1
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Denisov IG, Grinkova YV, Sligar SG. Optical annealing of peroxo-ferric intermediates in CYP17A1 and product formation. J Inorg Biochem 2024; 260:112701. [PMID: 39173495 DOI: 10.1016/j.jinorgbio.2024.112701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Revised: 08/13/2024] [Accepted: 08/14/2024] [Indexed: 08/24/2024]
Abstract
Human cytochrome P450 CYP17A1 catalyzes the hydroxylation of pregnenolone and progesterone at the C17 position, with subsequent C17-C20 bond scission, to form dehydroepiandrosterone and androstenedione respectively. The first hydroxylation reaction is faster in H2O than in D2O, while the second carbon‑carbon bond scission event demonstrates an inverse solvent isotope effect, which is more pronounced for 17-hydroxy pregnenolone. In order to better understand the cause of this difference, we compared the optical absorption spectra of oxygenated CYP17A1 with the four substrates (pregnenolone, progesterone, 17-hydroxy pregnenolone and 17-hydroxy progesterone) in both H2O and D2O. We also studied the temperature-dependent decay of the peroxo-ferric and hydroperoxo-ferric intermediates generated by cryoradiolysis of the corresponding oxygenated heme proteins at 77 K. For both pregnenolone and 17-hydroxypregnenolone, annealing of the peroxo-intermediates was observed at lower temperatures in H2O than in D2O. In contrast, no solvent isotope effect was detected when progesterone or 17-hydroxyprogesterone were used as substrates. These differences are attributed to their different positioning in the P450 active site with respect to the heme bound peroxo (Fe-OO-) moiety, which is in agreement with earlier structural and spectroscopic investigations. Analysis of the samples run in both H2O and in D2O, where 17-hydroxyprogesterone is the substrate, demonstrated significant (∼25%) yield of androstenedione product relative to the oxygenated starting material.
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Affiliation(s)
- Ilia G Denisov
- Departments of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Yelena V Grinkova
- Departments of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Stephen G Sligar
- Departments of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
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2
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Bolton R, Machelett MM, Stubbs J, Axford D, Caramello N, Catapano L, Malý M, Rodrigues MJ, Cordery C, Tizzard GJ, MacMillan F, Engilberge S, von Stetten D, Tosha T, Sugimoto H, Worrall JAR, Webb JS, Zubkov M, Coles S, Mathieu E, Steiner RA, Murshudov G, Schrader TE, Orville AM, Royant A, Evans G, Hough MA, Owen RL, Tews I. A redox switch allows binding of Fe(II) and Fe(III) ions in the cyanobacterial iron-binding protein FutA from Prochlorococcus. Proc Natl Acad Sci U S A 2024; 121:e2308478121. [PMID: 38489389 PMCID: PMC10962944 DOI: 10.1073/pnas.2308478121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Accepted: 02/16/2024] [Indexed: 03/17/2024] Open
Abstract
The marine cyanobacterium Prochlorococcus is a main contributor to global photosynthesis, whilst being limited by iron availability. Cyanobacterial genomes generally encode two different types of FutA iron-binding proteins: periplasmic FutA2 ABC transporter subunits bind Fe(III), while cytosolic FutA1 binds Fe(II). Owing to their small size and their economized genome Prochlorococcus ecotypes typically possess a single futA gene. How the encoded FutA protein might bind different Fe oxidation states was previously unknown. Here, we use structural biology techniques at room temperature to probe the dynamic behavior of FutA. Neutron diffraction confirmed four negatively charged tyrosinates, that together with a neutral water molecule coordinate iron in trigonal bipyramidal geometry. Positioning of the positively charged Arg103 side chain in the second coordination shell yields an overall charge-neutral Fe(III) binding state in structures determined by neutron diffraction and serial femtosecond crystallography. Conventional rotation X-ray crystallography using a home source revealed X-ray-induced photoreduction of the iron center with observation of the Fe(II) binding state; here, an additional positioning of the Arg203 side chain in the second coordination shell maintained an overall charge neutral Fe(II) binding site. Dose series using serial synchrotron crystallography and an XFEL X-ray pump-probe approach capture the transition between Fe(III) and Fe(II) states, revealing how Arg203 operates as a switch to accommodate the different iron oxidation states. This switching ability of the Prochlorococcus FutA protein may reflect ecological adaptation by genome streamlining and loss of specialized FutA proteins.
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Affiliation(s)
- Rachel Bolton
- Biological Sciences, Institute for Life Sciences, University of Southampton, SouthamptonSO17 1BJ, United Kingdom
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OxfordshireOX11 0DE, United Kingdom
| | - Moritz M. Machelett
- Biological Sciences, Institute for Life Sciences, University of Southampton, SouthamptonSO17 1BJ, United Kingdom
- National Oceanography Centre, SouthamptonSO14 3ZH, United Kingdom
| | - Jack Stubbs
- Biological Sciences, Institute for Life Sciences, University of Southampton, SouthamptonSO17 1BJ, United Kingdom
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OxfordshireOX11 0DE, United Kingdom
| | - Danny Axford
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OxfordshireOX11 0DE, United Kingdom
| | - Nicolas Caramello
- European Synchrotron Radiation Facility, Grenoble Cedex 938043, France
- Hamburg Centre for Ultrafast Imaging, Hamburg Advanced Research Centre for Bioorganic Chemistry, Universität Hamburg, Hamburg22761, Germany
| | - Lucrezia Catapano
- Randall Centre of Cell and Molecular Biophysics, King’s College London, New Hunt’s House, LondonSE1 1UL, United Kingdom
- Medical Research Council Laboratory of Molecular Biology, CambridgeCB2 0QH, United Kingdom
| | - Martin Malý
- Biological Sciences, Institute for Life Sciences, University of Southampton, SouthamptonSO17 1BJ, United Kingdom
| | - Matthew J. Rodrigues
- Biological Sciences, Institute for Life Sciences, University of Southampton, SouthamptonSO17 1BJ, United Kingdom
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OxfordshireOX11 0DE, United Kingdom
- Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen5232, Switzerland
| | - Charlotte Cordery
- Biological Sciences, Institute for Life Sciences, University of Southampton, SouthamptonSO17 1BJ, United Kingdom
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OxfordshireOX11 0DE, United Kingdom
| | - Graham J. Tizzard
- School of Chemistry, University of Southampton, SouthamptonSO17 1BJ, United Kingdom
| | - Fraser MacMillan
- School of Chemistry, University of East Anglia, NorwichNR4 7TJ, United Kingdom
| | - Sylvain Engilberge
- European Synchrotron Radiation Facility, Grenoble Cedex 938043, France
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, Grenoble Cedex 938044, France
| | - David von Stetten
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg22607, Germany
| | - Takehiko Tosha
- Synchrotron Radiation Life Science Instrumentation Team, RIKEN SPring-8 Center, Sayo, Hyogo679-5148, Japan
| | - Hiroshi Sugimoto
- Synchrotron Radiation Life Science Instrumentation Team, RIKEN SPring-8 Center, Sayo, Hyogo679-5148, Japan
| | | | - Jeremy S. Webb
- Biological Sciences, Institute for Life Sciences, University of Southampton, SouthamptonSO17 1BJ, United Kingdom
- National Biofilms Innovation Centre (NBIC), University of Southampton, Southampton, SO17 3DF, UK
| | - Mike Zubkov
- National Oceanography Centre, SouthamptonSO14 3ZH, United Kingdom
- Scottish Association for Marine Science, Oban, ScotlandPA37 1QA, United Kingdom
| | - Simon Coles
- School of Chemistry, University of Southampton, SouthamptonSO17 1BJ, United Kingdom
| | - Eric Mathieu
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, Grenoble Cedex 938044, France
| | - Roberto A. Steiner
- Randall Centre of Cell and Molecular Biophysics, King’s College London, New Hunt’s House, LondonSE1 1UL, United Kingdom
- Department of Biomedical Sciences, University of Padova, Padova35131, Italy
| | - Garib Murshudov
- Medical Research Council Laboratory of Molecular Biology, CambridgeCB2 0QH, United Kingdom
| | - Tobias E. Schrader
- Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science, Garching85748, Germany
| | - Allen M. Orville
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OxfordshireOX11 0DE, United Kingdom
- Research Complex at Harwell, Harwell Science and Innovation Campus, DidcotOX11 0FA, United KingdomRosalind Franklin Institute, Harwell Science and Innovation Campus, Didcot, OxfordshireOX11 0QX, United Kingdom
| | - Antoine Royant
- European Synchrotron Radiation Facility, Grenoble Cedex 938043, France
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, Grenoble Cedex 938044, France
| | - Gwyndaf Evans
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OxfordshireOX11 0DE, United Kingdom
- Rosalind Franklin Institute, Harwell Science and Innovation Campus, Didcot, OxfordshireOX11 0QX, United Kingdom
| | - Michael A. Hough
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OxfordshireOX11 0DE, United Kingdom
- School of Life Sciences, University of Essex, ColchesterCO4 3SQ, United Kingdom
- Research Complex at Harwell, Harwell Science and Innovation Campus, DidcotOX11 0FA, United KingdomRosalind Franklin Institute, Harwell Science and Innovation Campus, Didcot, OxfordshireOX11 0QX, United Kingdom
| | - Robin L. Owen
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OxfordshireOX11 0DE, United Kingdom
| | - Ivo Tews
- Biological Sciences, Institute for Life Sciences, University of Southampton, SouthamptonSO17 1BJ, United Kingdom
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3
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Ishigami I, Russi S, Cohen A, Yeh SR, Rousseau DL. Temperature-dependent structural transition following X-ray-induced metal center reduction in oxidized cytochrome c oxidase. J Biol Chem 2022; 298:101799. [PMID: 35257742 PMCID: PMC8971940 DOI: 10.1016/j.jbc.2022.101799] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 02/28/2022] [Accepted: 03/01/2022] [Indexed: 11/30/2022] Open
Abstract
Cytochrome c oxidase (CcO) is the terminal enzyme in the electron transfer chain in the inner membrane of mitochondria. It contains four metal redox centers, two of which, CuB and heme a3, form the binuclear center (BNC), where dioxygen is reduced to water. Crystal structures of CcO in various forms have been reported, from which ligand-binding states of the BNC and conformations of the protein matrix surrounding it have been deduced to elucidate the mechanism by which the oxygen reduction chemistry is coupled to proton translocation. However, metal centers in proteins can be susceptible to X-ray-induced radiation damage, raising questions about the reliability of conclusions drawn from these studies. Here, we used microspectroscopy-coupled X-ray crystallography to interrogate how the structural integrity of bovine CcO in the fully oxidized state (O) is modulated by synchrotron radiation. Spectroscopic data showed that, upon X-ray exposure, O was converted to a hybrid O∗ state where all the four metal centers were reduced, but the protein matrix was trapped in the genuine O conformation and the ligands in the BNC remained intact. Annealing the O∗ crystal above the glass transition temperature induced relaxation of the O∗ structure to a new R∗ structure, wherein the protein matrix converted to the fully reduced R conformation with the exception of helix X, which partly remained in the O conformation because of incomplete dissociation of the ligands from the BNC. We conclude from these data that reevaluation of reported CcO structures obtained with synchrotron light sources is merited.
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Affiliation(s)
- Izumi Ishigami
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Silvia Russi
- Structural Molecular Biology, Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, California, USA
| | - Aina Cohen
- Structural Molecular Biology, Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, California, USA
| | - Syun-Ru Yeh
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York, USA.
| | - Denis L Rousseau
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York, USA.
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4
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Pfanzagl V, Beale JH, Michlits H, Schmidt D, Gabler T, Obinger C, Djinović-Carugo K, Hofbauer S. X-ray-induced photoreduction of heme metal centers rapidly induces active-site perturbations in a protein-independent manner. J Biol Chem 2020; 295:13488-13501. [PMID: 32723869 DOI: 10.1074/jbc.ra120.014087] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 07/24/2020] [Indexed: 12/31/2022] Open
Abstract
Since the advent of protein crystallography, atomic-level macromolecular structures have provided a basis to understand biological function. Enzymologists use detailed structural insights on ligand coordination, interatomic distances, and positioning of catalytic amino acids to rationalize the underlying electronic reaction mechanisms. Often the proteins in question catalyze redox reactions using metal cofactors that are explicitly intertwined with their function. In these cases, the exact nature of the coordination sphere and the oxidation state of the metal is of utmost importance. Unfortunately, the redox-active nature of metal cofactors makes them especially susceptible to photoreduction, meaning that information obtained by photoreducing X-ray sources about the environment of the cofactor is the least trustworthy part of the structure. In this work we directly compare the kinetics of photoreduction of six different heme protein crystal species by X-ray radiation. We show that a dose of ∼40 kilograys already yields 50% ferrous iron in a heme protein crystal. We also demonstrate that the kinetics of photoreduction are completely independent from variables unique to the different samples tested. The photoreduction-induced structural rearrangements around the metal cofactors have to be considered when biochemical data of ferric proteins are rationalized by constraints derived from crystal structures of reduced enzymes.
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Affiliation(s)
- Vera Pfanzagl
- Department of Chemistry, Institute of Biochemistry, BOKU-University of Natural Resources and Life Sciences, Vienna, Austria.
| | | | - Hanna Michlits
- Department of Chemistry, Institute of Biochemistry, BOKU-University of Natural Resources and Life Sciences, Vienna, Austria
| | - Daniel Schmidt
- Department of Chemistry, Institute of Biochemistry, BOKU-University of Natural Resources and Life Sciences, Vienna, Austria
| | - Thomas Gabler
- Department of Chemistry, Institute of Biochemistry, BOKU-University of Natural Resources and Life Sciences, Vienna, Austria
| | - Christian Obinger
- Department of Chemistry, Institute of Biochemistry, BOKU-University of Natural Resources and Life Sciences, Vienna, Austria
| | - Kristina Djinović-Carugo
- Department of Structural and Computational Biology, Max Perutz Labs, University of Vienna, Vienna, Austria; Department of Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana, Slovenia
| | - Stefan Hofbauer
- Department of Chemistry, Institute of Biochemistry, BOKU-University of Natural Resources and Life Sciences, Vienna, Austria.
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5
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Sauter NK, Kern J, Yano J, Holton JM. Towards the spatial resolution of metalloprotein charge states by detailed modeling of XFEL crystallographic diffraction. Acta Crystallogr D Struct Biol 2020; 76:176-192. [PMID: 32038048 PMCID: PMC7008510 DOI: 10.1107/s2059798320000418] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 01/14/2020] [Indexed: 12/25/2022] Open
Abstract
Oxidation states of individual metal atoms within a metalloprotein can be assigned by examining X-ray absorption edges, which shift to higher energy for progressively more positive valence numbers. Indeed, X-ray crystallography is well suited for such a measurement, owing to its ability to spatially resolve the scattering contributions of individual metal atoms that have distinct electronic environments contributing to protein function. However, as the magnitude of the shift is quite small, about +2 eV per valence state for iron, it has only been possible to measure the effect when performed with monochromated X-ray sources at synchrotron facilities with energy resolutions in the range 2-3 × 10-4 (ΔE/E). This paper tests whether X-ray free-electron laser (XFEL) pulses, which have a broader bandpass (ΔE/E = 3 × 10-3) when used without a monochromator, might also be useful for such studies. The program nanoBragg is used to simulate serial femtosecond crystallography (SFX) diffraction images with sufficient granularity to model the XFEL spectrum, the crystal mosaicity and the wavelength-dependent anomalous scattering factors contributed by two differently charged iron centers in the 110-amino-acid protein, ferredoxin. Bayesian methods are then used to deduce, from the simulated data, the most likely X-ray absorption curves for each metal atom in the protein, which agree well with the curves chosen for the simulation. The data analysis relies critically on the ability to measure the incident spectrum for each pulse, and also on the nanoBragg simulator to predict the size, shape and intensity profile of Bragg spots based on an underlying physical model that includes the absorption curves, which are then modified to produce the best agreement with the simulated data. This inference methodology potentially enables the use of SFX diffraction for the study of metalloenzyme mechanisms and, in general, offers a more detailed approach to Bragg spot data reduction.
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Affiliation(s)
- Nicholas K. Sauter
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Jan Kern
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Junko Yano
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - James M. Holton
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- SSRL, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA
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6
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Ebrahim A, Moreno-Chicano T, Appleby MV, Chaplin AK, Beale JH, Sherrell DA, Duyvesteyn HME, Owada S, Tono K, Sugimoto H, Strange RW, Worrall JAR, Axford D, Owen RL, Hough MA. Dose-resolved serial synchrotron and XFEL structures of radiation-sensitive metalloproteins. IUCRJ 2019; 6:543-551. [PMID: 31316799 PMCID: PMC6608622 DOI: 10.1107/s2052252519003956] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Accepted: 03/22/2019] [Indexed: 05/18/2023]
Abstract
An approach is demonstrated to obtain, in a sample- and time-efficient manner, multiple dose-resolved crystal structures from room-temperature protein microcrystals using identical fixed-target supports at both synchrotrons and X-ray free-electron lasers (XFELs). This approach allows direct comparison of dose-resolved serial synchrotron and damage-free XFEL serial femtosecond crystallography structures of radiation-sensitive proteins. Specifically, serial synchrotron structures of a heme peroxidase enzyme reveal that X-ray induced changes occur at far lower doses than those at which diffraction quality is compromised (the Garman limit), consistent with previous studies on the reduction of heme proteins by low X-ray doses. In these structures, a functionally relevant bond length is shown to vary rapidly as a function of absorbed dose, with all room-temperature synchrotron structures exhibiting linear deformation of the active site compared with the XFEL structure. It is demonstrated that extrapolation of dose-dependent synchrotron structures to zero dose can closely approximate the damage-free XFEL structure. This approach is widely applicable to any protein where the crystal structure is altered by the synchrotron X-ray beam and provides a solution to the urgent requirement to determine intact structures of such proteins in a high-throughput and accessible manner.
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Affiliation(s)
- Ali Ebrahim
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK
| | - Tadeo Moreno-Chicano
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK
| | - Martin V. Appleby
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK
| | - Amanda K. Chaplin
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK
| | - John H. Beale
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK
| | - Darren A. Sherrell
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK
| | - Helen M. E. Duyvesteyn
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK
- Division of Structural Biology (STRUBI), The Henry Wellcome Building for Genomic Medicine, University of Oxford, Roosevelt Drive, Oxford, Oxfordshire OX3 7BN, UK
| | - Shigeki Owada
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
- Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan
| | - Kensuke Tono
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
- Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan
| | - Hiroshi Sugimoto
- Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan
| | - Richard W. Strange
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK
| | - Jonathan A. R. Worrall
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK
| | - Danny Axford
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK
| | - Robin L. Owen
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK
| | - Michael A. Hough
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK
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7
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Owen RL, Sherrell DA. Radiation damage and derivatization in macromolecular crystallography: a structure factor's perspective. Acta Crystallogr D Struct Biol 2016; 72:388-94. [PMID: 26960125 PMCID: PMC4784669 DOI: 10.1107/s2059798315021555] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 11/13/2015] [Indexed: 11/11/2022] Open
Abstract
During, or even after, data collection the presence and effects of radiation damage in macromolecular crystallography may not always be immediately obvious. Despite this, radiation damage is almost always present, with site-specific damage occurring on very short time (dose) scales well before global damage becomes apparent. A result of both site-specific radiation damage and derivatization is a change in the relative intensity of reflections. The size and approximate rate of onset of X-ray-induced transformations is compared with the changes expected from derivatization, and strategies for minimizing radiation damage are discussed.
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Affiliation(s)
- Robin L. Owen
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, England
| | - Darren A. Sherrell
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, England
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8
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Bernad S, Brunel A, Dorlet P, Sicard-Roselli C, Santolini J. A novel cryo-reduction method to investigate the molecular mechanism of nitric oxide synthases. J Phys Chem B 2012; 116:5595-603. [PMID: 22530945 DOI: 10.1021/jp300749b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nitric oxide synthases (NOSs) are hemoproteins responsible for the biosynthesis of NO in mammals. They catalyze two successive oxidation reactions. The mechanism of oxygen activation is based on the transfer of two electrons and two protons. Despite structural analogies with cytochromes P450, the molecular mechanism of NOS remains yet to be elucidated. Because of extremely high reaction rates, conventional kinetics methods failed to trap and characterize the major reaction intermediates. Cryo-reduction methods offer a possibility to circumvent this technological lock, by triggering oxygen activation at cryogenic temperatures by using water radiolysis. However, this method is not adapted to the NOS mechanism because of the high instability of the initial Fe(II)O2 complex (extremely fast autoxidation and/or reaction with the cofactor H4B). This imposed a protocol with a stable Fe(II)O2 complex (observed only for one NOS-like protein) and that excludes any redox role for H4B. A relevant approach to the NOS mechanism would use H4B to provide the (second) electron involved in oxygen activation; water radiolysis would thus provide the first electron (heme reduction). In this context, we report here an investigation of the first electron transfer by this alternative approach, i.e., the reduction of native NOS by water radiolysis. We combined EPR and resonance Raman spectroscopies to analyze NOS reduction for a combination of different substrates, cofactor, and oxygen concentrations, and for different NOS isoforms. Our results show that cryo-reduction of native NOS is achieved for all conditions that are relevant to the investigation of the NOS mechanism.
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Affiliation(s)
- Sophie Bernad
- Laboratoire de Chimie Physique, CNRS UMR 8000, Univ Paris-Sud, 91405 Orsay Cedex, France
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9
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Cryoradiolysis and cryospectroscopy for studies of heme-oxygen intermediates in cytochromes p450. Methods Mol Biol 2012; 875:375-91. [PMID: 22573452 DOI: 10.1007/978-1-61779-806-1_20] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Cryogenic radiolytic reduction is one of the most straightforward and convenient methods of generation and stabilization of reactive iron-oxygen intermediates for mechanistic studies in chemistry and biochemistry. The method is based on one-electron reduction of the precursor complex in frozen solution via exposure to the ionizing radiation at cryogenic temperatures. Such approach allows for accumulation of the fleeting reactive complexes which otherwise could not be generated at sufficient amount for structural and mechanistic studies. Application of this method allowed for characterizing of peroxo-ferric and hydroperoxo-ferric intermediates, which are common for the oxygen activation mechanism in cytochromes P450, heme oxygenases, and nitric oxide synthases, as well as for the peroxide metabolism by peroxidases and catalases.
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10
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Owen RL, Yorke BA, Gowdy JA, Pearson AR. Revealing low-dose radiation damage using single-crystal spectroscopy. JOURNAL OF SYNCHROTRON RADIATION 2011; 18:367-73. [PMID: 21525644 PMCID: PMC3083913 DOI: 10.1107/s0909049511004250] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2010] [Accepted: 02/03/2011] [Indexed: 05/21/2023]
Abstract
The structural information and functional insight obtained from X-ray crystallography can be enhanced by the use of complementary spectroscopies. Here the information that can be obtained from spectroscopic methods commonly used in conjunction with X-ray crystallography and best-practice single-crystal UV-Vis absorption data collection are briefly reviewed. Using data collected with the in situ system at the Swiss Light Source, the time and dose scales of low-dose X-ray-induced radiation damage and solvated electron generation in metalloproteins at 100 K are investigated. The effect of dose rate on these scales is also discussed.
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Affiliation(s)
- Robin L Owen
- Diamond Light Source Ltd, Diamond House, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK.
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11
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Cytochromes P450 in nanodiscs. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2010; 1814:223-9. [PMID: 20685623 DOI: 10.1016/j.bbapap.2010.05.017] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Revised: 05/17/2010] [Accepted: 05/24/2010] [Indexed: 01/20/2023]
Abstract
Nanodiscs have proven to be a versatile tool for the study all types of membrane proteins, including receptors, transporters, enzymes and viral antigens. The self-assembled Nanodisc system provides a robust and common means for rendering these targets soluble in aqueous media while providing a native like bilayer environment that maintains functional activity. This system has thus provided a means for studying the extensive collection of membrane bound cytochromes P450 with the same biochemical and biophysical tools that have been previously limited to use with the soluble P450s. These include a plethora of spectroscopic, kinetic and surface based methods. Significant improvements in homogeneity and stability of these preparations open new possibilities for detailed analysis of equilibrium and steady-state kinetic characteristics of catalytic mechanisms of human cytochromes P450 involved in xenobiotic metabolism and in steroid biosynthesis. The experimental methods developed for physico-chemical and functional studies of membrane cytochromes P450 incorporated in Nanodiscs allow for more detailed understanding of the scientific questions along the lines pioneered by Professor Klaus Ruckpaul and his array of colleagues and collaborators.
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Gantt SL, Denisov IG, Grinkova YV, Sligar SG. The critical iron-oxygen intermediate in human aromatase. Biochem Biophys Res Commun 2009; 387:169-73. [PMID: 19591804 DOI: 10.1016/j.bbrc.2009.06.154] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Accepted: 06/26/2009] [Indexed: 10/20/2022]
Abstract
Aromatase (CYP19) is the target of several therapeutics used for breast cancer treatment and catalyzes the three-step conversion of androgens to estrogens, with an unusual C-C cleavage reaction in the third step. To better understand the CYP19 reaction, the oxy-ferrous complex of CYP19 with androstenedione substrate was cryotrapped, characterized by UV-vis spectroscopy, and cryoreduced to generate the next reaction cycle intermediate. EPR analysis revealed that the initial intermediate observed following cryoreduction is the unprotonated g(1)=2.254 peroxo-ferric intermediate, which is stable up to 180K. Upon gradual cryoannealing, the low-spin (g(1)=2.39) product complex is formed, with no evidence for accumulation of the g(1)=2.30 hydroperoxo-ferric intermediate. The relative stabilization of the peroxo-ferric heme and the lack of observed hydroperoxo-ferric heme distinguish CYP19 from other P450s, suggesting that the proton delivery pathway is more hindered in CYP19 than in most other P450s.
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Affiliation(s)
- Stephanie L Gantt
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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Liu B, Chen Y, Doukov T, Soltis SM, Stout CD, Fee JA. Combined microspectrophotometric and crystallographic examination of chemically reduced and X-ray radiation-reduced forms of cytochrome ba3 oxidase from Thermus thermophilus: structure of the reduced form of the enzyme. Biochemistry 2009; 48:820-6. [PMID: 19140675 DOI: 10.1021/bi801759a] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Three paths for obtaining crystals of reduced (II-E4Q/I-K258R) cytochrome ba(3) are described, and the structures of these are reported at approximately 2.8-3.0 A resolution. Microspectrophotometry of single crystals of Thermus ba(3) oxidase at 100 K was used to show that crystals of the oxidized enzyme are reduced in an intense X-ray (beam line 7-1 at the Stanford Synchrotron Radiation Laboratory), being nearly complete in 1 min. The previously reported structures of ba(3) (Protein Data Bank entries 1EHK and 1XME ), having a crystallographically detectable water between the Cu(B) and Fe(a3) metals of the dinuclear center, actually represent the X-ray radiation-reduced enzyme. Dithionite-reduced crystals or crystals formed from dithionite-reduced enzyme revealed the absence of the above-mentioned water and an increase in the Cu(B)-Fe(a3) distance of approximately 0.3 A. The new structures are discussed in terms of enzyme function. An unexpected optical absorption envelope at approximately 590 nm is also reported. This spectral feature is tentatively thought to arise from a five-coordinate, low-spin, ferrous heme a(3) that is trapped in the frozen crystals.
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Affiliation(s)
- Bin Liu
- Department of Molecular Biology, The Scripps Research Institute, MB-8, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
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Hersleth HP, Hsiao YW, Ryde U, Görbitz CH, Andersson KK. The influence of X-rays on the structural studies of peroxide-derived myoglobin intermediates. Chem Biodivers 2008; 5:2067-2089. [PMID: 18972498 DOI: 10.1002/cbdv.200890189] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In recent years, the awareness of potential radiation damage of metal centers in protein crystals during crystallographic data collection has received increasing attention. The radiation damage can lead to radiation-induced changes and reduction of the metal sites. One of the research fields where these concerns have been comprehensively addressed is the study of the reaction intermediates of the heme peroxidase and oxygenase reaction cycles. For both the resting states and the high-valent intermediates, the X-rays used in the structure determination have given undesired side effects through radiation-induced changes to the trapped intermediates. However, X-rays have been used to generate and trap the peroxy/hydroperoxy state in crystals. In this review, the structural work and the influence of X-rays on these intermediates in myoglobin are summarized and viewed in light of analogous studies on similar intermediates in peroxidases and oxygenases.
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Affiliation(s)
- Hans-Petter Hersleth
- University of Oslo, Department of Molecular Biosciences, P. O. Box 1041 Blindern, N-0316 Oslo
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Denisov IG, Dawson JH, Hager LP, Sligar SG. The ferric-hydroperoxo complex of chloroperoxidase. Biochem Biophys Res Commun 2007; 363:954-8. [PMID: 17920039 DOI: 10.1016/j.bbrc.2007.09.085] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2007] [Accepted: 09/19/2007] [Indexed: 10/22/2022]
Abstract
The hydroperoxo-ferric complex, or Compound 0 (Cpd 0), is an unstable transient intermediate common for oxygen activating heme enzymes such as the cytochromes P450, nitric oxide synthases, and heme oxygenases, as well as the peroxidases and catalases which utilize hydrogen peroxide as a source of oxygen and reducing equivalents. Detailed understanding of the mechanism of oxygen activation and formation of the higher valent catalytically active intermediates in heme enzyme catalysis requires the structural and spectroscopic characterization of this immediate precursor, Cpd 0. Using the method of cryoradiolytic reduction of the oxy-ferrous heme complex, we have prepared and characterized hydroperoxo-ferric complex in chloroperoxidase (CPO) and compared this to the same intermediate generated in cytochrome P450 CYP101. Optical absorption spectrum of Cpd 0 in CPO has a Soret band at 449 nm and poorly resolved alpha, beta bands at 576 and 546 nm.
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Affiliation(s)
- Ilia G Denisov
- Department of Biochemistry, 116 Morrill Hall, University of Illinois, 505 South Goodwin Avenue, Urbana, IL 61801, USA
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