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Wörner S, Rauthe P, Werner J, Afonin S, Ulrich AS, Unterreiner AN, Wagenknecht HA. Flavin-induced charge separation in transmembrane model peptides. Org Biomol Chem 2024. [PMID: 38973494 DOI: 10.1039/d4ob00932k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/09/2024]
Abstract
Hydrophobic peptide models derived from the α-helical transmembrane segment of the epidermal growth factor receptor were synthetically modified with a flavin amino acid as a photo-inducible charge donor and decorated with tryptophans along the helix as charge acceptors. The helical conformation of the peptides was conserved despite the modifications, notably also in lipid vesicles and multibilayers. Their ability to facilitate photo-induced transmembrane charge transport was examined by means of steady-state and time-resolved optical spectroscopy. The first tryptophan next to the flavin donor plays a major role in initiating the charge transport near the N-terminus, while the other tryptophans might promote charge transport along the transmembrane helix. These artificially modified, but still naturally derived helical peptides are important models for studying transmembrane electron transfer and the principles of photosynthesis.
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Affiliation(s)
- Samantha Wörner
- Karlsruhe Institute of Technology (KIT), Institute of Organic Chemistry, Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany.
| | - Pascal Rauthe
- Institute of Physical Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 2, 76131 Karlsruhe, Germany
| | - Johannes Werner
- Institute of Physical Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 2, 76131 Karlsruhe, Germany
| | - Sergii Afonin
- Karlsruhe Institute of Technology (KIT), Institute of Biological Interfaces (IBG2), POB 3640, 76021 Karlsruhe, Germany
| | - Anne S Ulrich
- Karlsruhe Institute of Technology (KIT), Institute of Organic Chemistry, Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany.
- Karlsruhe Institute of Technology (KIT), Institute of Biological Interfaces (IBG2), POB 3640, 76021 Karlsruhe, Germany
| | - Andreas-Neil Unterreiner
- Institute of Physical Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 2, 76131 Karlsruhe, Germany
| | - Hans-Achim Wagenknecht
- Karlsruhe Institute of Technology (KIT), Institute of Organic Chemistry, Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany.
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2
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Uzhytchak M, Smolková B, Frtús A, Stupakov A, Lunova M, Scollo F, Hof M, Jurkiewicz P, Sullivan GJ, Dejneka A, Lunov O. Sensitivity of endogenous autofluorescence in HeLa cells to the application of external magnetic fields. Sci Rep 2023; 13:10818. [PMID: 37402779 DOI: 10.1038/s41598-023-38015-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Accepted: 06/30/2023] [Indexed: 07/06/2023] Open
Abstract
Dramatically increased levels of electromagnetic radiation in the environment have raised concerns over the potential health hazards of electromagnetic fields. Various biological effects of magnetic fields have been proposed. Despite decades of intensive research, the molecular mechanisms procuring cellular responses remain largely unknown. The current literature is conflicting with regards to evidence that magnetic fields affect functionality directly at the cellular level. Therefore, a search for potential direct cellular effects of magnetic fields represents a cornerstone that may propose an explanation for potential health hazards associated with magnetic fields. It has been proposed that autofluorescence of HeLa cells is magnetic field sensitive, relying on single-cell imaging kinetic measurements. Here, we investigate the magnetic field sensitivity of an endogenous autofluorescence in HeLa cells. Under the experimental conditions used, magnetic field sensitivity of an endogenous autofluorescence was not observed in HeLa cells. We present a number of arguments indicating why this is the case in the analysis of magnetic field effects based on the imaging of cellular autofluorescence decay. Our work indicates that new methods are required to elucidate the effects of magnetic fields at the cellular level.
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Affiliation(s)
- Mariia Uzhytchak
- Department of Optical and Biophysical Systems, Institute of Physics of the Czech Academy of Sciences, Prague, 18221, Czech Republic
| | - Barbora Smolková
- Department of Optical and Biophysical Systems, Institute of Physics of the Czech Academy of Sciences, Prague, 18221, Czech Republic
| | - Adam Frtús
- Department of Optical and Biophysical Systems, Institute of Physics of the Czech Academy of Sciences, Prague, 18221, Czech Republic
| | - Alexandr Stupakov
- Department of Optical and Biophysical Systems, Institute of Physics of the Czech Academy of Sciences, Prague, 18221, Czech Republic
| | - Mariia Lunova
- Department of Optical and Biophysical Systems, Institute of Physics of the Czech Academy of Sciences, Prague, 18221, Czech Republic
- Institute for Clinical and Experimental Medicine (IKEM), Prague, 14021, Czech Republic
| | - Federica Scollo
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Prague, 18223, Czech Republic
| | - Martin Hof
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Prague, 18223, Czech Republic
| | - Piotr Jurkiewicz
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Prague, 18223, Czech Republic
| | - Gareth John Sullivan
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
- Department of Pediatric Research, Oslo University Hospital, Oslo, Norway
- Department of Immunology, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Alexandr Dejneka
- Department of Optical and Biophysical Systems, Institute of Physics of the Czech Academy of Sciences, Prague, 18221, Czech Republic
| | - Oleg Lunov
- Department of Optical and Biophysical Systems, Institute of Physics of the Czech Academy of Sciences, Prague, 18221, Czech Republic.
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3
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Zhuang B, Liebl U, Vos MH. Flavoprotein Photochemistry: Fundamental Processes and Photocatalytic Perspectives. J Phys Chem B 2022; 126:3199-3207. [PMID: 35442696 DOI: 10.1021/acs.jpcb.2c00969] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Flavins are highly versatile redox-active and colored cofactors in a large variety of proteins. These do include photoenzymes and photoreceptors, although the vast majority performs non-light-driven physiological functions. Nevertheless, electron transfer between flavins and specific nearby amino acid residues (in particular tyrosine, tryptophan, and presumably histidine and arginine) takes place upon excitation of flavin in many flavoproteins. For oxidized flavoproteins these reactions potentially have a photoprotective role. In this Perspective, we outline work on the characterization of early reaction intermediates not only in the relatively well-studied resting oxidized forms but also in the fully reduced and the intrinsically unstable semireduced forms, where ultrafast photooxidation of flavin was recently demonstrated. Along different lines, flavoprotein-based novel photocatalysts for biotechnological applications are presently emerging, employing both substrate photooxidation and photoreduction strategies. Deep insight into the fundamental flavin photochemical reactions may help in guiding and optimizing their development and in the exploration of novel photocatalytic approaches.
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Affiliation(s)
- Bo Zhuang
- LOB, CNRS, INSERM, Ecole Polytechnique, Institut Polytechnique de Paris, 91128 Palaiseau Cedex, France
| | - Ursula Liebl
- LOB, CNRS, INSERM, Ecole Polytechnique, Institut Polytechnique de Paris, 91128 Palaiseau Cedex, France
| | - Marten H Vos
- LOB, CNRS, INSERM, Ecole Polytechnique, Institut Polytechnique de Paris, 91128 Palaiseau Cedex, France
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4
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Zhang Z, Pan B, Wang L, Sun G. Photoactivities of Two Vitamin B Derivatives and Their Applications in the Perpetration of Photoinduced Antibacterial Nanofibrous Membranes. ACS APPLIED BIO MATERIALS 2021; 4:8584-8596. [DOI: 10.1021/acsabm.1c01042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Zheng Zhang
- Department of Biological and Agricultural Engineering, University of California, Davis, California 95616, United States
| | - Bofeng Pan
- Department of Biological and Agricultural Engineering, University of California, Davis, California 95616, United States
| | - Luxin Wang
- Department of Food Science and Technology, University of California, Davis, California 95616, United States
| | - Gang Sun
- Department of Biological and Agricultural Engineering, University of California, Davis, California 95616, United States
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5
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Gurruchaga-Pereda J, Martínez-Martínez V, Formoso E, Azpitarte O, Rezabal E, Lopez X, Cortajarena AL, Salassa L. Enhancing the Photocatalytic Conversion of Pt(IV) Substrates by Flavoprotein Engineering. J Phys Chem Lett 2021; 12:4504-4508. [PMID: 33960797 DOI: 10.1021/acs.jpclett.1c00802] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Our recent work demonstrates that certain flavoproteins can catalyze the redox activation of Pt(IV) prodrug complexes under light irradiation. Herein, we used site-directed mutagenesis on the mini singlet oxygen generator (mSOG) to modulate the photocatalytic activity of this flavoprotein toward two model Pt(IV) substrates. Among the prepared mutants, Q103V mSOG displayed enhanced catalytic efficiency as a result of its longer triplet excited-state lifetime. This study shows, for the first time, that protein engineering can improve the catalytic capacity of a protein toward metal-containing substrates.
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Affiliation(s)
- Juan Gurruchaga-Pereda
- Donostia International Physics Center, Paseo Manuel de Lardizabal 4, Donostia 20018, Spain
- Center for Cooperative Research in Biomaterials (CIC biomaGUNE), Basque Research and Technology Alliance (BRTA), Paseo de Miramón 194, Donostia, San Sebastián 20014, Spain
| | | | - Elena Formoso
- Donostia International Physics Center, Paseo Manuel de Lardizabal 4, Donostia 20018, Spain
- Kimika Fisikoa, Farmazia Fakultatea, Euskal Herriko Unibertsitatea UPV/EHU, Paseo de la Universidad 7, Vitoria-Gasteiz 01006, Spain
| | - Oksana Azpitarte
- Donostia International Physics Center, Paseo Manuel de Lardizabal 4, Donostia 20018, Spain
- Polimero eta Material Aurreratuak: Fisika, Kimika eta Teknologia, Kimika Fakultatea, Euskal Herriko Unibertsitatea UPV/EHU, Paseo Manuel de Lardizabal 3, Donostia 20018, Spain
| | - Elixabete Rezabal
- Donostia International Physics Center, Paseo Manuel de Lardizabal 4, Donostia 20018, Spain
- Polimero eta Material Aurreratuak: Fisika, Kimika eta Teknologia, Kimika Fakultatea, Euskal Herriko Unibertsitatea UPV/EHU, Paseo Manuel de Lardizabal 3, Donostia 20018, Spain
| | - Xabier Lopez
- Donostia International Physics Center, Paseo Manuel de Lardizabal 4, Donostia 20018, Spain
- Polimero eta Material Aurreratuak: Fisika, Kimika eta Teknologia, Kimika Fakultatea, Euskal Herriko Unibertsitatea UPV/EHU, Paseo Manuel de Lardizabal 3, Donostia 20018, Spain
| | - Aitziber L Cortajarena
- Center for Cooperative Research in Biomaterials (CIC biomaGUNE), Basque Research and Technology Alliance (BRTA), Paseo de Miramón 194, Donostia, San Sebastián 20014, Spain
- Ikerbasque, Basque Foundation for Science, Bilbao 48011, Spain
| | - Luca Salassa
- Donostia International Physics Center, Paseo Manuel de Lardizabal 4, Donostia 20018, Spain
- Polimero eta Material Aurreratuak: Fisika, Kimika eta Teknologia, Kimika Fakultatea, Euskal Herriko Unibertsitatea UPV/EHU, Paseo Manuel de Lardizabal 3, Donostia 20018, Spain
- Ikerbasque, Basque Foundation for Science, Bilbao 48011, Spain
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6
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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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7
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Zhuang B, Seo D, Aleksandrov A, Vos MH. Characterization of Light-Induced, Short-Lived Interacting Radicals in the Active Site of Flavoprotein Ferredoxin-NADP + Oxidoreductase. J Am Chem Soc 2021; 143:2757-2768. [PMID: 33591179 DOI: 10.1021/jacs.0c09627] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Radicals of flavin adenine dinucleotide (FAD), as well as tyrosine and tryptophan, are widely involved as key reactive intermediates during electron-transfer (ET) reactions in flavoproteins. Due to the high reactivity of these species and their corresponding short lifetime, characterization of these intermediates in functional processes of flavoproteins is usually challenging but can be achieved by ultrafast spectroscopic studies of light-activatable flavoproteins. In ferredoxin-NADP+ oxidoreductase from Bacillus subtilis (BsFNR), fluorescence of the FAD cofactor that very closely interacts with a neighboring tyrosine residue (Tyr50) is strongly quenched. Here we study short-lived photoproducts of this enzyme and its variants, with Tyr50 replaced by tryptophan or glycine. Using time-resolved fluorescence and absorption spectroscopies, we show that, upon the excitation of WT BsFNR, ultrafast ET from Tyr50 to the excited FAD cofactor occurs in ∼260 fs, an order of magnitude faster than the decay by charge recombination, facilitating the characterization of the reaction intermediates in the charge-separated state with respect to other recently studied systems. These studies are corroborated by experiments on the Y50W mutant protein, which yield photoproducts qualitatively similar to those observed in other tryptophan-bearing flavoproteins. By combining the experimental results with molecular dynamics simulations and quantum mechanics calculations, we investigate in detail the effects of protein environment and relaxations on the spectral properties of those radical intermediates and demonstrate that the spectral features of radical anionic FAD are highly sensitive to its environment, and in particular to the dynamics and nature of the counterions formed in the photoproducts. Altogether, comprehensive characterizations are provided for important radical intermediates that are generally involved in functional processes of flavoproteins.
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Affiliation(s)
- Bo Zhuang
- LOB, CNRS, INSERM, École Polytechnique, Institut Polytechnique de Paris, 91128 Palaiseau, France
| | - Daisuke Seo
- Division of Material Science, Graduate School of Natural Science and Technology, Kanazawa University, 920-1192 Kanazawa, Ishikawa, Japan
| | - Alexey Aleksandrov
- LOB, CNRS, INSERM, École Polytechnique, Institut Polytechnique de Paris, 91128 Palaiseau, France
| | - Marten H Vos
- LOB, CNRS, INSERM, École Polytechnique, Institut Polytechnique de Paris, 91128 Palaiseau, France
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8
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Wörner S, Leier J, Michenfelder NC, Unterreiner A, Wagenknecht H. Directed Electron Transfer in Flavin Peptides with Oligoproline-Type Helical Conformation as Models for Flavin-Functional Proteins. ChemistryOpen 2020; 9:1264-1269. [PMID: 33318882 PMCID: PMC7729625 DOI: 10.1002/open.202000199] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 10/23/2020] [Indexed: 11/26/2022] Open
Abstract
To mimic the charge separation in functional proteins we studied flavin-modified peptides as models. They were synthesized as oligoprolines that typically form a polyproline type-II helix, because this secondary structure supports the electron transfer properties. We placed the flavin as photoexcitable chromophore and electron acceptor at the N-terminus. Tryptophans were placed as electron donors to direct the electron transfer over 0-3 intervening prolines. Spectroscopic studies revealed competitive photophysical pathways. The reference peptide without tryptophan shows dominant non-specific ET dynamics, leading to an ion pair formation, whereas peptides with tryptophans have weak non-specific ET and intensified directed electron transfer. By different excitation wavelengths, we can conclude that the corresponding ion pair state of flavin within the peptide environment has to be energetically located between the S1 and S4 states, whereas the directed electron transfer to tryptophan occurs directly from the S1 state. These photochemical results have fundamental significance for proteins with flavin as redoxactive cofactor.
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Affiliation(s)
- Samantha Wörner
- Institute of Organic ChemistryKarlsruhe Institute of Technology (KIT)Fritz-Haber-Weg 676131KarlsruheGermany
| | - Julia Leier
- Institute of Physical ChemistryKarlsruhe Institute of Technology (KIT)Fritz-Haber-Weg 276131KarlsruheGermany
| | - Nadine C. Michenfelder
- Institute of Physical ChemistryKarlsruhe Institute of Technology (KIT)Fritz-Haber-Weg 276131KarlsruheGermany
| | - Andreas‐Neil Unterreiner
- Institute of Physical ChemistryKarlsruhe Institute of Technology (KIT)Fritz-Haber-Weg 276131KarlsruheGermany
| | - Hans‐Achim Wagenknecht
- Institute of Organic ChemistryKarlsruhe Institute of Technology (KIT)Fritz-Haber-Weg 676131KarlsruheGermany
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