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Maity A, Wulffelé J, Ayala I, Favier A, Adam V, Bourgeois D, Brutscher B. Structural Heterogeneity in a Phototransformable Fluorescent Protein Impacts its Photochemical Properties. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2306272. [PMID: 38146132 PMCID: PMC10933604 DOI: 10.1002/advs.202306272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 11/29/2023] [Indexed: 12/27/2023]
Abstract
Photoconvertible fluorescent proteins (PCFP) are important cellular markers in advanced imaging modalities such as photoactivatable localization microscopy (PALM). However, their complex photophysical and photochemical behavior hampers applications such as quantitative and single-particle-tracking PALM. This work employs multidimensional NMR combined with ensemble fluorescence measurements to show that the popular mEos4b in its Green state populates two conformations (A and B), differing in side-chain protonation of the conserved residues E212 and H62, altering the hydrogen-bond network in the chromophore pocket. The interconversion (protonation/deprotonation) between these two states, which occurs on the minutes time scale in the dark, becomes strongly accelerated in the presence of UV light, leading to a population shift. This work shows that the reversible photoswitching and Green-to-Red photoconversion properties differ between the A and B states. The chromophore in the A-state photoswitches more efficiently and is proposed to be more prone to photoconversion, while the B-state shows a higher level of photobleaching. Altogether, this data highlights the central role of conformational heterogeneity in fluorescent protein photochemistry.
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Affiliation(s)
- Arijit Maity
- CEACNRSInstitut de Biologie Structurale (IBS)Université Grenoble Alpes71 avenue des Martyrs, Cedex 9Grenoble38044France
| | - Jip Wulffelé
- CEACNRSInstitut de Biologie Structurale (IBS)Université Grenoble Alpes71 avenue des Martyrs, Cedex 9Grenoble38044France
| | - Isabel Ayala
- CEACNRSInstitut de Biologie Structurale (IBS)Université Grenoble Alpes71 avenue des Martyrs, Cedex 9Grenoble38044France
| | - Adrien Favier
- CEACNRSInstitut de Biologie Structurale (IBS)Université Grenoble Alpes71 avenue des Martyrs, Cedex 9Grenoble38044France
| | - Virgile Adam
- CEACNRSInstitut de Biologie Structurale (IBS)Université Grenoble Alpes71 avenue des Martyrs, Cedex 9Grenoble38044France
| | - Dominique Bourgeois
- CEACNRSInstitut de Biologie Structurale (IBS)Université Grenoble Alpes71 avenue des Martyrs, Cedex 9Grenoble38044France
| | - Bernhard Brutscher
- CEACNRSInstitut de Biologie Structurale (IBS)Université Grenoble Alpes71 avenue des Martyrs, Cedex 9Grenoble38044France
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2
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Fadini A, Hutchison CDM, Morozov D, Chang J, Maghlaoui K, Perrett S, Luo F, Kho JCX, Romei MG, Morgan RML, Orr CM, Cordon-Preciado V, Fujiwara T, Nuemket N, Tosha T, Tanaka R, Owada S, Tono K, Iwata S, Boxer SG, Groenhof G, Nango E, van Thor JJ. Serial Femtosecond Crystallography Reveals that Photoactivation in a Fluorescent Protein Proceeds via the Hula Twist Mechanism. J Am Chem Soc 2023. [PMID: 37418747 PMCID: PMC10375524 DOI: 10.1021/jacs.3c02313] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/09/2023]
Abstract
Chromophore cis/trans photoisomerization is a fundamental process in chemistry and in the activation of many photosensitive proteins. A major task is understanding the effect of the protein environment on the efficiency and direction of this reaction compared to what is observed in the gas and solution phases. In this study, we set out to visualize the hula twist (HT) mechanism in a fluorescent protein, which is hypothesized to be the preferred mechanism in a spatially constrained binding pocket. We use a chlorine substituent to break the twofold symmetry of the embedded phenolic group of the chromophore and unambiguously identify the HT primary photoproduct. Through serial femtosecond crystallography, we then track the photoreaction from femtoseconds to the microsecond regime. We observe signals for the photoisomerization of the chromophore as early as 300 fs, obtaining the first experimental structural evidence of the HT mechanism in a protein on its femtosecond-to-picosecond timescale. We are then able to follow how chromophore isomerization and twisting lead to secondary structure rearrangements of the protein β-barrel across the time window of our measurements.
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Affiliation(s)
- Alisia Fadini
- Department of Life Sciences, Faculty of Natural Sciences, Imperial College London, London SW7 2AZ, U.K
| | - Christopher D M Hutchison
- Department of Life Sciences, Faculty of Natural Sciences, Imperial College London, London SW7 2AZ, U.K
| | - Dmitry Morozov
- Nanoscience Center and Department of Chemistry, University of Jyväskylä, Jyväskylä 40014, Finland
| | - Jeffrey Chang
- Department of Physics, Stanford University, Stanford, California 94305, United States
| | - Karim Maghlaoui
- Department of Life Sciences, Faculty of Natural Sciences, Imperial College London, London SW7 2AZ, U.K
| | - Samuel Perrett
- Department of Life Sciences, Faculty of Natural Sciences, Imperial College London, London SW7 2AZ, U.K
| | - Fangjia Luo
- RIKEN Spring-8 Center, 1-1-1 Kouto, Sayo, Sayo, Hyogo 679-5148, Japan
| | - Jeslyn C X Kho
- Department of Life Sciences, Faculty of Natural Sciences, Imperial College London, London SW7 2AZ, U.K
| | - Matthew G Romei
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - R Marc L Morgan
- Department of Life Sciences, Faculty of Natural Sciences, Imperial College London, London SW7 2AZ, U.K
| | - Christian M Orr
- Diamond Light Source Ltd, Harwell Science & Innovation Campus, Didcot OX11 0DE, U.K
| | - Violeta Cordon-Preciado
- Department of Life Sciences, Faculty of Natural Sciences, Imperial College London, London SW7 2AZ, U.K
| | - Takaaki Fujiwara
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba, Sendai, Miyagi 980-8577, Japan
| | - Nipawan Nuemket
- RIKEN Spring-8 Center, 1-1-1 Kouto, Sayo, Sayo, Hyogo 679-5148, Japan
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Yoshidakonoe, Sakyo, Kyoto 606-8501, Japan
| | - Takehiko Tosha
- RIKEN Spring-8 Center, 1-1-1 Kouto, Sayo, Sayo, Hyogo 679-5148, Japan
| | - Rie Tanaka
- RIKEN Spring-8 Center, 1-1-1 Kouto, Sayo, Sayo, Hyogo 679-5148, Japan
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Yoshidakonoe, Sakyo, Kyoto 606-8501, Japan
| | - Shigeki Owada
- RIKEN Spring-8 Center, 1-1-1 Kouto, Sayo, Sayo, Hyogo 679-5148, Japan
- Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo, Sayo, Hyogo 679-5198, Japan
| | - Kensuke Tono
- RIKEN Spring-8 Center, 1-1-1 Kouto, Sayo, Sayo, Hyogo 679-5148, Japan
- Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo, Sayo, Hyogo 679-5198, Japan
| | - So Iwata
- RIKEN Spring-8 Center, 1-1-1 Kouto, Sayo, Sayo, Hyogo 679-5148, Japan
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Yoshidakonoe, Sakyo, Kyoto 606-8501, Japan
| | - Steven G Boxer
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Gerrit Groenhof
- Nanoscience Center and Department of Chemistry, University of Jyväskylä, Jyväskylä 40014, Finland
| | - Eriko Nango
- RIKEN Spring-8 Center, 1-1-1 Kouto, Sayo, Sayo, Hyogo 679-5148, Japan
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba, Sendai, Miyagi 980-8577, Japan
| | - Jasper J van Thor
- Department of Life Sciences, Faculty of Natural Sciences, Imperial College London, London SW7 2AZ, U.K
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Bourges AC, Moeyaert B, Bui TYH, Bierbuesse F, Vandenberg W, Dedecker P. Quantitative determination of the full switching cycle of photochromic fluorescent proteins. Chem Commun (Camb) 2023. [PMID: 37377004 DOI: 10.1039/d3cc01617j] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/29/2023]
Abstract
In this study, we develop a general analytical model of the photochromism of fluorescent proteins and apply it to spectroscopic measurements performed on six different labels. Our approach provides quantitative explanations for phenomena such as the existence of positive and negative switching, limitations in the photochromism contrast, and the fact that initial switching cycles may differ from subsequent ones. It also allows us to perform the very first measurement of all four isomerization quantum yields involved in the switching process.
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4
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Zhu YH, Liu XX, Fang Q, Liu XY, Fang WH, Cui G. Multiple Photoisomerization Pathways of the Green Fluorescent Protein Chromophore in a Reversibly Photoswitchable Fluorescent Protein: Insights from Quantum Mechanics/Molecular Mechanics Simulations. J Phys Chem Lett 2023; 14:2588-2598. [PMID: 36881005 DOI: 10.1021/acs.jpclett.3c00165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Herein, we have employed a combined CASPT2//CASSCF approach within the quantum mechanics/molecular mechanics (QM/MM) framework to explore the early time photoisomerization of rsEGFP2 starting from its two OFF trans states, i.e., Trans1 and Trans2. The results show similar vertical excitation energies to the S1 state in their Franck-Condon regions. Considering the clockwise and counterclockwise rotations of the C11-C9 bond, four pairs of the S1 excited-state minima and low-lying S1/S0 conical intersections were optimized, based on which we determined four S1 photoisomerization paths that are essentially barrierless to the relevant S1/S0 conical intersections leading to efficient excited-state deactivation to the S0 state. Most importantly, our work first identified multiple photoisomerization and excited-state decay paths, which must be seriously considered in the future. This work not only sheds significant light on the primary trans-cis photoisomerization of rsEGFP2 but also aids in the understanding of the microscopic mechanism of GFP-like RSFPs and the design of novel GFP-like fluorescent proteins.
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Affiliation(s)
- Yun-Hua Zhu
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Xin-Xin Liu
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Qiu Fang
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Xiang-Yang Liu
- College of Chemistry and Material Science, Sichuan Normal University, Chengdu 610068, China
| | - Wei-Hai Fang
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Ganglong Cui
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
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5
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Nienhaus K, Nienhaus GU. Genetically encodable fluorescent protein markers in advanced optical imaging. Methods Appl Fluoresc 2022; 10. [PMID: 35767981 DOI: 10.1088/2050-6120/ac7d3f] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 06/29/2022] [Indexed: 11/12/2022]
Abstract
Optical fluorescence microscopy plays a pivotal role in the exploration of biological structure and dynamics, especially on live specimens. Progress in the field relies, on the one hand, on technical advances in imaging and data processing and, on the other hand, on progress in fluorescent marker technologies. Among these, genetically encodable fluorescent proteins (FPs) are invaluable tools, as they allow facile labeling of live cells, tissues or organisms, as these produce the FP markers all by themselves after introduction of a suitable gene. Here we cover FP markers from the GFP family of proteins as well as tetrapyrrole-binding proteins, which further complement the FP toolbox in important ways. A broad range of FP variants have been endowed, by using protein engineering, with photophysical properties that are essential for specific fluorescence microscopy techniques, notably those offering nanoscale image resolution. We briefly introduce various advanced imaging methods and show how they utilize the distinct properties of the FP markers in exciting imaging applications, with the aim to guide researchers toward the design of powerful imaging experiments that are optimally suited to address their biological questions.
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Affiliation(s)
- Karin Nienhaus
- Institute of Applied Physics, Karlsruhe Institute of Technology, Wolfgang Gaede Str. 1, Karlsruhe, 76131, GERMANY
| | - Gerd Ulrich Nienhaus
- Karlsruhe Institute of Technology, Wolfgang Gaede Str. 1, Karlsruhe, 76131, GERMANY
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6
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Jeong S, Widengren J, Lee JC. Fluorescent Probes for STED Optical Nanoscopy. NANOMATERIALS (BASEL, SWITZERLAND) 2021; 12:21. [PMID: 35009972 PMCID: PMC8746377 DOI: 10.3390/nano12010021] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 12/17/2021] [Accepted: 12/17/2021] [Indexed: 06/14/2023]
Abstract
Progress in developing fluorescent probes, such as fluorescent proteins, organic dyes, and fluorescent nanoparticles, is inseparable from the advancement in optical fluorescence microscopy. Super-resolution microscopy, or optical nanoscopy, overcame the far-field optical resolution limit, known as Abbe's diffraction limit, by taking advantage of the photophysical properties of fluorescent probes. Therefore, fluorescent probes for super-resolution microscopy should meet the new requirements in the probes' photophysical and photochemical properties. STED optical nanoscopy achieves super-resolution by depleting excited fluorophores at the periphery of an excitation laser beam using a depletion beam with a hollow core. An ideal fluorescent probe for STED nanoscopy must meet specific photophysical and photochemical properties, including high photostability, depletability at the depletion wavelength, low adverse excitability, and biocompatibility. This review introduces the requirements of fluorescent probes for STED nanoscopy and discusses the recent progress in the development of fluorescent probes, such as fluorescent proteins, organic dyes, and fluorescent nanoparticles, for the STED nanoscopy. The strengths and the limitations of the fluorescent probes are analyzed in detail.
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Affiliation(s)
- Sejoo Jeong
- Department of New Biology, Daegu Gyeongbuk Institute of Science & Technology, Daegu 42988, Korea;
| | - Jerker Widengren
- Experimental Biomolecular Physics, Department of Applied Physics, Royal Institute of Technology (KTH), Stockholm 10691, Sweden;
| | - Jong-Chan Lee
- Department of New Biology, Daegu Gyeongbuk Institute of Science & Technology, Daegu 42988, Korea;
- New Biology Research Center, Daegu Gyeongbuk Institute of Science & Technology, Daegu 42988, Korea
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7
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Nienhaus K, Nienhaus GU. Fluorescent proteins of the EosFP clade: intriguing marker tools with multiple photoactivation modes for advanced microscopy. RSC Chem Biol 2021; 2:796-814. [PMID: 34458811 PMCID: PMC8341165 DOI: 10.1039/d1cb00014d] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 03/27/2021] [Indexed: 02/04/2023] Open
Abstract
Optical fluorescence microscopy has taken center stage in the exploration of biological structure and dynamics, especially on live specimens, and super-resolution imaging methods continue to deliver exciting new insights into the molecular foundations of life. Progress in the field, however, crucially hinges on advances in fluorescent marker technology. Among these, fluorescent proteins (FPs) of the GFP family are advantageous because they are genetically encodable, so that live cells, tissues or organisms can produce these markers all by themselves. A subclass of them, photoactivatable FPs, allow for control of their fluorescence emission by light irradiation, enabling pulse-chase imaging and super-resolution microscopy. In this review, we discuss FP variants of the EosFP clade that have been optimized by amino acid sequence modification to serve as markers for various imaging techniques. In general, two different modes of photoactivation are found, reversible photoswitching between a fluorescent and a nonfluorescent state and irreversible green-to red photoconversion. First, we describe their basic structural and optical properties. We then summarize recent research aimed at elucidating the photochemical processes underlying photoactivation. Finally, we briefly introduce various advanced imaging methods facilitated by specific EosFP variants, and show some exciting sample applications.
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Affiliation(s)
- Karin Nienhaus
- Institute of Applied Physics, Karlsruhe Institute of Technology 76049 Karlsruhe Germany
| | - Gerd Ulrich Nienhaus
- Institute of Applied Physics, Karlsruhe Institute of Technology 76049 Karlsruhe Germany
- Institute of Nanotechnology, Karlsruhe Institute of Technology 76021 Karlsruhe Germany
- Institute of Biological and Chemical Systems, Karlsruhe Institute of Technology 76021 Karlsruhe Germany
- Department of Physics, University of Illinois at Urbana-Champaign Urbana IL 61801 USA
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8
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Christou NE, Giandoreggio-Barranco K, Ayala I, Glushonkov O, Adam V, Bourgeois D, Brutscher B. Disentangling Chromophore States in a Reversibly Switchable Green Fluorescent Protein: Mechanistic Insights from NMR Spectroscopy. J Am Chem Soc 2021; 143:7521-7530. [PMID: 33966387 DOI: 10.1021/jacs.1c02442] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The photophysical properties of fluorescent proteins, including phototransformable variants used in advanced microscopy applications, are influenced by the environmental conditions in which they are expressed and used. Rational design of improved fluorescent protein markers requires a better understanding of these environmental effects. We demonstrate here that solution NMR spectroscopy can detect subtle changes in the chemical structure, conformation, and dynamics of the photoactive chromophore moiety with atomic resolution, providing such mechanistic information. Studying rsFolder, a reversibly switchable green fluorescent protein, we have identified four distinct configurations of its p-HBI chromophore, corresponding to the cis and trans isomers, with each one either protonated (neutral) or deprotonated (anionic) at the benzylidene ring. The relative populations and interconversion kinetics of these chromophore species depend on sample pH and buffer composition that alter in a complex way the strength of H-bonds that contribute in stabilizing the chromophore within the protein scaffold. We show in particular the important role of histidine-149 in stabilizing the neutral trans chromophore at intermediate pH values, leading to ground-state cis-trans isomerization with a peculiar pH dependence. We discuss the potential implications of our findings on the pH dependence of the photoswitching contrast, a critical parameter in nanoscopy applications.
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Affiliation(s)
- Nina Eleni Christou
- Univ. Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale (IBS), 38000 Grenoble, France
| | | | - Isabel Ayala
- Univ. Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale (IBS), 38000 Grenoble, France
| | - Oleksandr Glushonkov
- Univ. Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale (IBS), 38000 Grenoble, France
| | - Virgile Adam
- Univ. Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale (IBS), 38000 Grenoble, France
| | - Dominique Bourgeois
- Univ. Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale (IBS), 38000 Grenoble, France
| | - Bernhard Brutscher
- Univ. Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale (IBS), 38000 Grenoble, France
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Chang J, Romei MG, Boxer SG. Structural Evidence of Photoisomerization Pathways in Fluorescent Proteins. J Am Chem Soc 2019; 141:15504-15508. [PMID: 31533429 PMCID: PMC7036281 DOI: 10.1021/jacs.9b08356] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Double-bond photoisomerization in molecules such as the green fluorescent protein (GFP) chromophore can occur either via a volume-demanding one-bond-flip pathway or via a volume-conserving hula-twist pathway. Understanding the factors that determine the pathway of photoisomerization would inform the rational design of photoswitchable GFPs as improved tools for super-resolution microscopy. In this communication, we reveal the photoisomerization pathway of a photoswitchable GFP, rsEGFP2, by solving crystal structures of cis and trans rsEGFP2 containing a monochlorinated chromophore. The position of the chlorine substituent in the trans state breaks the symmetry of the phenolate ring of the chromophore and allows us to distinguish the two pathways. Surprisingly, we find that the pathway depends on the arrangement of protein monomers within the crystal lattice: in a looser packing, the one-bond-flip occurs, whereas, in a tighter packing (7% smaller unit cell size), the hula-twist occurs.
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Affiliation(s)
- Jeffrey Chang
- Department of Physics, Stanford University, Stanford, California 94305, United States
| | - Matthew G. Romei
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Steven G. Boxer
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
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10
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Glazachev YI, Orlova DY, Řezníčková P, Bártová E. Effective scheme of photolysis of GFP in live cell as revealed with confocal fluorescence microscopy. Phys Biol 2018; 15:036008. [PMID: 29493532 DOI: 10.1088/1478-3975/aab31e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We proposed an effective kinetics scheme of photolysis of green fluorescent protein (GFP) observed in live cells with a commercial confocal fluorescence microscope. We investigated the photolysis of GFP-tagged heterochromatin protein, HP1β-GFP, in live nucleus with the pulse position modulation approach, which has several advantages over the classical pump-and-probe method. At the basis of the proposed scheme lies a process of photoswitching from the native fluorescence state to the intermediate fluorescence state, which has a lower fluorescence yield and recovers back to native state in the dark. This kinetics scheme includes four effective parameters (photoswitching, reverse switching, photodegradation rate constants, and relative brightness of the intermediate state) and covers the time scale from dozens of milliseconds to minutes of the experimental fluorescence kinetics. Additionally, the applicability of the scheme was demonstrated in the cases of continuous irradiation and the classical pump-and-probe approach using numerical calculations and analytical solutions. An interesting finding of experimental data analysis was that the overall photodegradation of GFP proceeds dominantly from the intermediate state, and demonstrated approximately the second-order reaction versus irradiation power. As a practical example, the proposed scheme elucidates the artifacts of fluorescence recovery after the photobleaching method, and allows us to propose some suggestions on how to diminish them.
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Affiliation(s)
- Yu I Glazachev
- Institute of Chemical Kinetics and Combustion, Siberian Branch of Russian academy of Science, Novosibirsk 630090, Russia. Author to whom any correspondence should be addressed
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11
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Correlative super-resolution fluorescence and electron microscopy using conventional fluorescent proteins in vacuo. J Struct Biol 2017; 199:120-131. [PMID: 28576556 PMCID: PMC5531056 DOI: 10.1016/j.jsb.2017.05.013] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 04/27/2017] [Accepted: 05/29/2017] [Indexed: 12/12/2022]
Abstract
Super-resolution light microscopy, correlative light and electron microscopy, and volume electron microscopy are revolutionising the way in which biological samples are examined and understood. Here, we combine these approaches to deliver super-accurate correlation of fluorescent proteins to cellular structures. We show that YFP and GFP have enhanced blinking properties when embedded in acrylic resin and imaged under partial vacuum, enabling in vacuo single molecule localisation microscopy. In conventional section-based correlative microscopy experiments, the specimen must be moved between imaging systems and/or further manipulated for optimal viewing. These steps can introduce undesirable alterations in the specimen, and complicate correlation between imaging modalities. We avoided these issues by using a scanning electron microscope with integrated optical microscope to acquire both localisation and electron microscopy images, which could then be precisely correlated. Collecting data from ultrathin sections also improved the axial resolution and signal-to-noise ratio of the raw localisation microscopy data. Expanding data collection across an array of sections will allow 3-dimensional correlation over unprecedented volumes. The performance of this technique is demonstrated on vaccinia virus (with YFP) and diacylglycerol in cellular membranes (with GFP).
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12
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Nienhaus K, Nienhaus GU. Chromophore photophysics and dynamics in fluorescent proteins of the GFP family. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:443001. [PMID: 27604321 DOI: 10.1088/0953-8984/28/44/443001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Proteins of the green fluorescent protein (GFP) family are indispensable for fluorescence imaging experiments in the life sciences, particularly of living specimens. Their essential role as genetically encoded fluorescence markers has motivated many researchers over the last 20 years to further advance and optimize these proteins by using protein engineering. Amino acids can be exchanged by site-specific mutagenesis, starting with naturally occurring proteins as templates. Optical properties of the fluorescent chromophore are strongly tuned by the surrounding protein environment, and a targeted modification of chromophore-protein interactions requires a profound knowledge of the underlying photophysics and photochemistry, which has by now been well established from a large number of structural and spectroscopic experiments and molecular-mechanical and quantum-mechanical computations on many variants of fluorescent proteins. Nevertheless, such rational engineering often does not meet with success and thus is complemented by random mutagenesis and selection based on the optical properties. In this topical review, we present an overview of the key structural and spectroscopic properties of fluorescent proteins. We address protein-chromophore interactions that govern ground state optical properties as well as processes occurring in the electronically excited state. Special emphasis is placed on photoactivation of fluorescent proteins. These light-induced reactions result in large structural changes that drastically alter the fluorescence properties of the protein, which enables some of the most exciting applications, including single particle tracking, pulse chase imaging and super-resolution imaging. We also present a few examples of fluorescent protein application in live-cell imaging experiments.
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Affiliation(s)
- Karin Nienhaus
- Institute of Applied Physics, Karlsruhe Institute of Technology (KIT), Wolfgang Gaede-Straße 1, 76131 Karlsruhe, Germany
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13
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Nienhaus K, Nienhaus GU. Photoswitchable Fluorescent Proteins: Do Not Always Look on the Bright Side. ACS NANO 2016; 10:9104-9108. [PMID: 27723301 DOI: 10.1021/acsnano.6b06298] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Photoactivatable fluorescent proteins (FPs) have become essential markers for nanoscopy on live specimens. In this issue of ACS Nano, Wang et al. present a reversibly photoswitching FP, GMars-Q, which they promote as an advanced marker for RESOLFT imaging because of its low residual intensity in the off state and low switching fatigue. Here, we explain the observed peculiar photobleaching behavior of GMars-Q by a mechanism that involves efficient shelving of proteins in dark states, resulting in low switching fatigue and low residual off intensity. There is a continuing demand for novel FP markers with properties optimized for specific imaging techniques. Endeavors to engineer such proteins can greatly benefit from increased efforts to acquire deeper mechanistic understanding of their photophysics and photochemistry.
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Affiliation(s)
- Karin Nienhaus
- Institute of Applied Physics, Karlsruhe Institute of Technology , 76131 Karlsruhe, Germany
| | - Gerd Ulrich Nienhaus
- Institute of Applied Physics, Karlsruhe Institute of Technology , 76131 Karlsruhe, Germany
- Institute of Nanotechnology, Karlsruhe Institute of Technology , 76344 Eggenstein-Leopoldshafen, Germany
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology , 76344 Eggenstein-Leopoldshafen, Germany
- Department of Physics, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
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14
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Nienhaus K, Nienhaus GU. Where Do We Stand with Super-Resolution Optical Microscopy? J Mol Biol 2016; 428:308-322. [DOI: 10.1016/j.jmb.2015.12.020] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 12/23/2015] [Accepted: 12/23/2015] [Indexed: 10/22/2022]
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15
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Hertel F, Mo GCH, Duwé S, Dedecker P, Zhang J. RefSOFI for Mapping Nanoscale Organization of Protein-Protein Interactions in Living Cells. Cell Rep 2015; 14:390-400. [PMID: 26748717 DOI: 10.1016/j.celrep.2015.12.036] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Revised: 09/04/2015] [Accepted: 12/06/2015] [Indexed: 11/27/2022] Open
Abstract
It has become increasingly clear that protein-protein interactions (PPIs) are compartmentalized in nanoscale domains that define the biochemical architecture of the cell. Despite tremendous advances in super-resolution imaging, strategies to observe PPIs at sufficient resolution to discern their organization are just emerging. Here we describe a strategy in which PPIs induce reconstitution of fluorescent proteins (FPs) that are capable of exhibiting single-molecule fluctuations suitable for stochastic optical fluctuation imaging (SOFI). Subsequently, spatial maps of these interactions can be resolved in super-resolution in living cells. Using this strategy, termed reconstituted fluorescence-based SOFI (refSOFI), we investigated the interaction between the endoplasmic reticulum (ER) Ca(2+) sensor STIM1 and the pore-forming channel subunit ORAI1, a crucial process in store-operated Ca(2+) entry (SOCE). Stimulating SOCE does not appear to change the size of existing STIM1/ORAI1 interaction puncta at the ER-plasma membrane junctions, but results in an apparent increase in the number of interaction puncta.
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Affiliation(s)
- Fabian Hertel
- Department of Pharmacology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Gary C H Mo
- Department of Pharmacology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Sam Duwé
- Department of Chemistry, University of Leuven, Celestijnenlaan 200F, 3001 Heverlee, Belgium
| | - Peter Dedecker
- Department of Chemistry, University of Leuven, Celestijnenlaan 200F, 3001 Heverlee, Belgium
| | - Jin Zhang
- Department of Pharmacology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA; Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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16
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Smyrnova D, Moeyaert B, Michielssens S, Hofkens J, Dedecker P, Ceulemans A. Molecular Dynamic Indicators of the Photoswitching Properties of Green Fluorescent Proteins. J Phys Chem B 2015; 119:12007-16. [DOI: 10.1021/acs.jpcb.5b04826] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Daryna Smyrnova
- Quantum
Chemistry and Physical Chemistry Division, Department of Chemistry, KU Leuven, Celestijnenenlaan 200F, 3001 Heverlee, Belgium
| | - Benjamien Moeyaert
- Molecular
Imaging and Photonics Division, Department of Chemistry, KU Leuven, Celestijnenenlaan 200F, 3001 Heverlee, Belgium
| | - Servaas Michielssens
- Quantum
Chemistry and Physical Chemistry Division, Department of Chemistry, KU Leuven, Celestijnenenlaan 200F, 3001 Heverlee, Belgium
| | - Johan Hofkens
- Molecular
Imaging and Photonics Division, Department of Chemistry, KU Leuven, Celestijnenenlaan 200F, 3001 Heverlee, Belgium
| | - Peter Dedecker
- Molecular
Imaging and Photonics Division, Department of Chemistry, KU Leuven, Celestijnenenlaan 200F, 3001 Heverlee, Belgium
| | - Arnout Ceulemans
- Quantum
Chemistry and Physical Chemistry Division, Department of Chemistry, KU Leuven, Celestijnenenlaan 200F, 3001 Heverlee, Belgium
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17
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Tiwari DK, Arai Y, Yamanaka M, Matsuda T, Agetsuma M, Nakano M, Fujita K, Nagai T. A fast- and positively photoswitchable fluorescent protein for ultralow-laser-power RESOLFT nanoscopy. Nat Methods 2015; 12:515-8. [DOI: 10.1038/nmeth.3362] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Accepted: 03/10/2015] [Indexed: 02/01/2023]
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18
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Walter A, Andresen M, Jakobs S, Schroeder J, Schwarzer D. Primary light-induced reaction steps of reversibly photoswitchable fluorescent protein Padron0.9 investigated by femtosecond spectroscopy. J Phys Chem B 2015; 119:5136-44. [PMID: 25802098 DOI: 10.1021/jp512610q] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The reversible photoswitching of the photochromic fluorescent protein Padron0.9 involves a cis-trans isomerization of the chromophore. Both isomers are subjected to a protonation equilibrium between a neutral and a deprotonated form. The observed pH dependent absorption spectra require at least two protonating groups in the chromophore environment modulating its proton affinity. Using femtosecond transient absorption spectroscopy, we elucidate the primary reaction steps of selectively excited chromophore species. Employing kinetic and spectral modeling of the time dependent transients, we identify intermediate states and their spectra. Excitation of the deprotonated trans species is followed by excited state relaxation and internal conversion to a hot ground state on a time scale of 1.1-6.5 ps. As the switching yield is very low (Φtrans→cis = 0.0003 ± 0.0001), direct formation of the cis isomer in the time-resolved experiment is not observed. The reverse switching route involves excitation of the neutral cis chromophore. A strong H/D isotope effect reveals the initial reaction step to be an excited state proton transfer with a rate constant of kH = (1.7 ps)(-1) (kD = (8.6 ps)(-1)) competing with internal conversion (kic = (4.5 ps)(-1)). The deprotonated excited cis intermediate relaxes to the well-known long-lived fluorescent species (kr = (24 ps)(-1)). The switching quantum yield is determined to be low as well, Φcis→trans = 0.02 ± 0.01. Excitation of both the neutral and deprotonated cis chromophores is followed by a ground state proton transfer reaction partially re-establishing the disturbed ground state equilibrium within 1.6 ps (deuterated species: 5.6 ps). The incomplete equilibration reveals an inhomogeneous population of deprotonated cis species which equilibrate on different time scales.
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Affiliation(s)
- Arne Walter
- †Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Martin Andresen
- †Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Stefan Jakobs
- †Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.,‡Department of Neurology, University Medical Center of Göttingen, Göttingen, Germany
| | - Jörg Schroeder
- §Institute for Physical Chemistry, Georg-August University of Göttingen, Göttingen, Germany
| | - Dirk Schwarzer
- †Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
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19
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Kang B, Baek KY, Lee JY. Electric Field Effect on trans-p-Hydroxybenzylideneimidazolidinone: A DFT Study and Implication to Green Fluorescent Protein. B KOREAN CHEM SOC 2015. [DOI: 10.1002/bkcs.10063] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Baotao Kang
- Department of Chemistry; Sungkyunkwan University; Suwon 440746 Korea
| | - Kyung Yup Baek
- Department of Chemistry; Sungkyunkwan University; Suwon 440746 Korea
| | - Jin Yong Lee
- Department of Chemistry; Sungkyunkwan University; Suwon 440746 Korea
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20
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Nienhaus K, Nienhaus GU. Fluorescent proteins for live-cell imaging with super-resolution. Chem Soc Rev 2014; 43:1088-106. [PMID: 24056711 DOI: 10.1039/c3cs60171d] [Citation(s) in RCA: 256] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Fluorescent proteins (FPs) from the GFP family have become indispensable as marker tools for imaging live cells, tissues and entire organisms. A wide variety of these proteins have been isolated from natural sources and engineered to optimize their properties as genetically encoded markers. Here we review recent developments in this field. A special focus is placed on photoactivatable FPs, for which the fluorescence emission can be controlled by light irradiation at specific wavelengths. They enable regional optical marking in pulse-chase experiments on live cells and tissues, and they are essential marker tools for live-cell optical imaging with super-resolution. Photoconvertible FPs, which can be activated irreversibly via a photo-induced chemical reaction that either turns on their emission or changes their emission wavelength, are excellent markers for localization-based super-resolution microscopy (e.g., PALM). Patterned illumination microscopy (e.g., RESOLFT), however, requires markers that can be reversibly photoactivated many times. Photoswitchable FPs can be toggled repeatedly between a fluorescent and a non-fluorescent state by means of a light-induced chromophore isomerization coupled to a protonation reaction. We discuss the mechanistic origins of the effect and illustrate how photoswitchable FPs are employed in RESOLFT imaging. For this purpose, special FP variants with low switching fatigue have been introduced in recent years. Despite nearly two decades of FP engineering by many laboratories, there is still room for further improvement of these important markers for live cell imaging.
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Affiliation(s)
- Karin Nienhaus
- Institute of Applied Physics and Center for Functional Nanostructures (CFN), Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Straβe 1, 76131 Karlsruhe, Germany
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21
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Adam V, Berardozzi R, Byrdin M, Bourgeois D. Phototransformable fluorescent proteins: Future challenges. Curr Opin Chem Biol 2014; 20:92-102. [DOI: 10.1016/j.cbpa.2014.05.016] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Revised: 05/19/2014] [Accepted: 05/22/2014] [Indexed: 01/28/2023]
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22
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Hedde PN, Nienhaus GU. Super-resolution localization microscopy with photoactivatable fluorescent marker proteins. PROTOPLASMA 2014; 251:349-62. [PMID: 24162869 DOI: 10.1007/s00709-013-0566-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Accepted: 10/08/2013] [Indexed: 05/02/2023]
Abstract
Fluorescent proteins (FPs) have become popular imaging tools because of their high specificity, minimal invasive labeling and allowing visualization of proteins and structures inside living organisms. FPs are genetically encoded and expressed in living cells, therefore, labeling involves minimal effort in comparison to approaches involving synthetic dyes. Photoactivatable FPs (paFPs) comprise a subclass of FPs that can change their absorption/emission properties such as brightness and color upon irradiation. This methodology has found a broad range of applications in the life sciences, especially in localization-based super-resolution microscopy of cells, tissues and even entire organisms. In this review, we discuss recent developments and applications of paFPs in super-resolution localization imaging.
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Affiliation(s)
- Per Niklas Hedde
- Institute of Applied Physics, Karlsruhe Institute of Technology (KIT), 76128, Karlsruhe, Germany
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23
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Duan C, Adam V, Byrdin M, Bourgeois D. Structural basis of photoswitching in fluorescent proteins. Methods Mol Biol 2014; 1148:177-202. [PMID: 24718802 DOI: 10.1007/978-1-4939-0470-9_12] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Fluorescent proteins have revolutionized life sciences because they allow noninvasive and highly specific labeling of biological samples. The subset of "phototransformable" fluorescent proteins recently attracted a widespread interest, as their fluorescence state can be modified upon excitation at defined wavelengths. The fluorescence emission of Reversibly Switchable Fluorescent Proteins (RSFPs), in particular, can be repeatedly switched on and off. RSFPs enable many new exciting modalities in fluorescence microscopy and biotechnology, including protein tracking, photochromic Förster Resonance Energy Transfer, super-resolution microscopy, optogenetics, and ultra-high-density optical data storage. Photoswitching in RSFPs typically results from chromophore cis-trans isomerization accompanied by a protonation change, but other switching schemes based on, e.g., chromophore hydration/dehydration have also been discovered. In this chapter, we review the main structural features at the basis of photoswitching in RSFPs.
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Affiliation(s)
- Chenxi Duan
- Institut de Biologie Structurale, Université Grenoble Alpes, Grenoble, France
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24
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Abstract
An engineered fluorescent protein exhibits visibly striking photochromism and thermochromism under ambient conditions.
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Affiliation(s)
- Y. Shen
- Department of Chemistry
- University of Alberta
- Edmonton, Canada
| | - M. D. Wiens
- Department of Chemistry
- University of Alberta
- Edmonton, Canada
| | - R. E. Campbell
- Department of Chemistry
- University of Alberta
- Edmonton, Canada
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25
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Ishitsuka Y, Nienhaus K, Nienhaus GU. Photoactivatable fluorescent proteins for super-resolution microscopy. Methods Mol Biol 2014; 1148:239-60. [PMID: 24718806 DOI: 10.1007/978-1-4939-0470-9_16] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Super-resolution fluorescence microscopy techniques such as simulated emission depletion (STED) microscopy and photoactivated localization microscopy (PALM) allow substructures, organelles or even proteins within a cell to be imaged with a resolution far below the diffraction limit of ~200 nm. The development of advanced fluorescent proteins, especially photoactivatable fluorescent proteins of the GFP family, has greatly contributed to the successful application of these techniques to live-cell imaging. Here, we will illustrate how two fluorescent proteins with different photoactivation mechanisms can be utilized in high resolution dual color PALM imaging to obtain insights into a cellular process that otherwise would not be accessible. We will explain how to set up and perform the experiment and how to use our latest software "a-livePALM" for fast and efficient data analysis.
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Affiliation(s)
- Yuji Ishitsuka
- Institute of Applied Physics and Center for Functional Nanostructures (CFN), Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Str. 1, Karlsruhe, 76131, Germany
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26
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Duan C, Adam V, Byrdin M, Ridard J, Kieffer-Jaquinod S, Morlot C, Arcizet D, Demachy I, Bourgeois D. Structural Evidence for a Two-Regime Photobleaching Mechanism in a Reversibly Switchable Fluorescent Protein. J Am Chem Soc 2013; 135:15841-50. [DOI: 10.1021/ja406860e] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Chenxi Duan
- Université Grenoble Alpes, Institut de Biologie Structurale
(IBS), F-38027 Grenoble, France
- CNRS, IBS, F-38027 Grenoble, France
- CEA, DSV, IBS, F-38027 Grenoble, France
- Laboratoire
de Physiologie Cellulaire et Végétale, IRTSV, CNRS/CEA/INRA/Université Grenoble Alpes, Grenoble, 38054, France
| | - Virgile Adam
- Université Grenoble Alpes, Institut de Biologie Structurale
(IBS), F-38027 Grenoble, France
- CNRS, IBS, F-38027 Grenoble, France
- CEA, DSV, IBS, F-38027 Grenoble, France
- Laboratoire
de Physiologie Cellulaire et Végétale, IRTSV, CNRS/CEA/INRA/Université Grenoble Alpes, Grenoble, 38054, France
| | - Martin Byrdin
- Université Grenoble Alpes, Institut de Biologie Structurale
(IBS), F-38027 Grenoble, France
- CNRS, IBS, F-38027 Grenoble, France
- CEA, DSV, IBS, F-38027 Grenoble, France
- Laboratoire
de Physiologie Cellulaire et Végétale, IRTSV, CNRS/CEA/INRA/Université Grenoble Alpes, Grenoble, 38054, France
| | - Jacqueline Ridard
- Laboratoire
de Chimie Physique, UMR 8000, CNRS, Université Paris Sud 11, 91405 Orsay, France
| | | | - Cécile Morlot
- Université Grenoble Alpes, Institut de Biologie Structurale
(IBS), F-38027 Grenoble, France
- CNRS, IBS, F-38027 Grenoble, France
- CEA, DSV, IBS, F-38027 Grenoble, France
| | - Delphine Arcizet
- Université Grenoble Alpes, Institut de Biologie Structurale
(IBS), F-38027 Grenoble, France
- CNRS, IBS, F-38027 Grenoble, France
- CEA, DSV, IBS, F-38027 Grenoble, France
- Laboratoire
de Physiologie Cellulaire et Végétale, IRTSV, CNRS/CEA/INRA/Université Grenoble Alpes, Grenoble, 38054, France
| | - Isabelle Demachy
- Laboratoire
de Chimie Physique, UMR 8000, CNRS, Université Paris Sud 11, 91405 Orsay, France
| | - Dominique Bourgeois
- Université Grenoble Alpes, Institut de Biologie Structurale
(IBS), F-38027 Grenoble, France
- CNRS, IBS, F-38027 Grenoble, France
- CEA, DSV, IBS, F-38027 Grenoble, France
- Laboratoire
de Physiologie Cellulaire et Végétale, IRTSV, CNRS/CEA/INRA/Université Grenoble Alpes, Grenoble, 38054, France
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