1
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Okasha M, Chen J, Ayekoi A, Jacob E, Radtke V, Schmidt A, Bacher A, Weber S, Schleicher E. Linear free energy relationship between reduction potential and photoreduction rate: studies on Drosophila cryptochrome. FEBS J 2025. [PMID: 40372360 DOI: 10.1111/febs.70129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2024] [Revised: 03/04/2025] [Accepted: 04/25/2025] [Indexed: 05/16/2025]
Abstract
Cryptochromes are flavin adenine dinucleotide (FAD)-containing blue-light photoreceptors involved in the regulation of the circadian clock and may play a role in magnetic field sensing. The photochemistry of cryptochromes is based on the isoalloxazine moiety, which can be photoreduced and subsequently reoxidized by an electron acceptor such as oxygen, corresponding to a photo-switch between the dark and signaling state. We replaced the FAD cofactor of Drosophila cryptochrome with a series of FAD cofactors modified at the 7α or 8α positions, in order to modulate the chemical properties of the electron acceptor. These modifications were shown to alter the kinetics of the light-dependent reactions. Notably, 7-halogenated FADs form the signaling state more than six times faster compared to the natural FAD cofactor. The more positive reduction potentials as well as the increased intersystem crossing rates due to heavy halogen atoms were identified as reasons for the altered photochemistry. Both parameters show a linear dependence on the reaction kinetics, according to the Hammett relationship. With this knowledge, the photochemistry of cryptochromes may be modified in a defined way without changing its amino acid sequence.
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Affiliation(s)
- Moustafa Okasha
- Institute of Physical Chemistry, University of Freiburg, Germany
| | - Jing Chen
- Institute of Physical Chemistry, University of Freiburg, Germany
| | - Audrey Ayekoi
- Institute of Physical Chemistry, University of Freiburg, Germany
| | - Eike Jacob
- Institute of Inorganic Chemistry, University of Freiburg, Germany
| | - Valentin Radtke
- Institute of Inorganic Chemistry, University of Freiburg, Germany
| | - Anton Schmidt
- Institute of Physical Chemistry, University of Freiburg, Germany
| | - Adelbert Bacher
- TUM School of Natural Sciences, Technical University of Munich, Germany
| | - Stefan Weber
- Institute of Physical Chemistry, University of Freiburg, Germany
| | - Erik Schleicher
- Institute of Physical Chemistry, University of Freiburg, Germany
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2
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Cao X, Yan L, Yang C, Wang L, Zhang M, Zhong D. Dynamics of DNA Repair by Class-II Photolyases via a Unified Electron-Transfer Bifurcating Mechanism. J Am Chem Soc 2025; 147:11291-11300. [PMID: 40108856 DOI: 10.1021/jacs.4c18557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/22/2025]
Abstract
The class-II photolyases (PLs) are distantly related to the microbial class-I photolyases with low sequence similarity, yet they maintain a similar structural topology and repair the same UV-induced cyclobutane pyrimidine dimer (CPD). The class-I photolyases have been well characterized through a direct electron-transfer (ET) tunneling mechanism with high repair quantum yield, but such a mechanism seemingly does not apply to all of the members in the diversified photolyase family. Here, using femtosecond spectroscopy, we show our systematic characterization of CPD repair by the class-II photolyases from Methanosarcina mazei and Drosophila melanogaster and reveal their complete photocycles with determination of reaction times of all ten elementary steps, including seven electron-transfer processes. We found that the initial electron injection bifurcates along two parallel routes, direct tunneling and two-step hopping. Unlike the class-I photolyases, the direct tunneling process here is significantly slower, occurring in several nanoseconds. This slow tunneling route leads to shifting of the branching yield toward the intrinsic two-step hopping pathway through the adenine intermediate. Throughout the photolyase family, the enzymes have adopted a unified bifurcating electron-transfer strategy as a universal repair mechanism through evolution.
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Affiliation(s)
- Xiaodan Cao
- Center for Ultrafast Science and Technology, School of Chemistry and Chemical Engineering, Zhangjiang Institute for Advanced Study, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Luyao Yan
- Center for Ultrafast Science and Technology, School of Physics and Astronomy, Zhangjiang Institute for Advanced Study, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Chao Yang
- Department of Physics, Department of Chemistry and Biochemistry, and Programs of Biophysics, Chemical Physics, and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Lijuan Wang
- Department of Physics, Department of Chemistry and Biochemistry, and Programs of Biophysics, Chemical Physics, and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Meng Zhang
- Department of Molecular and Cellular Biology, The Scripps Research Institute, La Jolla, California 92037, United States
| | - Dongping Zhong
- Center for Ultrafast Science and Technology, School of Chemistry and Chemical Engineering, Zhangjiang Institute for Advanced Study, Shanghai Jiao Tong University, Shanghai 200240, China
- Department of Physics, Department of Chemistry and Biochemistry, and Programs of Biophysics, Chemical Physics, and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
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3
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Mhanna R, Berger J, Jourdain M, Muth S, Kutta RJ, Jung G. Effect of Excitation Wavelength in Single-Molecule Photochemistry of Terrylene. Chemphyschem 2025; 26:e202400996. [PMID: 39778042 PMCID: PMC11963977 DOI: 10.1002/cphc.202400996] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2024] [Revised: 12/28/2024] [Accepted: 01/07/2025] [Indexed: 01/11/2025]
Abstract
The reaction of terrylene in p-terphenyl with molecular oxygen is reinvestigated by TIRF-microscopy with λexc=488 nm or λexc=561 nm and 488 nm. A similar range of fluorescent products is obtained under both experimental conditions with a reaction quantum yield Φr>10-7 for those molecules which undergo the photoreaction. The majority of these oxygen-susceptible molecules reacts via an electronically relaxed, dark intermediate, presumably an endoperoxide, with a lifetime of ~20 s. From this time constant, an activation energy EA<0.8 eV is estimated for the transition from the intermediate to the final product, the diepoxide, which nicely agrees with values calculated for the terrylene-derivative TDI. However, ~20 % of all reacting molecules at λexc=561 nm and even ~40 % at λexc=488 nm show an immediate change of the fluorescence colour within the time resolution of the experiment, bypassing any dark intermediate. Based on this experimentally observed impact of the excitation energy and the lack of relevant excited-state absorption, we hypothesize that oxygen forms a complex with ground-state terrylene which then undergoes a quasi-unimolecular reaction in the excited-state before vibrational relaxation takes place.
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Affiliation(s)
- Rana Mhanna
- Department of Biophysical ChemistrySaarland University66123SaarbrückenGermany
| | - Julia Berger
- Department of Biophysical ChemistrySaarland University66123SaarbrückenGermany
| | - Matthias Jourdain
- Department of Biophysical ChemistrySaarland University66123SaarbrückenGermany
| | - Stephan Muth
- Institute of Physical and Theoretical ChemistryUniversity of Regensburg93053RegensburgGermany
| | - Roger Jan Kutta
- Institute of Physical and Theoretical ChemistryUniversity of Regensburg93053RegensburgGermany
| | - Gregor Jung
- Department of Biophysical ChemistrySaarland University66123SaarbrückenGermany
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4
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Ramsay JL, Schuhmann F, Solov’yov IA, Kattnig DR. Cryptochrome magnetoreception: Time course of photoactivation from non-equilibrium coarse-grained molecular dynamics. Comput Struct Biotechnol J 2024; 26:58-69. [PMID: 39802491 PMCID: PMC11725172 DOI: 10.1016/j.csbj.2024.11.001] [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: 09/13/2024] [Revised: 11/01/2024] [Accepted: 11/01/2024] [Indexed: 01/16/2025] Open
Abstract
Magnetoreception, the ability to sense magnetic fields, is widespread in animals but remains poorly understood. The leading model links this ability in migratory birds to the photo-activation of the protein cryptochrome. Magnetic information is thought to induce structural changes in cryptochrome via a transient radical pair intermediate. This signal transduction pathway has been the subject of previous all-atom molecular dynamics (MD) simulations, but insights were limited to short timescales and equilibrium structures. To address this, we developed a non-equilibrium coarse-grained MD simulation approach, exploring cryptochrome's photo-reduction over 20 replicates of 20 µs each. Our results revealed significant structural changes across the protein, with an overall time constant of 3 µs. The C-terminal (CT) region responded on a timescale of 4.7 µs, followed by the EEE-motif, while the phosphate binding loop (PBL) showed slower dynamics (9 µs). Network analysis highlighted direct pathways connecting the tryptophan tetrad to the CT, and distant pathways involving the EEE and PBL regions. The CT-dynamics are significantly impacted by a rearrangement of tryptophan residues in the central electron transfer chain. Our findings underscore the importance of considering longer timescales when studying cryptochrome magnetoreception and highlight the potential of non-equilibrium coarse-grained MD simulations as a powerful tool to unravel protein photoactivation reactions.
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Affiliation(s)
- Jessica L. Ramsay
- Department of Physics, University of Exeter, Stocker Rd., Exeter EX4 4QL, UK
- Living Systems Institute, University of Exeter, Stocker Rd., Exeter EX4 4QD, UK
| | - Fabian Schuhmann
- Niels Bohr International Academy, Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, Copenhagen 2100, Denmark
| | - Ilia A. Solov’yov
- Institute of Physics, Carl von Ossietzky Universität Oldenburg, Carl-von-Ossietzky Str. 9–11, Oldenburg 26129, Germany
- Research Centre for Neurosensory Science, Carl von Ossietzky Universität Oldenburg, Carl-von-Ossietzky-Str. 9-11, Oldenburg 26129, Germany
- Center for Nanoscale Dynamics (CENAD), Carl von Ossietzky Universität Oldenburg, Ammerländer Heerstr. 114–118, Oldenburg 26129, Germany
| | - Daniel R. Kattnig
- Department of Physics, University of Exeter, Stocker Rd., Exeter EX4 4QL, UK
- Living Systems Institute, University of Exeter, Stocker Rd., Exeter EX4 4QD, UK
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5
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DeOliveira CC, Crane BR. A structural decryption of cryptochromes. Front Chem 2024; 12:1436322. [PMID: 39220829 PMCID: PMC11362059 DOI: 10.3389/fchem.2024.1436322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2024] [Accepted: 08/01/2024] [Indexed: 09/04/2024] Open
Abstract
Cryptochromes (CRYs), which are signaling proteins related to DNA photolyases, play pivotal roles in sensory responses throughout biology, including growth and development, metabolic regulation, circadian rhythm entrainment and geomagnetic field sensing. This review explores the evolutionary relationships and functional diversity of cryptochromes from the perspective of their molecular structures. In general, CRY biological activities derive from their core structural architecture, which is based on a Photolyase Homology Region (PHR) and a more variable and functionally specific Cryptochrome C-terminal Extension (CCE). The α/β and α-helical domains within the PHR bind FAD, modulate redox reactive residues, accommodate antenna cofactors, recognize small molecules and provide conformationally responsive interaction surfaces for a range of partners. CCEs add structural complexity and divergence, and in doing so, influence photoreceptor reactivity and tailor function. Primary and secondary pockets within the PHR bind myriad moieties and collaborate with the CCEs to tune recognition properties and propagate chemical changes to downstream partners. For some CRYs, changes in homo and hetero-oligomerization couple to light-induced conformational changes, for others, changes in posttranslational modifications couple to cascades of protein interactions with partners and effectors. The structural exploration of cryptochromes underscores how a broad family of signaling proteins with close relationship to light-dependent enzymes achieves a wide range of activities through conservation of key structural and chemical properties upon which function-specific features are elaborated.
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Affiliation(s)
| | - Brian R. Crane
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, United States
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6
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Märsch J, Reiter S, Rittner T, Rodriguez-Lugo RE, Whitfield M, Scott DJ, Kutta RJ, Nuernberger P, de Vivie-Riedle R, Wolf R. Cobalt-Mediated Photochemical C-H Arylation of Pyrroles. Angew Chem Int Ed Engl 2024; 63:e202405780. [PMID: 38693673 DOI: 10.1002/anie.202405780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2024] [Revised: 04/26/2024] [Accepted: 04/29/2024] [Indexed: 05/03/2024]
Abstract
Precious metal complexes remain ubiquitous in photoredox catalysis (PRC) despite concerted efforts to find more earth-abundant catalysts and replacements based on 3d metals in particular. Most otherwise plausible 3d metal complexes are assumed to be unsuitable due to short-lived excited states, which has led researchers to prioritize the pursuit of longer excited-state lifetimes through careful molecular design. However, we report herein that the C-H arylation of pyrroles and related substrates (which are benchmark reactions for assessing the efficacy of photoredox catalysts) can be achieved using a simple and readily accessible octahedral bis(diiminopyridine) cobalt complex, [1-Co](PF6)2. Notably, [1-Co]2+ efficiently functionalizes both chloro- and bromoarene substrates despite the short excited-state lifetime of the key photoexcited intermediate *[1-Co]2+ (8 ps). We present herein the scope of this C-H arylation protocol and provide mechanistic insights derived from detailed spectroscopic and computational studies. These indicate that, despite its transient existence, reduction of *[1-Co]2+ is facilitated via pre-assembly with the NEt3 reductant, highlighting an alternative strategy for the future development of 3d metal-catalyzed PRC.
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Affiliation(s)
- Julia Märsch
- Institute of Inorganic Chemistry, University of Regensburg, 93040, Regensburg, Germany
| | - Sebastian Reiter
- Department of Chemistry, Ludwig Maximilian University Munich, 81377, Munich, Germany
| | - Thomas Rittner
- Institute of Physical and Theoretical Chemistry, University of Regensburg, 93040, Regensburg, Germany
| | - Rafael E Rodriguez-Lugo
- Institute of Inorganic Chemistry, University of Regensburg, 93040, Regensburg, Germany
- present address: Istituto di Chimica dei Composti Organometallici, Consiglio Nazionale delle Ricerche, Via Madonna del Piano 10, Sesto Fiorentino, 50019, Italy
| | - Maximilian Whitfield
- Department of Chemistry, Ludwig Maximilian University Munich, 81377, Munich, Germany
| | - Daniel J Scott
- Institute of Inorganic Chemistry, University of Regensburg, 93040, Regensburg, Germany
- present address: Department of Chemistry, University of Bath, Claverton Down Bath, BA2 7AY, United Kingdom
| | - Roger Jan Kutta
- Institute of Physical and Theoretical Chemistry, University of Regensburg, 93040, Regensburg, Germany
| | - Patrick Nuernberger
- Institute of Physical and Theoretical Chemistry, University of Regensburg, 93040, Regensburg, Germany
| | | | - Robert Wolf
- Institute of Inorganic Chemistry, University of Regensburg, 93040, Regensburg, Germany
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7
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Grotjahn S, Graf C, Zelenka J, Pattanaik A, Müller L, Kutta RJ, Rehbein J, Roithová J, Gschwind RM, Nuernberger P, König B. Reactivity of Superbasic Carbanions Generated via Reductive Radical-Polar Crossover in the Context of Photoredox Catalysis. Angew Chem Int Ed Engl 2024; 63:e202400815. [PMID: 38408163 DOI: 10.1002/anie.202400815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Revised: 02/06/2024] [Accepted: 02/09/2024] [Indexed: 02/28/2024]
Abstract
Photocatalytic reactions involving a reductive radical-polar crossover (RRPCO) generate intermediates with carbanionic reactivity. Many of these proposed intermediates resemble highly reactive organometallic compounds. However, conditions of their formation are generally not tolerated by their isolated organometallic versions and often a different reactivity is observed. Our investigations on their nature and reactivity under commonly used photocatalytic conditions demonstrate that these intermediates are indeed best described as free, superbasic carbanions capable of deprotonating common polar solvents usually assumed to be inert such as acetonitrile, dimethylformamide, and dimethylsulfoxide. Their basicity not only towards solvents but also towards electrophiles, such as aldehydes, ketones, and esters, is comparable to the reactivity of isolated carbanions in the gas-phase. Previously unsuccessful transformations thought to result from a lack of reactivity are explained by their high reactivity towards the solvent and weakly acidic protons of reaction partners. An intuitive explanation for the mode of action of photocatalytically generated carbanions is provided, which enables methods to verify reaction mechanisms proposed to involve an RRPCO step and to identify the reasons for the limitations of current methods.
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Affiliation(s)
- Sascha Grotjahn
- Faculty of Chemistry and Pharmacy, Institute of Organic Chemistry, University of Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany
| | - Christina Graf
- Faculty of Chemistry and Pharmacy, Institute of Physical and Theoretical Chemistry, University of Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany
| | - Jan Zelenka
- Department of Spectroscopy and Catalysis, Radboud University Nijmegen, Heyendaalseweg 135, 6525AJ, Nijmegen, the Netherlands
| | - Aryaman Pattanaik
- Faculty of Chemistry and Pharmacy, Institute of Organic Chemistry, University of Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany
| | - Lea Müller
- Faculty of Chemistry and Pharmacy, Institute of Organic Chemistry, University of Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany
| | - Roger Jan Kutta
- Faculty of Chemistry and Pharmacy, Institute of Physical and Theoretical Chemistry, University of Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany
| | - Julia Rehbein
- Faculty of Chemistry and Pharmacy, Institute of Organic Chemistry, University of Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany
| | - Jana Roithová
- Department of Spectroscopy and Catalysis, Radboud University Nijmegen, Heyendaalseweg 135, 6525AJ, Nijmegen, the Netherlands
| | - Ruth M Gschwind
- Faculty of Chemistry and Pharmacy, Institute of Organic Chemistry, University of Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany
| | - Patrick Nuernberger
- Faculty of Chemistry and Pharmacy, Institute of Physical and Theoretical Chemistry, University of Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany
| | - Burkhard König
- Faculty of Chemistry and Pharmacy, Institute of Organic Chemistry, University of Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany
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8
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Archipowa N, Wittmann L, Köckenberger J, Ertl FJ, Gleixner J, Keller M, Heinrich MR, Kutta RJ. Characterization of Fluorescent Dyes Frequently Used for Bioimaging: Photophysics and Photocatalytical Reactions with Proteins. J Phys Chem B 2023; 127:9532-9542. [PMID: 37903729 DOI: 10.1021/acs.jpcb.3c04484] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2023]
Abstract
Derivatives of the rhodamine-based dye 5-TAMRA (5-carboxy-tetramethylrhodamine) and the indocarbocyanine-type Cy3B (cyclized derivative of the cyanine dye Cy3), both representing important fluorophores frequently used for the labeling of biomolecules (proteins, nucleic acids) and bioactive compounds, such as receptor ligands, were photophysically investigated in aqueous solution, i.e., in neat phosphate-buffered saline (PBS) and in PBS supplemented with 1 wt % bovine serum albumin (BSA). The dyes exhibit comparable absorption (λabs,max: 550-569 nm) and emission wavelengths (λem,max: 580-582 nm), and similar S1 lifetimes (2.27-2.75 ns), and their excited state deactivation proceeds mainly via the lowest excited singlet state (triplet quantum yield ca. 1%). However, the probes show marked differences with respect to their fluorescence quantum yield and photostability. While 5-TAMRA shows a lower quantum yield (37-39%) than the Cy3B derivative (ca. 57%), its photostability is considerably higher compared to Cy3B. Generally, the impact of the protein on the photophysics is low. However, on prolonged illumination, both fluorescent dyes undergo a photocatalytic reaction with tryptophan residues of BSA mediated by sensitized singlet oxygen resulting in a tryptophan photoproduct with an absorption maximum around 330 nm. The overall results of this work will assist in choosing the right dye for the labeling of bioactive compounds, and the study demonstrates that experiments performed with 5-TAMRA or Cy3B-labeled compounds in a biological environment may be influenced by photochemical modification of experimentally relevant proteins at aromatic amino acid residues.
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Affiliation(s)
- Nataliya Archipowa
- Institute of Biophysics and Physical Biochemistry, Faculty of Biology and Preclinical Medicine, University of Regensburg, D-93053 Regensburg, Germany
| | - Lukas Wittmann
- Institute of Physical and Theoretical Chemistry, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
| | - Johannes Köckenberger
- Department of Chemistry and Pharmacy, Molecular and Clinical Pharmacy, Friedrich-Alexander-University Erlangen-Nürnberg, Nikolaus-Fiebiger-Straße 10, D-91058 Erlangen, Germany
| | - Fabian J Ertl
- Institute of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
| | - Jakob Gleixner
- Institute of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
| | - Max Keller
- Institute of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
| | - Markus R Heinrich
- Department of Chemistry and Pharmacy, Molecular and Clinical Pharmacy, Friedrich-Alexander-University Erlangen-Nürnberg, Nikolaus-Fiebiger-Straße 10, D-91058 Erlangen, Germany
| | - Roger Jan Kutta
- Institute of Physical and Theoretical Chemistry, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
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9
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Knorr J, Sülzner N, Geissler B, Spies C, Grandjean A, Kutta RJ, Jung G, Nuernberger P. Ultrafast transient absorption and solvation of a super-photoacid in acetoneous environments. PHOTOCHEMICAL & PHOTOBIOLOGICAL SCIENCES : OFFICIAL JOURNAL OF THE EUROPEAN PHOTOCHEMISTRY ASSOCIATION AND THE EUROPEAN SOCIETY FOR PHOTOBIOLOGY 2022; 21:2179-2192. [PMID: 36178669 DOI: 10.1007/s43630-022-00287-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Accepted: 08/08/2022] [Indexed: 12/13/2022]
Abstract
The phenomenon of photoacidity, i.e., an increase in acidity by several orders of magnitude upon electronic excitation, is frequently encountered in aromatic alcohols capable of transferring a proton to a suitable acceptor. A promising new class of neutral super-photoacids based on pyranine derivatives has been shown to exhibit pronounced solvatochromic effects. To disclose the underlying mechanisms contributing to excited-state proton transfer (ESPT) and the temporal characteristics of solvation and ESPT, we scrutinize the associated ultrafast dynamics of the strongest photoacid of this class, namely tris(1,1,1,3,3,3-hexafluoropropan-2-yl)8-hydroxypyrene-1,3,6-trisulfonate, in acetoneous environment, thereby finding experimental evidence for ESPT even under these adverse conditions for proton transfer. Juxtaposing results from time-correlated single-photon counting and femtosecond transient absorption measurements combined with a complete decomposition of all signal components, i.e., absorption of ground and excited states as well as stimulated emission, we disclose dynamics of solvation, rotational diffusion, and radiative relaxation processes in acetone and identify the relevant steps of ESPT along with the associated time scales.
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Affiliation(s)
- Johannes Knorr
- Physikalische Chemie II, Ruhr-Universität Bochum, 44780, Bochum, Germany.,Erlangen Graduate School in Advanced Optical Technologies (SAOT), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Paul-Gordan-Straße 6, 91052, Erlangen, Germany
| | - Niklas Sülzner
- Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, 44780, Bochum, Germany.,Physikalische Chemie II, Ruhr-Universität Bochum, 44780, Bochum, Germany
| | - Bastian Geissler
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, Universitätsstraße 31, 95053, Regensburg, Germany.,Physikalische Chemie II, Ruhr-Universität Bochum, 44780, Bochum, Germany
| | - Christian Spies
- Biophysikalische Chemie, Universität des Saarlandes, 66123, Saarbrücken, Germany.,Physikalische Chemie II, Ruhr-Universität Bochum, 44780, Bochum, Germany
| | - Alexander Grandjean
- Biophysikalische Chemie, Universität des Saarlandes, 66123, Saarbrücken, Germany
| | - Roger Jan Kutta
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, Universitätsstraße 31, 95053, Regensburg, Germany
| | - Gregor Jung
- Biophysikalische Chemie, Universität des Saarlandes, 66123, Saarbrücken, Germany
| | - Patrick Nuernberger
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, Universitätsstraße 31, 95053, Regensburg, Germany. .,Physikalische Chemie II, Ruhr-Universität Bochum, 44780, Bochum, Germany.
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10
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Kyriacou CP, Rosato E. Genetic analysis of cryptochrome in insect magnetosensitivity. Front Physiol 2022; 13:928416. [PMID: 36035470 PMCID: PMC9399412 DOI: 10.3389/fphys.2022.928416] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Accepted: 07/05/2022] [Indexed: 11/18/2022] Open
Abstract
The earth's magnetic field plays an important role in the spectacular migrations and navigational abilities of many higher animals, particularly birds. However, these organisms are not amenable to genetic analysis, unlike the model fruitfly, Drosophila melanogaster, which can respond to magnetic fields under laboratory conditions. We therefore review the field of insect magnetosensitivity focusing on the role of the Cryptochromes (CRYs) that were first identified in Arabidopsis and Drosophila as key molecular components of circadian photo-entrainment pathways. Physico-chemical studies suggest that photo-activation of flavin adenine dinucleotide (FAD) bound to CRY generates a FADo- Trpo+ radical pair as electrons skip along a chain of specific Trp residues and that the quantum spin chemistry of these radicals is sensitive to magnetic fields. The manipulation of CRY in several insect species has been performed using gene editing, replacement/rescue and knockdown methods. The effects of these various mutations on magnetosensitivity have revealed a number of surprises that are discussed in the light of recent developments from both in vivo and in vitro studies.
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Affiliation(s)
- Charalambos P. Kyriacou
- Department of Genetics and Genome Biology, University of Leicester, Leicester, United Kingdom
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11
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Wong SY, Wei Y, Mouritsen H, Solov'yov IA, Hore PJ. Cryptochrome magnetoreception: four tryptophans could be better than three. J R Soc Interface 2021; 18:20210601. [PMID: 34753309 PMCID: PMC8580466 DOI: 10.1098/rsif.2021.0601] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 10/14/2021] [Indexed: 12/28/2022] Open
Abstract
The biophysical mechanism of the magnetic compass sensor in migratory songbirds is thought to involve photo-induced radical pairs formed in cryptochrome (Cry) flavoproteins located in photoreceptor cells in the eyes. In Cry4a-the most likely of the six known avian Crys to have a magnetic sensing function-four radical pair states are formed sequentially by the stepwise transfer of an electron along a chain of four tryptophan residues to the photo-excited flavin. In purified Cry4a from the migratory European robin, the third of these flavin-tryptophan radical pairs is more magnetically sensitive than the fourth, consistent with the smaller separation of the radicals in the former. Here, we explore the idea that these two radical pair states of Cry4a could exist in rapid dynamic equilibrium such that the key magnetic and kinetic properties are weighted averages. Spin dynamics simulations suggest that the third radical pair is largely responsible for magnetic sensing while the fourth may be better placed to initiate magnetic signalling particularly if the terminal tryptophan radical can be reduced by a nearby tyrosine. Such an arrangement could have allowed independent optimization of the essential sensing and signalling functions of the protein. It might also rationalize why avian Cry4a has four tryptophans while Crys from plants have only three.
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Affiliation(s)
- Siu Ying Wong
- Institut für Physik, Carl-von-Ossietzky Universität Oldenburg, Oldenburg 26111, Germany
| | - Yujing Wei
- Department of Chemistry, University of Oxford, Oxford OX1 3QZ, UK
| | - Henrik Mouritsen
- Institut für Biologie und Umweltwissenschaften, Carl-von-Ossietzky Universität Oldenburg, Oldenburg 26111, Germany
- Research Centre for Neurosensory Science, University of Oldenburg, Oldenburg 26111, Germany
| | - Ilia A. Solov'yov
- Institut für Physik, Carl-von-Ossietzky Universität Oldenburg, Oldenburg 26111, Germany
| | - P. J. Hore
- Department of Chemistry, University of Oxford, Oxford OX1 3QZ, UK
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12
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Wang Y, Zhang H, Zhang Z, Sun B, Tang C, Zhang L, Jiang Z, Ding B, Liao Y, Cai P. Simulated mobile communication frequencies (3.5 GHz) emitted by a signal generator affects the sleep of Drosophila melanogaster. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 283:117087. [PMID: 33894629 DOI: 10.1016/j.envpol.2021.117087] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 03/12/2021] [Accepted: 04/02/2021] [Indexed: 06/12/2023]
Abstract
With the rapid development of science and technology, 5G technology will be widely used, and biosafety concerns about the effects of 5G radiofrequency radiation on health have been raised. Drosophila melanogaster was selected as the model organism for our study, in which a 3.5 GHz radiofrequency radiation (RF-EMR) environment was simulated at intensities of 0.1 W/m2, 1 W/m2, and 10 W/m2. The activity of parent male and offspring (F1) male flies was measured using a Drosophila activity monitoring system under short-term and long-term 3.5 GHz RF-EMR exposure. Core genes associated with heat stress, the circadian clock and neurotransmitters were detected by QRT-PCR technology, and the contents of GABA and glutamate were detected by UPLC-MS. The results show that short-term RF-EMR exposure increased the activity level and reduced the sleep duration while long-term RF-EMR exposure reduced the activity level and increased the sleep duration of F1 male flies. Under long-term RF-EMR, the expression of heat stress response-related hsp22, hsp26 and hsp70 genes was increased, the expression of circadian clock-related per, cyc, clk, cry, and tim genes was altered, the content of GABA and glutamate was reduced, and the expression levels of synthesis, transport and receptor genes were altered. In conclusion, long-term RF-EMR exposure enhances the heat stress response of offspring flies and then affects the expression of circadian clock and neurotransmitter genes, which leads to decreased activity, prolonged sleep duration, and improved sleep quality.
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Affiliation(s)
- Yahong Wang
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China; University of the Chinese Academy of Sciences, Beijing, PR China; Xiamen Key Laboratory of Physical Environment, Xiamen, 361021, China
| | - Hongying Zhang
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China; University of the Chinese Academy of Sciences, Beijing, PR China; Xiamen Key Laboratory of Physical Environment, Xiamen, 361021, China
| | - Ziyan Zhang
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China; Xiamen Key Laboratory of Physical Environment, Xiamen, 361021, China; Shanghai Institute of Nutrition and Health, Chinese Academy of Sciences, Shanghai, 200031, China.
| | - Boqun Sun
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China; University of the Chinese Academy of Sciences, Beijing, PR China; Xiamen Key Laboratory of Physical Environment, Xiamen, 361021, China
| | - Chao Tang
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China; University of the Chinese Academy of Sciences, Beijing, PR China; Xiamen Key Laboratory of Physical Environment, Xiamen, 361021, China
| | - Lu Zhang
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China; University of the Chinese Academy of Sciences, Beijing, PR China; Xiamen Key Laboratory of Physical Environment, Xiamen, 361021, China
| | - Zhihao Jiang
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China; University of the Chinese Academy of Sciences, Beijing, PR China; Xiamen Key Laboratory of Physical Environment, Xiamen, 361021, China
| | - Bo Ding
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China; University of the Chinese Academy of Sciences, Beijing, PR China; Xiamen Key Laboratory of Physical Environment, Xiamen, 361021, China
| | - Yanyan Liao
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China; University of the Chinese Academy of Sciences, Beijing, PR China; Xiamen Key Laboratory of Physical Environment, Xiamen, 361021, China
| | - Peng Cai
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China; Xiamen Key Laboratory of Physical Environment, Xiamen, 361021, China; Shanghai Institute of Nutrition and Health, Chinese Academy of Sciences, Shanghai, 200031, China.
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13
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Lünemann DC, Thomas AR, Xu J, Bartölke R, Mouritsen H, De Sio A, Lienau C. Distinguishing between coherent and incoherent signals in excitation-emission spectroscopy. OPTICS EXPRESS 2021; 29:24326-24337. [PMID: 34614680 DOI: 10.1364/oe.428850] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 06/15/2021] [Indexed: 06/13/2023]
Abstract
The separation of incoherent emission signals from coherent light scattering often poses a challenge in (time-resolved) microscopy or excitation-emission spectroscopy. While in spectro-microscopy with narrowband excitation this is commonly overcome using spectral filtering, it is less straightforward when using broadband Fourier-transform techniques that are now becoming commonplace in, e.g., single molecule or ultrafast nonlinear spectroscopy. Here we show that such a separation is readily achieved using highly stable common-path interferometers for both excitation and detection. The approach is demonstrated for suppression of scattering from flavin adenine dinucleotide (FAD) and weakly emissive cryptochrome 4 (Cry4) protein samples. We expect that the approach will be beneficial, e.g., for fluorescence lifetime or Raman-based imaging and spectroscopy of various samples, including single quantum emitters.
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14
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Wu Y, Paul CE, Hollmann F. Stabilisation of the Fatty Acid Decarboxylase from Chlorella variabilis by Caprylic Acid. Chembiochem 2021; 22:2420-2423. [PMID: 34002919 PMCID: PMC8362199 DOI: 10.1002/cbic.202100182] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 05/17/2021] [Indexed: 11/25/2022]
Abstract
The fatty acid photodecarboxylase from Chlorella variabilis NC64 A (CvFAP) catalyses the light-dependent decarboxylation of fatty acids. Photoinactivation of CvFAP still represents one of the major limitations of this interesting enzyme en route to practical application. In this study we demonstrate that the photostability of CvFAP can easily be improved by the administration of medium-chain length carboxylic acids such as caprylic acid indicating that the best way of maintaining CvFAP stability is 'to keep the enzyme busy'.
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Affiliation(s)
- Yinqi Wu
- Department of BiotechnologyDelft University of TechnologyVan der Maasweg 92629HZDelftThe Netherlands
| | - Caroline E. Paul
- Department of BiotechnologyDelft University of TechnologyVan der Maasweg 92629HZDelftThe Netherlands
| | - Frank Hollmann
- Department of BiotechnologyDelft University of TechnologyVan der Maasweg 92629HZDelftThe Netherlands
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15
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Chandrasekaran S, Schneps CM, Dunleavy R, Lin C, DeOliveira CC, Ganguly A, Crane BR. Tuning flavin environment to detect and control light-induced conformational switching in Drosophila cryptochrome. Commun Biol 2021; 4:249. [PMID: 33637846 PMCID: PMC7910608 DOI: 10.1038/s42003-021-01766-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 01/22/2021] [Indexed: 12/12/2022] Open
Abstract
Light-induction of an anionic semiquinone (SQ) flavin radical in Drosophila cryptochrome (dCRY) alters the dCRY conformation to promote binding and degradation of the circadian clock protein Timeless (TIM). Specific peptide ligation with sortase A attaches a nitroxide spin-probe to the dCRY C-terminal tail (CTT) while avoiding deleterious side reactions. Pulse dipolar electron-spin resonance spectroscopy from the CTT nitroxide to the SQ shows that flavin photoreduction shifts the CTT ~1 nm and increases its motion, without causing full displacement from the protein. dCRY engineered to form the neutral SQ serves as a dark-state proxy to reveal that the CTT remains docked when the flavin ring is reduced but uncharged. Substitutions of flavin-proximal His378 promote CTT undocking in the dark or diminish undocking in the light, consistent with molecular dynamics simulations and TIM degradation activity. The His378 variants inform on recognition motifs for dCRY cellular turnover and strategies for developing optogenetic tools. Chandrasekaran et al. engineered the Drosophila circadian clock protein Cryptochrome (dCRY) to form the neutral semiquinone, which serves as a dark-state proxy. They find that the C-terminal tail of dCRY remains docked when the flavin ring is reduced but uncharged. dCRY His378 variants provide insights into the recognition motifs for dCRY turnover and strategies for optogenetic tools.
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Affiliation(s)
| | - Connor M Schneps
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, USA
| | - Robert Dunleavy
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, USA
| | - Changfan Lin
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, USA
| | | | - Abir Ganguly
- Institute for Quantitative Biomedicine, Rutgers University, Piscataway, NJ, USA
| | - Brian R Crane
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, USA.
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16
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Hartman T, Reisnerová M, Chudoba J, Svobodová E, Archipowa N, Kutta RJ, Cibulka R. Photocatalytic Oxidative [2+2] Cycloelimination Reactions with Flavinium Salts: Mechanistic Study and Influence of the Catalyst Structure. Chempluschem 2021; 86:373-386. [DOI: 10.1002/cplu.202000767] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 12/22/2020] [Indexed: 01/19/2023]
Affiliation(s)
- Tomáš Hartman
- Department of Organic Chemistry University of Chemistry and Technology, Prague Technická 5 166 28 Prague 6 Czech Republic
| | - Martina Reisnerová
- Department of Organic Chemistry University of Chemistry and Technology, Prague Technická 5 166 28 Prague 6 Czech Republic
| | - Josef Chudoba
- Central Laboratories University of Chemistry and Technology, Prague Technická 5 166 28 Prague 6 Czech Republic
| | - Eva Svobodová
- Department of Organic Chemistry University of Chemistry and Technology, Prague Technická 5 166 28 Prague 6 Czech Republic
| | - Nataliya Archipowa
- Manchester Institute of Biotechnology and School of Chemistry The University of Manchester Manchester M1 7DN United Kingdom
| | - Roger Jan Kutta
- Institute of Physical and Theoretical Chemistry University of Regensburg 93040 Regensburg Germany
| | - Radek Cibulka
- Department of Organic Chemistry University of Chemistry and Technology, Prague Technická 5 166 28 Prague 6 Czech Republic
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17
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Klocke JL, Kottke T. A quantum cascade laser setup for studying irreversible photoreactions in H 2O with nanosecond resolution and microlitre consumption. Phys Chem Chem Phys 2020; 22:26459-26467. [PMID: 33185227 DOI: 10.1039/d0cp03164j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Time-resolved infrared spectroscopy on irreversible reactions requires in general an exchange of sample for thousands of acquisitions leading to high sample consumption. Here, we present a setup employing a modern quantum cascade laser (QCL) as a probe light source to record time-resolved difference spectra of irreversible photoreactions in H2O. The combination of the focused QCL with a pressure-tolerant flow cell and a micrometre stage orthogonal to the flow allowed us to drastically reduce the sample consumption. We investigated the irreversible photoreduction of the cofactor flavin mononucleotide (FMN) in H2O, which is a common reaction taking place in biological photoreceptors. A broad time range from 20 nanoseconds to 1 second was accessible, because the approach minimized any signal drift by the flow. Kinetics were recorded at 46 selected wavenumbers consuming 12 microlitres for a complete dataset. The tuning range of 1490-1740 cm-1 included relevant carbonyl vibrations and the region of strong water absorption at around 1650 cm-1. A continuous dataset in the spectral dimension was generated by applying a fit with a sum of Lorentzians. Subsequent global analysis allowed us to resolve reference spectra and kinetics of the photoreaction proceeding from the triplet excited state via the intermediate flavin anion radical to the product, the fully reduced state of FMN. Accordingly, the neutral radical state is not populated in the disproportionation. The approach strongly facilitates the spectroscopic access to irreversible reactions of flavin-containing photoreceptors and photoenzymes with high time resolution and small sample consumption.
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Affiliation(s)
- Jessica L Klocke
- Physical and Biophysical Chemistry, Department of Chemistry, Bielefeld University, Universitätsstr. 25, 33615 Bielefeld, Germany.
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18
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Krassovka JM, Suschek CV, Prost M, Grotheer V, Schiefer JL, Demir E, Fuchs PC, Windolf J, Stürmer EK, Opländer C. The impact of non-toxic blue light (453 nm) on cellular antioxidative capacity, TGF-β1 signaling, and myofibrogenesis of human skin fibroblasts. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2020; 209:111952. [PMID: 32659647 DOI: 10.1016/j.jphotobiol.2020.111952] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 05/25/2020] [Accepted: 06/29/2020] [Indexed: 12/19/2022]
Abstract
Studies have demonstrated that blue light induces biological effects, such as cell death, and inhibition of proliferation and differentiation. Since blue light at longer wavelength (>440 nm) exerts less injurious effects on cells than at shorter wavelengths, (400-440 nm), we have investigated the impact of non-toxic (LED) blue light at 453 nm wavelength on human skin fibroblasts (hsFBs). We found that besides its decreasing effects on the proliferation rate, repeated blue light irradiations (80 J/cm2) also significantly reduced TGF-β1-induced myofibrogenesis as shown by diminished α-SMA and EDA-FN expression accompanied by reduced protein expression and phosphorylation of ERK 1/2, SMAD 2/3, and p38-key players of TGF-β1-induced myofibrogenesis. In parallel, catalase protein expression, intracellular FAD concentrations as well as NADP+/NADPH ratio were reduced, whereas intracellular reactive oxygen species (ROS) were increased. We postulate that as a molecular mechanism downregulation of catalase and photoreduction of FAD induce intracellular oxidative stress which, in turn, affects the signaling factors of myofibrogenesis leading to a lower rate of α-SMA and EDA-FN expression and, therefore, myofibroblast formation. In conclusion, blue light even at longer wavelengths shows antifibrotic activity and may represent a suitable and safe approach in the treatment of fibrotic skin diseases including hypertrophic scarring and scleroderma.
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Affiliation(s)
- Julia M Krassovka
- Department of Orthopedics and Trauma Surgery, Medical Faculty of the Heinrich-Heine-University, Düsseldorf, Germany
| | - Christoph V Suschek
- Department of Orthopedics and Trauma Surgery, Medical Faculty of the Heinrich-Heine-University, Düsseldorf, Germany
| | - Max Prost
- Department of Orthopedics and Trauma Surgery, Medical Faculty of the Heinrich-Heine-University, Düsseldorf, Germany
| | - Vera Grotheer
- Department of Orthopedics and Trauma Surgery, Medical Faculty of the Heinrich-Heine-University, Düsseldorf, Germany
| | - Jennifer L Schiefer
- Department of Plastic Surgery, Hand Surgery, Burn Center, Merheim Hospital Cologne, University of Witten/Herdecke, Köln, Germany
| | - Erhan Demir
- Department of Plastic Surgery, Hand Surgery, Burn Center, Merheim Hospital Cologne, University of Witten/Herdecke, Köln, Germany
| | - Paul C Fuchs
- Department of Plastic Surgery, Hand Surgery, Burn Center, Merheim Hospital Cologne, University of Witten/Herdecke, Köln, Germany
| | - Joachim Windolf
- Department of Orthopedics and Trauma Surgery, Medical Faculty of the Heinrich-Heine-University, Düsseldorf, Germany
| | - Ewa K Stürmer
- Department of Vascular Medicine, University Heart Center, Translational Wound Research, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; Department of Translational Wound Research, Centre for Biomedical Education and Research (ZBAF), University Witten/Herdecke, 58453 Witten, Germany
| | - Christian Opländer
- Department of Translational Wound Research, Centre for Biomedical Education and Research (ZBAF), University Witten/Herdecke, 58453 Witten, Germany.
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19
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Deazaflavin reductive photocatalysis involves excited semiquinone radicals. Nat Commun 2020; 11:3174. [PMID: 32576821 PMCID: PMC7311442 DOI: 10.1038/s41467-020-16909-y] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Accepted: 06/02/2020] [Indexed: 11/30/2022] Open
Abstract
Flavin-mediated photocatalytic oxidations are established in synthetic chemistry. In contrast, their use in reductive chemistry is rare. Deazaflavins with a much lower reduction potential are even better suited for reductive chemistry rendering also deazaflavin semiquinones as strong reductants. However, no direct evidence exists for the involvement of these radical species in reductive processes. Here, we synthesise deazaflavins with different substituents at C5 and demonstrate their photocatalytic activity in the dehalogenation of p-halogenanisoles with best performance under basic conditions. Mechanistic investigations reveal a consecutive photo-induced electron transfer via the semiquinone form of the deazaflavin as part of a triplet-correlated radical pair after electron transfer from a sacrificial electron donor to the triplet state. A second electron transfer from the excited semiquinone to p-halogenanisoles triggers the final product formation. This study provides first evidence that the reductive power of excited deazaflavin semiquinones can be used in photocatalytic reductive chemistry. Flavins and deazaflavins are well suited for photoredox processes but their application in photoreductions is challenging. Here, the authors provide direct evidence of the high reductive power of excited deazaflavin semiquinones and their application in catalytic photodehalogenations.
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20
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Lakavath B, Hedison TM, Heyes DJ, Shanmugam M, Sakuma M, Hoeven R, Tilakaratna V, Scrutton NS. Radical-based photoinactivation of fatty acid photodecarboxylases. Anal Biochem 2020; 600:113749. [PMID: 32348726 DOI: 10.1016/j.ab.2020.113749] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 04/16/2020] [Accepted: 04/17/2020] [Indexed: 11/25/2022]
Abstract
Fatty acid photodecarboxylases (FAP) are a recently discovered family of FAD-containing, light-activated enzymes, which convert fatty acids to n-alkanes/alkenes with potential applications in the manufacture of fine and speciality chemicals and fuels. Poor catalytic stability of FAPs is however a major limitation. Here, we describe a methodology to purify catalytically stable and homogeneous samples of recombinant Chlorella variabilis NC64A FAP (CvFAP) from Escherichia coli. We demonstrate however that blue light-exposure, which is required for photodecarboxylase activity, also leads to irreversible inactivation of the enzyme, especially in the absence of palmitate substrate. Photoinactivation is attributed to formation of protein based organic radicals, which were observed by EPR spectroscopy. To suppress photoinactivation, we prepared stable and catalytically active FAP in the dark. The steady-state kinetic parameters of CvFAP (kcat: 0.31 ± 0.06 s-1 and KM: 98.8 ± 53.3 μM) for conversion of palmitic acid to pentadecane were determined using gas chromatography. Methods described here should now enable studies of the catalytic mechanism and exploitation of FAPs in biotechnology.
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Affiliation(s)
- Balaji Lakavath
- The Manchester Institute of Biotechnology and Department of Chemistry, The University of Manchester, Manchester, M1 7DN, United Kingdom
| | - Tobias M Hedison
- The Manchester Institute of Biotechnology and Department of Chemistry, The University of Manchester, Manchester, M1 7DN, United Kingdom; EPSRC/BBSRC Future Biomanufacturing Research Hub, Manchester Institute of Biotechnology, The University of Manchester, Manchester, M1 7DN, United Kingdom
| | - Derren J Heyes
- The Manchester Institute of Biotechnology and Department of Chemistry, The University of Manchester, Manchester, M1 7DN, United Kingdom
| | - Muralidharan Shanmugam
- The Manchester Institute of Biotechnology and Department of Chemistry, The University of Manchester, Manchester, M1 7DN, United Kingdom
| | - Michiyo Sakuma
- The Manchester Institute of Biotechnology and Department of Chemistry, The University of Manchester, Manchester, M1 7DN, United Kingdom
| | - Robin Hoeven
- The Manchester Institute of Biotechnology and Department of Chemistry, The University of Manchester, Manchester, M1 7DN, United Kingdom
| | - Viranga Tilakaratna
- EPSRC/BBSRC Future Biomanufacturing Research Hub, Manchester Institute of Biotechnology, The University of Manchester, Manchester, M1 7DN, United Kingdom
| | - Nigel S Scrutton
- The Manchester Institute of Biotechnology and Department of Chemistry, The University of Manchester, Manchester, M1 7DN, United Kingdom; EPSRC/BBSRC Future Biomanufacturing Research Hub, Manchester Institute of Biotechnology, The University of Manchester, Manchester, M1 7DN, United Kingdom.
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21
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22
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Damulewicz M, Mazzotta GM. One Actor, Multiple Roles: The Performances of Cryptochrome in Drosophila. Front Physiol 2020; 11:99. [PMID: 32194430 PMCID: PMC7066326 DOI: 10.3389/fphys.2020.00099] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 01/27/2020] [Indexed: 01/19/2023] Open
Abstract
Cryptochromes (CRYs) are flavoproteins that are sensitive to blue light, first identified in Arabidopsis and then in Drosophila and mice. They are evolutionarily conserved and play fundamental roles in the circadian clock of living organisms, enabling them to adapt to the daily 24-h cycles. The role of CRYs in circadian clocks differs among different species: in plants, they have a blue light-sensing activity whereas in mammals they act as light-independent transcriptional repressors within the circadian clock. These two different functions are accomplished by two principal types of CRYs, the light-sensitive plant/insect type 1 CRY and the mammalian type 2 CRY acting as a negative autoregulator in the molecular circadian clockwork. Drosophila melanogaster possesses just one CRY, belonging to type 1 CRYs. Nevertheless, this single CRY appears to have different functions, specific to different organs, tissues, and even subset of cells in which it is expressed. In this review, we will dissect the multiple roles of this single CRY in Drosophila, focusing on the regulatory mechanisms that make its pleiotropy possible.
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Affiliation(s)
- Milena Damulewicz
- Department of Cell Biology and Imaging, Jagiellonian University, Kraków, Poland
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23
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Oldemeyer S, Haddad AZ, Fleming GR. Interconnection of the Antenna Pigment 8-HDF and Flavin Facilitates Red-Light Reception in a Bifunctional Animal-like Cryptochrome. Biochemistry 2019; 59:594-604. [PMID: 31846308 DOI: 10.1021/acs.biochem.9b00875] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Cryptochromes are ubiquitous flavin-binding light sensors closely related to DNA-repairing photolyases. The animal-like cryptochrome CraCRY from the green alga Chlamydomonas reinhardtii challenges the paradigm of cryptochromes as pure blue-light receptors by acting as a (6-4) photolyase, using 8-hydroxy-5-deazaflavin (8-HDF) as a light-harvesting antenna with a 17.4 Å distance to flavin and showing spectral sensitivity up to 680 nm. The expanded action spectrum is attributed to the presence of the flavin neutral radical (FADH•) in the dark, despite a rapid FADH• decay observed in vitro in samples exclusively carrying flavin. Herein, the red-light response of CraCRY carrying flavin and 8-HDF was studied, revealing a 3-fold prolongation of the FADH• lifetime in the presence of 8-HDF. Millisecond time-resolved ultraviolet-visible spectroscopy showed the red-light-induced formation and decay of an absorbance band at 458 nm concomitant with flavin reduction. Time-resolved Fourier transform infrared (FTIR) spectroscopy and density functional theory attributed these changes to the deprotonation of 8-HDF, challenging the paradigm of 8-HDF being permanently deprotonated in photolyases. FTIR spectra showed changes in the hydrogen bonding network of asparagine 395, a residue suggested to indirectly control flavin protonation, indicating the involvement of N395 in the stabilization of FADH•. Fluorescence spectroscopy revealed a decrease in the energy transfer efficiency of 8-HDF upon flavin reduction, possibly linked to 8-HDF deprotonation. The discovery of the interdependence of flavin and 8-HDF beyond energy transfer processes highlights the essential role of the antenna, introducing a new concept enabling CraCRY and possibly other bifunctional cryptochromes to fulfill their dual function.
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Affiliation(s)
- Sabine Oldemeyer
- Department of Chemistry , University of California , Berkeley , California 94720 , United States.,Molecular Biophysics and Integrated Bioimaging Division , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Andrew Z Haddad
- Energy Technologies Area , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Graham R Fleming
- Department of Chemistry , University of California , Berkeley , California 94720 , United States.,Molecular Biophysics and Integrated Bioimaging Division , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States.,Kavli Energy Nanoscience Institute , Berkeley , California 94720 , United States
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