1
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Flores-Ibarra A, Maia RNA, Olasz B, Church JR, Gotthard G, Schapiro I, Heberle J, Nogly P. Light-Oxygen-Voltage (LOV)-sensing Domains: Activation Mechanism and Optogenetic Stimulation. J Mol Biol 2024; 436:168356. [PMID: 37944792 DOI: 10.1016/j.jmb.2023.168356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2023] [Revised: 10/11/2023] [Accepted: 11/02/2023] [Indexed: 11/12/2023]
Abstract
The light-oxygen-voltage (LOV) domains of phototropins emerged as essential constituents of light-sensitive proteins, helping initiate blue light-triggered responses. Moreover, these domains have been identified across all kingdoms of life. LOV domains utilize flavin nucleotides as co-factors and undergo structural rearrangements upon exposure to blue light, which activates an effector domain that executes the final output of the photoreaction. LOV domains are versatile photoreceptors that play critical roles in cellular signaling and environmental adaptation; additionally, they can noninvasively sense and control intracellular processes with high spatiotemporal precision, making them ideal candidates for use in optogenetics, where a light signal is linked to a cellular process through a photoreceptor. The ongoing development of LOV-based optogenetic tools, driven by advances in structural biology, spectroscopy, computational methods, and synthetic biology, has the potential to revolutionize the study of biological systems and enable the development of novel therapeutic strategies.
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Affiliation(s)
- Andrea Flores-Ibarra
- Dioscuri Center for Structural Dynamics of Receptors, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Krakow, Poland
| | - Raiza N A Maia
- Department of Chemistry, The University of Texas at Austin, 78712-1224 Austin, TX, USA
| | - Bence Olasz
- Dioscuri Center for Structural Dynamics of Receptors, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Krakow, Poland
| | - Jonathan R Church
- Institute of Chemistry, The Hebrew University of Jerusalem, 91905 Jerusalem, Israel
| | | | - Igor Schapiro
- Institute of Chemistry, The Hebrew University of Jerusalem, 91905 Jerusalem, Israel
| | - Joachim Heberle
- Department of Physics, Freie Universität Berlin, 14195 Berlin, Germany
| | - Przemyslaw Nogly
- Dioscuri Center for Structural Dynamics of Receptors, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Krakow, Poland.
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2
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Marin-Beloqui JM, Gómez S, Gonev HI, Comí M, Al-Hashimi M, Clarke TM. Truncated conjugation in fused heterocycle-based conducting polymers: when greater planarity does not enhance conjugation. Chem Sci 2023; 14:812-821. [PMID: 36755723 PMCID: PMC9890783 DOI: 10.1039/d2sc06271b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Accepted: 11/28/2022] [Indexed: 12/13/2022] Open
Abstract
One of the main assumptions in the design of new conjugated polymer materials for their use in organic electronics is that higher coplanarity leads to greater conjugation along the polymer backbone. Conventionally, a more planar monomer structure induces a larger backbone coplanarity, thus leading to a greater overlap of the carbon π-orbitals and therefore a higher degree of π-electron delocalisation. However, here we present a case that counters the validity of this assumption. Different diselenophene-based polymers were studied where one polymer possesses two selenophene rings fused together to create a more rigid, planar structure. The effects of this greater polymer coplanarity were examined using Raman spectroscopy and theoretical calculations. Raman spectra showed a large difference between the vibrational modes of the fused and unfused polymers, indicating very different electronic structures. Resonance Raman spectroscopy confirmed the rigidity of the fused selenophene polymer and also revealed, by studying the excitation profiles of the different bands, the presence of two shorter, uncoupled conjugation pathways. Supported by Density Functional Theory (DFT) calculations, we have demonstrated that the reason for this lack of conjugation is a distortion of the selenophene rings due to the induced planarity, forming a new truncated conjugation pathway through the selenophene β-position and bypassing the beneficial α-position. This effect was studied using DFT in an ample range of derivatives, where substitution of the selenium atom with other heteroatoms still maintained the same unconventional conjugation-planarity relationship, confirming the generality of this phenomenon. This work establishes an important structure-property relationship for conjugated polymers that will help rational design of more efficient organic electronics materials.
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Affiliation(s)
- Jose Manuel Marin-Beloqui
- Department of Chemistry, University College London Christopher Ingold Building London WC1H 0AJ UK .,Department of Physical Chemistry, University of Malaga Blvrd Louis Pasteur 31 29010 Malaga Spain
| | - Sandra Gómez
- Department of Physical Chemistry, University of SalamancaCaidos Sq.37008SalamancaSpain
| | - Hristo Ivov Gonev
- Department of Chemistry, University College London Christopher Ingold Building London WC1H 0AJ UK
| | - Marc Comí
- Department of Chemistry, Texas A&M University at QatarEducation City, P. O. Box 23874DohaQatar
| | - Mohammed Al-Hashimi
- Department of Chemistry, Texas A&M University at QatarEducation City, P. O. Box 23874DohaQatar
| | - Tracey M. Clarke
- Department of Chemistry, University College LondonChristopher Ingold BuildingLondon WC1H 0AJUK
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3
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Sub-Millisecond Photoinduced Dynamics of Free and EL222-Bound FMN by Stimulated Raman and Visible Absorption Spectroscopies. Biomolecules 2023; 13:biom13010161. [PMID: 36671546 PMCID: PMC9855911 DOI: 10.3390/biom13010161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 01/05/2023] [Accepted: 01/08/2023] [Indexed: 01/15/2023] Open
Abstract
Time-resolved femtosecond-stimulated Raman spectroscopy (FSRS) provides valuable information on the structural dynamics of biomolecules. However, FSRS has been applied mainly up to the nanoseconds regime and above 700 cm-1, which covers only part of the spectrum of biologically relevant time scales and Raman shifts. Here we report on a broadband (~200-2200 cm-1) dual transient visible absorption (visTA)/FSRS set-up that can accommodate time delays from a few femtoseconds to several hundreds of microseconds after illumination with an actinic pump. The extended time scale and wavenumber range allowed us to monitor the complete excited-state dynamics of the biological chromophore flavin mononucleotide (FMN), both free in solution and embedded in two variants of the bacterial light-oxygen-voltage (LOV) photoreceptor EL222. The observed lifetimes and intermediate states (singlet, triplet, and adduct) are in agreement with previous time-resolved infrared spectroscopy experiments. Importantly, we found evidence for additional dynamical events, particularly upon analysis of the low-frequency Raman region below 1000 cm-1. We show that fs-to-sub-ms visTA/FSRS with a broad wavenumber range is a useful tool to characterize short-lived conformationally excited states in flavoproteins and potentially other light-responsive proteins.
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4
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Hontani Y, Mehlhorn J, Domratcheva T, Beck S, Kloz M, Hegemann P, Mathes T, Kennis JTM. Spectroscopic and Computational Observation of Glutamine Tautomerization in the Blue Light Sensing Using Flavin Domain Photoreaction. J Am Chem Soc 2023; 145:1040-1052. [PMID: 36607126 PMCID: PMC9853863 DOI: 10.1021/jacs.2c10621] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Blue light sensing using flavin (BLUF) domains constitute a family of flavin-binding photoreceptors of bacteria and eukaryotic algae. BLUF photoactivation proceeds via a light-driven hydrogen-bond switch among flavin adenine dinucleotide (FAD) and glutamine and tyrosine side chains, whereby FAD undergoes electron and proton transfer with tyrosine and is subsequently re-oxidized by a hydrogen back-shuttle in picoseconds, constituting an important model system to understand proton-coupled electron transfer in biology. The specific structure of the hydrogen-bond patterns and the prevalence of glutamine tautomeric states in dark-adapted (DA) and light-activated (LA) states have remained controversial. Here, we present a combined femtosecond stimulated Raman spectroscopy (FSRS), computational chemistry, and site-selective isotope labeling Fourier-transform infrared spectroscopy (FTIR) study of the Slr1694 BLUF domain. FSRS showed distinct vibrational bands from the FADS1 singlet excited state. We observed small but significant shifts in the excited-state vibrational frequency patterns of the DA and LA states, indicating that these frequencies constitute a sensitive probe for the hydrogen-bond arrangement around FAD. Excited-state model calculations utilizing four different realizations of hydrogen bond patterns and glutamine tautomeric states were consistent with a BLUF reaction model that involved glutamine tautomerization to imidic acid, accompanied by a rotation of its side chain. A combined FTIR and double-isotope labeling study, with 13C labeling of FAD and 15N labeling of glutamine, identified the glutamine imidic acid C═N stretch vibration in the LA state and the Gln C═O in the DA state. Hence, our study provides support for glutamine tautomerization and side-chain rotation in the BLUF photoreaction.
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Affiliation(s)
- Yusaku Hontani
- Department
of Physics and Astronomy, Vrije Universiteit
Amsterdam, 1081 HV Amsterdam, De Boelelaan, The Netherlands
| | - Jennifer Mehlhorn
- Institut
für Biologie, Experimentelle Biophysik, Humboldt Universität zu Berlin, Invalidenstrasse 42, D-10115 Berlin, Germany
| | - Tatiana Domratcheva
- Department
of Biomolecular Mechanisms, Max Planck Institute
for Medical Research, 69120 Heidelberg, Germany,Department
of Chemistry, Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Sebastian Beck
- Department
of Chemistry, Humboldt-Universität
zu Berlin, Brook-Taylor-Str.
2, 12489 Berlin, Germany
| | - Miroslav Kloz
- Department
of Physics and Astronomy, Vrije Universiteit
Amsterdam, 1081 HV Amsterdam, De Boelelaan, The Netherlands,Institute
of Physics, ELI-Beamlines, Na Slovance 2, 182
21 Praha 8, Czech Republic
| | - Peter Hegemann
- Institut
für Biologie, Experimentelle Biophysik, Humboldt Universität zu Berlin, Invalidenstrasse 42, D-10115 Berlin, Germany
| | - Tilo Mathes
- Department
of Physics and Astronomy, Vrije Universiteit
Amsterdam, 1081 HV Amsterdam, De Boelelaan, The Netherlands,Institut
für Biologie, Experimentelle Biophysik, Humboldt Universität zu Berlin, Invalidenstrasse 42, D-10115 Berlin, Germany
| | - John T. M. Kennis
- Department
of Physics and Astronomy, Vrije Universiteit
Amsterdam, 1081 HV Amsterdam, De Boelelaan, The Netherlands,
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5
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QuasAr Odyssey: the origin of fluorescence and its voltage sensitivity in microbial rhodopsins. Nat Commun 2022; 13:5501. [PMID: 36127376 PMCID: PMC9489792 DOI: 10.1038/s41467-022-33084-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 08/26/2022] [Indexed: 11/29/2022] Open
Abstract
Rhodopsins had long been considered non-fluorescent until a peculiar voltage-sensitive fluorescence was reported for archaerhodopsin-3 (Arch3) derivatives. These proteins named QuasArs have been used for imaging membrane voltage changes in cell cultures and small animals. However due to the low fluorescence intensity, these constructs require use of much higher light intensity than other optogenetic tools. To develop the next generation of sensors, it is indispensable to first understand the molecular basis of the fluorescence and its modulation by the membrane voltage. Based on spectroscopic studies of fluorescent Arch3 derivatives, we propose a unique photo-reaction scheme with extended excited-state lifetimes and inefficient photoisomerization. Molecular dynamics simulations of Arch3, of the Arch3 fluorescent derivative Archon1, and of several its mutants have revealed different voltage-dependent changes of the hydrogen-bonding networks including the protonated retinal Schiff-base and adjacent residues. Experimental observations suggest that under negative voltage, these changes modulate retinal Schiff base deprotonation and promote a decrease in the populations of fluorescent species. Finally, we identified molecular constraints that further improve fluorescence quantum yield and voltage sensitivity. The authors present an in-depth investigation of excited state dynamics and molecular mechanism of the voltage sensing in microbial rhodopsins. Using a combination of spectroscopic investigations and molecular dynamics simulations, the study proposes the voltage-modulated deprotonation of the chromophore as the key event in the voltage sensing. Thus, molecular constraints that may further improve the fluorescence quantum yield and the voltage sensitivity are presented.
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6
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Baumschlager A. Engineering Light-Control in Biology. Front Bioeng Biotechnol 2022; 10:901300. [PMID: 35573251 PMCID: PMC9096073 DOI: 10.3389/fbioe.2022.901300] [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: 03/21/2022] [Accepted: 04/14/2022] [Indexed: 11/13/2022] Open
Abstract
Unraveling the transformative power of optogenetics in biology requires sophisticated engineering for the creation and optimization of light-regulatable proteins. In addition, diverse strategies have been used for the tuning of these light-sensitive regulators. This review highlights different protein engineering and synthetic biology approaches, which might aid in the development and optimization of novel optogenetic proteins (Opto-proteins). Focusing on non-neuronal optogenetics, chromophore availability, general strategies for creating light-controllable functions, modification of the photosensitive domains and their fusion to effector domains, as well as tuning concepts for Opto-proteins are discussed. Thus, this review shall not serve as an encyclopedic summary of light-sensitive regulators but aims at discussing important aspects for the engineering of light-controllable proteins through selected examples.
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Affiliation(s)
- Armin Baumschlager
- Department of Biosystems Science and Engineering (D-BSSE), ETH Zürich, Basel, Switzerland
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7
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Understanding flavin electronic structure and spectra. WIRES COMPUTATIONAL MOLECULAR SCIENCE 2022. [DOI: 10.1002/wcms.1541] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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8
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Comparing ultrafast excited state quenching of flavin 1,N 6-ethenoadenine dinucleotide and flavin adenine dinucleotide by optical spectroscopy and DFT calculations. Photochem Photobiol Sci 2022; 21:959-982. [PMID: 35218554 DOI: 10.1007/s43630-022-00187-2] [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: 05/04/2021] [Accepted: 02/01/2022] [Indexed: 10/19/2022]
Abstract
Flavins are photoenzymatic cofactors often exploiting the absorption of light to energize photoinduced redox chemistry in a variety of contexts. Both flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN) are used for this function. The study of these photoenzymes has been facilitated using flavin analogs. Most of these analogs involve modification of the flavin ring, and there is recent evidence that adenine (Ade)-modified FAD can affect enzyme turnover, but so far this has only been shown for enzymes where the adenine and flavin rings are close to each other in a stacked conformation. FAD is also stacked in aqueous solution, and its photodynamics are quite different from unstacked FAD or FMN. Oxidized photoexcited FAD decays rapidly, presumably through PET with Ade as donor and Fl* as acceptor. Definitive identification of the spectral signatures of Ade∙+ and Fl∙- radicals is elusive. Here we use the FAD analog Flavin 1,N6-Ethenoadenine Dinucleotide (εFAD) to study how different photochemical outcomes depend on the identity of the Ade moiety in stacked FAD and its analog εFAD. We have used UV-Vis transient absorption spectroscopy complemented by TD-DFT calculations to investigate the excited state evolution of the flavins. In FAD*, no radicals were observed, suggesting that FAD* does not undergo PET. εFAD* kinetics showed a broad absorption band that suggests a charge transfer state exists upon photoexcitation with evidence for radical pair formation. Surprisingly, significant triplet flavin was produced from εFAD* We hypothesize that the dipolar (ε)Ade moieties differentially modulate the singlet-triplet energy gap, resulting in different intersystem crossing rates. The additional electron density on the etheno group of εFAD supplies better orbital overlap with the flavin S1 state, accelerating charge transfer in that molecule.
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9
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McLean JT, Benny A, Nolan MD, Swinand G, Scanlan EM. Cysteinyl radicals in chemical synthesis and in nature. Chem Soc Rev 2021; 50:10857-10894. [PMID: 34397045 DOI: 10.1039/d1cs00254f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Nature harnesses the unique properties of cysteinyl radical intermediates for a diverse range of essential biological transformations including DNA biosynthesis and repair, metabolism, and biological photochemistry. In parallel, the synthetic accessibility and redox chemistry of cysteinyl radicals renders them versatile reactive intermediates for use in a vast array of synthetic applications such as lipidation, glycosylation and fluorescent labelling of proteins, peptide macrocyclization and stapling, desulfurisation of peptides and proteins, and development of novel therapeutics. This review provides the reader with an overview of the role of cysteinyl radical intermediates in both chemical synthesis and biological systems, with a critical focus on mechanistic details. Direct insights from biological systems, where applied to chemical synthesis, are highlighted and potential avenues from nature which are yet to be explored synthetically are presented.
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Affiliation(s)
- Joshua T McLean
- Trinity Biomedical Sciences Institute, Trinity College Dublin, The University of Dublin, 152-160 Pearse St., Dublin, D02 R590, Ireland.
| | - Alby Benny
- Trinity Biomedical Sciences Institute, Trinity College Dublin, The University of Dublin, 152-160 Pearse St., Dublin, D02 R590, Ireland.
| | - Mark D Nolan
- Trinity Biomedical Sciences Institute, Trinity College Dublin, The University of Dublin, 152-160 Pearse St., Dublin, D02 R590, Ireland.
| | - Glenna Swinand
- Trinity Biomedical Sciences Institute, Trinity College Dublin, The University of Dublin, 152-160 Pearse St., Dublin, D02 R590, Ireland.
| | - Eoin M Scanlan
- Trinity Biomedical Sciences Institute, Trinity College Dublin, The University of Dublin, 152-160 Pearse St., Dublin, D02 R590, Ireland.
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10
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Genetic Factors Affect the Survival and Behaviors of Selected Bacteria during Antimicrobial Blue Light Treatment. Int J Mol Sci 2021; 22:ijms221910452. [PMID: 34638788 PMCID: PMC8508746 DOI: 10.3390/ijms221910452] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 09/22/2021] [Accepted: 09/24/2021] [Indexed: 12/26/2022] Open
Abstract
Antimicrobial resistance is a global, mounting and dynamic issue that poses an immediate threat to human, animal, and environmental health. Among the alternative antimicrobial treatments proposed to reduce the external use of antibiotics is electromagnetic radiation, such as blue light. The prevailing mechanistic model is that blue light can be absorbed by endogenous porphyrins within the bacterial cell, inducing the production of reactive oxygen species, which subsequently inflict oxidative damages upon different cellular components. Nevertheless, it is unclear whether other mechanisms are involved, particularly those that can affect the efficacy of antimicrobial blue light treatments. In this review, we summarize evidence of inherent factors that may confer protection to a selected group of bacteria against blue light-induced oxidative damages or modulate the physiological characteristics of the treated bacteria, such as virulence and motility. These include descriptions of three major photoreceptors in bacteria, chemoreceptors, SOS-dependent DNA repair and non-SOS protective mechanisms. Future directions are also provided to assist with research efforts to increase the efficacy of antimicrobial blue light and to minimize the development of blue light-tolerant phenotypes.
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11
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Maia RNA, Ehrenberg D, Oldemeyer S, Knieps-Grünhagen E, Krauss U, Heberle J. Real-Time Tracking of Proton Transfer from the Reactive Cysteine to the Flavin Chromophore of a Photosensing Light Oxygen Voltage Protein. J Am Chem Soc 2021; 143:12535-12542. [PMID: 34347468 DOI: 10.1021/jacs.1c03409] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
LOV (light oxygen voltage) proteins are photosensors ubiquitous to all domains of life. A variant of the short LOV protein from Dinoroseobacter shibae (DsLOV) exhibits an exceptionally fast photocycle. We performed time-resolved molecular spectroscopy on DsLOV-M49S and characterized the formation of the thio-adduct state with a covalent bond between the reactive cysteine (C72) and C4a of the FMN. By use of a tunable quantum cascade laser, the weak absorption change of the vibrational band of S-H stretching vibration of C57 was resolved with a time resolution of 10 ns. Deprotonation of C72 proceeded with a time constant of 12 μs which tallies the rise of the thio-adduct state. These results provide valuable information for the mechanistic interpretation of light-induced structural changes in LOV domains, which involves the choreographed sequence of proton transfers, changes in electron density distributions, spin alterations of the latter, and transient bond formation and breakage. Such molecular insight will help develop new optogenetic tools based on flavin photoreceptors.
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Affiliation(s)
- Raiza N A Maia
- Experimental Molecular Biophysics, Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - David Ehrenberg
- Experimental Molecular Biophysics, Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Sabine Oldemeyer
- Experimental Molecular Biophysics, Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Esther Knieps-Grünhagen
- Institut für Molekulare Enzymtechnologie, Heinrich-Heine-Universität Düsseldorf, Forschungszentrum Jülich, D-52426 Jülich, Germany
| | - Ulrich Krauss
- Institut für Molekulare Enzymtechnologie, Heinrich-Heine-Universität Düsseldorf, Forschungszentrum Jülich, D-52426 Jülich, Germany.,Institute of Bio- and Geosciences (IBG-1): Biotechnology, Forschungszentrum Jülich, D-52426 Jülich, Germany
| | - Joachim Heberle
- Experimental Molecular Biophysics, Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
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12
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Green D, Roy P, Hall CR, Iuliano JN, Jones GA, Lukacs A, Tonge PJ, Meech SR. Excited State Resonance Raman of Flavin Mononucleotide: Comparison of Theory and Experiment. J Phys Chem A 2021; 125:6171-6179. [PMID: 34240863 DOI: 10.1021/acs.jpca.1c04063] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Blue light absorbing flavoproteins play important roles in a variety of photobiological processes. Consequently, there have been numerous investigations of their excited state structure and dynamics, in particular by time-resolved vibrational spectroscopy. The isoalloxazine chromophore of the flavoprotein cofactors has been studied in detail by time-resolved Raman, lending it a benchmark status for mode assignments in excited electronic states of large molecules. However, detailed comparisons of calculated and measured spectra have proven challenging, as there are many more modes calculated than are observed, and the role of resonance enhancement is difficult to characterize in excited electronic states. Here we employ a recently developed approach due to Elles and co-workers ( J. Phys. Chem. A 2018, 122, 8308-8319) for the calculation of resonance-enhanced Raman spectra of excited states and apply it to the lowest singlet and triplet excited states of the isoalloxazine chromophore. There is generally good agreement between calculated and observed enhancements, which allows assignment of vibrational bands of the flavoprotein cofactors to be refined. However, some prominently enhanced bands are found to be absent from the calculations, suggesting the need for further development of the theory.
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Affiliation(s)
- Dale Green
- School of Chemistry, University of East Anglia, Norwich NR4 7TJ, U.K
| | - Palas Roy
- School of Chemistry, University of East Anglia, Norwich NR4 7TJ, U.K
| | | | - James N Iuliano
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States
| | - Garth A Jones
- School of Chemistry, University of East Anglia, Norwich NR4 7TJ, U.K
| | - Andras Lukacs
- Department of Biophysics, Medical School, University of Pecs, Szigeti ut 12, 7624 Pecs, Hungary
| | - Peter J Tonge
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States
| | - Stephen R Meech
- School of Chemistry, University of East Anglia, Norwich NR4 7TJ, U.K
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13
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Andrikopoulos PC, Chaudhari AS, Liu Y, Konold PE, Kennis JTM, Schneider B, Fuertes G. QM calculations predict the energetics and infrared spectra of transient glutamine isomers in LOV photoreceptors. Phys Chem Chem Phys 2021; 23:13934-13950. [PMID: 34142688 PMCID: PMC8246142 DOI: 10.1039/d1cp00447f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 06/04/2021] [Indexed: 11/21/2022]
Abstract
Photosensory receptors containing the flavin-binding light-oxygen-voltage (LOV) domain are modular proteins that fulfil a variety of biological functions ranging from gene expression to phototropism. The LOV photocycle is initiated by blue-light and involves a cascade of intermediate species, including an electronically excited triplet state, that leads to covalent bond formation between the flavin mononucleotide (FMN) chromophore and a nearby cysteine residue. Subsequent conformational changes in the polypeptide chain arise due to the remodelling of the hydrogen bond network in the cofactor binding pocket, whereby a conserved glutamine residue plays a key role in coupling FMN photochemistry with LOV photobiology. Although the dark-to-light transition of LOV photosensors has been previously addressed by spectroscopy and computational approaches, the mechanistic basis of the underlying reactions is still not well understood. Here we present a detailed computational study of three distinct LOV domains: EL222 from Erythrobacter litoralis, AsLOV2 from the second LOV domain of Avena sativa phototropin 1, and RsLOV from Rhodobacter sphaeroides LOV protein. Extended protein-chromophore models containing all known crucial residues involved in the initial steps (femtosecond-to-microsecond) of the photocycle were employed. Energies and rotational barriers were calculated for possible rotamers and tautomers of the critical glutamine side chain, which allowed us to postulate the most energetically favoured glutamine orientation for each LOV domain along the assumed reaction path. In turn, for each evolving species, infrared difference spectra were constructed and compared to experimental EL222 and AsLOV2 transient infrared spectra, the former from original work presented here and the latter from the literature. The good agreement between theory and experiment permitted the assignment of the majority of observed bands, notably the ∼1635 cm-1 transient of the adduct state to the carbonyl of the glutamine side chain after rotation. Moreover, both the energetic and spectroscopic approaches converge in suggesting a facile glutamine flip at the adduct intermediate for EL222 and more so for AsLOV2, while for RsLOV the glutamine keeps its initial configuration. Additionally, the computed infrared shifts of the glutamine and interacting residues could guide experimental research addressing early events of signal transduction in LOV proteins.
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Affiliation(s)
- Prokopis C Andrikopoulos
- Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Průmyslová 595, CZ-252 50 Vestec, Czechia.
| | - Aditya S Chaudhari
- Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Průmyslová 595, CZ-252 50 Vestec, Czechia.
| | - Yingliang Liu
- Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Průmyslová 595, CZ-252 50 Vestec, Czechia.
| | - Patrick E Konold
- Department of Physics and Astronomy, Faculty of Sciences, Vrije Universiteit, 1081 De Boelelaan, 1081HV Amsterdam, The Netherlands
| | - John T M Kennis
- Department of Physics and Astronomy, Faculty of Sciences, Vrije Universiteit, 1081 De Boelelaan, 1081HV Amsterdam, The Netherlands
| | - Bohdan Schneider
- Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Průmyslová 595, CZ-252 50 Vestec, Czechia.
| | - Gustavo Fuertes
- Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Průmyslová 595, CZ-252 50 Vestec, Czechia.
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14
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Yee EF, Oldemeyer S, Böhm E, Ganguly A, York DM, Kottke T, Crane BR. Peripheral Methionine Residues Impact Flavin Photoreduction and Protonation in an Engineered LOV Domain Light Sensor. Biochemistry 2021; 60:1148-1164. [PMID: 33787242 DOI: 10.1021/acs.biochem.1c00064] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Proton-coupled electron transfer reactions play critical roles in many aspects of sensory phototransduction. In the case of flavoprotein light sensors, reductive quenching of flavin excited states initiates chemical and conformational changes that ultimately transmit light signals to downstream targets. These reactions generally require neighboring aromatic residues and proton-donating side chains for rapid and coordinated electron and proton transfer to flavin. Although photoreduction of flavoproteins can produce either the anionic (ASQ) or neutral semiquinone (NSQ), the factors that favor one over the other are not well understood. Here we employ a biologically active variant of the light-oxygen-voltage (LOV) domain protein VVD devoid of the adduct-forming Cys residue (VVD-III) to probe the mechanism of flavin photoreduction and protonation. A series of isosteric and conservative residue replacements studied by rate measurements, fluorescence quantum yields, FTIR difference spectroscopy, and molecular dynamics simulations indicate that tyrosine residues facilitate charge recombination reactions that limit sustained flavin reduction, whereas methionine residues facilitate radical propagation and quenching and also gate solvent access for flavin protonation. Replacement of a single surface Met residue with Leu favors formation of the ASQ over the NSQ and desensitizes photoreduction to oxidants. In contrast, increasing site hydrophilicity by Gln substitution promotes rapid NSQ formation and weakens the influence of the redox environment. Overall, the photoreactivity of VVD-III can be understood in terms of redundant electron donors, internal hole quenching, and coupled proton transfer reactions that all depend upon protein conformation, dynamics, and solvent penetration.
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Affiliation(s)
- Estella F Yee
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Sabine Oldemeyer
- Physical and Biophysical Chemistry, Department of Chemistry, Bielefeld University, 33615 Bielefeld, Germany
| | - Elena Böhm
- Physical and Biophysical Chemistry, Department of Chemistry, Bielefeld University, 33615 Bielefeld, Germany
| | - Abir Ganguly
- Laboratory for Biomolecular Simulation Research, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854-8076, United States.,Institute for Quantitative Biomedicine, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854-8076, United States
| | - Darrin M York
- Laboratory for Biomolecular Simulation Research, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854-8076, United States.,Institute for Quantitative Biomedicine, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854-8076, United States.,Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Tilman Kottke
- Physical and Biophysical Chemistry, Department of Chemistry, Bielefeld University, 33615 Bielefeld, Germany
| | - Brian R Crane
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
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15
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Duan HD, Khan SA, Miller AF. Photogeneration and reactivity of flavin anionic semiquinone in a bifurcating electron transfer flavoprotein. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2021; 1862:148415. [PMID: 33727071 DOI: 10.1016/j.bbabio.2021.148415] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 10/18/2020] [Revised: 02/15/2021] [Accepted: 03/10/2021] [Indexed: 02/04/2023]
Abstract
Electron transfer bifurcation allows production of a strongly reducing carrier at the expense of a weaker one, by redistributing energy among a pair of electrons. Thus, two weakly-reducing electrons from NADH are consumed to produce a strongly reducing ferredoxin or flavodoxin, paid for by reduction of an oxidizing acceptor. The prevailing mechanism calls for participation of a strongly reducing flavin semiquinone which has been difficult to observe with site-certainly in multi-flavin systems. Using blue light (450 nm) to photoexcite the flavins of bifurcating electron transfer flavoprotein (ETF), we demonstrate accumulation of anionic flavin semiquinone in excess of what is observed in equilibrium titrations, and establish its ability to reduce the low-potential electron acceptor benzyl viologen. This must occur at the bifurcating flavin because the midpoint potentials of the electron transfer (ET) flavin are not sufficiently negative. We show that bis-tris propane buffer is an effective electron donor to the flavin photoreduction, but that if the system is prepared with the ET flavin chemically reduced, so that only the bifurcating flavin is oxidized and photochemically active, flavin anionic semiquinone is formed more rapidly. Thus, excited bifurcating flavin is able to draw on an electron stored at the ET flavin. Flavin semiquinone photogenerated at the bifurcation site must therefore be accompanied by additional semiquinone formation by oxidation of the ET flavin. Consistent with the expected instability of bifurcating flavin semiquinone, it subsides immediately upon cessation of illumination. However comparison with yields of semiquinone in equilibrium titrations suggest that during continuous illumination at pH 9 a steady state population of 0.3 equivalents of bifurcating flavin semiquinone accumulates, and then undergoes further photoreduction to the hydroquinone. Although transient, the population of bifurcating flavin semiquinone explains the system's ability to conduct light-driven electron transfer from bis-tris propane to benzyl viologen, in effect trapping energy from light.
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Affiliation(s)
- H Diessel Duan
- Department of Chemistry, University of Kentucky, Lexington, KY 40506, USA
| | - Sharique A Khan
- Department of Chemistry, University of Kentucky, Lexington, KY 40506, USA
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16
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Baumschlager A, Khammash M. Synthetic Biological Approaches for Optogenetics and Tools for Transcriptional Light-Control in Bacteria. Adv Biol (Weinh) 2021; 5:e2000256. [PMID: 34028214 DOI: 10.1002/adbi.202000256] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 01/11/2021] [Indexed: 12/22/2022]
Abstract
Light has become established as a tool not only to visualize and investigate but also to steer biological systems. This review starts by discussing the unique features that make light such an effective control input in biology. It then gives an overview of how light-control came to progress, starting with photoactivatable compounds and leading up to current genetic implementations using optogenetic approaches. The review then zooms in on optogenetics, focusing on photosensitive proteins, which form the basis for optogenetic engineering using synthetic biological approaches. As the regulation of transcription provides a highly versatile means for steering diverse biological functions, the focus of this review then shifts to transcriptional light regulators, which are presented in the biotechnologically highly relevant model organism Escherichia coli.
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Affiliation(s)
- Armin Baumschlager
- Department of Biosystems Science and Engineering (D-BSSE), ETH-Zürich, Mattenstrasse 26, Basel, 4058, Switzerland
| | - Mustafa Khammash
- Department of Biosystems Science and Engineering (D-BSSE), ETH-Zürich, Mattenstrasse 26, Basel, 4058, Switzerland
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17
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Lu X, Shen Y, Campbell RE. Engineering Photosensory Modules of Non-Opsin-Based Optogenetic Actuators. Int J Mol Sci 2020; 21:E6522. [PMID: 32906617 PMCID: PMC7555876 DOI: 10.3390/ijms21186522] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 09/03/2020] [Accepted: 09/04/2020] [Indexed: 11/17/2022] Open
Abstract
Optogenetic (photo-responsive) actuators engineered from photoreceptors are widely used in various applications to study cell biology and tissue physiology. In the toolkit of optogenetic actuators, the key building blocks are genetically encodable light-sensitive proteins. Currently, most optogenetic photosensory modules are engineered from naturally-occurring photoreceptor proteins from bacteria, fungi, and plants. There is a growing demand for novel photosensory domains with improved optical properties and light-induced responses to satisfy the needs of a wider variety of studies in biological sciences. In this review, we focus on progress towards engineering of non-opsin-based photosensory domains, and their representative applications in cell biology and physiology. We summarize current knowledge of engineering of light-sensitive proteins including light-oxygen-voltage-sensing domain (LOV), cryptochrome (CRY2), phytochrome (PhyB and BphP), and fluorescent protein (FP)-based photosensitive domains (Dronpa and PhoCl).
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Affiliation(s)
- Xiaocen Lu
- Department of Chemistry, University of Alberta, Edmonton, AB T6G 2G2, Canada; (X.L.); (Y.S.)
| | - Yi Shen
- Department of Chemistry, University of Alberta, Edmonton, AB T6G 2G2, Canada; (X.L.); (Y.S.)
| | - Robert E. Campbell
- Department of Chemistry, University of Alberta, Edmonton, AB T6G 2G2, Canada; (X.L.); (Y.S.)
- Department of Chemistry, The University of Tokyo, Tokyo 113-0033, Japan
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18
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Kobayashi I, Nakajima H, Hisatomi O. Molecular Mechanism of Light-Induced Conformational Switching of the LOV Domain in Aureochrome-1. Biochemistry 2020; 59:2592-2601. [PMID: 32567839 DOI: 10.1021/acs.biochem.0c00271] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Light oxygen voltage-sensing (LOV) domains are widely found in photoreceptor proteins of plants, algae, fungi, and bacteria. Structural studies of LOV domains suggest that Phe and Gln residues located in the proximity of the chromophore undergo conformational changes upon illumination; however, the molecular mechanism associated with activation of the effector domain remains to be elucidated. Photozipper (PZ) protein is an N-terminally truncated aureochrome-1 comprising a LOV domain and a basic leucine zipper domain. Blue light (BL) induces PZ dimerization and subsequently increases its affinity for target DNA. In this study, we prepared PZ mutants with substitutions of F298 and Q317 and performed quantitative analyses in dark and light states. Substitutions of Q317 significantly reduced the light-induced changes in PZ affinity for the target DNA, especially in the case of the high affinities observed in the dark state. Upon illumination, all PZ mutants showed increased affinity for the target sequence, which demonstrated a clear correlation with the dimer fraction of each PZ mutant. These results suggest the existence of a conformational equilibrium and that its shift by a synergistic interaction between the chromophore and protein moiety probably enables BL-regulated switching of aureochrome-1.
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Affiliation(s)
- Itsuki Kobayashi
- Department of Earth and Space Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Hiroto Nakajima
- Department of Earth and Space Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Osamu Hisatomi
- Department of Earth and Space Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
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19
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Hontani Y, Broser M, Luck M, Weißenborn J, Kloz M, Hegemann P, Kennis JTM. Dual Photoisomerization on Distinct Potential Energy Surfaces in a UV-Absorbing Rhodopsin. J Am Chem Soc 2020; 142:11464-11473. [PMID: 32475117 PMCID: PMC7315636 DOI: 10.1021/jacs.0c03229] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
![]()
UV-absorbing rhodopsins are essential
for UV vision and sensing
in all kingdoms of life. Unlike the well-known visible-absorbing rhodopsins,
which bind a protonated retinal Schiff base for light absorption,
UV-absorbing rhodopsins bind an unprotonated retinal Schiff base.
Thus far, the photoreaction dynamics and mechanisms of UV-absorbing
rhodopsins have remained essentially unknown. Here, we report the
complete excited- and ground-state dynamics of the UV form of histidine
kinase rhodopsin 1 (HKR1) from eukaryotic algae, using femtosecond
stimulated Raman spectroscopy (FSRS) and transient absorption spectroscopy,
covering time scales from femtoseconds to milliseconds. We found that
energy-level ordering is inverted with respect to visible-absorbing
rhodopsins, with an optically forbidden low-lying S1 excited
state that has Ag– symmetry and a higher-lying UV-absorbing
S2 state of Bu+ symmetry. UV-photoexcitation
to the S2 state elicits a unique dual-isomerization reaction:
first, C13=C14 cis–trans isomerization occurs during S2–S1 evolution
in <100 fs. This very fast reaction features the remarkable property
that the newly formed isomer appears in the excited state rather than
in the ground state. Second, C15=N16 anti–syn isomerization occurs on the S1–S0 evolution to the ground state in 4.8 ps. We detected two
ground-state unprotonated retinal photoproducts, 13-trans/15-anti (all-trans) and 13-cis/15-syn, after relaxation to the ground
state. These isomers become protonated in 58 μs and 3.2 ms,
respectively, resulting in formation of the blue-absorbing form of
HKR1. Our results constitute a benchmark of UV-induced photochemistry
of animal and microbial rhodopsins.
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Affiliation(s)
- Yusaku Hontani
- Department of Physics and Astronomy, Vrije Universiteit Amsterdam, De Boelelaan, Amsterdam 1081 HV, The Netherlands
| | - Matthias Broser
- Institut für Biologie, Experimentelle Biophysik, Humboldt Universität zu Berlin, Invalidenstrasse 42, D-10115 Berlin, Germany
| | - Meike Luck
- Institut für Biologie, Experimentelle Biophysik, Humboldt Universität zu Berlin, Invalidenstrasse 42, D-10115 Berlin, Germany
| | - Jörn Weißenborn
- Department of Physics and Astronomy, Vrije Universiteit Amsterdam, De Boelelaan, Amsterdam 1081 HV, The Netherlands
| | - Miroslav Kloz
- Department of Physics and Astronomy, Vrije Universiteit Amsterdam, De Boelelaan, Amsterdam 1081 HV, The Netherlands.,ELI-Beamlines, Institute of Physics, Na Slovance 2, 182 21 Praha 8, Czech Republic
| | - Peter Hegemann
- Institut für Biologie, Experimentelle Biophysik, Humboldt Universität zu Berlin, Invalidenstrasse 42, D-10115 Berlin, Germany
| | - John T M Kennis
- Department of Physics and Astronomy, Vrije Universiteit Amsterdam, De Boelelaan, Amsterdam 1081 HV, The Netherlands
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20
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Gamboa L, Zamat AH, Kwong GA. Synthetic immunity by remote control. Theranostics 2020; 10:3652-3667. [PMID: 32206114 PMCID: PMC7069089 DOI: 10.7150/thno.41305] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 02/03/2020] [Indexed: 12/11/2022] Open
Abstract
Cell-based immunotherapies, such as T cells engineered with chimeric antigen receptors (CARs), have the potential to cure patients of disease otherwise refractory to conventional treatments. Early-on-treatment and long-term durability of patient responses depend critically on the ability to control the potency of adoptively transferred T cells, as overactivation can lead to complications like cytokine release syndrome, and immunosuppression can result in ineffective responses to therapy. Drugs or biologics (e.g., cytokines) that modulate immune activity are limited by mass transport barriers that reduce the local effective drug concentration, and lack site or target cell specificity that results in toxicity. Emerging technologies that enable site-targeted, remote control of key T cell functions - including proliferation, antigen-sensing, and target-cell killing - have the potential to increase treatment precision and safety profile. These technologies are broadly applicable to other immune cells to expand immune cell therapies across many cancers and diseases. In this review, we highlight the opportunities, challenges and the current state-of-the-art for remote control of synthetic immunity.
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Affiliation(s)
- Lena Gamboa
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology & Emory University, Atlanta, GA 30332, USA
| | - Ali H. Zamat
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology & Emory University, Atlanta, GA 30332, USA
| | - Gabriel A. Kwong
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology & Emory University, Atlanta, GA 30332, USA
- Institute for Electronics and Nanotechnology, Georgia Institute of Technology, Atlanta, GA 30332, USA
- Parker H. Petit Institute of Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, USA
- Integrated Cancer Research Center, Georgia Institute of Technology, Atlanta, GA 30332, USA
- Georgia Immunoengineering Consortium, Emory University and Georgia Institute of Technology, Atlanta, GA 30332, USA
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21
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Andrikopoulos PC, Liu Y, Picchiotti A, Lenngren N, Kloz M, Chaudhari AS, Precek M, Rebarz M, Andreasson J, Hajdu J, Schneider B, Fuertes G. Femtosecond-to-nanosecond dynamics of flavin mononucleotide monitored by stimulated Raman spectroscopy and simulations. Phys Chem Chem Phys 2020; 22:6538-6552. [PMID: 31994556 DOI: 10.1039/c9cp04918e] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Flavin mononucleotide (FMN) belongs to the large family of flavins, ubiquitous yellow-coloured biological chromophores that contain an isoalloxazine ring system. As a cofactor in flavoproteins, it is found in various enzymes and photosensory receptors, like those featuring the light-oxygen-voltage (LOV) domain. The photocycle of FMN is triggered by blue light and proceeds via a cascade of intermediate states. In this work, we have studied isolated FMN in an aqueous solution in order to elucidate the intrinsic electronic and vibrational changes of the chromophore upon excitation. The ultrafast transitions of excited FMN were monitored through the joint use of femtosecond stimulated Raman spectroscopy (FSRS) and transient absorption spectroscopy encompassing a time window between 0 ps and 6 ns with 50 fs time resolution. Global analysis of the obtained transient visible absorption and transient Raman spectra in combination with extensive quantum chemistry calculations identified unambiguously the singlet and triplet FMN populations and addressed solvent dynamics effects. The good agreement between the experimental and theoretical spectra facilitated the assignment of electronic transitions and vibrations. Our results represent the first steps towards more complex experiments aimed at tracking structural changes of FMN embedded in light-inducible proteins upon photoexcitation.
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Affiliation(s)
- Prokopis C Andrikopoulos
- Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Průmyslová 595, CZ-252 50 Vestec, Czech Republic.
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22
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Möglich A. Signal transduction in photoreceptor histidine kinases. Protein Sci 2019; 28:1923-1946. [PMID: 31397927 PMCID: PMC6798134 DOI: 10.1002/pro.3705] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 08/06/2019] [Accepted: 08/06/2019] [Indexed: 12/14/2022]
Abstract
Two-component systems (TCS) constitute the predominant means by which prokaryotes read out and adapt to their environment. Canonical TCSs comprise a sensor histidine kinase (SHK), usually a transmembrane receptor, and a response regulator (RR). In signal-dependent manner, the SHK autophosphorylates and in turn transfers the phosphoryl group to the RR which then elicits downstream responses, often in form of altered gene expression. SHKs also catalyze the hydrolysis of the phospho-RR, hence, tightly adjusting the overall degree of RR phosphorylation. Photoreceptor histidine kinases are a subset of mostly soluble, cytosolic SHKs that sense light in the near-ultraviolet to near-infrared spectral range. Owing to their experimental tractability, photoreceptor histidine kinases serve as paradigms and provide unusually detailed molecular insight into signal detection, decoding, and regulation of SHK activity. The synthesis of recent results on receptors with light-oxygen-voltage, bacteriophytochrome and microbial rhodopsin sensor units identifies recurring, joint signaling strategies. Light signals are initially absorbed by the sensor module and converted into subtle rearrangements of α helices, mostly through pivoting and rotation. These conformational transitions propagate through parallel coiled-coil linkers to the effector unit as changes in left-handed superhelical winding. Within the effector, subtle conformations are triggered that modulate the solvent accessibility of residues engaged in the kinase and phosphatase activities. Taken together, a consistent view of the entire trajectory from signal detection to regulation of output emerges. The underlying allosteric mechanisms could widely apply to TCS signaling in general.
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Affiliation(s)
- Andreas Möglich
- Department of BiochemistryUniversität BayreuthBayreuthGermany
- Bayreuth Center for Biochemistry & Molecular BiologyUniversität BayreuthBayreuthGermany
- North‐Bavarian NMR CenterUniversität BayreuthBayreuthGermany
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23
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Hontani Y, Ganapathy S, Frehan S, Kloz M, de Grip WJ, Kennis JTM. Photoreaction Dynamics of Red-Shifting Retinal Analogues Reconstituted in Proteorhodopsin. J Phys Chem B 2019; 123:4242-4250. [PMID: 30998011 PMCID: PMC6526469 DOI: 10.1021/acs.jpcb.9b01136] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
![]()
Microbial rhodopsins
constitute a key protein family in optobiotechnological
applications such as optogenetics and voltage imaging. Spectral tuning
of rhodopsins into the deep-red and near-infrared spectral regions
is of great demand in such applications because more bathochromic
light into the near-infrared range penetrates deeper in living tissue.
Recently, retinal analogues have been successfully used in ion transporting
and fluorescent rhodopsins to achieve red-shifted absorption, activity,
and emission properties. Understanding their photochemical mechanism
is essential for further design of appropriate retinal analogues but
is yet only poorly understood for most retinal analogue pigments.
Here, we report the photoreaction dynamics of red-shifted analogue
pigments of the proton pump proteorhodopsin (PR) containing A2 (all-trans-3,4-dehydroretinal), MOA2 (all-trans-3-methoxy-3,4-dehydroretinal), or DMAR (all-trans-3-dimethylamino-16-nor-1,2,3,4-didehydroretinal), utilizing femto-
to submillisecond transient absorption spectroscopy. We found that
the A2 analogue photoisomerizes in 1.4, 3.0, and/or 13 ps upon 510
nm light illumination, which is comparable to the native retinal (A1)
in PR. On the other hand, the deprotonation of the A2 pigment Schiff
base was observed with a dominant time constant of 67 μs, which
is significantly slower than the A1 pigment. In the MOA2 pigment,
no isomerization or photoproduct formation was detected upon 520 nm
excitation, implying that all the excited molecules returned to the
initial ground state in 2.0 and 4.2 ps. The DMAR pigment showed very
slow excited state dynamics similar to the previously studied MMAR
pigment, but only very little photoproduct was formed. The low efficiency
of the photoproduct formation likely is the reason why DMAR analogue
pigments of PR showed very weak proton pumping activity.
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Affiliation(s)
- Yusaku Hontani
- Department of Physics and Astronomy , Vrije Universiteit , Amsterdam 1081 HV , The Netherlands
| | - Srividya Ganapathy
- Department of Biophysical Organic Chemistry, Leiden Institute of Chemistry, Gorlaeus Laboratories , Leiden University , Leiden 2300 RA , The Netherlands
| | - Sean Frehan
- Department of Physics and Astronomy , Vrije Universiteit , Amsterdam 1081 HV , The Netherlands
| | - Miroslav Kloz
- ELI-Beamlines , Institute of Physics , Na Slovance 2 , Praha 8 182 21 , Czech Republic
| | - Willem J de Grip
- Department of Biophysical Organic Chemistry, Leiden Institute of Chemistry, Gorlaeus Laboratories , Leiden University , Leiden 2300 RA , The Netherlands.,Department of Biochemistry , Radboud University Medical Center , Nijmegen 6500 HB , The Netherlands
| | - John T M Kennis
- Department of Physics and Astronomy , Vrije Universiteit , Amsterdam 1081 HV , The Netherlands
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24
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Zayner JP, Mathes T, Sosnick TR, Kennis JTM. Helical Contributions Mediate Light-Activated Conformational Change in the LOV2 Domain of Avena sativa Phototropin 1. ACS OMEGA 2019; 4:1238-1243. [PMID: 31459397 PMCID: PMC6648828 DOI: 10.1021/acsomega.8b02872] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 01/02/2019] [Indexed: 06/10/2023]
Abstract
Algae, plants, bacteria, and fungi contain flavin-binding light-oxygen-voltage (LOV) domains that function as blue light sensors to control cellular responses to light. In the second LOV domain of phototropins, called LOV2 domains, blue light illumination leads to covalent bond formation between protein and flavin that induces the dissociation and unfolding of a C-terminally attached α helix (Jα) and the N-terminal helix (A'α). To date, the majority of studies on these domains have focused on versions that contain truncations in the termini, which creates difficulties when extrapolating to the much larger proteins that contain these domains. Here, we study the influence of deletions and extensions of the A'α helix of the LOV2 domain of Avena sativa phototropin 1 (AsLOV2) on the light-triggered structural response of the protein by Fourier-transform infrared difference spectroscopy. Deletion of the A'α helix abolishes the light-induced unfolding of Jα, whereas extensions of the A'α helix lead to an attenuated structural change of Jα. These results are different from shorter constructs, indicating that the conformational changes in full-length phototropin LOV domains might not be as large as previously assumed, and that the well-characterized full unfolding of the Jα helix in AsLOV2 with short A'α helices may be considered a truncation artifact. It also suggests that the N- and C-terminal helices of phot-LOV2 domains are necessary for allosteric regulation of the phototropin kinase domain and may provide a basis for signal integration of LOV1 and LOV2 domains in phototropins.
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Affiliation(s)
- Josiah P. Zayner
- Department of Biochemistry
and Molecular Biology, The University of
Chicago, Chicago 60637, United States
| | - Tilo Mathes
- Biophysics
Section, Department of Physics and Astronomy, Faculty of Sciences, Vrije Universiteit, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - Tobin R. Sosnick
- Department of Biochemistry
and Molecular Biology, The University of
Chicago, Chicago 60637, United States
- Institute
for Biophysical Dynamics, The University
of Chicago, Chicago, Illinois 60637 United States
| | - John T. M. Kennis
- Biophysics
Section, Department of Physics and Astronomy, Faculty of Sciences, Vrije Universiteit, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
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25
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Konold PE, van Stokkum IHM, Muzzopappa F, Wilson A, Groot ML, Kirilovsky D, Kennis JTM. Photoactivation Mechanism, Timing of Protein Secondary Structure Dynamics and Carotenoid Translocation in the Orange Carotenoid Protein. J Am Chem Soc 2019; 141:520-530. [PMID: 30511841 PMCID: PMC6331140 DOI: 10.1021/jacs.8b11373] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Indexed: 01/10/2023]
Abstract
The orange carotenoid protein (OCP) is a two-domain photoactive protein that noncovalently binds an echinenone (ECN) carotenoid and mediates photoprotection in cyanobacteria. In the dark, OCP assumes an orange, inactive state known as OCPO; blue light illumination results in the red active state, known as OCPR. The OCPR state is characterized by large-scale structural changes that involve dissociation and separation of C-terminal and N-terminal domains accompanied by carotenoid translocation into the N-terminal domain. The mechanistic and dynamic-structural relations between photon absorption and formation of the OCPR state have remained largely unknown. Here, we employ a combination of time-resolved UV-visible and (polarized) mid-infrared spectroscopy to assess the electronic and structural dynamics of the carotenoid and the protein secondary structure, from femtoseconds to 0.5 ms. We identify a hereto unidentified carotenoid excited state in OCP, the so-called S* state, which we propose to play a key role in breaking conserved hydrogen-bond interactions between carotenoid and aromatic amino acids in the binding pocket. We arrive at a comprehensive reaction model where the hydrogen-bond rupture with conserved aromatic side chains at the carotenoid β1-ring in picoseconds occurs at a low yield of <1%, whereby the β1-ring retains a trans configuration with respect to the conjugated π-electron chain. This event initiates structural changes at the N-terminal domain in 1 μs, which allow the carotenoid to translocate into the N-terminal domain in 10 μs. We identified infrared signatures of helical elements that dock on the C-terminal domain β-sheet in the dark and unfold in the light to allow domain separation. These helical elements do not move within the experimental range of 0.5 ms, indicating that domain separation occurs on longer time scales, lagging carotenoid translocation by at least 2 decades of time.
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Affiliation(s)
- Patrick E. Konold
- Department of Physics
and Astronomy, Faculty of Sciences, Vrije
Universiteit, De Boelelaan
1081, 1081HV Amsterdam, The Netherlands
| | - Ivo H. M. van Stokkum
- Department of Physics
and Astronomy, Faculty of Sciences, Vrije
Universiteit, De Boelelaan
1081, 1081HV Amsterdam, The Netherlands
| | - Fernando Muzzopappa
- Institute for Integrative Biology of the
Cell (I2BC), CEA, CNRS, Universite Paris-Sud,
Universite Paris-Saclay, 91198 Gif-sur-Yvette, France
- Institut Joliot, Commissariat a l’Energie
Atomique (CEA), 91191 Gif-sur-Yvette, France
| | - Adjélé Wilson
- Institute for Integrative Biology of the
Cell (I2BC), CEA, CNRS, Universite Paris-Sud,
Universite Paris-Saclay, 91198 Gif-sur-Yvette, France
- Institut Joliot, Commissariat a l’Energie
Atomique (CEA), 91191 Gif-sur-Yvette, France
| | - Marie-Louise Groot
- Department of Physics
and Astronomy, Faculty of Sciences, Vrije
Universiteit, De Boelelaan
1081, 1081HV Amsterdam, The Netherlands
| | - Diana Kirilovsky
- Institute for Integrative Biology of the
Cell (I2BC), CEA, CNRS, Universite Paris-Sud,
Universite Paris-Saclay, 91198 Gif-sur-Yvette, France
- Institut Joliot, Commissariat a l’Energie
Atomique (CEA), 91191 Gif-sur-Yvette, France
| | - John T. M. Kennis
- Department of Physics
and Astronomy, Faculty of Sciences, Vrije
Universiteit, De Boelelaan
1081, 1081HV Amsterdam, The Netherlands
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26
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Kar RK, Borin VA, Ding Y, Matysik J, Schapiro I. Spectroscopic Properties of Lumiflavin: A Quantum Chemical Study. Photochem Photobiol 2018; 95:662-674. [DOI: 10.1111/php.13023] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 09/05/2018] [Indexed: 12/24/2022]
Affiliation(s)
- Rajiv Kumar Kar
- Fritz Haber Center for Molecular Dynamics Research Institute of Chemistry Hebrew University of Jerusalem Jerusalem Israel
| | - Veniamin A. Borin
- Fritz Haber Center for Molecular Dynamics Research Institute of Chemistry Hebrew University of Jerusalem Jerusalem Israel
| | - Yonghong Ding
- Institute of Analytical Chemistry University of Leipzig Leipzig Germany
| | - Jörg Matysik
- Institute of Analytical Chemistry University of Leipzig Leipzig Germany
| | - Igor Schapiro
- Fritz Haber Center for Molecular Dynamics Research Institute of Chemistry Hebrew University of Jerusalem Jerusalem Israel
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27
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Tsukuno H, Ozeki K, Kobayashi I, Hisatomi O, Mino H. Flavin-Radical Formation in the Light-Oxygen-Voltage-Sensing Domain of the Photozipper Blue-light Sensor Protein. J Phys Chem B 2018; 122:8819-8823. [PMID: 30157376 DOI: 10.1021/acs.jpcb.8b05808] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Formation of the neutral flavin radical in the light-oxygen-voltage-sensing (LOV-sensing) domain of photozipper, based on VfAUREO1, was investigated by electron paramagnetic resonance spectroscopy. The flavin radical was observed in the presence of dithiothreitol by illumination of a LOV-domain mutant (C254S), in which a photoactive cysteine residue in close proximity to flavin was replaced with a serine. The radical did not form under low initial protein-concentration conditions (less than 20 μM). The flavin radicals accumulated with logistic time-dependent kinetics when the protein concentrations were higher than 30 μM. These results indicate that the radical is produced by concerted reactions involving protein interactions and that the radical is formed from the LOV dimer but not the LOV monomer. In contrast, logistic time dependencies were not observed for the sample adapted to the dark following radical formation by illumination, indicating that initialization of the proton pathway is essential for this fast sensing reaction.
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Affiliation(s)
- Hiroyuki Tsukuno
- Division of Material Science, Graduate School of Science , Nagoya University , Chikusa-ku, Furo-cho, Nagoya 464-8602 , Japan
| | - Kohei Ozeki
- Division of Material Science, Graduate School of Science , Nagoya University , Chikusa-ku, Furo-cho, Nagoya 464-8602 , Japan
| | - Itsuki Kobayashi
- Department of Earth and Space Science, Graduate School of Science , Osaka University , Osaka 560-0043 , Japan
| | - Osamu Hisatomi
- Department of Earth and Space Science, Graduate School of Science , Osaka University , Osaka 560-0043 , Japan
| | - Hiroyuki Mino
- Division of Material Science, Graduate School of Science , Nagoya University , Chikusa-ku, Furo-cho, Nagoya 464-8602 , Japan
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28
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Abstract
Sensory photoreceptors underpin light-dependent adaptations of organismal physiology, development, and behavior in nature. Adapted for optogenetics, sensory photoreceptors become genetically encoded actuators and reporters to enable the noninvasive, spatiotemporally accurate and reversible control by light of cellular processes. Rooted in a mechanistic understanding of natural photoreceptors, artificial photoreceptors with customized light-gated function have been engineered that greatly expand the scope of optogenetics beyond the original application of light-controlled ion flow. As we survey presently, UV/blue-light-sensitive photoreceptors have particularly allowed optogenetics to transcend its initial neuroscience applications by unlocking numerous additional cellular processes and parameters for optogenetic intervention, including gene expression, DNA recombination, subcellular localization, cytoskeleton dynamics, intracellular protein stability, signal transduction cascades, apoptosis, and enzyme activity. The engineering of novel photoreceptors benefits from powerful and reusable design strategies, most importantly light-dependent protein association and (un)folding reactions. Additionally, modified versions of these same sensory photoreceptors serve as fluorescent proteins and generators of singlet oxygen, thereby further enriching the optogenetic toolkit. The available and upcoming UV/blue-light-sensitive actuators and reporters enable the detailed and quantitative interrogation of cellular signal networks and processes in increasingly more precise and illuminating manners.
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Affiliation(s)
- Aba Losi
- Department of Mathematical, Physical and Computer Sciences , University of Parma , Parco Area delle Scienze 7/A-43124 Parma , Italy
| | - Kevin H Gardner
- Structural Biology Initiative, CUNY Advanced Science Research Center , New York , New York 10031 , United States.,Department of Chemistry and Biochemistry, City College of New York , New York , New York 10031 , United States.,Ph.D. Programs in Biochemistry, Chemistry, and Biology , The Graduate Center of the City University of New York , New York , New York 10016 , United States
| | - Andreas Möglich
- Lehrstuhl für Biochemie , Universität Bayreuth , 95447 Bayreuth , Germany.,Research Center for Bio-Macromolecules , Universität Bayreuth , 95447 Bayreuth , Germany.,Bayreuth Center for Biochemistry & Molecular Biology , Universität Bayreuth , 95447 Bayreuth , Germany
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29
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Correlating structural and photochemical heterogeneity in cyanobacteriochrome NpR6012g4. Proc Natl Acad Sci U S A 2018; 115:4387-4392. [PMID: 29632180 DOI: 10.1073/pnas.1720682115] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Phytochrome photoreceptors control plant growth, development, and the shade avoidance response that limits crop yield in high-density agricultural plantings. Cyanobacteriochromes (CBCRs) are distantly related photosensory proteins that control cyanobacterial metabolism and behavior in response to light. Photoreceptors in both families reversibly photoconvert between two photostates via photoisomerization of linear tetrapyrrole (bilin) chromophores. Spectroscopic and biochemical studies have demonstrated heterogeneity in both photostates, but the structural basis for such heterogeneity remains unclear. We report solution NMR structures for both photostates of the red/green CBCR NpR6012g4 from Nostoc punctiforme In addition to identifying structural changes accompanying photoconversion, these structures reveal structural heterogeneity for residues Trp655 and Asp657 in the red-absorbing NpR6012g4 dark state, yielding two distinct environments for the phycocyanobilin chromophore. We use site-directed mutagenesis and fluorescence and absorbance spectroscopy to assign an orange-absorbing population in the NpR6012g4 dark state to the minority configuration for Asp657. This population does not undergo full, productive photoconversion, as shown by time-resolved spectroscopy and absorption spectroscopy at cryogenic temperature. Our studies thus elucidate the spectral and photochemical consequences of structural heterogeneity in a member of the phytochrome superfamily, insights that should inform efforts to improve photochemical or fluorescence quantum yields in the phytochrome superfamily.
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30
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Iuliano JN, Gil AA, Laptenok SP, Hall CR, Collado JT, Lukacs A, Hag Ahmed SA, Abyad J, Daryaee T, Greetham GM, Sazanovich IV, Illarionov B, Bacher A, Fischer M, Towrie M, French JB, Meech SR, Tonge PJ. Variation in LOV Photoreceptor Activation Dynamics Probed by Time-Resolved Infrared Spectroscopy. Biochemistry 2018; 57:620-630. [PMID: 29239168 PMCID: PMC5801046 DOI: 10.1021/acs.biochem.7b01040] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The light, oxygen, voltage (LOV) domain proteins are blue light photoreceptors that utilize a noncovalently bound flavin mononucleotide (FMN) cofactor as the chromophore. The modular nature of these proteins has led to their wide adoption in the emerging fields of optogenetics and optobiology, where the LOV domain has been fused to a variety of output domains leading to novel light-controlled applications. In this work, we extend our studies of the subpicosecond to several hundred microsecond transient infrared spectroscopy of the isolated LOV domain AsLOV2 to three full-length photoreceptors in which the LOV domain is fused to an output domain: the LOV-STAS protein, YtvA, the LOV-HTH transcription factor, EL222, and the LOV-histidine kinase, LovK. Despite differences in tertiary structure, the overall pathway leading to cysteine adduct formation from the FMN triplet state is highly conserved, although there are slight variations in rate. However, significant differences are observed in the vibrational spectra and kinetics after adduct formation, which are directly linked to the specific output function of the LOV domain. While the rate of adduct formation varies by only 3.6-fold among the proteins, the subsequent large-scale structural changes in the full-length LOV photoreceptors occur over the micro- to submillisecond time scales and vary by orders of magnitude depending on the different output function of each LOV domain.
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Affiliation(s)
- James N. Iuliano
- Department of Chemistry, Stony Brook University, New York, 11794, United States
| | - Agnieszka A. Gil
- Department of Chemistry, Stony Brook University, New York, 11794, United States
| | | | | | | | - Andras Lukacs
- School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, U.K
- Department of Biophysics, Medical School, University of Pecs, Szigeti út 12, 7624 Pecs, Hungary
| | - Safaa A. Hag Ahmed
- Department of Chemistry, Stony Brook University, New York, 11794, United States
| | - Jenna Abyad
- Department of Chemistry, Stony Brook University, New York, 11794, United States
| | - Taraneh Daryaee
- Department of Chemistry, Stony Brook University, New York, 11794, United States
| | - Gregory M. Greetham
- Central Laser Facility, Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, OX11 0QX, U.K
| | - Igor V. Sazanovich
- Central Laser Facility, Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, OX11 0QX, U.K
| | - Boris Illarionov
- Institut für Biochemie und Lebensmittelchemie, Universität Hamburg, Grindelallee 117, D-20146 Hamburg, Germany
| | - Adelbert Bacher
- Department Chemie, Technische Universität München, D-85747 Garching, Germany
| | - Markus Fischer
- Institut für Biochemie und Lebensmittelchemie, Universität Hamburg, Grindelallee 117, D-20146 Hamburg, Germany
| | - Michael Towrie
- Central Laser Facility, Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, OX11 0QX, U.K
| | - Jarrod B. French
- Department of Chemistry, Stony Brook University, New York, 11794, United States
| | - Stephen R. Meech
- School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, U.K
| | - Peter J. Tonge
- Department of Chemistry, Stony Brook University, New York, 11794, United States
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31
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Ozeki K, Tsukuno H, Nagashima H, Hisatomi O, Mino H. Dimeric Structure of the Blue Light Sensor Protein Photozipper in the Active State. Biochemistry 2017; 57:494-497. [DOI: 10.1021/acs.biochem.7b01045] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Kohei Ozeki
- Division
of Material Science, Graduate School of Science, Nagoya University, Chikusa-ku, Furo-cho, Nagoya 464-8602, Japan
| | - Hiroyuki Tsukuno
- Division
of Material Science, Graduate School of Science, Nagoya University, Chikusa-ku, Furo-cho, Nagoya 464-8602, Japan
| | - Hiroki Nagashima
- Division
of Material Science, Graduate School of Science, Nagoya University, Chikusa-ku, Furo-cho, Nagoya 464-8602, Japan
| | - Osamu Hisatomi
- Department
of Earth and Space Science, Graduate School of Science, Osaka University, Osaka 560-0043, Japan
| | - Hiroyuki Mino
- Division
of Material Science, Graduate School of Science, Nagoya University, Chikusa-ku, Furo-cho, Nagoya 464-8602, Japan
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32
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Nakagawa S, Weingart O, Marian CM. Dual Photochemical Reaction Pathway in Flavin-Based Photoreceptor LOV Domain: A Combined Quantum-Mechanics/Molecular-Mechanics Investigation. J Phys Chem B 2017; 121:9583-9596. [PMID: 28926259 DOI: 10.1021/acs.jpcb.7b09207] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The primary photochemical reaction of the light, oxygen, and voltage (LOV) domain of the blue-light photosensor YtvA of Bacillus subtilis were investigated using high-level QM(DFT/MRCI)/MM methods. After blue-light excitation, the Sγ atom of the reactive cysteine forms a covalent bond with the C4a of the flavin mononucleotide (FMN) ring. Two conformations for the side chain of reactive cysteine with occupancies of 70% (conf A) and 30% (conf B) are observed in the X-ray crystallographic structures of the YtvA-LOV ( Möglich , A. ; Moffat , K. J. Mol. Biol. 2007 , 373 , 112 - 126 ). In conf A, the thiol group is directed toward the dimethylbenzene moiety of the FMN ring whereas it is placed directly above the N5 atom of the FMN ring in conf B. Starting from both conformations, the singlet and triplet excited pathways were evaluated. The singlet states excited from conf A decay nonradiatively to the triplet states by intersystem crossing (ISC). After the formation of a neutral biradical, the triplet states cross over to the electronic ground state by a second ISC and the adducts are efficiently formed. The singlet states excited from conf B are located near the S1/S0 conical intersection (CIn). A major fraction returns to the initial states through the CIn. The rest may directly reach the adduct state. Thus, the photoexcitation has a dual reaction pathway. In YtvA-LOV, it is inferred that the efficient triplet excitation from conf A was chosen by bypassing the less efficient singlet excitation from conf B.
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Affiliation(s)
- Setsuko Nakagawa
- Department of Human Life and Environment, Kinjo Gakuin University , Omori, Moriyama-ku, Nagoya 463-8521, Japan
| | - Oliver Weingart
- Institute of Theoretical and Computational Chemistry, Heinrich Heine University Düsseldorf , Universitätsstrasse 1, D-40225 Düsseldorf, Germany
| | - Christel M Marian
- Institute of Theoretical and Computational Chemistry, Heinrich Heine University Düsseldorf , Universitätsstrasse 1, D-40225 Düsseldorf, Germany
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33
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Abstract
Channelrhodopsin (ChR) is a key protein of the optogenetic toolkit. C1C2, a functional chimeric protein of Chlamydomonas reinhardtii ChR1 and ChR2, is the only ChR whose crystal structure has been solved, and thus uniquely suitable for structure-based analysis. We report C1C2 photoreaction dynamics with ultrafast transient absorption and multi-pulse spectroscopy combined with target analysis and structure-based hybrid quantum mechanics/molecular mechanics calculations. Two relaxation pathways exist on the excited (S1) state through two conical intersections CI1 and CI2, that are reached via clockwise and counter-clockwise rotations: (i) the C13=C14 isomerization path with 450 fs via CI1 and (ii) a relaxation path to the initial ground state with 2.0 ps and 11 ps via CI2, depending on the hydrogen-bonding network, hence indicating active-site structural heterogeneity. The presence of the additional conical intersection CI2 rationalizes the relatively low quantum yield of photoisomerization (30 ± 3%), reported here. Furthermore, we show the photoreaction dynamics from picoseconds to seconds, characterizing the complete photocycle of C1C2.
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34
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Gil AA, Laptenok SP, French JB, Iuliano JN, Lukacs A, Hall CR, Sazanovich IV, Greetham GM, Bacher A, Illarionov B, Fischer M, Tonge PJ, Meech SR. Femtosecond to Millisecond Dynamics of Light Induced Allostery in the Avena sativa LOV Domain. J Phys Chem B 2017; 121:1010-1019. [PMID: 28068090 DOI: 10.1021/acs.jpcb.7b00088] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The rational engineering of photosensor proteins underpins the field of optogenetics, in which light is used for spatiotemporal control of cell signaling. Optogenetic elements function by converting electronic excitation of an embedded chromophore into structural changes on the microseconds to seconds time scale, which then modulate the activity of output domains responsible for biological signaling. Using time-resolved vibrational spectroscopy coupled with isotope labeling, we have mapped the structural evolution of the LOV2 domain of the flavin binding phototropin Avena sativa (AsLOV2) over 10 decades of time, reporting structural dynamics between 100 fs and 1 ms after optical excitation. The transient vibrational spectra contain contributions from both the flavin chromophore and the surrounding protein matrix. These contributions are resolved and assigned through the study of four different isotopically labeled samples. High signal-to-noise data permit the detailed analysis of kinetics associated with the light activated structural evolution. A pathway for the photocycle consistent with the data is proposed. The earliest events occur in the flavin binding pocket, where a subpicosecond perturbation of the protein matrix occurs. In this perturbed environment, the previously characterized reaction between triplet state isoalloxazine and an adjacent cysteine leads to formation of the adduct state; this step is shown to exhibit dispersive kinetics. This reaction promotes coupling of the optical excitation to successive time-dependent structural changes, initially in the β-sheet and then α-helix regions of the AsLOV2 domain, which ultimately gives rise to Jα-helix unfolding, yielding the signaling state. This model is tested through point mutagenesis, elucidating in particular the key mediating role played by Q513.
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Affiliation(s)
- Agnieszka A Gil
- Department of Chemistry, Stony Brook University , New York 11794-3400, United States
| | - Sergey P Laptenok
- School of Chemistry, University of East Anglia , Norwich, NR4 7TJ, U.K
| | - Jarrod B French
- Department of Chemistry, Stony Brook University , New York 11794-3400, United States
| | - James N Iuliano
- Department of Chemistry, Stony Brook University , New York 11794-3400, United States
| | - Andras Lukacs
- School of Chemistry, University of East Anglia , Norwich, NR4 7TJ, U.K.,Department of Biophysics, Medical School, University of Pecs , Szigeti ut 12, 7624 Pecs, Hungary
| | | | - Igor V Sazanovich
- Central Laser Facility, Research Complex at Harwell, Rutherford Appleton Laboratory , Didcot, Oxon OX11 0QX, U.K
| | - Gregory M Greetham
- Central Laser Facility, Research Complex at Harwell, Rutherford Appleton Laboratory , Didcot, Oxon OX11 0QX, U.K
| | - Adelbert Bacher
- Department Chemie, Technische Universität München , D-85747 Garching, Germany
| | - Boris Illarionov
- Institut für Biochemie und Lebensmittelchemie, Universität Hamburg , Grindelallee 117, D-20146 Hamburg, Germany
| | - Markus Fischer
- Institut für Biochemie und Lebensmittelchemie, Universität Hamburg , Grindelallee 117, D-20146 Hamburg, Germany
| | - Peter J Tonge
- Department of Chemistry, Stony Brook University , New York 11794-3400, United States
| | - Stephen R Meech
- School of Chemistry, University of East Anglia , Norwich, NR4 7TJ, U.K
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35
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Zhu J, Mathes T, Hontani Y, Alexandre MTA, Toh KC, Hegemann P, Kennis JTM. Photoadduct Formation from the FMN Singlet Excited State in the LOV2 Domain of Chlamydomonas reinhardtii Phototropin. J Phys Chem Lett 2016; 7:4380-4384. [PMID: 27766868 DOI: 10.1021/acs.jpclett.6b02075] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The two light, oxygen, and voltage domains of phototropin are blue-light photoreceptor domains that control various functions in plants and green algae. The key step of the light-driven reaction is the formation of a photoadduct between its FMN chromophore and a conserved cysteine, where the canonical reaction proceeds through the FMN triplet state. Here, complete photoreaction mapping of CrLOV2 from Chlamydomonas reinhardtii phototropin and AsLOV2 from Avena sativa phototropin-1 was realized by ultrafast broadband spectroscopy from femtoseconds to microseconds. We demonstrate that in CrLOV2, a direct photoadduct formation channel originates from the initially excited singlet state, in addition to the canonical reaction through the triplet state. This direct photoadduct reaction is coupled by a proton or hydrogen transfer process, as indicated by a significant kinetic isotope effect of 1.4 on the fluorescence lifetime. Kinetic model analyses showed that 38% of the photoadducts are generated from the singlet excited state.
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Affiliation(s)
- Jingyi Zhu
- Department of Physics and Astronomy, Faculty of Sciences, Vrije Universiteit , 1081 De Boelelaan, 1081 HV Amsterdam, The Netherlands
| | - Tilo Mathes
- Department of Physics and Astronomy, Faculty of Sciences, Vrije Universiteit , 1081 De Boelelaan, 1081 HV Amsterdam, The Netherlands
| | - Yusaku Hontani
- Department of Physics and Astronomy, Faculty of Sciences, Vrije Universiteit , 1081 De Boelelaan, 1081 HV Amsterdam, The Netherlands
| | - Maxime T A Alexandre
- Department of Physics and Astronomy, Faculty of Sciences, Vrije Universiteit , 1081 De Boelelaan, 1081 HV Amsterdam, The Netherlands
| | - K C Toh
- Department of Physics and Astronomy, Faculty of Sciences, Vrije Universiteit , 1081 De Boelelaan, 1081 HV Amsterdam, The Netherlands
| | - Peter Hegemann
- Department of Biology, Experimental Biophysics, Humboldt-Universität zu Berlin , Invalidenstraße 42, 10115 Berlin, Germany
| | - John T M Kennis
- Department of Physics and Astronomy, Faculty of Sciences, Vrije Universiteit , 1081 De Boelelaan, 1081 HV Amsterdam, The Netherlands
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36
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Konold PE, Mathes T, Weiβenborn J, Groot ML, Hegemann P, Kennis JTM. Unfolding of the C-Terminal Jα Helix in the LOV2 Photoreceptor Domain Observed by Time-Resolved Vibrational Spectroscopy. J Phys Chem Lett 2016; 7:3472-6. [PMID: 27537211 DOI: 10.1021/acs.jpclett.6b01484] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Light-triggered reactions of biological photoreceptors have gained immense attention for their role as molecular switches in their native organisms and for optogenetic application. The light, oxygen, and voltage 2 (LOV2) sensing domain of plant phototropin binds a C-terminal Jα helix that is docked on a β-sheet and unfolds upon light absorption by the flavin mononucleotide (FMN) chromophore. In this work, the signal transduction pathway of LOV2 from Avena sativa was investigated using time-resolved infrared spectroscopy from picoseconds to microseconds. In D2O buffer, FMN singlet-to-triplet conversion occurs in 2 ns and formation of the covalent cysteinyl-FMN adduct in 10 μs. We observe a two-step unfolding of the Jα helix: The first phase occurs concomitantly with Cys-FMN covalent adduct formation in 10 μs, along with hydrogen-bond rupture of the FMN C4═O with Gln-513, motion of the β-sheet, and an additional helical element. The second phase occurs in approximately 240 μs. The final spectrum at 500 μs is essentially identical to the steady-state light-minus-dark Fourier transform infrared spectrum, indicating that Jα helix unfolding is complete on that time scale.
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Affiliation(s)
- Patrick E Konold
- Department of Physics and Astronomy, Faculty of Sciences, Vrije Universiteit , 1081 De Boelelaan, 1081HV Amsterdam, The Netherlands
| | - Tilo Mathes
- Department of Physics and Astronomy, Faculty of Sciences, Vrije Universiteit , 1081 De Boelelaan, 1081HV Amsterdam, The Netherlands
| | - Jörn Weiβenborn
- Department of Physics and Astronomy, Faculty of Sciences, Vrije Universiteit , 1081 De Boelelaan, 1081HV Amsterdam, The Netherlands
| | - Marie Louise Groot
- Department of Physics and Astronomy, Faculty of Sciences, Vrije Universiteit , 1081 De Boelelaan, 1081HV Amsterdam, The Netherlands
| | - Peter Hegemann
- Department of Biology, Experimental Biophysics, Humboldt-Universität zu Berlin , Invalidenstraße 42, 10115 Berlin, Germany
| | - John T M Kennis
- Department of Physics and Astronomy, Faculty of Sciences, Vrije Universiteit , 1081 De Boelelaan, 1081HV Amsterdam, The Netherlands
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37
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Hontani Y, Inoue K, Kloz M, Kato Y, Kandori H, Kennis JTM. The photochemistry of sodium ion pump rhodopsin observed by watermarked femto- to submillisecond stimulated Raman spectroscopy. Phys Chem Chem Phys 2016; 18:24729-36. [PMID: 27550793 DOI: 10.1039/c6cp05240a] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Krokinobacter rhodopsin 2 (KR2) is a recently discovered light-driven Na(+) pump that holds significant promise for application as a neural silencer in optogenetics. KR2 transports Na(+) (in NaCl solution) or H(+) (in larger cation solution, e.g. in CsCl) during its photocycle. Here, we investigate the photochemistry of KR2 with the recently developed watermarked, baseline-free femto- to submillisecond transient stimulated Raman spectroscopy (TSRS), which enables us to investigate retinal chromophore dynamics in real time with high spectral resolution over a large time range. We propose a new photocycle from femtoseconds to submilliseconds: J (formed in ∼200 fs) → K (∼3 ps) → K/L1 (∼20 ps) → K/L2 (∼30 ns) → L/M (∼20 μs). KR2 binds a Na(+) ion that is not transported on the extracellular side, of which the function is unclear. We demonstrate with TSRS that for the D102N mutant in NaCl (with Na(+) unbound, Na(+) transport) and for WT KR2 in CsCl (with Na(+) unbound, H(+) transport), the extracellular Na(+) binding significantly influences the intermediate K/L/M state equilibrium on the photocycle, while the identity of the transported ion, Na(+) or H(+), does not affect the photocycle. Our findings will contribute to further elucidation of the molecular mechanisms of KR2.
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Affiliation(s)
- Yusaku Hontani
- Department of Physics and Astronomy, Faculty of Sciences, VU University Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands.
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38
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Signal transduction in light-oxygen-voltage receptors lacking the adduct-forming cysteine residue. Nat Commun 2015; 6:10079. [PMID: 26648256 PMCID: PMC4682037 DOI: 10.1038/ncomms10079] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Accepted: 10/30/2015] [Indexed: 01/19/2023] Open
Abstract
Light–oxygen–voltage (LOV) receptors sense blue light through the photochemical generation of a covalent adduct between a flavin-nucleotide chromophore and a strictly conserved cysteine residue. Here we show that, after cysteine removal, the circadian-clock LOV-protein Vivid still undergoes light-induced dimerization and signalling because of flavin photoreduction to the neutral semiquinone (NSQ). Similarly, photoreduction of the engineered LOV histidine kinase YF1 to the NSQ modulates activity and downstream effects on gene expression. Signal transduction in both proteins hence hinges on flavin protonation, which is common to both the cysteinyl adduct and the NSQ. This general mechanism is also conserved by natural cysteine-less, LOV-like regulators that respond to chemical or photoreduction of their flavin cofactors. As LOV proteins can react to light even when devoid of the adduct-forming cysteine, modern LOV photoreceptors may have arisen from ancestral redox-active flavoproteins. The ability to tune LOV reactivity through photoreduction may have important implications for LOV mechanism and optogenetic applications. Light-oxygen-voltage receptors sense blue light through the photochemical generation of a covalent adduct between a flavin-nucleotide chromophore and a strictly conserved cysteine residue. Here, the authors show that these proteins can react to light even when devoid of the adduct-forming cysteine.
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39
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Kutta RJ, Magerl K, Kensy U, Dick B. A search for radical intermediates in the photocycle of LOV domains. Photochem Photobiol Sci 2015; 14:288-99. [PMID: 25380177 DOI: 10.1039/c4pp00155a] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
LOV domains are the light sensitive parts of phototropins and many other light-activated enzymes that regulate the response to blue light in plants and algae as well as some fungi and bacteria. Unlike all other biological photoreceptors known so far, the photocycle of LOV domains involves the excited triplet state of the chromophore. This chromophore is flavin mononucleotide (FMN) which forms a covalent adduct with a cysteine residue in the signaling state. Since the formation of this adduct from the triplet state involves breaking and forming of two bonds as well as a change from the triplet to the singlet spin state, various intermediates have been proposed, e.g. a protonated triplet state (3)FMNH(+), the radical anion (2)FMN˙(-), or the neutral semiquinone radical (2)FMNH˙. We performed an extensive search for these intermediates by two-dimensional transient absorption (2D-TA) with a streak camera. However, no transient with a rate constant between the decay of fluorescence and the decay of the triplet state could be detected. Analysis of the decay associated difference spectra results in quantum yields for the formation of the adduct from the triplet of ΦA(LOV1) ≈ 0.75 and ΦA(LOV2) ≈ 0.80. This is lower than the values ΦA(LOV1) ≈ 0.95 and ΦA(LOV2) ≈ 0.99 calculated from the rate constants, giving indirect evidence of an intermediate that reacts either to form the adduct or to decay back to the ground state. Since there is no measurable delay between the decay of the triplet and the formation of the adduct, we conclude that this intermediate reacts much faster than it is formed. The LOV1-C57S mutant shows a weak and slowly decaying (τ > 100 μs) transient whose decay associated spectrum has bands at 375 and 500 nm, with a shoulder at 400 nm. This transient is insensitive to the pH change in the range 6.5-10.0 but increases on addition of β-mercaptoethanol as the reducing agent. We assign this intermediate to the radical anion which is protected from protonation by the protein. We propose that the adduct is formed via the same intermediate by combination of the radical ion pair.
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Affiliation(s)
- Roger Jan Kutta
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, 93053 Regensburg, Germany.
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40
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Ritter E, Puskar L, Bartl FJ, Aziz EF, Hegemann P, Schade U. Time-resolved infrared spectroscopic techniques as applied to channelrhodopsin. Front Mol Biosci 2015. [PMID: 26217670 PMCID: PMC4493399 DOI: 10.3389/fmolb.2015.00038] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Among optogenetic tools, channelrhodopsins, the light gated ion channels of the plasma membrane from green algae, play the most important role. Properties like channel selectivity, timing parameters or color can be influenced by the exchange of selected amino acids. Although widely used, in the field of neurosciences for example, there is still little known about their photocycles and the mechanism of ion channel gating and conductance. One of the preferred methods for these studies is infrared spectroscopy since it allows observation of proteins and their function at a molecular level and in near-native environment. The absorption of a photon in channelrhodopsin leads to retinal isomerization within femtoseconds, the conductive states are reached in the microsecond time scale and the return into the fully dark-adapted state may take more than minutes. To be able to cover all these time regimes, a range of different spectroscopical approaches are necessary. This mini-review focuses on time-resolved applications of the infrared technique to study channelrhodopsins and other light triggered proteins. We will discuss the approaches with respect to their suitability to the investigation of channelrhodopsin and related proteins.
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Affiliation(s)
- Eglof Ritter
- Experimentelle Biophysik, Institut für Biologie, Humboldt-Universität zu Berlin Berlin, Germany
| | - Ljiljana Puskar
- Methods for Material Development, Helmholtz-Zentrum für Materialien und Energie GmbH Berlin, Germany
| | - Franz J Bartl
- Institut für medizinische Physik und Biophysik, Charité - Universitätsmedizin Berlin Berlin, Germany
| | - Emad F Aziz
- Methods for Material Development, Helmholtz-Zentrum für Materialien und Energie GmbH Berlin, Germany ; Fachbereich Physik, Freie Universität Berlin Berlin, Germany
| | - Peter Hegemann
- Experimentelle Biophysik, Institut für Biologie, Humboldt-Universität zu Berlin Berlin, Germany
| | - Ulrich Schade
- Methods for Material Development, Helmholtz-Zentrum für Materialien und Energie GmbH Berlin, Germany
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41
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Nakatani Y, Hisatomi O. Molecular Mechanism of Photozipper, a Light-Regulated Dimerizing Module Consisting of the bZIP and LOV Domains of Aureochrome-1. Biochemistry 2015; 54:3302-13. [DOI: 10.1021/acs.biochem.5b00320] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yoichi Nakatani
- Department of Earth and Space
Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Osamu Hisatomi
- Department of Earth and Space
Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
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42
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Pudasaini A, El-Arab KK, Zoltowski BD. LOV-based optogenetic devices: light-driven modules to impart photoregulated control of cellular signaling. Front Mol Biosci 2015; 2:18. [PMID: 25988185 PMCID: PMC4428443 DOI: 10.3389/fmolb.2015.00018] [Citation(s) in RCA: 141] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 04/27/2015] [Indexed: 12/31/2022] Open
Abstract
The Light-Oxygen-Voltage domain family of proteins is widespread in biology where they impart sensory responses to signal transduction domains. The small, light responsive LOV modules offer a novel platform for the construction of optogenetic tools. Currently, the design and implementation of these devices is partially hindered by a lack of understanding of how light drives allosteric changes in protein conformation to activate diverse signal transduction domains. Further, divergent photocycle properties amongst LOV family members complicate construction of highly sensitive devices with fast on/off kinetics. In the present review we discuss the history of LOV domain research with primary emphasis on tuning LOV domain chemistry and signal transduction to allow for improved optogenetic tools.
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Affiliation(s)
- Ashutosh Pudasaini
- Department of Chemistry, Center for Drug Discovery, Design and Delivery at Dedman College, Southern Methodist University Dallas, TX, USA
| | - Kaley K El-Arab
- Department of Chemistry, Center for Drug Discovery, Design and Delivery at Dedman College, Southern Methodist University Dallas, TX, USA
| | - Brian D Zoltowski
- Department of Chemistry, Center for Drug Discovery, Design and Delivery at Dedman College, Southern Methodist University Dallas, TX, USA
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43
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Conrad KS, Manahan CC, Crane BR. Photochemistry of flavoprotein light sensors. Nat Chem Biol 2014; 10:801-9. [PMID: 25229449 DOI: 10.1038/nchembio.1633] [Citation(s) in RCA: 167] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2014] [Accepted: 08/18/2014] [Indexed: 12/22/2022]
Abstract
Three major classes of flavin photosensors, light oxygen voltage (LOV) domains, blue light sensor using FAD (BLUF) proteins and cryptochromes (CRYs), regulate diverse biological activities in response to blue light. Recent studies of structure, spectroscopy and chemical mechanism have provided unprecedented insight into how each family operates at the molecular level. In general, the photoexcitation of the flavin cofactor leads to changes in redox and protonation states that ultimately remodel protein conformation and molecular interactions. For LOV domains, issues remain regarding early photochemical events, but common themes in conformational propagation have emerged across a diverse family of proteins. For BLUF proteins, photoinduced electron transfer reactions critical to light conversion are defined, but the subsequent rearrangement of hydrogen bonding networks key for signaling remains highly controversial. For CRYs, the relevant photocycles are actively debated, but mechanistic and functional studies are converging. Despite these challenges, our current understanding has enabled the engineering of flavoprotein photosensors for control of signaling processes within cells.
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Affiliation(s)
- Karen S Conrad
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York, USA
| | - Craig C Manahan
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York, USA
| | - Brian R Crane
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York, USA
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44
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Kothe G, Lukaschek M, Link G, Kacprzak S, Illarionov B, Fischer M, Eisenreich W, Bacher A, Weber S. Detecting a new source for photochemically induced dynamic nuclear polarization in the LOV2 domain of phototropin by magnetic-field dependent (13)C NMR spectroscopy. J Phys Chem B 2014; 118:11622-32. [PMID: 25207844 DOI: 10.1021/jp507134y] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Phototropin is a flavin mononucleotide (FMN) containing blue-light receptor, which regulates, governed by its two LOV domains, the phototropic response of higher plants. Upon photoexcitation, the FMN cofactor triplet state, (3)F, reacts with a nearby cysteine to form a covalent adduct. Cysteine-to-alanine mutants of LOV domains instead generate a flavin radical upon illumination. Here, we explore the formation of photochemically induced dynamic nuclear polarization (CIDNP) in LOV2-C450A of Avena sativa phototropin and demonstrate that photo-CIDNP observed in solution (13)C NMR spectra can reliably be interpreted in terms of solid-state mechanisms including a novel triplet mechanism. To minimize cross-polarization, which transfers light-induced magnetization to adjacent (13)C nuclei, our experiments were performed on proteins reconstituted with specifically (13)C-labeled flavins. Two potential sources for photo-CIDNP can be identified: The photogenerated triplet state, (3)F, and the triplet radical pair (3)(F(-•)W(+•)), formed by electron abstraction of (3)F from tryptophan W491. To separate the two contributions, photo-CIDNP studies were performed at four different magnetic fields ranging from 4.7 to 11.8 T. Analysis revealed that, at fields <9 T, both (3)(F(-•)W(+•)) and (3)F contribute to photo-CIDNP, whereas at high magnetic fields, the calculated enhancement factors of (3)F agree favorably with their experimental counterparts. Thus, we have for the first time detected that a triplet state is the major source for photo-CIDNP in a photoactive protein. Since triplet states are frequently encountered upon photoexcitation of flavoproteins, the novel triplet mechanism opens up new means of studying electronic structures of the active cofactors in these proteins at atomic resolution.
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Affiliation(s)
- Gerd Kothe
- Institut für Physikalische Chemie, Albert-Ludwigs-Universität Freiburg , Albertstr. 21, 79104 Freiburg, Germany
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45
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Spexard M, Thöing C, Beel B, Mittag M, Kottke T. Response of the Sensory Animal-like Cryptochrome aCRY to Blue and Red Light As Revealed by Infrared Difference Spectroscopy. Biochemistry 2014; 53:1041-50. [DOI: 10.1021/bi401599z] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Meike Spexard
- Physical
and Biophysical Chemistry, Department of Chemistry, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Christian Thöing
- Physical
and Biophysical Chemistry, Department of Chemistry, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
| | - Benedikt Beel
- Institute
of General Botany and Plant Physiology, Friedrich Schiller University, Am Planetarium 1, 07743 Jena, Germany
| | - Maria Mittag
- Institute
of General Botany and Plant Physiology, Friedrich Schiller University, Am Planetarium 1, 07743 Jena, Germany
| | - Tilman Kottke
- Physical
and Biophysical Chemistry, Department of Chemistry, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
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Abstract
The ZTL/FKF1/LKP2 group proteins are LOV-domain-based blue-light photoreceptors that control protein degradation by ubiquitination. These proteins were identified relatively recently and are known to be involved in the regulation of the circadian clock and photoperiodic flowering in Arabidopsis. In this review, we focus on two topics. First, we summarize the molecular mechanisms by which ZTL and FKF1 regulate these biological phenomena based on genetic and biochemical analyses. Next, we discuss the chemical properties of the ZTL family LOV domains obtained from structural, biophysical, and photochemical characterizations of the LOV domains. These two different levels of approach unveiled the molecular mechanisms by which plants utilize ZTL and FKF1 proteins to monitor light for daily and seasonal adaptation.
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Affiliation(s)
- Brian D Zoltowski
- Department of Chemistry, Southern Methodist University, Dallas, Texas, USA.
| | - Takato Imaizumi
- Department of Biology, University of Washington, Seattle, Washington, USA.
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47
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Domratcheva T, Udvarhelyi A, Shahi ARM. Computational spectroscopy, dynamics, and photochemistry of photosensory flavoproteins. Methods Mol Biol 2014; 1146:191-228. [PMID: 24764094 DOI: 10.1007/978-1-4939-0452-5_10] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Extensive interest in photosensory proteins stimulated computational studies of flavins and flavoproteins in the past decade. This review is dedicated to the three central topics of these studies: calculations of flavin UV-visible and IR spectra, simulated dynamics of photoreceptor proteins, and flavin photochemistry. Accordingly, this chapter is divided into three parts; each part describes corresponding computational protocols, summarizes computational results, and discusses the emerging mechanistic picture.
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Affiliation(s)
- Tatiana Domratcheva
- Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Jahnstraße 29, 69120, Heidelberg, Germany,
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48
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Mathes T, van Stokkum IHM, Kennis JTM. Photoactivation mechanisms of flavin-binding photoreceptors revealed through ultrafast spectroscopy and global analysis methods. Methods Mol Biol 2014; 1146:401-442. [PMID: 24764100 DOI: 10.1007/978-1-4939-0452-5_16] [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
Flavin-binding photoreceptor proteins use the isoalloxazine moiety of flavin cofactors to absorb light in the blue/UV-A wavelength region and subsequently translate it into biological information. The underlying photochemical reactions and protein structural dynamics are delicately tuned by the protein environment and represent fundamental reactions in biology and chemistry. Due to their photo-switchable nature, these proteins can be studied efficiently with laser-flash induced transient absorption and emission spectroscopy with temporal precision down to the femtosecond time domain. Here, we describe the application of both visible and mid-IR ultrafast transient absorption and time-resolved fluorescence methods in combination with sophisticated global analysis procedures to elucidate the photochemistry and signal transduction of BLUF (Blue light receptors using FAD) and LOV (Light oxygen voltage) photoreceptor domains.
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Affiliation(s)
- Tilo Mathes
- Department of Physics, Faculty of Sciences, VU University Amsterdam, De Boelelaan 1081, Amsterdam, 1081HV, The Netherlands
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49
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Zoltowski BD, Motta-Mena LB, Gardner KH. Blue light-induced dimerization of a bacterial LOV-HTH DNA-binding protein. Biochemistry 2013; 52:6653-61. [PMID: 23992349 DOI: 10.1021/bi401040m] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
With their utilization of light-driven allostery to control biochemical activities, photosensory proteins are of great interest as model systems and novel reagents for use by the basic science and engineering communities. One such protein, the light-activated EL222 transcription factor, from the marine bacterium Erythrobacter litoralis HTCC2594, is appealing for such studies, as it harnesses blue light to drive the reorientation of light-oxygen-voltage (LOV) sensory and helix-turn-helix (HTH) effector domains to allow photoactivation of gene transcription in natural and artificial systems. The protein conformational changes required for this process are not well understood, in part because of the relatively short lifetime of the EL222 photoexcited state (τ ∼ 29 s), which complicates its characterization via certain biophysical methods. Here we report how we have circumvented this limitation by creating an EL222 variant harboring V41I, L52I, A79Q, and V121I point mutations (AQTrip) that stabilizes the photoactivated state. Using the wild-type and AQTrip EL222 proteins, we have probed EL222 activation using a combination of solution scattering, nuclear magnetic resonance (NMR), and electromobility shift assays. Size-exclusion chromatography and light scattering indicate that AQTrip oligomerizes in the absence of DNA and selects for an EL222 dimer-DNA complex in the presence of DNA substrates. These results are confirmed in wild-type EL222 with a high-affinity DNA-binding site that stabilizes the complex. NMR analyses of the EL222-DNA complex confirm a 2:1 stoichiometry in the presence of a previously characterized DNA substrate. Combined, these novel approaches have validated a key mechanistic step, whereby blue light induces EL222 dimerization through LOV and HTH interfaces.
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Affiliation(s)
- Brian D Zoltowski
- Departments of Biophysics and Biochemistry, University of Texas Southwestern Medical Center , Dallas, Texas 75390-8816, United States
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50
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Vdovin A, Slenczka A, Dick B. Electronic spectroscopy of lumiflavin in superfluid helium nanodroplets. Chem Phys 2013. [DOI: 10.1016/j.chemphys.2012.11.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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