 10.1007/s00604-022-05577-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Accepted: 11/14/2022] [Indexed: 11/29/2022]
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8
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Zhu X, Wang X, Zhang H, Zhang F. Luminescence Lifetime Imaging Based on Lanthanide Nanoparticles. Angew Chem Int Ed Engl 2022; 61:e202209378. [DOI: 10.1002/anie.202209378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Indexed: 11/06/2022]
Affiliation(s)
- Xinyan Zhu
- Department of Chemistry State Key Laboratory of Molecular Engineering of Polymers Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials Fudan University Shanghai 200433 China
| | - Xiaohan Wang
- Department of Chemistry State Key Laboratory of Molecular Engineering of Polymers Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials Fudan University Shanghai 200433 China
| | - Hongxin Zhang
- Department of Chemistry State Key Laboratory of Molecular Engineering of Polymers Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials Fudan University Shanghai 200433 China
| | - Fan Zhang
- Department of Chemistry State Key Laboratory of Molecular Engineering of Polymers Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials Fudan University Shanghai 200433 China
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9
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Zhu X, Wang X, Zhang H, Zhang F. Luminescence Lifetime Imaging Based on Lanthanide Nanoparticles. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202209378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Xinyan Zhu
- Fudan University chemistry department Room 631, Advanced materials lab,2205 songhu road, yangpu district,Shanghai 200438 Shanghai CHINA
| | | | | | - Fan Zhang
- Fudan University Chemistry 2205 Songhu Road 200438 Shanghai CHINA
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10
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Roßmann K, Akkaya KC, Poc P, Charbonnier C, Eichhorst J, Gonschior H, Valavalkar A, Wendler N, Cordes T, Dietzek-Ivanšić B, Jones B, Lehmann M, Broichhagen J. N-Methyl deuterated rhodamines for protein labelling in sensitive fluorescence microscopy. Chem Sci 2022; 13:8605-8617. [PMID: 35974762 PMCID: PMC9337740 DOI: 10.1039/d1sc06466e] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 06/02/2022] [Indexed: 11/21/2022] Open
Abstract
Rhodamine fluorophores are setting benchmarks in fluorescence microscopy. Herein, we report the deuterium (d12) congeners of tetramethyl(silicon)rhodamine, obtained by isotopic labelling of the four methyl groups, show improved photophysical parameters (i.e. brightness, lifetimes) and reduced chemical bleaching. We explore this finding for SNAP- and Halo-tag labelling in live cells, and highlight enhanced properties in several applications, such as fluorescence activated cell sorting, fluorescence lifetime microscopy, stimulated emission depletion nanoscopy and single-molecule Förster-resonance energy transfer. We finally extend this idea to other dye families and envision deuteration as a generalizable concept to improve existing and to develop new chemical biology probes.
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Affiliation(s)
- Kilian Roßmann
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie Berlin Germany
| | - Kerem C Akkaya
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie Berlin Germany
| | - Pascal Poc
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie Berlin Germany
| | | | - Jenny Eichhorst
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie Berlin Germany
| | - Hannes Gonschior
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie Berlin Germany
| | - Abha Valavalkar
- Leibniz Institute for Photonic Technology Jena e.V. (Leibniz-IPHT), Research Department Functional Interfaces Jena Germany
| | - Nicolas Wendler
- Physical and Synthetic Biology, Faculty of Biology, Ludwig-Maximilians-Universität München Großhaderner Str. 2-4, Planegg-Martinsried 82152 Germany
| | - Thorben Cordes
- Physical and Synthetic Biology, Faculty of Biology, Ludwig-Maximilians-Universität München Großhaderner Str. 2-4, Planegg-Martinsried 82152 Germany
| | - Benjamin Dietzek-Ivanšić
- Leibniz Institute for Photonic Technology Jena e.V. (Leibniz-IPHT), Research Department Functional Interfaces Jena Germany
| | - Ben Jones
- Section of Endocrinology and Investigative Medicine, Imperial College London London W12 0NN UK
| | - Martin Lehmann
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie Berlin Germany
| | - Johannes Broichhagen
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie Berlin Germany
- Department of Chemical Biology, Max Planck Institute for Medical Research Heidelberg Germany
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11
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Peter MF, Gebhardt C, Mächtel R, Muñoz GGM, Glaenzer J, Narducci A, Thomas GH, Cordes T, Hagelueken G. Cross-validation of distance measurements in proteins by PELDOR/DEER and single-molecule FRET. Nat Commun 2022; 13:4396. [PMID: 35906222 PMCID: PMC9338047 DOI: 10.1038/s41467-022-31945-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 07/11/2022] [Indexed: 11/09/2022] Open
Abstract
Pulsed electron-electron double resonance spectroscopy (PELDOR/DEER) and single-molecule Förster resonance energy transfer spectroscopy (smFRET) are frequently used to determine conformational changes, structural heterogeneity, and inter probe distances in biological macromolecules. They provide qualitative information that facilitates mechanistic understanding of biochemical processes and quantitative data for structural modelling. To provide a comprehensive comparison of the accuracy of PELDOR/DEER and smFRET, we use a library of double cysteine variants of four proteins that undergo large-scale conformational changes upon ligand binding. With either method, we use established standard experimental protocols and data analysis routines to determine inter-probe distances in the presence and absence of ligands. The results are compared to distance predictions from structural models. Despite an overall satisfying and similar distance accuracy, some inconsistencies are identified, which we attribute to the use of cryoprotectants for PELDOR/DEER and label-protein interactions for smFRET. This large-scale cross-validation of PELDOR/DEER and smFRET highlights the strengths, weaknesses, and synergies of these two important and complementary tools in integrative structural biology.
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Affiliation(s)
- Martin F Peter
- Institute of Structural Biology, University of Bonn, Bonn, Germany
| | - Christian Gebhardt
- Physical and Synthetic Biology, Faculty of Biology, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
| | - Rebecca Mächtel
- Physical and Synthetic Biology, Faculty of Biology, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
| | - Gabriel G Moya Muñoz
- Physical and Synthetic Biology, Faculty of Biology, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
| | - Janin Glaenzer
- Institute of Structural Biology, University of Bonn, Bonn, Germany
| | - Alessandra Narducci
- Physical and Synthetic Biology, Faculty of Biology, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
| | - Gavin H Thomas
- Department of Biology (Area 10), University of York, York, UK
| | - Thorben Cordes
- Physical and Synthetic Biology, Faculty of Biology, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany.
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12
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Barth A, Opanasyuk O, Peulen TO, Felekyan S, Kalinin S, Sanabria H, Seidel CAM. Unraveling multi-state molecular dynamics in single-molecule FRET experiments. I. Theory of FRET-lines. J Chem Phys 2022; 156:141501. [PMID: 35428384 PMCID: PMC9014241 DOI: 10.1063/5.0089134] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Conformational dynamics of biomolecules are of fundamental importance for their function. Single-molecule studies of Förster Resonance Energy Transfer (smFRET) between a tethered donor and acceptor dye pair are a powerful tool to investigate the structure and dynamics of labeled molecules. However, capturing and quantifying conformational dynamics in intensity-based smFRET experiments remains challenging when the dynamics occur on the sub-millisecond timescale. The method of multiparameter fluorescence detection addresses this challenge by simultaneously registering fluorescence intensities and lifetimes of the donor and acceptor. Together, two FRET observables, the donor fluorescence lifetime τD and the intensity-based FRET efficiency E, inform on the width of the FRET efficiency distribution as a characteristic fingerprint for conformational dynamics. We present a general framework for analyzing dynamics that relates average fluorescence lifetimes and intensities in two-dimensional burst frequency histograms. We present parametric relations of these observables for interpreting the location of FRET populations in E–τD diagrams, called FRET-lines. To facilitate the analysis of complex exchange equilibria, FRET-lines serve as reference curves for a graphical interpretation of experimental data to (i) identify conformational states, (ii) resolve their dynamic connectivity, (iii) compare different kinetic models, and (iv) infer polymer properties of unfolded or intrinsically disordered proteins. For a simplified graphical analysis of complex kinetic networks, we derive a moment-based representation of the experimental data that decouples the motion of the fluorescence labels from the conformational dynamics of the biomolecule. Importantly, FRET-lines facilitate exploring complex dynamic models via easily computed experimental observables. We provide extensive computational tools to facilitate applying FRET-lines.
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Affiliation(s)
- Anders Barth
- Institut für Physikalische Chemie, Lehrstuhl für Molekulare Physikalische Chemie, Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Oleg Opanasyuk
- Institut für Physikalische Chemie, Lehrstuhl für Molekulare Physikalische Chemie, Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Thomas-Otavio Peulen
- Institut für Physikalische Chemie, Lehrstuhl für Molekulare Physikalische Chemie, Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Suren Felekyan
- Institut für Physikalische Chemie, Lehrstuhl für Molekulare Physikalische Chemie, Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Stanislav Kalinin
- Institut für Physikalische Chemie, Lehrstuhl für Molekulare Physikalische Chemie, Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Hugo Sanabria
- Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29631, USA
| | - Claus A. M. Seidel
- Institut für Physikalische Chemie, Lehrstuhl für Molekulare Physikalische Chemie, Heinrich-Heine-Universität, Düsseldorf, Germany
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13
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Chakraborty A, Krause L, Klostermeier D. Determination of rate constants for conformational changes of RNA helicases by single-molecule FRET TIRF microscopy. Methods 2022; 204:428-441. [PMID: 35304246 DOI: 10.1016/j.ymeth.2022.03.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 03/10/2022] [Accepted: 03/13/2022] [Indexed: 12/18/2022] Open
Abstract
RNA helicases couple nucleotide-driven conformational changes to the unwinding of RNA duplexes. Interaction partners can regulate helicase activity by altering the rate constants of these conformational changes. Single-molecule FRET experiments on donor/acceptor-labeled, immobilized molecules are ideally suited to monitor conformational changes in real time and to extract rate constants for these processes. This article provides guidance on how to design, perform, and analyze single-molecule FRET experiments by TIRF microscopy. It covers the theoretical background of FRET and single-molecule TIRF microscopy, the considerations to prepare proteins of interest for donor/acceptor labeling and surface immobilization, and the principles and procedures of data analysis, including image analysis and the determination of FRET time traces, the extraction of rate constants from FRET time traces, and the general conclusions that can be drawn from these data. A case study, using the DEAD-box protein eIF4A as an example, highlights how single-molecule FRET studies have been instrumental in understanding the role of conformational changes for duplex unwinding and for the regulation of helicase activities. Selected examples illustrate which conclusions can be drawn from the kinetic data obtained, highlight possible pitfalls in data analysis and interpretation, and outline how kinetic models can be related to functionally relevant states.
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Affiliation(s)
| | - Linda Krause
- University of Muenster, Institute for Physical Chemistry, Muenster, Germany
| | - Dagmar Klostermeier
- University of Muenster, Institute for Physical Chemistry, Muenster, Germany.
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14
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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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15
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Gebhardt C, Lehmann M, Reif MM, Zacharias M, Gemmecker G, Cordes T. Molecular and Spectroscopic Characterization of Green and Red Cyanine Fluorophores from the Alexa Fluor and AF Series*. Chemphyschem 2021; 22:1566-1583. [PMID: 34185946 PMCID: PMC8457111 DOI: 10.1002/cphc.202000935] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 06/01/2021] [Indexed: 12/23/2022]
Abstract
The use of fluorescence techniques has an enormous impact on various research fields including imaging, biochemical assays, DNA-sequencing and medical technologies. This has been facilitated by the development of numerous commercial dyes with optimized photophysical and chemical properties. Often, however, information about the chemical structures of dyes and the attached linkers used for bioconjugation remain a well-kept secret. This can lead to problems for research applications where knowledge of the dye structure is necessary to predict or understand (unwanted) dye-target interactions, or to establish structural models of the dye-target complex. Using a combination of optical spectroscopy, mass spectrometry, NMR spectroscopy and molecular dynamics simulations, we here investigate the molecular structures and spectroscopic properties of dyes from the Alexa Fluor (Alexa Fluor 555 and 647) and AF series (AF555, AF647, AFD647). Based on available data and published structures of the AF and Cy dyes, we propose a structure for Alexa Fluor 555 and refine that of AF555. We also resolve conflicting reports on the linker composition of Alexa Fluor 647 maleimide. We also conducted a comprehensive comparison between Alexa Fluor and AF dyes by continuous-wave absorption and emission spectroscopy, quantum yield determination, fluorescence lifetime and anisotropy spectroscopy of free and protein-attached dyes. All these data support the idea that Alexa Fluor and AF dyes have a cyanine core and are a derivative of Cy3 and Cy5. In addition, we compared Alexa Fluor 555 and Alexa Fluor 647 to their structural homologs AF555 and AF(D)647 in single-molecule FRET applications. Both pairs showed excellent performance in solution-based smFRET experiments using alternating laser excitation. Minor differences in apparent dye-protein interactions were investigated by molecular dynamics simulations. Our findings clearly demonstrate that the AF-fluorophores are an attractive alternative to Alexa- and Cy-dyes in smFRET studies or other fluorescence applications.
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Affiliation(s)
- Christian Gebhardt
- Physical and Synthetic Biology, Faculty of BiologyLudwig-Maximilians-Universität MünchenGroßhadernerstr. 2–482152Planegg-MartinsriedGermany
| | - Martin Lehmann
- Plant Molecular Biology, Faculty of BiologyLudwig-Maximilians-Universität MünchenGroßhadernerstr. 2–482152Planegg-MartinsriedGermany
| | - Maria M. Reif
- Theoretical Biophysics (T38), Physics DepartmentTechnical University of MunichCenter for Functional Protein Assemblies (CPA), Ernst-Otto-Fischer-Str. 885748GarchingGermany
| | - Martin Zacharias
- Theoretical Biophysics (T38), Physics DepartmentTechnical University of MunichCenter for Functional Protein Assemblies (CPA), Ernst-Otto-Fischer-Str. 885748GarchingGermany
| | - Gerd Gemmecker
- Bavarian NMR Center (B NMRZ), Department of ChemistryTechnical University of MunichLichtenbergstr. 485748GarchingGermany
| | - Thorben Cordes
- Physical and Synthetic Biology, Faculty of BiologyLudwig-Maximilians-Universität MünchenGroßhadernerstr. 2–482152Planegg-MartinsriedGermany
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16
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Götz C, Hinze G, Gellert A, Maus H, von Hammerstein F, Hammerschmidt SJ, Lauth LM, Hellmich UA, Schirmeister T, Basché T. Conformational Dynamics of the Dengue Virus Protease Revealed by Fluorescence Correlation and Single-Molecule FRET Studies. J Phys Chem B 2021; 125:6837-6846. [PMID: 34137269 DOI: 10.1021/acs.jpcb.1c01797] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The dengue virus protease (DENV-PR) represents an attractive target for counteracting DENV infections. It is generally assumed that DENV-PR can exist in an open and a closed conformation and that active site directed ligands stabilize the closed state. While crystal structures of both the open and the closed conformation were successfully resolved, information about the prevalence of these conformations in solution remains elusive. Herein, we address the question of whether there is an equilibrium between different conformations in solution which can be influenced by addition of a competitive inhibitor. To this end, DENV-PR was statistically labeled by two dye molecules constituting a FRET (fluorescence resonance energy transfer) couple. Fluorescence correlation spectroscopy and photon-burst detection were employed to examine FRET pair labeled DENV-PRs freely diffusing in solution. The measurements were performed with two double mutants and with two dye couples. The data provide strong evidence that an equilibrium of at least two conformations of DENV-PR exists in solution. The competitive inhibitor stabilizes the closed state. Because the open and closed conformations appear to coexist in solution, our results support the picture of a conformational selection rather than that of an induced fit mechanism with respect to the inhibitor-induced formation of the closed state.
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Affiliation(s)
- Christian Götz
- Department of Chemistry, Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Gerald Hinze
- Department of Chemistry, Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Andrea Gellert
- Institute for Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Hannah Maus
- Institute for Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Franziska von Hammerstein
- Institute for Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Stefan J Hammerschmidt
- Institute for Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Luca M Lauth
- Department of Chemistry, Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Ute A Hellmich
- Department of Chemistry, Johannes Gutenberg-University Mainz, Mainz, Germany.,Centre for Biomolecular Magnetic Resonance (BMRZ), Goethe-University Frankfurt, Frankfurt, Germany
| | - Tanja Schirmeister
- Institute for Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Thomas Basché
- Department of Chemistry, Johannes Gutenberg-University Mainz, Mainz, Germany
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17
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Qiao Y, Luo Y, Long N, Xing Y, Tu J. Single-Molecular Förster Resonance Energy Transfer Measurement on Structures and Interactions of Biomolecules. MICROMACHINES 2021; 12:492. [PMID: 33925350 PMCID: PMC8145425 DOI: 10.3390/mi12050492] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 04/21/2021] [Accepted: 04/23/2021] [Indexed: 12/15/2022]
Abstract
Single-molecule Förster resonance energy transfer (smFRET) inherits the strategy of measurement from the effective "spectroscopic ruler" FRET and can be utilized to observe molecular behaviors with relatively high throughput at nanometer scale. The simplicity in principle and configuration of smFRET make it easy to apply and couple with other technologies to comprehensively understand single-molecule dynamics in various application scenarios. Despite its widespread application, smFRET is continuously developing and novel studies based on the advanced platforms have been done. Here, we summarize some representative examples of smFRET research of recent years to exhibit the versatility and note typical strategies to further improve the performance of smFRET measurement on different biomolecules.
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Affiliation(s)
- Yi Qiao
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China; (Y.Q.); (Y.L.); (N.L.)
| | - Yuhan Luo
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China; (Y.Q.); (Y.L.); (N.L.)
| | - Naiyun Long
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China; (Y.Q.); (Y.L.); (N.L.)
| | - Yi Xing
- Institute of Child and Adolescent Health, School of Public Health, Peking University, Beijing 100191, China;
| | - Jing Tu
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China; (Y.Q.); (Y.L.); (N.L.)
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18
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Shoup D, Roth A, Thapa R, Puchalla J, Rye HS. Development and application of multicolor burst analysis spectroscopy. Biophys J 2021; 120:2192-2204. [PMID: 33831389 DOI: 10.1016/j.bpj.2021.03.035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 02/24/2021] [Accepted: 03/24/2021] [Indexed: 10/21/2022] Open
Abstract
The formation and disassembly of macromolecular particles is a ubiquitous and essential feature of virtually all living organisms. Additionally, diseases are often associated with the accumulation and propagation of biologically active nanoparticles, like the formation of toxic protein aggregates in protein misfolding diseases and the growth of infectious viral particles. The heterogeneous and dynamic nature of biologically active particles can make them exceedingly challenging to study. The single-particle fluorescence technique known as burst analysis spectroscopy (BAS) was developed to facilitate real-time measurement of macromolecular particle distributions in the submicron range in a minimally perturbing, free-solution environment. Here, we develop a multicolor version of BAS and employ it to examine two problems in macromolecular assembly: 1) the extent of DNA packing heterogeneity in bacteriophage viral particles and 2) growth models of non-native protein aggregates. We show that multicolor BAS provides a powerful and flexible approach to studying hidden properties of important biological particles like viruses and protein aggregates.
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Affiliation(s)
- Daniel Shoup
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas
| | - Andrew Roth
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas
| | - Rajan Thapa
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas
| | - Jason Puchalla
- Department of Physics, Princeton University, Princeton, New Jersey.
| | - Hays S Rye
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas.
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Peter MF, Gebhardt C, Glaenzer J, Schneberger N, de Boer M, Thomas GH, Cordes T, Hagelueken G. Triggering Closure of a Sialic Acid TRAP Transporter Substrate Binding Protein through Binding of Natural or Artificial Substrates. J Mol Biol 2021; 433:166756. [PMID: 33316271 DOI: 10.1016/j.jmb.2020.166756] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 12/07/2020] [Accepted: 12/07/2020] [Indexed: 12/20/2022]
Abstract
The pathogens Vibrio cholerae and Haemophilus influenzae use tripartite ATP-independent periplasmic transporters (TRAPs) to scavenge sialic acid from host tissues. They use it as a nutrient or to evade the innate immune system by sialylating surface lipopolysaccharides. An essential component of TRAP transporters is a periplasmic substrate binding protein (SBP). Without substrate, the SBP has been proposed to rest in an open-state, which is not recognised by the transporter. Substrate binding induces a conformational change of the SBP and it is thought that this closed state is recognised by the transporter, triggering substrate translocation. Here we use real time single molecule FRET experiments and crystallography to investigate the open- to closed-state transition of VcSiaP, the SBP of the sialic acid TRAP transporter from V. cholerae. We show that the conformational switching of VcSiaP is strictly substrate induced, confirming an important aspect of the proposed transport mechanism. Two new crystal structures of VcSiaP provide insights into the closing mechanism. While the first structure contains the natural ligand, sialic acid, the second structure contains an artificial peptide in the sialic acid binding site. Together, the two structures suggest that the ligand itself stabilises the closed state and that SBP closure is triggered by physically bridging the gap between the two lobes of the SBP. Finally, we demonstrate that the affinity for the artificial peptide substrate can be substantially increased by varying its amino acid sequence and by this, serve as a starting point for the development of peptide-based inhibitors of TRAP transporters.
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Affiliation(s)
- Martin F Peter
- Institute of Structural Biology, University of Bonn, 53127 Bonn, Germany
| | - Christian Gebhardt
- Physical and Synthetic Biology, Faculty of Biology, Ludwig-Maximilians-Universität München, 82152 Planegg-Martinsried, Germany
| | - Janin Glaenzer
- Institute of Structural Biology, University of Bonn, 53127 Bonn, Germany
| | - Niels Schneberger
- Institute of Structural Biology, University of Bonn, 53127 Bonn, Germany
| | - Marijn de Boer
- Molecular Microscopy Research Group, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Gavin H Thomas
- Department of Biology (Area 10), University of York, York YO10 5YW, UK
| | - Thorben Cordes
- Physical and Synthetic Biology, Faculty of Biology, Ludwig-Maximilians-Universität München, 82152 Planegg-Martinsried, Germany; Molecular Microscopy Research Group, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Gregor Hagelueken
- Institute of Structural Biology, University of Bonn, 53127 Bonn, Germany.
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20
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Abstract
Intrinsically disordered proteins (IDPs) are now widely recognized as playing critical roles in a broad range of cellular functions as well as being implicated in diverse diseases. Their lack of stable secondary structure and tertiary interactions, coupled with their sensitivity to measurement conditions, stymies many traditional structural biology approaches. Single-molecule Förster resonance energy transfer (smFRET) is now widely used to characterize the physicochemical properties of these proteins in isolation and is being increasingly applied to more complex assemblies and experimental environments. This review provides an overview of confocal diffusion-based smFRET as an experimental tool, including descriptions of instrumentation, data analysis, and protein labeling. Recent papers are discussed that illustrate the unique capability of smFRET to provide insight into aggregation-prone IDPs, protein–protein interactions involving IDPs, and IDPs in complex experimental milieus.
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Affiliation(s)
- Lauren Ann Metskas
- Department of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, USA
| | - Elizabeth Rhoades
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
- Biochemistry and Molecular Biophysics Graduate Group, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104, USA
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22
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Resolving dynamics and function of transient states in single enzyme molecules. Nat Commun 2020; 11:1231. [PMID: 32144241 PMCID: PMC7060211 DOI: 10.1038/s41467-020-14886-w] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 02/08/2020] [Indexed: 11/23/2022] Open
Abstract
We use a hybrid fluorescence spectroscopic toolkit to monitor T4 Lysozyme (T4L) in action by unraveling the kinetic and dynamic interplay of the conformational states. In particular, by combining single-molecule and ensemble multiparameter fluorescence detection, EPR spectroscopy, mutagenesis, and FRET-positioning and screening, and other biochemical and biophysical tools, we characterize three short-lived conformational states over the ns-ms timescale. The use of 33 FRET-derived distance sets, to screen available T4L structures, reveal that T4L in solution mainly adopts the known open and closed states in exchange at 4 µs. A newly found minor state, undisclosed by, at present, more than 500 crystal structures of T4L and sampled at 230 µs, may be actively involved in the product release step in catalysis. The presented fluorescence spectroscopic toolkit will likely accelerate the development of dynamic structural biology by identifying transient conformational states that are highly abundant in biology and critical in enzymatic reactions. T4 Lysozyme (T4L) is a model protein whose structure is extensively studied. Here the authors combine single-molecule and ensemble FRET measurements, FRET-positioning and screening and EPR spectroscopy to study the structural dynamics of T4L and describe its conformational landscape during the catalytic cycle by an extended Michaelis–Menten mechanism and identify an excited conformational state of the enzyme.
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23
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High-throughput smFRET analysis of freely diffusing nucleic acid molecules and associated proteins. Methods 2019; 169:21-45. [PMID: 31356875 DOI: 10.1016/j.ymeth.2019.07.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 06/24/2019] [Accepted: 07/22/2019] [Indexed: 11/21/2022] Open
Abstract
Single-molecule Förster resonance energy transfer (smFRET) is a powerful technique for nanometer-scale studies of single molecules. Solution-based smFRET, in particular, can be used to study equilibrium intra- and intermolecular conformations, binding/unbinding events and conformational changes under biologically relevant conditions without ensemble averaging. However, single-spot smFRET measurements in solution are slow. Here, we detail a high-throughput smFRET approach that extends the traditional single-spot confocal geometry to a multispot one. The excitation spots are optically conjugated to two custom silicon single photon avalanche diode (SPAD) arrays. Two-color excitation is implemented using a periodic acceptor excitation (PAX), allowing distinguishing between singly- and doubly-labeled molecules. We demonstrate the ability of this setup to rapidly and accurately determine FRET efficiencies and population stoichiometries by pooling the data collected independently from the multiple spots. We also show how the high throughput of this approach can be used o increase the temporal resolution of single-molecule FRET population characterization from minutes to seconds. Combined with microfluidics, this high-throughput approach will enable simple real-time kinetic studies as well as powerful molecular screening applications.
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24
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Thongyod W, Buranachai C, Pengpan T, Punwong C. Fluorescence quenching by photoinduced electron transfer between 7-methoxycoumarin and guanine base facilitated by hydrogen bonds: an in silico study. Phys Chem Chem Phys 2019; 21:16258-16269. [PMID: 31304496 DOI: 10.1039/c9cp02037c] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this study, the effects of hydrogen bond (H-bond) formation on fluorescence quenching of 7-methoxycoumarin (7MC) via photo-induced electron transfer from a guanine base (Gua) are investigated using a combined quantum mechanics/molecular mechanics simulation. The electronic structure is calculated by the floating occupation molecular orbital complete active space configuration interaction modification on a semiempirical method. Then the full multiple spawning method is employed for the dynamics simulations on multiple electronic states. The methods employed here are validated by simulating direct dynamics of 7MC (without Gua) and compared with available experimental results. Our computational results are in good agreement with the previously reported experimental results in terms of spectroscopic properties of 7MC. In the case of a H-bonded 7MC-Gua complex, the results from constrained dynamics simulations and single-point calculations suggest that the electron transfer occurs on the second excited state and it depends not only on the H-bond length but also on the intermolecular planarity between 7MC and Gua. Moreover, a proton coupled electron transfer can occur at ≈1 Å of H-bond length, where a proton from Gua is also transferred together with the electron to 7MC. The obtained simulations are expected to be greatly beneficial for designing effective fluorescently labeled nucleotide probes as well as providing information for precise fluorescence signal interpretation.
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Affiliation(s)
- Wutthinan Thongyod
- Department of Physics, Faculty of Science, Prince of Songkla University, Songkhla 90112, Thailand. and Center of Excellence for Trace Analysis and Biosensor, Prince of Songkla University, Songkhla 90112, Thailand
| | - Chittanon Buranachai
- Department of Physics, Faculty of Science, Prince of Songkla University, Songkhla 90112, Thailand. and Center of Excellence for Trace Analysis and Biosensor, Prince of Songkla University, Songkhla 90112, Thailand
| | - Teparksorn Pengpan
- Department of Physics, Faculty of Science, Prince of Songkla University, Songkhla 90112, Thailand.
| | - Chutintorn Punwong
- Department of Physics, Faculty of Science, Prince of Songkla University, Songkhla 90112, Thailand.
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Hagai D, Lerner E. Systematic Assessment of Burst Impurity in Confocal-Based Single-Molecule Fluorescence Detection Using Brownian Motion Simulations. Molecules 2019; 24:molecules24142557. [PMID: 31337081 PMCID: PMC6680824 DOI: 10.3390/molecules24142557] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2019] [Revised: 07/05/2019] [Accepted: 07/12/2019] [Indexed: 11/25/2022] Open
Abstract
Single-molecule fluorescence detection (SMFD) experiments are useful in distinguishing sub-populations of molecular species when measuring heterogeneous samples. One experimental platform for SMFD is based on a confocal microscope, where molecules randomly traverse an effective detection volume. The non-uniformity of the excitation profile and the random nature of Brownian motion, produce fluctuating fluorescence signals. For these signals to be distinguished from the background, burst analysis is frequently used. Yet, the relation between the results of burst analyses and the underlying information of the diffusing molecules is still obscure and requires systematic assessment. In this work we performed three-dimensional Brownian motion simulations of SMFD, and tested the positions at which molecules emitted photons that passed the burst analysis criteria for different values of burst analysis parameters. The results of this work verify which of the burst analysis parameters and experimental conditions influence both the position of molecules in space when fluorescence is detected and taken into account, and whether these bursts of photons arise purely from single molecules, or not entirely. Finally, we show, as an example, the effect of bursts that are not purely from a single molecule on the accuracy in single-molecule Förster resonance energy transfer measurements.
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Affiliation(s)
- Dolev Hagai
- 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.
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26
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Squires A, Lavania AA, Dahlberg PD, Moerner WE. Interferometric Scattering Enables Fluorescence-Free Electrokinetic Trapping of Single Nanoparticles in Free Solution. NANO LETTERS 2019; 19:4112-4117. [PMID: 31117762 PMCID: PMC6604838 DOI: 10.1021/acs.nanolett.9b01514] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 05/13/2019] [Indexed: 05/05/2023]
Abstract
Anti-Brownian traps confine single particles in free solution by closed-loop feedback forces that directly counteract Brownian motion. Extended-duration measurements on trapped objects allow detailed characterization of photophysical and transport properties as well as observation of infrequent or rare dynamics. However, this approach has been generally limited to particles that can be tracked by fluorescence emission. Here we present the Interferometric Scattering Anti-Brownian ELectrokinetic (ISABEL) trap, which uses interferometric scattering rather than fluorescence to monitor particle position. By decoupling the ability to track (and therefore trap) a particle from collection of its spectroscopic data, the ISABEL trap enables confinement and extended study of single particles that do not fluoresce, only weakly fluoresce, or exhibit intermittent fluorescence or photobleaching. This new technique significantly expands the range of nanoscale objects that may be investigated at the single-particle level in free solution.
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Affiliation(s)
- Allison
H. Squires
- Department
of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Abhijit A. Lavania
- Department
of Chemistry, Stanford University, Stanford, California 94305, United States
- Department
of Applied Physics, Stanford University, Stanford, California 94305, United States
| | - Peter D. Dahlberg
- Department
of Chemistry, Stanford University, Stanford, California 94305, United States
| | - W. E. Moerner
- Department
of Chemistry, Stanford University, Stanford, California 94305, United States
- Department
of Applied Physics, Stanford University, Stanford, California 94305, United States
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27
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Barth A, Voith von Voithenberg L, Lamb DC. Quantitative Single-Molecule Three-Color Förster Resonance Energy Transfer by Photon Distribution Analysis. J Phys Chem B 2019; 123:6901-6916. [PMID: 31117611 DOI: 10.1021/acs.jpcb.9b02967] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Single-molecule Förster resonance energy transfer (FRET) is a powerful tool to study conformational dynamics of biomolecules. Using solution-based single-pair FRET by burst analysis, conformational heterogeneities and fluctuations of fluorescently labeled proteins or nucleic acids can be studied by monitoring a single distance at a time. Three-color FRET is sensitive to three distances simultaneously and can thus elucidate complex coordinated motions within single molecules. While three-color FRET has been applied on the single-molecule level before, a detailed quantitative description of the obtained FRET efficiency distributions is still missing. Direct interpretation of three-color FRET data is additionally complicated by an increased shot noise contribution when converting photon counts to FRET efficiencies. However, to address the question of coordinated motion, it is of special interest to extract information about the underlying distance heterogeneity, which is not easily extracted from the FRET efficiency histograms directly. Here, we present three-color photon distribution analysis (3C-PDA), a method to extract distributions of interdye distances from three-color FRET measurements. We present a model for diffusion-based three-color FRET experiments and apply Bayesian inference to extract information about the physically relevant distance heterogeneity in the sample. The approach is verified using simulated data sets and experimentally applied to triple-labeled DNA duplexes. Finally, three-color FRET experiments on the Hsp70 chaperone BiP reveal conformational coordinated changes between individual domains. The possibility to address the co-occurrence of intramolecular distances makes 3C-PDA a powerful method to study the coordination of domain motions within biomolecules undergoing conformational dynamics.
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Affiliation(s)
- Anders Barth
- Department of Chemistry, Center for Integrated Protein Science Munich, Nanosystems Initiative Munich and Center for Nanoscience , Ludwig-Maximilians-Universität München , Butenandtstr. 5-13 , 81377 Munich , Germany
| | - Lena Voith von Voithenberg
- Department of Chemistry, Center for Integrated Protein Science Munich, Nanosystems Initiative Munich and Center for Nanoscience , Ludwig-Maximilians-Universität München , Butenandtstr. 5-13 , 81377 Munich , Germany
| | - Don C Lamb
- Department of Chemistry, Center for Integrated Protein Science Munich, Nanosystems Initiative Munich and Center for Nanoscience , Ludwig-Maximilians-Universität München , Butenandtstr. 5-13 , 81377 Munich , Germany
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29
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Barth A, Hendrix J, Fried D, Barak Y, Bayer EA, Lamb DC. Dynamic interactions of type I cohesin modules fine-tune the structure of the cellulosome of Clostridium thermocellum. Proc Natl Acad Sci U S A 2018; 115:E11274-E11283. [PMID: 30429330 PMCID: PMC6275499 DOI: 10.1073/pnas.1809283115] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Efficient degradation of plant cell walls by selected anaerobic bacteria is performed by large extracellular multienzyme complexes termed cellulosomes. The spatial arrangement within the cellulosome is organized by a protein called scaffoldin, which recruits the cellulolytic subunits through interactions between cohesin modules on the scaffoldin and dockerin modules on the enzymes. Although many structural studies of the individual components of cellulosomal scaffoldins have been performed, the role of interactions between individual cohesin modules and the flexible linker regions between them are still not entirely understood. Here, we report single-molecule measurements using FRET to study the conformational dynamics of a bimodular cohesin segment of the scaffoldin protein CipA of Clostridium thermocellum We observe compacted structures in solution that persist on the timescale of milliseconds. The compacted conformation is found to be in dynamic equilibrium with an extended state that shows distance fluctuations on the microsecond timescale. Shortening of the intercohesin linker does not destabilize the interactions but reduces the rate of contact formation. Upon addition of dockerin-containing enzymes, an extension of the flexible state is observed, but the cohesin-cohesin interactions persist. Using all-atom molecular-dynamics simulations of the system, we further identify possible intercohesin binding modes. Beyond the view of scaffoldin as "beads on a string," we propose that cohesin-cohesin interactions are an important factor for the precise spatial arrangement of the enzymatic subunits in the cellulosome that leads to the high catalytic synergy in these assemblies and should be considered when designing cellulosomes for industrial applications.
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Affiliation(s)
- Anders Barth
- Physical Chemistry, Department of Chemistry, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
- Center for Integrated Protein Science Munich, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
- Nanosystems Initative Munich, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
- Center for Nanoscience, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - Jelle Hendrix
- Physical Chemistry, Department of Chemistry, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
- Center for Integrated Protein Science Munich, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
- Nanosystems Initative Munich, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
- Center for Nanoscience, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - Daniel Fried
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Yoav Barak
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Edward A Bayer
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Don C Lamb
- Physical Chemistry, Department of Chemistry, Ludwig-Maximilians-Universität München, 81377 Munich, Germany;
- Center for Integrated Protein Science Munich, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
- Nanosystems Initative Munich, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
- Center for Nanoscience, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
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30
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Bravo JPK, Borodavka A, Barth A, Calabrese AN, Mojzes P, Cockburn JJB, Lamb DC, Tuma R. Stability of local secondary structure determines selectivity of viral RNA chaperones. Nucleic Acids Res 2018; 46:7924-7937. [PMID: 29796667 PMCID: PMC6125681 DOI: 10.1093/nar/gky394] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 04/24/2018] [Accepted: 04/30/2018] [Indexed: 01/02/2023] Open
Abstract
To maintain genome integrity, segmented double-stranded RNA viruses of the Reoviridae family must accurately select and package a complete set of up to a dozen distinct genomic RNAs. It is thought that the high fidelity segmented genome assembly involves multiple sequence-specific RNA-RNA interactions between single-stranded RNA segment precursors. These are mediated by virus-encoded non-structural proteins with RNA chaperone-like activities, such as rotavirus (RV) NSP2 and avian reovirus σNS. Here, we compared the abilities of NSP2 and σNS to mediate sequence-specific interactions between RV genomic segment precursors. Despite their similar activities, NSP2 successfully promotes inter-segment association, while σNS fails to do so. To understand the mechanisms underlying such selectivity in promoting inter-molecular duplex formation, we compared RNA-binding and helix-unwinding activities of both proteins. We demonstrate that octameric NSP2 binds structured RNAs with high affinity, resulting in efficient intramolecular RNA helix disruption. Hexameric σNS oligomerizes into an octamer that binds two RNAs, yet it exhibits only limited RNA-unwinding activity compared to NSP2. Thus, the formation of intersegment RNA-RNA interactions is governed by both helix-unwinding capacity of the chaperones and stability of RNA structure. We propose that this protein-mediated RNA selection mechanism may underpin the high fidelity assembly of multi-segmented RNA genomes in Reoviridae.
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Affiliation(s)
- Jack P K Bravo
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK
- School of Molecular and Cellular Biology, University of Leeds, Leeds, UK
| | - Alexander Borodavka
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK
- School of Molecular and Cellular Biology, University of Leeds, Leeds, UK
- Department of Chemistry, Center for NanoScience (CeNS), Nanosystems Initiative Munich (NIM) and Centre for Integrated Protein Science Munich (CiPSM), Ludwig Maximilian University of Munich, Munich, Germany
| | - Anders Barth
- Department of Chemistry, Center for NanoScience (CeNS), Nanosystems Initiative Munich (NIM) and Centre for Integrated Protein Science Munich (CiPSM), Ludwig Maximilian University of Munich, Munich, Germany
| | - Antonio N Calabrese
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK
- School of Molecular and Cellular Biology, University of Leeds, Leeds, UK
| | - Peter Mojzes
- Institute of Physics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, CZ-12116 Prague 2, Czech Republic
| | - Joseph J B Cockburn
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK
- School of Molecular and Cellular Biology, University of Leeds, Leeds, UK
| | - Don C Lamb
- Department of Chemistry, Center for NanoScience (CeNS), Nanosystems Initiative Munich (NIM) and Centre for Integrated Protein Science Munich (CiPSM), Ludwig Maximilian University of Munich, Munich, Germany
| | - Roman Tuma
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK
- School of Molecular and Cellular Biology, University of Leeds, Leeds, UK
- Faculty of Science, University of South Bohemia, Ceske Budejovice, Czech Republic
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31
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Fessl T, Watkins D, Oatley P, Allen WJ, Corey RA, Horne J, Baldwin SA, Radford SE, Collinson I, Tuma R. Dynamic action of the Sec machinery during initiation, protein translocation and termination. eLife 2018; 7:35112. [PMID: 29877797 PMCID: PMC6021171 DOI: 10.7554/elife.35112] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 06/05/2018] [Indexed: 11/13/2022] Open
Abstract
Protein translocation across cell membranes is a ubiquitous process required for protein secretion and membrane protein insertion. In bacteria, this is mostly mediated by the conserved SecYEG complex, driven through rounds of ATP hydrolysis by the cytoplasmic SecA, and the trans-membrane proton motive force. We have used single molecule techniques to explore SecY pore dynamics on multiple timescales in order to dissect the complex reaction pathway. The results show that SecA, both the signal sequence and mature components of the pre-protein, and ATP hydrolysis each have important and specific roles in channel unlocking, opening and priming for transport. After channel opening, translocation proceeds in two phases: a slow phase independent of substrate length, and a length-dependent transport phase with an intrinsic translocation rate of ~40 amino acids per second for the proOmpA substrate. Broad translocation rate distributions reflect the stochastic nature of polypeptide transport.
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Affiliation(s)
- Tomas Fessl
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom.,School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom.,Faculty of Science, University of South Bohemia, Ceske Budejovice, Czech Republic
| | - Daniel Watkins
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | - Peter Oatley
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom.,School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | | | - Robin Adam Corey
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | - Jim Horne
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom.,School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Steve A Baldwin
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom.,School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Sheena E Radford
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom.,School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Ian Collinson
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | - Roman Tuma
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom.,School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom.,Faculty of Science, University of South Bohemia, Ceske Budejovice, Czech Republic
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32
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Potentials and pitfalls of inverse fluorescence correlation spectroscopy. Methods 2018; 140-141:23-31. [DOI: 10.1016/j.ymeth.2018.01.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2017] [Revised: 12/19/2017] [Accepted: 01/12/2018] [Indexed: 11/21/2022] Open
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33
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Mongwaketsi N, Mayedwa N, Matinise N, Kaviyarasu K, Sparrow R, Maaza M. Polymer matrices for porphyrin nanorods incorporation. Artificial light harvesting applications. J PORPHYR PHTHALOCYA 2018. [DOI: 10.1142/s1088424618500268] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
This contribution is focused on the supramolecular approach in exploration of aggregates formation by two different porphyrins wherein self-assembly plays an important role. Spectroscopic and microscopic studies usually provide information on investigations regarding the effects of various parameters on the fabrication of porphyrin aggregates by ionic self- assembly. Various properties of ionic self-assembled porphyrin nanorods have been investigated, including nonlinear optical (NLO) properties, and these studies were influenced by the fact that porphyrins have great thermal stability and extended [Formula: see text]conjugated macro cyclic rings which give them large nonlinear optical effects. The major reasons limiting porphyrin nanorods photonic applications include the difficulty of handling them in liquid solutions and their degradation with long exposure to light. This necessitates the use of appropriate solid matrices to host the nanorods. Inspired by the precise organization and orientation of the chromophores in natural systems, attention has been on the design of nanometer sized chromophoric assemblies, which may find applications in the field of molecular photonics. However, it is challenging to design multicomponent systems with controlled structural arrangement at the molecular level. A lack of precise arrangement may have a negative impact on the construction of an efficient artificial light harvesting system. This review is focused on exploring the possibility of incorporating nanorods into polymer matrices to overcome the limiting factors of applications of these materials in photonic devices.
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Affiliation(s)
- Nametso Mongwaketsi
- National Research Foundation, iThemba LABS, P.O. Box 722, Somerset West Cape Town, 7129, South Africa
| | - Noluthando Mayedwa
- UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, P.O. Box 392, Pretoria 0001, South Africa
| | - Nolubabalo Matinise
- National Research Foundation, iThemba LABS, P.O. Box 722, Somerset West Cape Town, 7129, South Africa
| | - Kasinathan Kaviyarasu
- UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, P.O. Box 392, Pretoria 0001, South Africa
| | - Raymond Sparrow
- Council for Scientific & Industrial Research (CSIR), Bioscience, P.O. Box 395, Pretoria 0001, South Africa
| | - Malik Maaza
- National Research Foundation, iThemba LABS, P.O. Box 722, Somerset West Cape Town, 7129, South Africa
- UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, P.O. Box 392, Pretoria 0001, South Africa
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34
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Schrimpf W, Barth A, Hendrix J, Lamb DC. PAM: A Framework for Integrated Analysis of Imaging, Single-Molecule, and Ensemble Fluorescence Data. Biophys J 2018; 114:1518-1528. [PMID: 29642023 PMCID: PMC5954487 DOI: 10.1016/j.bpj.2018.02.035] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 01/15/2018] [Accepted: 02/12/2018] [Indexed: 11/24/2022] Open
Abstract
Fluorescence microscopy and spectroscopy data hold a wealth of information on the investigated molecules, structures, or organisms. Nowadays, the same fluorescence data set can be analyzed in many ways to extract different properties of the measured sample. Yet, doing so remains slow and cumbersome, often requiring incompatible software packages. Here, we present PAM (pulsed interleaved excitation analysis with MATLAB), an open-source software package written in MATLAB that offers a simple and efficient workflow through its graphical user interface. PAM is a framework for integrated and robust analysis of fluorescence ensemble, single-molecule, and imaging data. Although it was originally developed for the analysis of pulsed interleaved excitation experiments, PAM has since been extended to support most types of data collection modalities. It combines a multitude of powerful analysis algorithms, ranging from time- and space-correlation analysis, over single-molecule burst analysis, to lifetime imaging microscopy, while offering intrinsic support for multicolor experiments. We illustrate the key concepts and workflow of the software by discussing data handling and sorting and provide step-by-step descriptions for the individual usage cases.
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Affiliation(s)
- Waldemar Schrimpf
- Department of Physical Chemistry, Center for Integrated Protein Science Munich (CIPSM), Nanosystems Initiative Munich (NIM) and Center for Nanoscience (CeNS), Ludwig-Maximilians-Universität, Munich, Germany
| | - Anders Barth
- Department of Physical Chemistry, Center for Integrated Protein Science Munich (CIPSM), Nanosystems Initiative Munich (NIM) and Center for Nanoscience (CeNS), Ludwig-Maximilians-Universität, Munich, Germany
| | - Jelle Hendrix
- Dynamic Bioimaging Lab, Biomedical Research Institute (BIOMED), Advanced Optical Microscopy Centre, Faculty of Medicine and Life Sciences, Hasselt University, Diepenbeek, Belgium; Laboratory for Photochemistry and Spectroscopy, Molecular Imaging and Photonics Division, KU Leuven, Heverlee, Belgium
| | - Don C Lamb
- Department of Physical Chemistry, Center for Integrated Protein Science Munich (CIPSM), Nanosystems Initiative Munich (NIM) and Center for Nanoscience (CeNS), Ludwig-Maximilians-Universität, Munich, Germany.
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35
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Peulen TO, Opanasyuk O, Seidel CAM. Combining Graphical and Analytical Methods with Molecular Simulations To Analyze Time-Resolved FRET Measurements of Labeled Macromolecules Accurately. J Phys Chem B 2017; 121:8211-8241. [PMID: 28709377 PMCID: PMC5592652 DOI: 10.1021/acs.jpcb.7b03441] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
![]()
Förster resonance energy transfer
(FRET) measurements from
a donor, D, to an acceptor, A, fluorophore are frequently used in vitro and in live cells to reveal information on the
structure and dynamics of DA labeled macromolecules. Accurate descriptions
of FRET measurements by molecular models are complicated because the
fluorophores are usually coupled to the macromolecule via flexible
long linkers allowing for diffusional exchange between multiple states
with different fluorescence properties caused by distinct environmental
quenching, dye mobilities, and variable DA distances. It is often
assumed for the analysis of fluorescence intensity decays that DA
distances and D quenching are uncorrelated (homogeneous quenching
by FRET) and that the exchange between distinct fluorophore states
is slow (quasistatic). This allows us to introduce the FRET-induced
donor decay, εD(t), a function solely
depending on the species fraction distribution of the rate constants
of energy transfer by FRET, for a convenient joint analysis of fluorescence
decays of FRET and reference samples by integrated graphical and analytical
procedures. Additionally, we developed a simulation toolkit to model
dye diffusion, fluorescence quenching by the protein surface, and
FRET. A benchmark study with simulated fluorescence decays of 500
protein structures demonstrates that the quasistatic homogeneous model
works very well and recovers for single conformations the average
DA distances with an accuracy of < 2%. For more complex
cases, where proteins adopt multiple conformations with significantly
different dye environments (heterogeneous case), we introduce a general
analysis framework and evaluate its power in resolving heterogeneities
in DA distances. The developed fast simulation methods, relying on
Brownian dynamics of a coarse-grained dye in its sterically accessible
volume, allow us to incorporate structural information in the decay
analysis for heterogeneous cases by relating dye states with protein
conformations to pave the way for fluorescence and FRET-based dynamic
structural biology. Finally, we present theories and simulations to
assess the accuracy and precision of steady-state and time-resolved
FRET measurements in resolving DA distances on the single-molecule
and ensemble level and provide a rigorous framework for estimating
approximation, systematic, and statistical errors.
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Affiliation(s)
- Thomas-Otavio Peulen
- Lehrstuhl für Molekulare Physikalische Chemie, Heinrich-Heine-Universität , Universitätsstraße 1, 40225 Düsseldorf, Germany
| | - Oleg Opanasyuk
- Lehrstuhl für Molekulare Physikalische Chemie, Heinrich-Heine-Universität , Universitätsstraße 1, 40225 Düsseldorf, Germany
| | - Claus A M Seidel
- Lehrstuhl für Molekulare Physikalische Chemie, Heinrich-Heine-Universität , Universitätsstraße 1, 40225 Düsseldorf, Germany
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36
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Ma J, Yanez-Orozco IS, Rezaei Adariani S, Dolino D, Jayaraman V, Sanabria H. High Precision FRET at Single-molecule Level for Biomolecule Structure Determination. J Vis Exp 2017. [PMID: 28570518 DOI: 10.3791/55623] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
A protocol on how to perform high-precision interdye distance measurements using Förster resonance energy transfer (FRET) at the single-molecule level in multiparameter fluorescence detection (MFD) mode is presented here. MFD maximizes the usage of all "dimensions" of fluorescence to reduce photophysical and experimental artifacts and allows for the measurement of interdye distance with an accuracy up to ~1 Å in rigid biomolecules. This method was used to identify three conformational states of the ligand-binding domain of the N-methyl-D-aspartate (NMDA) receptor to explain the activation of the receptor upon ligand binding. When comparing the known crystallographic structures with experimental measurements, they agreed within less than 3 Å for more dynamic biomolecules. Gathering a set of distance restraints that covers the entire dimensionality of the biomolecules would make it possible to provide a structural model of dynamic biomolecules.
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Affiliation(s)
- Junyan Ma
- Department of Chemistry, Clemson University
| | | | | | - Drew Dolino
- Department of Biochemistry and Molecular Biology, Center for Membrane Biology, Graduate School for Biomedical Sciences, University of Texas Health Science Center
| | - Vasanthi Jayaraman
- Department of Biochemistry and Molecular Biology, Center for Membrane Biology, Graduate School for Biomedical Sciences, University of Texas Health Science Center
| | - Hugo Sanabria
- Department of Physics and Astronomy, Clemson University;
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37
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Lu M, Lu HP. Revealing Multiple Pathways in T4 Lysozyme Substep Conformational Motions by Single-Molecule Enzymology and Modeling. J Phys Chem B 2017; 121:5017-5024. [DOI: 10.1021/acs.jpcb.7b03039] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Maolin Lu
- Department of Chemistry and
Center for Photochemical Sciences, Bowling Green State University, Bowling
Green, Ohio 43403, United States
| | - H. Peter Lu
- Department of Chemistry and
Center for Photochemical Sciences, Bowling Green State University, Bowling
Green, Ohio 43403, United States
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38
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Ingargiola A, Peronio P, Lerner E, Gulinatti A, Rech I, Ghioni M, Weiss S, Michalet X. 16-Ch Time-resolved Single-Molecule Spectroscopy Using Line Excitation. PROCEEDINGS OF SPIE--THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING 2017; 10071:100710Q. [PMID: 28603333 PMCID: PMC5463578 DOI: 10.1117/12.2256367] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Single-molecule spectroscopy on freely-diffusing molecules allows detecting conformational changes of biomolecules without perturbation from surface immobilization. Resolving fluorescence lifetimes increases the sensitivity in detecting conformational changes and overcomes artifacts common in intensity-based measurements. Common to all freely-diffusing techniques, however, are the long acquisition times. We report a time-resolved multispot system employing a 16-channel SPAD array and TCSPC electronics, which overcomes the throughput issue. Excitation is obtained by shaping a 532 nm pulsed laser into a line, matching the linear SPAD array geometry. We show that the line-excitation is a robust and cost-effective approach to implement multispot systems based on linear detector arrays.
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Affiliation(s)
- Antonino Ingargiola
- Dept. Chemistry & Biochemistry, University of California Los Angeles, Los Angeles, CA, USA
| | | | - Eitan Lerner
- Dept. Chemistry & Biochemistry, University of California Los Angeles, Los Angeles, CA, USA
| | | | - Ivan Rech
- DEIB, Politecnico di Milano, Milan, Italy
| | | | - Shimon Weiss
- Dept. Chemistry & Biochemistry, University of California Los Angeles, Los Angeles, CA, USA
| | - Xavier Michalet
- Dept. Chemistry & Biochemistry, University of California Los Angeles, Los Angeles, CA, USA
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39
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Ingargiola A, Lerner E, Chung S, Weiss S, Michalet X. FRETBursts: An Open Source Toolkit for Analysis of Freely-Diffusing Single-Molecule FRET. PLoS One 2016; 11:e0160716. [PMID: 27532626 PMCID: PMC4988647 DOI: 10.1371/journal.pone.0160716] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 07/22/2016] [Indexed: 12/04/2022] Open
Abstract
Single-molecule Förster Resonance Energy Transfer (smFRET) allows probing intermolecular interactions and conformational changes in biomacromolecules, and represents an invaluable tool for studying cellular processes at the molecular scale. smFRET experiments can detect the distance between two fluorescent labels (donor and acceptor) in the 3-10 nm range. In the commonly employed confocal geometry, molecules are free to diffuse in solution. When a molecule traverses the excitation volume, it emits a burst of photons, which can be detected by single-photon avalanche diode (SPAD) detectors. The intensities of donor and acceptor fluorescence can then be related to the distance between the two fluorophores. While recent years have seen a growing number of contributions proposing improvements or new techniques in smFRET data analysis, rarely have those publications been accompanied by software implementation. In particular, despite the widespread application of smFRET, no complete software package for smFRET burst analysis is freely available to date. In this paper, we introduce FRETBursts, an open source software for analysis of freely-diffusing smFRET data. FRETBursts allows executing all the fundamental steps of smFRET bursts analysis using state-of-the-art as well as novel techniques, while providing an open, robust and well-documented implementation. Therefore, FRETBursts represents an ideal platform for comparison and development of new methods in burst analysis. We employ modern software engineering principles in order to minimize bugs and facilitate long-term maintainability. Furthermore, we place a strong focus on reproducibility by relying on Jupyter notebooks for FRETBursts execution. Notebooks are executable documents capturing all the steps of the analysis (including data files, input parameters, and results) and can be easily shared to replicate complete smFRET analyzes. Notebooks allow beginners to execute complex workflows and advanced users to customize the analysis for their own needs. By bundling analysis description, code and results in a single document, FRETBursts allows to seamless share analysis workflows and results, encourages reproducibility and facilitates collaboration among researchers in the single-molecule community.
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Affiliation(s)
- Antonino Ingargiola
- Dept. Chemistry and Biochemistry, Univ. of California Los Angeles, Los Angeles, CA, United States of America
- * E-mail:
| | - Eitan Lerner
- Dept. Chemistry and Biochemistry, Univ. of California Los Angeles, Los Angeles, CA, United States of America
| | - SangYoon Chung
- Dept. Chemistry and Biochemistry, Univ. of California Los Angeles, Los Angeles, CA, United States of America
| | - Shimon Weiss
- Dept. Chemistry and Biochemistry, Univ. of California Los Angeles, Los Angeles, CA, United States of America
| | - Xavier Michalet
- Dept. Chemistry and Biochemistry, Univ. of California Los Angeles, Los Angeles, CA, United States of America
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40
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Jäger S, Garbow N, Kirsch A, Preckel H, Gandenberger FU, Herrenknecht K, Rüdiger M, Hutchinson JP, Bingham RP, Ramon F, Bardera A, Martin J. A Modular, Fully Integrated Ultra-High-Throughput Screening System Based on Confocal Fluorescence Analysis Techniques. ACTA ACUST UNITED AC 2016; 8:648-59. [PMID: 14711390 DOI: 10.1177/1087057103258475] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The rapid increase in size of compound libraries, as well as new targets emerging from the Human Genome Project, require progress in ultra-high-throughput screening (uHTS) systems. In a joint effort with scientists and engineers from the biotech and the pharmaceutical industry, a modular, fully integrated system for miniaturized uHTS was developed. The goal was to achieve high data quality in small assay volumes (1-4 μL) combined with reliable and unattended operation. Two new confocal fluorescence readers have been designed. One of the instruments is a 4-channel confocal fluorescence reader, measuring with 4 objectives in parallel. The fluorescence readout is based on single-molecule detection methods, allowing high sensitivity at low tracer concentrationsand delivering an information-rich output. The other instrument isa confocal fluorescence im aging reader, where the imagesare analyzed in terms of generic patternsand quantified in units of intensity per pixel. Both readers are spanning the application range from assays with isolated targets in homogenous solution or membrane vesiclebased assays (4-channel reader) to cell-based assays (imaging reader). Results from a comprehensive test on these assay types demonstrate the high quality and robustness of this screening system.
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Affiliation(s)
- Stefan Jäger
- Evotec OAI/Evotec Technologies, Hamburg, Germany.
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41
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Bera SC, Sanyal K, Senapati D, Mishra PP. Conformational Changes Followed by Complete Unzipping of DNA Double Helix by Charge-Tuned Gold Nanoparticles. J Phys Chem B 2016; 120:4213-20. [DOI: 10.1021/acs.jpcb.6b01323] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Subhas C. Bera
- Chemical Sciences Division, Saha Institute of Nuclear Physics, Kolkata, India
| | - Kasturi Sanyal
- Chemical Sciences Division, Saha Institute of Nuclear Physics, Kolkata, India
| | - Dulal Senapati
- Chemical Sciences Division, Saha Institute of Nuclear Physics, Kolkata, India
| | - Padmaja P. Mishra
- Chemical Sciences Division, Saha Institute of Nuclear Physics, Kolkata, India
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42
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Lau CS, Sadeghi H, Rogers G, Sangtarash S, Dallas P, Porfyrakis K, Warner J, Lambert CJ, Briggs GAD, Mol JA. Redox-Dependent Franck-Condon Blockade and Avalanche Transport in a Graphene-Fullerene Single-Molecule Transistor. NANO LETTERS 2016; 16:170-176. [PMID: 26633125 DOI: 10.1021/acs.nanolett.5b03434] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We report transport measurements on a graphene-fullerene single-molecule transistor. The device architecture where a functionalized C60 binds to graphene nanoelectrodes results in strong electron-vibron coupling and weak vibron relaxation. Using a combined approach of transport spectroscopy, Raman spectroscopy, and DFT calculations, we demonstrate center-of-mass oscillations, redox-dependent Franck-Condon blockade, and a transport regime characterized by avalanche tunnelling in a single-molecule transistor.
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Affiliation(s)
- Chit Siong Lau
- Department of Materials, University of Oxford , 16 Parks Road, Oxford OX1 3PH, United Kingdom
| | - Hatef Sadeghi
- Quantum Technology Center, Physics Department, Lancaster University , Lancaster LA1 4YB, United Kingdom
| | - Gregory Rogers
- Department of Materials, University of Oxford , 16 Parks Road, Oxford OX1 3PH, United Kingdom
| | - Sara Sangtarash
- Quantum Technology Center, Physics Department, Lancaster University , Lancaster LA1 4YB, United Kingdom
| | - Panagiotis Dallas
- Department of Materials, University of Oxford , 16 Parks Road, Oxford OX1 3PH, United Kingdom
| | - Kyriakos Porfyrakis
- Department of Materials, University of Oxford , 16 Parks Road, Oxford OX1 3PH, United Kingdom
| | - Jamie Warner
- Department of Materials, University of Oxford , 16 Parks Road, Oxford OX1 3PH, United Kingdom
| | - Colin J Lambert
- Quantum Technology Center, Physics Department, Lancaster University , Lancaster LA1 4YB, United Kingdom
| | - G Andrew D Briggs
- Department of Materials, University of Oxford , 16 Parks Road, Oxford OX1 3PH, United Kingdom
| | - Jan A Mol
- Department of Materials, University of Oxford , 16 Parks Road, Oxford OX1 3PH, United Kingdom
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Kuchlyan J, Banik D, Kundu N, Roy A, Sarkar N. Interaction of fluorescence dyes with 5-fluorouracil: A photoinduced electron transfer study in bulk and biologically relevant water. Chem Phys Lett 2014. [DOI: 10.1016/j.cplett.2014.08.062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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44
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Gust A, Zander A, Gietl A, Holzmeister P, Schulz S, Lalkens B, Tinnefeld P, Grohmann D. A starting point for fluorescence-based single-molecule measurements in biomolecular research. Molecules 2014; 19:15824-65. [PMID: 25271426 PMCID: PMC6271140 DOI: 10.3390/molecules191015824] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Revised: 09/17/2014] [Accepted: 09/17/2014] [Indexed: 01/24/2023] Open
Abstract
Single-molecule fluorescence techniques are ideally suited to provide information about the structure-function-dynamics relationship of a biomolecule as static and dynamic heterogeneity can be easily detected. However, what type of single-molecule fluorescence technique is suited for which kind of biological question and what are the obstacles on the way to a successful single-molecule microscopy experiment? In this review, we provide practical insights into fluorescence-based single-molecule experiments aiming for scientists who wish to take their experiments to the single-molecule level. We especially focus on fluorescence resonance energy transfer (FRET) experiments as these are a widely employed tool for the investigation of biomolecular mechanisms. We will guide the reader through the most critical steps that determine the success and quality of diffusion-based confocal and immobilization-based total internal reflection fluorescence microscopy. We discuss the specific chemical and photophysical requirements that make fluorescent dyes suitable for single-molecule fluorescence experiments. Most importantly, we review recently emerged photoprotection systems as well as passivation and immobilization strategies that enable the observation of fluorescently labeled molecules under biocompatible conditions. Moreover, we discuss how the optical single-molecule toolkit has been extended in recent years to capture the physiological complexity of a cell making it even more relevant for biological research.
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Affiliation(s)
- Alexander Gust
- Physikalische und Theoretische Chemie - NanoBioSciences, Technische Universität Braunschweig, Hans-Sommer-Strasse 10, Braunschweig 38106, Germany
| | - Adrian Zander
- Physikalische und Theoretische Chemie - NanoBioSciences, Technische Universität Braunschweig, Hans-Sommer-Strasse 10, Braunschweig 38106, Germany
| | - Andreas Gietl
- Physikalische und Theoretische Chemie - NanoBioSciences, Technische Universität Braunschweig, Hans-Sommer-Strasse 10, Braunschweig 38106, Germany
| | - Phil Holzmeister
- Physikalische und Theoretische Chemie - NanoBioSciences, Technische Universität Braunschweig, Hans-Sommer-Strasse 10, Braunschweig 38106, Germany
| | - Sarah Schulz
- Physikalische und Theoretische Chemie - NanoBioSciences, Technische Universität Braunschweig, Hans-Sommer-Strasse 10, Braunschweig 38106, Germany
| | - Birka Lalkens
- Physikalische und Theoretische Chemie - NanoBioSciences, Technische Universität Braunschweig, Hans-Sommer-Strasse 10, Braunschweig 38106, Germany
| | - Philip Tinnefeld
- Physikalische und Theoretische Chemie - NanoBioSciences, Technische Universität Braunschweig, Hans-Sommer-Strasse 10, Braunschweig 38106, Germany
| | - Dina Grohmann
- Physikalische und Theoretische Chemie - NanoBioSciences, Technische Universität Braunschweig, Hans-Sommer-Strasse 10, Braunschweig 38106, Germany.
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Lu Y, Lu J, Zhao J, Cusido J, Raymo FM, Yuan J, Yang S, Leif RC, Huo Y, Piper JA, Paul Robinson J, Goldys EM, Jin D. On-the-fly decoding luminescence lifetimes in the microsecond region for lanthanide-encoded suspension arrays. Nat Commun 2014; 5:3741. [PMID: 24796249 PMCID: PMC4024748 DOI: 10.1038/ncomms4741] [Citation(s) in RCA: 119] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2014] [Accepted: 03/27/2014] [Indexed: 12/23/2022] Open
Abstract
Significant multiplexing capacity of optical time-domain coding has been recently demonstrated by tuning luminescence lifetimes of the upconversion nanoparticles called 'τ-Dots'. It provides a large dynamic range of lifetimes from microseconds to milliseconds, which allows creating large libraries of nanotags/microcarriers. However, a robust approach is required to rapidly and accurately measure the luminescence lifetimes from the relatively slow-decaying signals. Here we show a fast algorithm suitable for the microsecond region with precision closely approaching the theoretical limit and compatible with the rapid scanning cytometry technique. We exploit this approach to further extend optical time-domain multiplexing to the downconversion luminescence, using luminescence microspheres wherein lifetimes are tuned through luminescence resonance energy transfer. We demonstrate real-time discrimination of these microspheres in the rapid scanning cytometry, and apply them to the multiplexed probing of pathogen DNA strands. Our results indicate that tunable luminescence lifetimes have considerable potential in high-throughput analytical sciences.
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Affiliation(s)
- Yiqing Lu
- Advanced Cytometry Laboratories, ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP), Macquarie University, Sydney, New South Wales 2109, Australia
| | - Jie Lu
- Advanced Cytometry Laboratories, ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP), Macquarie University, Sydney, New South Wales 2109, Australia
| | - Jiangbo Zhao
- Advanced Cytometry Laboratories, ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP), Macquarie University, Sydney, New South Wales 2109, Australia
| | - Janet Cusido
- Laboratory for Molecular Photonics, University of Miami, 1301 Memorial Drive, Coral Gables, Florida 33146-0431, USA
| | - Françisco M Raymo
- Laboratory for Molecular Photonics, University of Miami, 1301 Memorial Drive, Coral Gables, Florida 33146-0431, USA
| | - Jingli Yuan
- State Key Laboratory of Fine Chemicals, School of Chemistry, Dalian University of Technology, Dalian 116024, China
| | - Sean Yang
- Newport Instruments, 3345 Hopi Place, San Diego, California 92117-3516, USA
| | - Robert C. Leif
- Newport Instruments, 3345 Hopi Place, San Diego, California 92117-3516, USA
| | - Yujing Huo
- Department of Electronic Engineering, Tsinghua University, Beijing 100084, China
| | - James A. Piper
- Advanced Cytometry Laboratories, ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP), Macquarie University, Sydney, New South Wales 2109, Australia
| | - J Paul Robinson
- Purdue University Cytometry Laboratories, Bindley Bioscience Center, Purdue University, West Lafayette, Indiana 47907, USA
| | - Ewa M. Goldys
- Advanced Cytometry Laboratories, ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP), Macquarie University, Sydney, New South Wales 2109, Australia
| | - Dayong Jin
- Advanced Cytometry Laboratories, ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP), Macquarie University, Sydney, New South Wales 2109, Australia
- Purdue University Cytometry Laboratories, Bindley Bioscience Center, Purdue University, West Lafayette, Indiana 47907, USA
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Chattoraj S, Chowdhury R, Ghosh S, Bhattacharyya K. Heterogeneity in binary mixtures of dimethyl sulfoxide and glycerol: fluorescence correlation spectroscopy. J Chem Phys 2014; 138:214507. [PMID: 23758388 DOI: 10.1063/1.4808217] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Diffusion of four coumarin dyes in a binary mixture of dimethyl sulfoxide (DMSO) and glycerol is studied using fluorescence correlation spectroscopy (FCS). The coumarin dyes are C151, C152, C480, and C481. In pure DMSO, all the four dyes exhibit a very narrow (almost uni-modal) distribution of diffusion coefficient (Dt). In contrast, in the binary mixtures all of them display a bimodal distribution of Dt with broadly two components. One of the components of D(t) corresponds to the bulk viscosity. The other one is similar to that in pure DMSO. This clearly indicates the presence of two distinctly different nano-domains inside the binary mixture. In the first, the micro-environment of the solute consists of both DMSO and glycerol approximately at the bulk composition. The other corresponds to a situation where the first layer of the solute consists of DMSO only. The burst integrated fluorescence lifetime (BIFL) analysis also indicates presence of two micro-environments one of which resembles DMSO. The relative contribution of the DMSO-like environment obtained from the BIFL analysis is much larger than that obtained from FCS measurements. It is proposed that BIFL corresponds to an instantaneous environment in a small region (a few nm) around the probe. FCS, on the contrary, describes the long time trajectory of the probes in a region of dimension ~200 nm. The results are explained in terms of the theory of binary mixtures and recent simulations of binary mixtures containing DMSO.
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Affiliation(s)
- Shyamtanu Chattoraj
- Department of Physical Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India
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Joshi H, Sengupta A, Gavvala K, Hazra P. Unraveling the mode of binding of the anticancer drug topotecan with dsDNA. RSC Adv 2014. [DOI: 10.1039/c3ra42462f] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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48
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Pallikkuth S, Blackwell D, Hu Z, Hou Z, Zieman D, Svensson B, Thomas D, Robia S. Phosphorylated phospholamban stabilizes a compact conformation of the cardiac calcium-ATPase. Biophys J 2013; 105:1812-21. [PMID: 24138857 PMCID: PMC3797577 DOI: 10.1016/j.bpj.2013.08.045] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Revised: 08/02/2013] [Accepted: 08/26/2013] [Indexed: 11/29/2022] Open
Abstract
The sarcoendoplasmic reticulum calcium ATPase (SERCA) plays a key role in cardiac calcium handling and is considered a high-value target for the treatment of heart failure. SERCA undergoes conformational changes as it harnesses the chemical energy of ATP for active transport. X-ray crystallography has provided insight into SERCA structural substates, but it is not known how well these static snapshots describe in vivo conformational dynamics. The goals of this work were to quantify the direction and magnitude of SERCA motions as the pump performs work in live cardiac myocytes, and to identify structural determinants of SERCA regulation by phospholamban. We measured intramolecular fluorescence resonance energy transfer (FRET) between fluorescent proteins fused to SERCA cytoplasmic domains. We detected four discrete structural substates for SERCA expressed in cardiac muscle cells. The relative populations of these discrete states oscillated with electrical pacing. Low FRET states were most populated in low Ca (diastole), and were indicative of an open, disordered structure for SERCA in the E2 (Ca-free) enzymatic substate. High FRET states increased with Ca (systole), suggesting rigidly closed conformations for the E1 (Ca-bound) enzymatic substates. Notably, a special compact E1 state was observed after treatment with β-adrenergic agonist or with coexpression of phosphomimetic mutants of phospholamban. The data suggest that SERCA calcium binding induces the pump to undergo a transition from an open, dynamic conformation to a closed, ordered structure. Phosphorylated phospholamban stabilizes a unique conformation of SERCA that is characterized by a compact architecture.
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Affiliation(s)
- Sandeep Pallikkuth
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois
| | - Daniel J. Blackwell
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois
| | - Zhihong Hu
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois
| | - Zhanjia Hou
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois
| | - Dane T. Zieman
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois
| | - Bengt Svensson
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota
| | - David D. Thomas
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota
| | - Seth L. Robia
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois
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Ishii K, Tahara T. Two-Dimensional Fluorescence Lifetime Correlation Spectroscopy. 2. Application. J Phys Chem B 2013; 117:11423-32. [DOI: 10.1021/jp406864e] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Kunihiko Ishii
- Molecular Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Tahei Tahara
- Molecular Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
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50
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Mashaghi A, Kramer G, Lamb DC, Mayer MP, Tans SJ. Chaperone Action at the Single-Molecule Level. Chem Rev 2013; 114:660-76. [DOI: 10.1021/cr400326k] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Alireza Mashaghi
- AMOLF Institute, Science Park
104, 1098 XG Amsterdam, The Netherlands
| | - Günter Kramer
- Zentrum
für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Allianz, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
| | - Don C. Lamb
- Physical
Chemistry, Department of Chemistry, Munich Center for Integrated Protein
Science (CiPSM) and Center for Nanoscience, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13, Gerhard-Ertl-Building, 81377 Munich, Germany
| | - Matthias P. Mayer
- Zentrum
für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Allianz, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
| | - Sander J. Tans
- AMOLF Institute, Science Park
104, 1098 XG Amsterdam, The Netherlands
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