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Wang WL, Min Y, Yu SS, Chen W, Chen JJ, Liu XY, Yu HQ. Probing electron transfer between hemin and riboflavin using a combination of analytical approaches and theoretical calculations. Phys Chem Chem Phys 2017; 19:32580-32588. [DOI: 10.1039/c7cp06492f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Proton-coupled electron transfer mechanisms of riboflavin bound hemin in aqueous solution are elucidated by spectroelectrochemical analysis, the electron paramagnetic resonance method and theoretical calculations.
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Affiliation(s)
- Wen-Lan Wang
- CAS Key Laboratory of Urban Pollutant Conversion
- Department of Chemistry
- University of Science & Technology of China
- Hefei
- China
| | - Yuan Min
- CAS Key Laboratory of Urban Pollutant Conversion
- Department of Chemistry
- University of Science & Technology of China
- Hefei
- China
| | - Sheng-Song Yu
- CAS Key Laboratory of Urban Pollutant Conversion
- Department of Chemistry
- University of Science & Technology of China
- Hefei
- China
| | - Wei Chen
- CAS Key Laboratory of Urban Pollutant Conversion
- Department of Chemistry
- University of Science & Technology of China
- Hefei
- China
| | - Jie-Jie Chen
- CAS Key Laboratory of Urban Pollutant Conversion
- Department of Chemistry
- University of Science & Technology of China
- Hefei
- China
| | - Xiao-Yang Liu
- CAS Key Laboratory of Urban Pollutant Conversion
- Department of Chemistry
- University of Science & Technology of China
- Hefei
- China
| | - Han-Qing Yu
- CAS Key Laboratory of Urban Pollutant Conversion
- Department of Chemistry
- University of Science & Technology of China
- Hefei
- China
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2
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Xu J, Eriksson SE, Cebula M, Sandalova T, Hedström E, Pader I, Cheng Q, Myers CR, Antholine WE, Nagy P, Hellman U, Selivanova G, Lindqvist Y, Arnér ESJ. The conserved Trp114 residue of thioredoxin reductase 1 has a redox sensor-like function triggering oligomerization and crosslinking upon oxidative stress related to cell death. Cell Death Dis 2015; 6:e1616. [PMID: 25611390 PMCID: PMC4669772 DOI: 10.1038/cddis.2014.574] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Revised: 11/19/2014] [Accepted: 12/03/2014] [Indexed: 12/19/2022]
Abstract
The selenoprotein thioredoxin reductase 1 (TrxR1) has several key roles in cellular redox systems and reductive pathways. Here we discovered that an evolutionarily conserved and surface-exposed tryptophan residue of the enzyme (Trp114) is excessively reactive to oxidation and exerts regulatory functions. The results indicate that it serves as an electron relay communicating with the FAD moiety of the enzyme, and, when oxidized, it facilitates oligomerization of TrxR1 into tetramers and higher multimers of dimers. A covalent link can also be formed between two oxidized Trp114 residues of two subunits from two separate TrxR1 dimers, as found both in cell extracts and in a crystal structure of tetrameric TrxR1. Formation of covalently linked TrxR1 subunits became exaggerated in cells on treatment with the pro-oxidant p53-reactivating anticancer compound RITA, in direct correlation with triggering of a cell death that could be prevented by antioxidant treatment. These results collectively suggest that Trp114 of TrxR1 serves a function reminiscent of an irreversible sensor for excessive oxidation, thereby presenting a previously unrecognized level of regulation of TrxR1 function in relation to cellular redox state and cell death induction.
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Affiliation(s)
- J Xu
- Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-17177 Stockholm, Sweden
| | - S E Eriksson
- Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-17177 Stockholm, Sweden
| | - M Cebula
- Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-17177 Stockholm, Sweden
| | - T Sandalova
- Division of Molecular Structural Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-17177 Stockholm, Sweden
| | - E Hedström
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, SE-17177 Stockholm, Sweden
| | - I Pader
- Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-17177 Stockholm, Sweden
| | - Q Cheng
- Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-17177 Stockholm, Sweden
| | - C R Myers
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
| | - W E Antholine
- Department of Biophysics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
| | - P Nagy
- Department of Molecular Immunology and Toxicology, National Institute of Oncology, Rath György ut 7-91, 1122, Budapest, Hungary
| | - U Hellman
- Ludwig Institutet for Cancer Research Ltd., Uppsala University BMC, SE-75 124 Uppsala, Sweden
| | - G Selivanova
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, SE-17177 Stockholm, Sweden
| | - Y Lindqvist
- Division of Molecular Structural Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-17177 Stockholm, Sweden
| | - E S J Arnér
- Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-17177 Stockholm, Sweden
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3
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Xu L, Zhu G. The Roles of Several Residues of Escherichia coli DNA Photolyase in the Highly Efficient Photo-Repair of Cyclobutane Pyrimidine Dimers. J Nucleic Acids 2010; 2010. [PMID: 20871655 PMCID: PMC2939405 DOI: 10.4061/2010/794782] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2010] [Revised: 07/07/2010] [Accepted: 08/07/2010] [Indexed: 11/20/2022] Open
Abstract
Escherichia coli DNA photolyase is an enzyme that repairs the major kind of UV-induced lesions, cyclobutane pyrimidine dimer (CPD) in DNA utilizing 350-450 nm light as energy source. The enzyme has very high photo-repair efficiency (the quantum yield of the reaction is ~0.85), which is significantly greater than many model compounds that mimic photolyase. This suggests that some residues of the protein play important roles in the photo-repair of CPD. In this paper, we have focused on several residues discussed their roles in catalysis by reviewing the existing literature and some hypotheses.
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Affiliation(s)
- Lei Xu
- Institute of Molecular Biology and Biotechnology, Anhui Normal University, Wuhu 241000, China
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4
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Weber S, Bittl R. Studies of Organic Protein Cofactors Using Electron Paramagnetic Resonance. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2007. [DOI: 10.1246/bcsj.80.2270] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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5
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Song QH, Tang WJ, Ji XB, Wang HB, Guo QX. Do photolyases need to provide considerable activation energy for the splitting of cyclobutane pyrimidine dimer radical anions? Chemistry 2007; 13:7762-70. [PMID: 17568458 DOI: 10.1002/chem.200700251] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
cis-syn Cyclobutane pyrimidine dimers, major UV-induced DNA lesions, are efficiently repaired by DNA photolyases. The key step of the repair reaction is a light-driven electron transfer from the FADH(-) cofactor to the dimer; the resulting radical anion splits spontaneously. Whether the splitting reaction requires considerable activation energy is still under dispute. Recent reports show that the splitting reaction of a dimer radical anion has a significant activation barrier (0.45 eV), and so photolyases have to provide considerable energy. However, these results contradict observations that cis-syn dimer radical anions split into monomers at -196 degrees C, and that the full process of DNA photoreactivation was fast (1.5-2 ns). To investigate the activation energies of dimer radical anions, three model compounds 1-3 were prepared. These include a covalently linked cyclobutane thymine dimer and a tryptophan residue (1) or a flavin unit (3), and the covalently linked uracil dimer and tryptophan (2). Their properties of photosensitised splitting of the dimer units by tryptophan or flavin unit were investigated over a large temperature range, -196 to 70 degrees C. The activation energies were obtained from the temperature dependency of splitting reactions for 1 and 2, 1.9 kJ mol(-1) and 0.9 kJ mol(-1) for the thymine and uracil dimer radical anions, respectively. These values are much lower than that obtained for E. coli photolyase (0.45 eV), and are surmountable at -196 degrees C. The activation energies provide support for previous observations that repair efficiencies for uracil dimers are higher than thymine dimers, both in enzymatic and model systems. The mechanisms of highly efficient enzymatic DNA repair are discussed.
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Affiliation(s)
- Qin-Hua Song
- Department of Chemistry, University of Science and Technology of China, Hefei 230026, Anhui, P. R. China.
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6
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Weber S. Light-driven enzymatic catalysis of DNA repair: a review of recent biophysical studies on photolyase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2005; 1707:1-23. [PMID: 15721603 DOI: 10.1016/j.bbabio.2004.02.010] [Citation(s) in RCA: 254] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2003] [Accepted: 02/02/2004] [Indexed: 11/19/2022]
Abstract
More than 50 years ago, initial experiments on enzymatic photorepair of ultraviolet (UV)-damaged DNA were reported [Proc. Natl. Acad. Sci. U. S. A. 35 (1949) 73]. Soon after this discovery, it was recognized that one enzyme, photolyase, is able to repair UV-induced DNA lesions by effectively reversing their formation using blue light. The enzymatic process named DNA photoreactivation depends on a non-covalently bound cofactor, flavin adenine dinucleotide (FAD). Flavins are ubiquitous redox-active catalysts in one- and two-electron transfer reactions of numerous biological processes. However, in the case of photolyase, not only the ground-state redox properties of the FAD cofactor are exploited but also, and perhaps more importantly, its excited-state properties. In the catalytically active, fully reduced redox form, the FAD absorbs in the blue and near-UV ranges of visible light. Although there is no direct experimental evidence, it appears generally accepted that starting from the excited singlet state, the chromophore initiates a reductive cleavage of the two major DNA photodamages, cyclobutane pyrimidine dimers and (6-4) photoproducts, by short-distance electron transfer to the DNA lesion. Back electron transfer from the repaired DNA segment is believed to eventually restore the initial redox states of the cofactor and the DNA nucleobases, resulting in an overall reaction with net-zero exchanged electrons. Thus, the entire process represents a true catalytic cycle. Many biochemical and biophysical studies have been carried out to unravel the fundamentals of this unique mode of action. The work has culminated in the elucidation of the three-dimensional structure of the enzyme in 1995 that revealed remarkable details, such as the FAD-cofactor arrangement in an unusual U-shaped configuration. With the crystal structure of the enzyme at hand, research on photolyases did not come to an end but, for good reason, intensified: the geometrical structure of the enzyme alone is not sufficient to fully understand the enzyme's action on UV-damaged DNA. Much effort has therefore been invested to learn more about, for example, the geometry of the enzyme-substrate complex, and the mechanism and pathways of intra-enzyme and enzyme <-->DNA electron transfer. Many of the key results from biochemical and molecular biology characterizations of the enzyme or the enzyme-substrate complex have been summarized in a number of reviews. Complementary to these articles, this review focuses on recent biophysical studies of photoreactivation comprising work performed from the early 1990s until the present.
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Affiliation(s)
- Stefan Weber
- Institute of Experimental Physics, Free University Berlin, Arnimallee 14, 14195 Berlin, Germany.
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Bittl R, Weber S. Transient radical pairs studied by time-resolved EPR. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2005; 1707:117-26. [PMID: 15721610 DOI: 10.1016/j.bbabio.2004.03.012] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2003] [Accepted: 03/05/2004] [Indexed: 12/20/2022]
Abstract
Photogenerated short-lived radical pairs (RP) are common in biological photoprocesses such as photosynthesis and enzymatic DNA repair. They can be favorably probed by time-resolved electron paramagnetic resonance (EPR) methods with adequate time resolution. Two EPR techniques have proven to be particularly useful to extract information on the working states of photoinduced biological processes that is only difficult or sometimes even impossible to obtain by other types of spectroscopy. Firstly, transient EPR yields crucial information on the chemical nature and the geometry of the individual RP halves in a doublet-spin pair generated by a short laser pulse. This time-resolved method is applicable in all magnetic field/microwave frequency regimes that are used for continuous-wave EPR, and is nowadays routinely utilized with a time resolution reaching about 10 ns. Secondly, a pulsed EPR method named out-of-phase electron spin echo envelope modulation (OOP-ESEEM) is increasingly becoming popular. By this pulsed technique, the mutual spin-spin interaction between the RP halves in a doublet-spin pair manifests itself as an echo modulation detected as a function of the microwave-pulse spacing of a two-pulse echo sequence subsequent to a laser pulse. From the dipolar coupling, the distance between the radicals is readily derived. Since the spin-spin interaction parameters are typically not observable by transient EPR, the two techniques complement each other favorably. Both EPR methods have recently been applied to a variety of light-induced RPs in photobiology. This review summarizes the results obtained from such studies in the fields of plant and bacterial photosynthesis and DNA repair mediated by the enzyme DNA photolyase.
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Affiliation(s)
- Robert Bittl
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
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8
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Heyerick A, Huvaere K, De Keukeleire D, Forbes MDE. Fate of flavins in sensitized photodegradation of isohumulones and reduced derivatives: studies on formation of radicals via EPR combined with detailed product analyses. Photochem Photobiol Sci 2005; 4:412-9. [PMID: 15875074 DOI: 10.1039/b500285k] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Photodegradation of isohumulones accounts for formation of the lightstruck flavor in beer. The reactions involved are mediated by riboflavin, a natural photosensitizer present in beer in ppb quantities. The results of an investigation of this sensitized degradation process are presented herein. Product analyses and electron paramagnetic resonance spectroscopy, in steady-state as well as in time-resolved mode, offer extensive insight into the photophysical and photochemical details of the degradation mechanism. In contrast to energy transfer and Norrish type I alpha-cleavage reactions that take place on direct irradiation of isohumulones, the sensitization pathway proceeds via one-electron redox chemistry involving the excited triplet state of riboflavin and derivatives. The flavin semiquinone radical thus formed could be readily detected, either by steady state or by time-resolved electron paramagnetic resonance spectroscopy. Superimposed signals in the spectra revealed the presence of radical fragments derived from isohumulones or tetrahydroisohumulones, which, on recombination with riboflavin semiquinone radicals, produced stable reaction products that were identified by HPLC-MS. However, no superimposed signals were observed on sensitized irradiation of dihydroisohumulones.
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Affiliation(s)
- Arne Heyerick
- Laboratory of Pharmacognosy and Phytochemistry, Ghent University, Faculty of Pharmaceutical Sciences, Harelbekestraat 72, B-9000, Ghent, Belgium.
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9
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Fuchs MR, Schleicher E, Schnegg A, Kay CWM, Törring JT, Bittl R, Bacher A, Richter G, Möbius K, Weber S. g-Tensor of the Neutral Flavin Radical Cofactor of DNA Photolyase Revealed by 360-GHz Electron Paramagnetic Resonance Spectroscopy. J Phys Chem B 2002. [DOI: 10.1021/jp0259869] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Martin R. Fuchs
- Institute of Experimental Physics, Free University Berlin, 14195 Berlin, Germany, and Institute of Organic Chemistry and Biochemistry, Technical University Munich, 85747 Garching, Germany
| | - Erik Schleicher
- Institute of Experimental Physics, Free University Berlin, 14195 Berlin, Germany, and Institute of Organic Chemistry and Biochemistry, Technical University Munich, 85747 Garching, Germany
| | - Alexander Schnegg
- Institute of Experimental Physics, Free University Berlin, 14195 Berlin, Germany, and Institute of Organic Chemistry and Biochemistry, Technical University Munich, 85747 Garching, Germany
| | - Christopher W. M. Kay
- Institute of Experimental Physics, Free University Berlin, 14195 Berlin, Germany, and Institute of Organic Chemistry and Biochemistry, Technical University Munich, 85747 Garching, Germany
| | - Jens T. Törring
- Institute of Experimental Physics, Free University Berlin, 14195 Berlin, Germany, and Institute of Organic Chemistry and Biochemistry, Technical University Munich, 85747 Garching, Germany
| | - Robert Bittl
- Institute of Experimental Physics, Free University Berlin, 14195 Berlin, Germany, and Institute of Organic Chemistry and Biochemistry, Technical University Munich, 85747 Garching, Germany
| | - Adelbert Bacher
- Institute of Experimental Physics, Free University Berlin, 14195 Berlin, Germany, and Institute of Organic Chemistry and Biochemistry, Technical University Munich, 85747 Garching, Germany
| | - Gerald Richter
- Institute of Experimental Physics, Free University Berlin, 14195 Berlin, Germany, and Institute of Organic Chemistry and Biochemistry, Technical University Munich, 85747 Garching, Germany
| | - Klaus Möbius
- Institute of Experimental Physics, Free University Berlin, 14195 Berlin, Germany, and Institute of Organic Chemistry and Biochemistry, Technical University Munich, 85747 Garching, Germany
| | - Stefan Weber
- Institute of Experimental Physics, Free University Berlin, 14195 Berlin, Germany, and Institute of Organic Chemistry and Biochemistry, Technical University Munich, 85747 Garching, Germany
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10
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Weber S, Kay CWM, Mögling H, Möbius K, Hitomi K, Todo T. Photoactivation of the flavin cofactor in Xenopus laevis (6 - 4) photolyase: observation of a transient tyrosyl radical by time-resolved electron paramagnetic resonance. Proc Natl Acad Sci U S A 2002; 99:1319-22. [PMID: 11805294 PMCID: PMC122188 DOI: 10.1073/pnas.032469399] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The light-induced electron transfer reaction of flavin cofactor photoactivation in Xenopus laevis (6-4) photolyase has been studied by continuous-wave and time-resolved electron paramagnetic resonance spectroscopy. When the photoactivation is initiated from the fully oxidized form of the flavin, a neutral flavin radical is observed as a long-lived paramagnetic intermediate of two consecutive single-electron reductions under participation of redox-active amino acid residues. By time-resolved electron paramagnetic resonance, a spin-polarized transient radical-pair signal was detected that shows remarkable differences to the signals observed in the related cyclobutane pyrimidine dimer photolyase enzyme. In (6-4) photolyase, a neutral tyrosine radical has been identified as the final electron donor, on the basis of the characteristic line width, hyperfine splitting pattern, and resonance magnetic field position of the tyrosine resonances of the transient radical pair.
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Affiliation(s)
- Stefan Weber
- Free University Berlin, Institute of Experimental Physics, Arnimallee 14, 14195 Berlin, Germany.
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11
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Abstract
Flavins and flavoproteins are versatile redox cofactors that can perform both one- and two-electron transfer. Because they are highly colored in all three oxidation states, optical spectroscopy has been exploited for decades to study these redox changes. This review summarizes the application of optical spectroscopies to flavins and flavoproteins since 1990. Special emphasis is placed on new techniques, such as Stark spectroscopy, as well as significant refinements in more well known techniques, such as resonance Raman spectroscopy and ultrafast spectroscopy.
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Affiliation(s)
- R J Stanley
- Department of Chemistry, Temple University, Philadelphia, PA 19122, USA.
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12
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Weber S, Richter G, Schleicher E, Bacher A, Möbius K, Kay CW. Substrate binding to DNA photolyase studied by electron paramagnetic resonance spectroscopy. Biophys J 2001; 81:1195-204. [PMID: 11463661 PMCID: PMC1301589 DOI: 10.1016/s0006-3495(01)75777-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Structural changes in Escherichia coli DNA photolyase induced by binding of a (cis,syn)-cyclobutane pyrimidine dimer (CPD) are studied by continuous-wave electron paramagnetic resonance and electron-nuclear double resonance spectroscopies, using the flavin adenine dinucleotide (FAD) cofactor in its neutral radical form as a naturally occurring electron spin probe. The electron paramagnetic resonance/electron-nuclear double resonance spectral changes are consistent with a large distance (> or =0.6 nm) between the CPD lesion and the 7,8-dimethyl isoalloxazine ring of FAD, as was predicted by recent model calculations on photolyase enzyme-substrate complexes. Small shifts of the isotropic proton hyperfine coupling constants within the FAD's isoalloxazine moiety can be understood in terms of the cofactor binding site becoming more nonpolar because of the displacement of water molecules upon CPD docking to the enzyme. Molecular orbital calculations of hyperfine couplings using density functional theory, in conjunction with an isodensity polarized continuum model, are presented to rationalize these shifts in terms of the changed polarity of the medium surrounding the FAD cofactor.
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Affiliation(s)
- S Weber
- Institute of Experimental Physics, Free University Berlin, 14195 Berlin, Germany.
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13
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Gindt YM, Vollenbroek E, Westphal K, Sackett H, Sancar A, Babcock GT. Origin of the transient electron paramagnetic resonance signals in DNA photolyase. Biochemistry 1999; 38:3857-66. [PMID: 10194296 DOI: 10.1021/bi981191+] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
DNA photolyase repairs pyrimidine dimer lesions in DNA through light-induced electron donation to the dimer. During isolation of the enzyme, the flavin cofactor necessary for catalytic activity becomes one-electron-oxidized to a semiquinone radical. In the absence of external reducing agents, the flavin can be cycled through the semiquinone radical to the fully reduced state with light-induced electron transfer from a nearby tryptophan residue. This cycle provides a convenient means of studying the process of electron transfer within the protein by using transient EPR. By studying the excitation wavelength dependence of the time-resolved EPR signals we observe, we show that the spin-polarized EPR signal reported earlier from this laboratory as being initiated by semiquinone photochemistry actually originates from the fully oxidized form of the flavin cofactor. Exciting the semiquinone form of the flavin produces two transient EPR signals: a fast signal that is limited by the time response of the instrument and a slower signal with a lifetime of approximately 6 ms. The fast component appears to correlate with a dismutation reaction occurring with the flavin. The longer lifetime process occurs on a time scale that agrees with transient absorption data published earlier; the magnetic field dependence of the amplitude of this kinetic component is consistent with redox chemistry that involves electron transfer between flavin and tryptophan. We also report a new procedure for the rapid isolation of DNA photolyase.
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Affiliation(s)
- Y M Gindt
- Department of Chemistry, Michigan State University, East Lansing 48824, USA
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14
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15
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Langenbacher T, Zhao X, Bieser G, Heelis PF, Sancar A, Michel-Beyerle ME. Substrate and Temperature Dependence of DNA Photolyase Repair Activity Examined with Ultrafast Spectroscopy. J Am Chem Soc 1997. [DOI: 10.1021/ja9721024] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Thomas Langenbacher
- Contribution from the Institute of Physical Chemistry, Technical University Munich, Lichtenbergstrasse 4, D-85748 Garching, Germany, North East Wales Institute, Mold Rd, Wrexham, LL11 2AW, UK, and Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599-7260
| | - Xiaodong Zhao
- Contribution from the Institute of Physical Chemistry, Technical University Munich, Lichtenbergstrasse 4, D-85748 Garching, Germany, North East Wales Institute, Mold Rd, Wrexham, LL11 2AW, UK, and Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599-7260
| | - Gero Bieser
- Contribution from the Institute of Physical Chemistry, Technical University Munich, Lichtenbergstrasse 4, D-85748 Garching, Germany, North East Wales Institute, Mold Rd, Wrexham, LL11 2AW, UK, and Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599-7260
| | - Paul F. Heelis
- Contribution from the Institute of Physical Chemistry, Technical University Munich, Lichtenbergstrasse 4, D-85748 Garching, Germany, North East Wales Institute, Mold Rd, Wrexham, LL11 2AW, UK, and Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599-7260
| | - Aziz Sancar
- Contribution from the Institute of Physical Chemistry, Technical University Munich, Lichtenbergstrasse 4, D-85748 Garching, Germany, North East Wales Institute, Mold Rd, Wrexham, LL11 2AW, UK, and Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599-7260
| | - Maria Elisabeth Michel-Beyerle
- Contribution from the Institute of Physical Chemistry, Technical University Munich, Lichtenbergstrasse 4, D-85748 Garching, Germany, North East Wales Institute, Mold Rd, Wrexham, LL11 2AW, UK, and Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599-7260
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16
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Lipman RS, Bailey SW, Jarrett JT, Matthews RG, Jorns MS. Stereospecificity of folate binding to DNA photolyase from Escherichia coli. Biochemistry 1995; 34:11217-20. [PMID: 7669779 DOI: 10.1021/bi00035a030] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
DNA photolyase from Escherichia coli contains folate ([6S]-5,10-CH(+)-H4Pte(Glu)n = 3-6) and reduced FAD. The folate chromophore acts as an antenna, harvesting light energy which is transferred to the reduced flavin where DNA repair occurs. The folate binding stereospecificity of the enzyme was investigated by reconstituting the apoenzyme with [6R,S]-5,10-CH(+)-H4folate and reduced FAD. The isomer composition of [methyl-3H]-5-CH3-H4folate, released into solution upon reduction of the reconstituted enzyme with [3H]NaBH4, was analyzed by enzymatic and chiral chromatographic methods. Both methods showed that the reconstituted enzyme contained nearly equimolar amounts of [6R]- and [6S]-5,10-CH(+)-H4folate.
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Affiliation(s)
- R S Lipman
- Department of Biological Chemistry, Hahnemann University School of Medicine, Philadelphia, Pennsylvania 19102, USA
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