1
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Renouard E, Nowinska M, Lacombat F, Plaza P, Müller P, Espagne A. Multiscale Transient Absorption Study of the Fluorescent Protein Dreiklang and Two Point Variants Provides Insight into Photoswitching and Nonproductive Reaction Pathways. J Phys Chem Lett 2023:6477-6485. [PMID: 37437305 DOI: 10.1021/acs.jpclett.3c00431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/14/2023]
Abstract
Dreiklang is a reversibly photoswitchable fluorescent protein used as a probe in advanced fluorescence imaging. It undergoes a unique and still poorly understood photoswitching mechanism based on the reversible addition of a water molecule to the chromophore. We report the first comprehensive study of the dynamics of this reaction by transient absorption spectroscopy from 100 fs to seconds in the original Dreiklang protein and two point variants. The picture that emerges from our work is that of a competition between photoswitching and nonproductive reaction pathways. We found that photoswitching had a low quantum yield of 0.4%. It involves electron transfer from a tyrosine residue (Tyr203) to the chromophore and is completed in 33 ns. Nonproductive deactivation pathways comprise recombination of a charge transfer intermediate, excited-state proton transfer from the chromophore to a histidine residue (His145), and decay to the ground state via micro-/millisecond-lived intermediates.
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Affiliation(s)
- Emilie Renouard
- PASTEUR, Département de chimie, École normale supérieure, PSL University, Sorbonne Université, CNRS, 75005 Paris, France
| | - Magdalena Nowinska
- PASTEUR, Département de chimie, École normale supérieure, PSL University, Sorbonne Université, CNRS, 75005 Paris, France
| | - Fabien Lacombat
- PASTEUR, Département de chimie, École normale supérieure, PSL University, Sorbonne Université, CNRS, 75005 Paris, France
| | - Pascal Plaza
- PASTEUR, Département de chimie, École normale supérieure, PSL University, Sorbonne Université, CNRS, 75005 Paris, France
| | - Pavel Müller
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
| | - Agathe Espagne
- PASTEUR, Département de chimie, École normale supérieure, PSL University, Sorbonne Université, CNRS, 75005 Paris, France
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2
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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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3
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Tang L, Fang C. Photoswitchable Fluorescent Proteins: Mechanisms on Ultrafast Timescales. Int J Mol Sci 2022; 23:6459. [PMID: 35742900 PMCID: PMC9223536 DOI: 10.3390/ijms23126459] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Revised: 06/06/2022] [Accepted: 06/08/2022] [Indexed: 12/15/2022] Open
Abstract
The advancement of super-resolution imaging (SRI) relies on fluorescent proteins with novel photochromic properties. Using light, the reversibly switchable fluorescent proteins (RSFPs) can be converted between bright and dark states for many photocycles and their emergence has inspired the invention of advanced SRI techniques. The general photoswitching mechanism involves the chromophore cis-trans isomerization and proton transfer for negative and positive RSFPs and hydration-dehydration for decoupled RSFPs. However, a detailed understanding of these processes on ultrafast timescales (femtosecond to millisecond) is lacking, which fundamentally hinders the further development of RSFPs. In this review, we summarize the current progress of utilizing various ultrafast electronic and vibrational spectroscopies, and time-resolved crystallography in investigating the on/off photoswitching pathways of RSFPs. We show that significant insights have been gained for some well-studied proteins, but the real-time "action" details regarding the bidirectional cis-trans isomerization, proton transfer, and intermediate states remain unclear for most systems, and many other relevant proteins have not been studied yet. We expect this review to lay the foundation and inspire more ultrafast studies on existing and future engineered RSFPs. The gained mechanistic insights will accelerate the rational development of RSFPs with enhanced two-way switching rate and efficiency, better photostability, higher brightness, and redder emission colors.
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Affiliation(s)
- Longteng Tang
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, OR 97331-4003, USA
| | - Chong Fang
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, OR 97331-4003, USA
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4
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Konen T, Stumpf D, Grotjohann T, Jansen I, Bossi M, Weber M, Jensen N, Hell SW, Jakobs S. The Positive Switching Fluorescent Protein Padron2 Enables Live-Cell Reversible Saturable Optical Linear Fluorescence Transitions (RESOLFT) Nanoscopy without Sequential Illumination Steps. ACS NANO 2021; 15:9509-9521. [PMID: 34019380 PMCID: PMC8291764 DOI: 10.1021/acsnano.0c08207] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Reversibly switchable fluorescent proteins (RSFPs) can be repeatedly transferred between a fluorescent on- and a nonfluorescent off-state by illumination with light of different wavelengths. Negative switching RSFPs are switched from the on- to the off-state with the same wavelength that also excites fluorescence. Positive switching RSFPs have a reversed light response, where the fluorescence excitation wavelength induces the transition from the off- to the on-state. Reversible saturable optical linear (fluorescence) transitions (RESOLFT) nanoscopy utilizes these switching states to achieve diffraction-unlimited resolution but so far has primarily relied on negative switching RSFPs by using time sequential switching schemes. On the basis of the green fluorescent RSFP Padron, we engineered the positive switching RSFP Padron2. Compared to its predecessor, it can undergo 50-fold more switching cycles while displaying a contrast ratio between the on- and the off-states of more than 100:1. Because of its robust switching behavior, Padron2 supports a RESOLFT imaging scheme that entirely refrains from sequential switching as it only requires beam scanning of two spatially overlaid light distributions. Using Padron2, we demonstrate live-cell RESOLFT nanoscopy without sequential illumination steps.
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Affiliation(s)
- Timo Konen
- Department
of NanoBiophotonics, Max Planck Institute
for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Daniel Stumpf
- Department
of NanoBiophotonics, Max Planck Institute
for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Tim Grotjohann
- Department
of NanoBiophotonics, Max Planck Institute
for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Isabelle Jansen
- Department
of NanoBiophotonics, Max Planck Institute
for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Mariano Bossi
- Department
of Optical Nanoscopy, Max Planck Institute
for Medical Research, 69120 Heidelberg, Germany
| | - Michael Weber
- Department
of NanoBiophotonics, Max Planck Institute
for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Nickels Jensen
- Department
of NanoBiophotonics, Max Planck Institute
for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Stefan W. Hell
- Department
of NanoBiophotonics, Max Planck Institute
for Biophysical Chemistry, 37077 Göttingen, Germany
- Department
of Optical Nanoscopy, Max Planck Institute
for Medical Research, 69120 Heidelberg, Germany
| | - Stefan Jakobs
- Department
of NanoBiophotonics, Max Planck Institute
for Biophysical Chemistry, 37077 Göttingen, Germany
- Clinic
of Neurology, University of Göttingen, 37075 Göttingen, Germany
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5
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Zimara J, Stevens H, Oswald R, Demeshko S, Dechert S, Mata RA, Meyer F, Schwarzer D. Time-Resolved Spectroscopy of Photoinduced Electron Transfer in Dinuclear and Tetranuclear Fe/Co Prussian Blue Analogues. Inorg Chem 2020; 60:449-459. [PMID: 33332100 DOI: 10.1021/acs.inorgchem.0c03249] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The dynamics of the photodriven charge transfer-induced spin transition (CTIST) in two Fe/Co Prussian Blue Analogues (PBAs) are revealed by femtosecond IR and UV/vis pump-probe spectroscopy. Depending on temperature, the known tetranuclear square-type complex [Co2Fe2(CN)6(tp*)2(4,4'-dtbbpy)4](PF6)2 (1) exists in two electronic states. In acetonitrile solution, at <240 K, the low temperature (LT) phase is prevalent consisting of low-spin Fe(II) and low-spin Co(III), [FeIILSCoIIILS]2. Temperature rise is the reason behind thermally-induced CTIST toward the high temperature (HT) phase consisting of low-spin Fe(III) and high-spin Co(II), [FeIIILSCoIIHS]2, being prevalent at >300 K. Photoexcitation into the intervalence charge transfer (IVCT) band of the LT phase at 800 nm induces electron transfer in one Fe-Co edge of PBA 1 and produces a [FeIIILSCoIILS] intermediate which by spin-crossover (SCO) is stabilized within 400 fs to a long-lived (>1 ns) [FeIIILSCoIIHS] species. In contrast, IVCT excitation of the HT phase at 400 nm generates a [FeIILSCoIIIHS] species with a lifetime of 3.6 ps. Subsequent back-electron transfer populates the vibrationally hot ground state, which thermalizes within 8 ps. The newly synthesized dinuclear PBA, [CoFe(CN)3(tp*)(pz*4Lut)]ClO4 (2), provides a benchmark of the HT phase of 1, i.e., [FeIIILSCoIIHS], as verified by variable temperature magnetic susceptibility measurements and 57Fe Mössbauer spectroscopy. The photoinduced charge transfer dynamics of PBA 2 indeed are almost identical to that of the HT phase of PBA 1 with a lifetime of the excited [FeIILSCoIIIHS] species of 3.8 ps.
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Affiliation(s)
- Jennifer Zimara
- Max-Planck-Institute for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany
| | - Hendrik Stevens
- University of Göttingen, Institute for Inorganic Chemistry, Tammannstrasse 4, D-37077 Göttingen, Germany
| | - Rainer Oswald
- University of Göttingen, Institute for Physical Chemistry, Tammannstrasse 6, D-37077 Göttingen, Germany
| | - Serhiy Demeshko
- University of Göttingen, Institute for Inorganic Chemistry, Tammannstrasse 4, D-37077 Göttingen, Germany
| | - Sebastian Dechert
- University of Göttingen, Institute for Inorganic Chemistry, Tammannstrasse 4, D-37077 Göttingen, Germany
| | - Ricardo A Mata
- University of Göttingen, Institute for Physical Chemistry, Tammannstrasse 6, D-37077 Göttingen, Germany
| | - Franc Meyer
- University of Göttingen, Institute for Inorganic Chemistry, Tammannstrasse 4, D-37077 Göttingen, Germany.,International Center for Advanced Studies of Energy Conversion (ICASEC), Tammannstrasse 6, D-37077 Göttingen, Germany
| | - Dirk Schwarzer
- Max-Planck-Institute for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany
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6
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Dajnowicz S, Langan PS, Weiss KL, Ivanov IN, Kovalevsky A. Room-temperature photo-induced martensitic transformation in a protein crystal. IUCRJ 2019; 6:619-629. [PMID: 31316806 PMCID: PMC6608640 DOI: 10.1107/s2052252519005761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 04/26/2019] [Indexed: 06/10/2023]
Abstract
Martensitic transformations are the first-order crystal-to-crystal phase transitions that occur mostly in materials such as steel, alloys and ceramics, thus having many technological applications. These phase transitions are rarely observed in molecular crystals and have not been detected in protein crystals. Reversibly switchable fluorescent proteins are widely used in biotechnology, including super-resolution molecular imaging, and hold promise as candidate biomaterials for future high-tech applications. Here, we report on a reversibly switchable fluorescent protein, Tetdron, whose crystals undergo a photo-induced martensitic transformation at room temperature. Room-temperature X-ray crystallography demonstrates that at equilibrium Tetdron chromophores are all in the trans configuration, with an ∼1:1 mixture of their protonated and deprotonated forms. Irradiation of a Tetdron crystal with 400 nm light induces a martensitic transformation, which results in Tetdron tetramerization at room temperature revealed by X-ray photocrystallography. Crystal and solution spectroscopic measurements provide evidence that the photo-induced martensitic phase transition is coupled with the chromophore deprotonation, but no trans-cis isomerization is detected in the structure of an irradiated crystal. It is hypothesized that protein dynamics assists in the light-induced proton transfer from the chromophore to the bulk solvent and in the ensuing martensitic phase transition. The unique properties of Tetdron may be useful in developing novel biomaterials for optogenetics, data storage and nanotechnology.
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Affiliation(s)
- Steven Dajnowicz
- Department of Chemistry and Biochemistry, University of Toledo, Toledo, Ohio 43606, USA
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Patricia S. Langan
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Kevin L. Weiss
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Ilia N. Ivanov
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Andrey Kovalevsky
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
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7
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Lacombat F, Plaza P, Plamont MA, Espagne A. Photoinduced Chromophore Hydration in the Fluorescent Protein Dreiklang Is Triggered by Ultrafast Excited-State Proton Transfer Coupled to a Low-Frequency Vibration. J Phys Chem Lett 2017; 8:1489-1495. [PMID: 28300413 DOI: 10.1021/acs.jpclett.7b00348] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Because of growing applications in advanced fluorescence imaging, the mechanisms and dynamics of photoinduced reactions in reversibly photoswitchable fluorescent proteins are currently attracting much interest. We report the first time-resolved study of the photoswitching of Dreiklang, so far the only fluorescent protein to undergo reversible photoinduced chromophore hydration. Using broadband femtosecond transient absorption spectroscopy, we show that the reaction is triggered by an ultrafast deprotonation of the chromophore phenol group in the excited state in 100 fs. This primary step is accompanied by coherent oscillations that we assign to its coupling with a low-frequency mode, possibly a deformation of the chromophore hydrogen bond network. A ground-state intermediate is formed in the picosecond-nanosecond regime that we tentatively assign to the deprotonated water adduct. We suggest that proton ejection from the phenol group leads to a charge transfer from the phenol to the imidazolinone ring, which triggers imidazolinone protonation by nearby Glu222 and catalyzes the addition of the water molecule.
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Affiliation(s)
- Fabien Lacombat
- Ecole normale supérieure, PSL Research University , Département de Chimie, PASTEUR, 24 rue Lhomond, 75005 Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, PASTEUR, 24 rue Lhomond, 75005 Paris, France
- CNRS , PASTEUR, 24 rue Lhomond, 75005 Paris, France
| | - Pascal Plaza
- Ecole normale supérieure, PSL Research University , Département de Chimie, PASTEUR, 24 rue Lhomond, 75005 Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, PASTEUR, 24 rue Lhomond, 75005 Paris, France
- CNRS , PASTEUR, 24 rue Lhomond, 75005 Paris, France
| | - Marie-Aude Plamont
- Ecole normale supérieure, PSL Research University , Département de Chimie, PASTEUR, 24 rue Lhomond, 75005 Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, PASTEUR, 24 rue Lhomond, 75005 Paris, France
- CNRS , PASTEUR, 24 rue Lhomond, 75005 Paris, France
| | - Agathe Espagne
- Ecole normale supérieure, PSL Research University , Département de Chimie, PASTEUR, 24 rue Lhomond, 75005 Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, PASTEUR, 24 rue Lhomond, 75005 Paris, France
- CNRS , PASTEUR, 24 rue Lhomond, 75005 Paris, France
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8
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Acharya A, Bogdanov AM, Grigorenko BL, Bravaya KB, Nemukhin AV, Lukyanov KA, Krylov AI. Photoinduced Chemistry in Fluorescent Proteins: Curse or Blessing? Chem Rev 2016; 117:758-795. [PMID: 27754659 DOI: 10.1021/acs.chemrev.6b00238] [Citation(s) in RCA: 178] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Photoinduced reactions play an important role in the photocycle of fluorescent proteins from the green fluorescent protein (GFP) family. Among such processes are photoisomerization, photooxidation/photoreduction, breaking and making of covalent bonds, and excited-state proton transfer (ESPT). Many of these transformations are initiated by electron transfer (ET). The quantum yields of these processes vary significantly, from nearly 1 for ESPT to 10-4-10-6 for ET. Importantly, even when quantum yields are relatively small, at the conditions of repeated illumination the overall effect is significant. Depending on the task at hand, fluorescent protein photochemistry is regarded either as an asset facilitating new applications or as a nuisance leading to the loss of optical output. The phenomena arising due to phototransformations include (i) large Stokes shifts, (ii) photoconversions, photoactivation, and photoswitching, (iii) phototoxicity, (iv) blinking, (v) permanent bleaching, and (vi) formation of long-lived intermediates. The focus of this review is on the most recent experimental and theoretical work on photoinduced transformations in fluorescent proteins. We also provide an overview of the photophysics of fluorescent proteins, highlighting the interplay between photochemistry and other channels (fluorescence, radiationless relaxation, and intersystem crossing). The similarities and differences with photochemical processes in other biological systems and in dyes are also discussed.
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Affiliation(s)
- Atanu Acharya
- Department of Chemistry, University of Southern California , Los Angeles, California 90089-0482, United States
| | - Alexey M Bogdanov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry , Moscow, Russia.,Nizhny Novgorod State Medical Academy , Nizhny Novgorod, Russia
| | - Bella L Grigorenko
- Department of Chemistry, Lomonosov Moscow State University , Moscow, Russia.,Emanuel Institute of Biochemical Physics, Russian Academy of Sciences , Moscow, Russia
| | - Ksenia B Bravaya
- Department of Chemistry, Boston University , Boston, Massachusetts United States
| | - Alexander V Nemukhin
- Department of Chemistry, Lomonosov Moscow State University , Moscow, Russia.,Emanuel Institute of Biochemical Physics, Russian Academy of Sciences , Moscow, Russia
| | - Konstantin A Lukyanov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry , Moscow, Russia.,Nizhny Novgorod State Medical Academy , Nizhny Novgorod, Russia
| | - Anna I Krylov
- Department of Chemistry, University of Southern California , Los Angeles, California 90089-0482, United States
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9
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Oruganti B, Fang C, Durbeej B. Assessment of a composite CC2/DFT procedure for calculating 0–0 excitation energies of organic molecules. Mol Phys 2016. [DOI: 10.1080/00268976.2016.1235736] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Baswanth Oruganti
- Division of Theoretical Chemistry, IFM, Linköping University, Linköping, Sweden
| | - Changfeng Fang
- Division of Theoretical Chemistry, IFM, Linköping University, Linköping, Sweden
| | - Bo Durbeej
- Division of Theoretical Chemistry, IFM, Linköping University, Linköping, Sweden
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10
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Colletier JP, Sliwa M, Gallat FX, Sugahara M, Guillon V, Schirò G, Coquelle N, Woodhouse J, Roux L, Gotthard G, Royant A, Uriarte LM, Ruckebusch C, Joti Y, Byrdin M, Mizohata E, Nango E, Tanaka T, Tono K, Yabashi M, Adam V, Cammarata M, Schlichting I, Bourgeois D, Weik M. Serial Femtosecond Crystallography and Ultrafast Absorption Spectroscopy of the Photoswitchable Fluorescent Protein IrisFP. J Phys Chem Lett 2016; 7:882-887. [PMID: 26866390 DOI: 10.1021/acs.jpclett.5b02789] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Reversibly photoswitchable fluorescent proteins find growing applications in cell biology, yet mechanistic details, in particular on the ultrafast photochemical time scale, remain unknown. We employed time-resolved pump-probe absorption spectroscopy on the reversibly photoswitchable fluorescent protein IrisFP in solution to study photoswitching from the nonfluorescent (off) to the fluorescent (on) state. Evidence is provided for the existence of several intermediate states on the pico- and microsecond time scales that are attributed to chromophore isomerization and proton transfer, respectively. Kinetic modeling favors a sequential mechanism with the existence of two excited state intermediates with lifetimes of 2 and 15 ps, the second of which controls the photoswitching quantum yield. In order to support that IrisFP is suited for time-resolved experiments aiming at a structural characterization of these ps intermediates, we used serial femtosecond crystallography at an X-ray free electron laser and solved the structure of IrisFP in its on state. Sample consumption was minimized by embedding crystals in mineral grease, in which they remain photoswitchable. Our spectroscopic and structural results pave the way for time-resolved serial femtosecond crystallography aiming at characterizing the structure of ultrafast intermediates in reversibly photoswitchable fluorescent proteins.
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Affiliation(s)
| | - Michel Sliwa
- Université de Lille , CNRS, UMR 8516, LASIR, Laboratoire de Spectrochimie Infrarouge et Raman, F59 000 Lille, France
| | - François-Xavier Gallat
- Institut de Biologie Structurale , Université de Grenoble Alpes, CEA, CNRS, F-38044 Grenoble, France
| | - Michihiro Sugahara
- RIKEN SPring-8 Center , 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
| | - Virginia Guillon
- Institut de Biologie Structurale , Université de Grenoble Alpes, CEA, CNRS, F-38044 Grenoble, France
| | - Giorgio Schirò
- Institut de Biologie Structurale , Université de Grenoble Alpes, CEA, CNRS, F-38044 Grenoble, France
| | - Nicolas Coquelle
- Institut de Biologie Structurale , Université de Grenoble Alpes, CEA, CNRS, F-38044 Grenoble, France
| | - Joyce Woodhouse
- Institut de Biologie Structurale , Université de Grenoble Alpes, CEA, CNRS, F-38044 Grenoble, France
| | - Laure Roux
- Institut de Biologie Structurale , Université de Grenoble Alpes, CEA, CNRS, F-38044 Grenoble, France
| | - Guillaume Gotthard
- Institut de Biologie Structurale , Université de Grenoble Alpes, CEA, CNRS, F-38044 Grenoble, France
- The European Synchrotron Radiation Facility (ESRF) , 6 rue Jules Horowitz, BP 220, 38043 Grenoble Cedex, France
| | - Antoine Royant
- Institut de Biologie Structurale , Université de Grenoble Alpes, CEA, CNRS, F-38044 Grenoble, France
- The European Synchrotron Radiation Facility (ESRF) , 6 rue Jules Horowitz, BP 220, 38043 Grenoble Cedex, France
| | - Lucas Martinez Uriarte
- Université de Lille , CNRS, UMR 8516, LASIR, Laboratoire de Spectrochimie Infrarouge et Raman, F59 000 Lille, France
| | - Cyril Ruckebusch
- Université de Lille , CNRS, UMR 8516, LASIR, Laboratoire de Spectrochimie Infrarouge et Raman, F59 000 Lille, France
| | - Yasumasa Joti
- Japan Synchrotron Radiation Research Institute , 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan
| | - Martin Byrdin
- Institut de Biologie Structurale , Université de Grenoble Alpes, CEA, CNRS, F-38044 Grenoble, France
| | - Eiichi Mizohata
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University , Osaka 565-0871, Japan
| | - Eriko Nango
- RIKEN SPring-8 Center , 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
| | - Tomoyuki Tanaka
- RIKEN SPring-8 Center , 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
| | - Kensuke Tono
- Japan Synchrotron Radiation Research Institute , 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan
| | - Makina Yabashi
- RIKEN SPring-8 Center , 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
| | - Virgile Adam
- Institut de Biologie Structurale , Université de Grenoble Alpes, CEA, CNRS, F-38044 Grenoble, France
| | - Marco Cammarata
- Department of Physics, UMR UR1-CNRS 6251, University of Rennes 1 , Rennes, France
| | - Ilme Schlichting
- Max-Planck-Institut für medizinische Forschung , Jahnstrasse 29, 69120 Heidelberg, Germany
| | - Dominique Bourgeois
- Institut de Biologie Structurale , Université de Grenoble Alpes, CEA, CNRS, F-38044 Grenoble, France
| | - Martin Weik
- Institut de Biologie Structurale , Université de Grenoble Alpes, CEA, CNRS, F-38044 Grenoble, France
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