1
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Schmidt D, Falb N, Serra I, Bellei M, Pfanzagl V, Hofbauer S, Van Doorslaer S, Battistuzzi G, Furtmüller PG, Obinger C. Compound I Formation and Reactivity in Dimeric Chlorite Dismutase: Impact of pH and the Dynamics of the Catalytic Arginine. Biochemistry 2023; 62:835-850. [PMID: 36706455 PMCID: PMC9910045 DOI: 10.1021/acs.biochem.2c00696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 01/02/2023] [Indexed: 01/28/2023]
Abstract
The heme enzyme chlorite dismutase (Cld) catalyzes the degradation of chlorite to chloride and dioxygen. Many questions about the molecular reaction mechanism of this iron protein have remained unanswered, including the electronic nature of the catalytically relevant oxoiron(IV) intermediate and its interaction with the distal, flexible, and catalytically active arginine. Here, we have investigated the dimeric Cld from Cyanothece sp. PCC7425 (CCld) and two variants having the catalytic arginine R127 (i) hydrogen-bonded to glutamine Q74 (wild-type CCld), (ii) arrested in a salt bridge with a glutamate (Q74E), or (iii) being fully flexible (Q74V). Presented stopped-flow spectroscopic studies demonstrate the initial and transient appearance of Compound I in the reaction between CCld and chlorite at pH 5.0 and 7.0 and the dominance of spectral features of an oxoiron(IV) species (418, 528, and 551 nm) during most of the chlorite degradation period at neutral and alkaline pH. Arresting the R127 in a salt bridge delays chlorite decomposition, whereas increased flexibility accelerates the reaction. The dynamics of R127 does not affect the formation of Compound I mediated by hypochlorite but has an influence on Compound I stability, which decreases rapidly with increasing pH. The decrease in activity is accompanied by the formation of protein-based amino acid radicals. Compound I is demonstrated to oxidize iodide, chlorite, and serotonin but not hypochlorite. Serotonin is able to dampen oxidative damage and inactivation of CCld at neutral and alkaline pH. Presented data are discussed with respect to the molecular mechanism of Cld and the pronounced pH dependence of chlorite degradation.
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Affiliation(s)
- Daniel Schmidt
- Institute
of Biochemistry, Department of Chemistry, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, A-1190Vienna, Austria
| | - Nikolaus Falb
- Institute
of Biochemistry, Department of Chemistry, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, A-1190Vienna, Austria
| | - Ilenia Serra
- BIMEF
Laboratory, Department of Chemistry, University
of Antwerp, 2000Antwerp, Belgium
| | - Marzia Bellei
- Department
of Life Sciences, University of Modena and
Reggio Emilia, 41100Modena, Italy
| | - Vera Pfanzagl
- Institute
of Biochemistry, Department of Chemistry, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, A-1190Vienna, Austria
| | - Stefan Hofbauer
- Institute
of Biochemistry, Department of Chemistry, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, A-1190Vienna, Austria
| | - Sabine Van Doorslaer
- BIMEF
Laboratory, Department of Chemistry, University
of Antwerp, 2000Antwerp, Belgium
| | - Gianantonio Battistuzzi
- Department
of Chemistry and Geology, University of
Modena and Reggio Emilia, 41100Modena, Italy
| | - Paul G. Furtmüller
- Institute
of Biochemistry, Department of Chemistry, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, A-1190Vienna, Austria
| | - Christian Obinger
- Institute
of Biochemistry, Department of Chemistry, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, A-1190Vienna, Austria
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2
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Schroeter AL, Yang H, James CD, Hoffman BM, Doan PE. A New Reaction for Improved Calibration of EPR Rapid-Freeze Quench Times: Kinetics of Ethylene Diamine Tetraacetate (EDTA) Transfer from Calcium(II) to Copper(II). APPLIED MAGNETIC RESONANCE 2022; 53:1195-1210. [PMID: 37026114 PMCID: PMC10072867 DOI: 10.1007/s00723-021-01448-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 10/18/2021] [Accepted: 10/24/2021] [Indexed: 06/19/2023]
Abstract
The kinetics of the transfer of the chelate, ethylenediamine tetraacetate (EDTA), from Calcium(II) to Copper(II) in imidazole (Im) buffers near neutral pH, corresponding to the conversion, [Cu(II)Im4]2+→ [Cu(II)EDTA]2-, are characterized with stopped-flow absorption spectroscopy and implemented as a tool for calibrating the interval between mixing and freezing, the freeze-quench time (t Q ), of a rapid freeze-quench (RFQ) apparatus. The kinetics of this reaction are characterized by monitoring changes in UV-visible spectra (300 nm) due to changes in the charge-transfer band associated with the Cu2+ ions upon EDTA binding. Stopped-flow measurements show that the rates of conversion of the Cu2+ ions exhibit exponential kinetics on millisecond time scales at pH values less than 6.8. In parallel, we have developed a simple but precise method to quantitate the speciation of frozen solution mixtures of [Cu(II)(EDTA)]2- and tetraimidazole Cu(II) ([Cu(Im)4]2+) in X-band EPR spectra. The results are implemented in a simple high-precision 'recipe' for determining t Q . These procedures are more accurate and precise than the venerable reaction of aquometmyoglobin with azide for calibrating RFQ apparatus, with the benefit of avoiding high-concentrations of toxic azide solutions.
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Affiliation(s)
- Abigail L. Schroeter
- Department of Chemistry, Northwestern University, Evanston, IL, USA
- Present Address: Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, USA
| | - Hao Yang
- Department of Chemistry, Northwestern University, Evanston, IL, USA
| | | | - Brian M. Hoffman
- Department of Chemistry, Northwestern University, Evanston, IL, USA
| | - Peter E. Doan
- Department of Chemistry, Northwestern University, Evanston, IL, USA
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3
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Jeon J, Blake Wilson C, Yau WM, Thurber KR, Tycko R. Time-resolved solid state NMR of biomolecular processes with millisecond time resolution. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2022; 342:107285. [PMID: 35998398 PMCID: PMC9463123 DOI: 10.1016/j.jmr.2022.107285] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2022] [Revised: 08/10/2022] [Accepted: 08/11/2022] [Indexed: 05/21/2023]
Abstract
We review recent efforts to develop and apply an experimental approach to the structural characterization of transient intermediate states in biomolecular processes that involve large changes in molecular conformation or assembly state. This approach depends on solid state nuclear magnetic resonance (ssNMR) measurements that are performed at very low temperatures, typically 25-30 K, with signal enhancements from dynamic nuclear polarization (DNP). This approach also involves novel technology for initiating the process of interest, either by rapid mixing of two solutions or by a rapid inverse temperature jump, and for rapid freezing to trap intermediate states. Initiation by rapid mixing or an inverse temperature jump can be accomplished in approximately-one millisecond. Freezing can be accomplished in approximately 100 microseconds. Thus, millisecond time resolution can be achieved. Recent applications to the process by which the biologically essential calcium sensor protein calmodulin forms a complex with one of its target proteins and the process by which the bee venom peptide melittin converts from an unstructured monomeric state to a helical, tetrameric state after a rapid change in pH or temperature are described briefly. Future applications of millisecond time-resolved ssNMR are also discussed briefly.
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Affiliation(s)
- Jaekyun Jeon
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0520, USA
| | - C Blake Wilson
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0520, USA
| | - Wai-Ming Yau
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0520, USA
| | - Kent R Thurber
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0520, USA
| | - Robert Tycko
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0520, USA.
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4
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Time-resolved DEER EPR and solid-state NMR afford kinetic and structural elucidation of substrate binding to Ca 2+-ligated calmodulin. Proc Natl Acad Sci U S A 2022; 119:2122308119. [PMID: 35105816 PMCID: PMC8833187 DOI: 10.1073/pnas.2122308119] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/28/2021] [Indexed: 12/29/2022] Open
Abstract
Complex formation between calmodulin and target proteins underlies numerous calcium signaling processes in biology, yet structural and mechanistic details, which entail major conformational changes in both calmodulin and its substrates, have been unclear. We show that a combination of time-resolved electron paramagnetic and NMR measurements can elucidate the molecular mechanism, at the quantitative kinetic and structural levels, of the binding pathway of a peptide substrate from skeletal muscle myosin light-chain kinase to calcium-loaded calmodulin. The mechanism involves coupled folding and binding and comprises a bifurcated process, with rapid, direct complex formation when the peptide interacts first with the C-terminal domain of calmodulin or a slower, two-step complex formation when the peptide interacts initially with the N-terminal domain. Recent advances in rapid mixing and freeze quenching have opened the path for time-resolved electron paramagnetic resonance (EPR)-based double electron-electron resonance (DEER) and solid-state NMR of protein–substrate interactions. DEER, in conjunction with phase memory time filtering to quantitatively extract species populations, permits monitoring time-dependent probability distance distributions between pairs of spin labels, while solid-state NMR provides quantitative residue-specific information on the appearance of structural order and the development of intermolecular contacts between substrate and protein. Here, we demonstrate the power of these combined approaches to unravel the kinetic and structural pathways in the binding of the intrinsically disordered peptide substrate (M13) derived from myosin light-chain kinase to the universal eukaryotic calcium regulator, calmodulin. Global kinetic analysis of the data reveals coupled folding and binding of the peptide associated with large spatial rearrangements of the two domains of calmodulin. The initial binding events involve a bifurcating pathway in which the M13 peptide associates via either its N- or C-terminal regions with the C- or N-terminal domains, respectively, of calmodulin/4Ca2+ to yield two extended “encounter” complexes, states A and A*, without conformational ordering of M13. State A is immediately converted to the final compact complex, state C, on a timescale τ ≤ 600 μs. State A*, however, only reaches the final complex via a collapsed intermediate B (τ ∼ 1.5 to 2.5 ms), in which the peptide is only partially ordered and not all intermolecular contacts are formed. State B then undergoes a relatively slow (τ ∼ 7 to 18 ms) conformational rearrangement to state C.
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5
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Hett T, Zbik T, Mukherjee S, Matsuoka H, Bönigk W, Klose D, Rouillon C, Brenner N, Peuker S, Klement R, Steinhoff HJ, Grubmüller H, Seifert R, Schiemann O, Kaupp UB. Spatiotemporal Resolution of Conformational Changes in Biomolecules by Combining Pulsed Electron-Electron Double Resonance Spectroscopy with Microsecond Freeze-Hyperquenching. J Am Chem Soc 2021; 143:6981-6989. [PMID: 33905249 DOI: 10.1021/jacs.1c01081] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The function of proteins is linked to their conformations that can be resolved with several high-resolution methods. However, only a few methods can provide the temporal order of intermediates and conformational changes, with each having its limitations. Here, we combine pulsed electron-electron double resonance spectroscopy with a microsecond freeze-hyperquenching setup to achieve spatiotemporal resolution in the angstrom range and lower microsecond time scale. We show that the conformational change of the Cα-helix in the cyclic nucleotide-binding domain of the Mesorhizobium loti potassium channel occurs within about 150 μs and can be resolved with angstrom precision. Thus, this approach holds great promise for obtaining 4D landscapes of conformational changes in biomolecules.
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Affiliation(s)
- Tobias Hett
- Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstraße 12, 53115 Bonn, Germany
| | - Tobias Zbik
- Center of Advanced European Studies and Research (caesar), Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
| | - Shatanik Mukherjee
- Center of Advanced European Studies and Research (caesar), Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
| | - Hideto Matsuoka
- Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstraße 12, 53115 Bonn, Germany
| | - Wolfgang Bönigk
- Center of Advanced European Studies and Research (caesar), Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
| | - Daniel Klose
- Fachbereich Physik, Universität Osnabrück, Barbarastraße 7, 49076 Osnabrück, Germany
| | - Christophe Rouillon
- Center of Advanced European Studies and Research (caesar), Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
| | - Norbert Brenner
- Center of Advanced European Studies and Research (caesar), Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
| | - Sebastian Peuker
- Center of Advanced European Studies and Research (caesar), Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
| | - Reinhard Klement
- Department of Theoretical and Computational Biophysics, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | | | - Helmut Grubmüller
- Department of Theoretical and Computational Biophysics, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Reinhard Seifert
- Center of Advanced European Studies and Research (caesar), Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
| | - Olav Schiemann
- Institute of Physical and Theoretical Chemistry, University of Bonn, Wegelerstraße 12, 53115 Bonn, Germany
| | - U Benjamin Kaupp
- Center of Advanced European Studies and Research (caesar), Ludwig-Erhard-Allee 2, 53175 Bonn, Germany.,Life & Medical Sciences Institute (LIMES), University of Bonn, Carl-Troll-Straße 31, 53115 Bonn, Germany
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6
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Calvey GD, Katz AM, Zielinski KA, Dzikovski B, Pollack L. Characterizing Enzyme Reactions in Microcrystals for Effective Mix-and-Inject Experiments using X-ray Free-Electron Lasers. Anal Chem 2020; 92:13864-13870. [PMID: 32955854 PMCID: PMC8367009 DOI: 10.1021/acs.analchem.0c02569] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Mix-and-inject serial crystallography is an emerging technique that utilizes X-ray free-electron lasers (XFELs) and microcrystalline samples to capture atomically detailed snapshots of biomolecules as they function. Early experiments have yielded exciting results; however, there are limited options to characterize reactions in crystallo in advance of the beamtime. Complementary measurements are needed to identify the best conditions and timescales for observing structural intermediates. Here, we describe the interface of XFEL compatible mixing injectors with rapid freeze-quenching and X-band EPR spectroscopy, permitting characterization of reactions in crystals under the same conditions as an XFEL experiment. We demonstrate this technology by tracking the reaction of azide with microcrystalline myoglobin, using only a fraction of the sample required for a mix-and-inject experiment. This spectroscopic method enables optimization of sample and mixer conditions to maximize the populations of intermediate states, eliminating the guesswork of current mix-and-inject experiments.
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Affiliation(s)
- George D Calvey
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, United States
| | - Andrea M Katz
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, United States
| | - Kara A Zielinski
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, United States
| | - Boris Dzikovski
- Department of Chemistry and Chemical Biology and National Biomedical Center for Advanced ESR Technology, Cornell University, Ithaca, New York 14853, United States
| | - Lois Pollack
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, United States
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7
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Ghosh R, Kragelj J, Xiao Y, Frederick KK. Cryogenic Sample Loading into a Magic Angle Spinning Nuclear Magnetic Resonance Spectrometer that Preserves Cellular Viability. J Vis Exp 2020:10.3791/61733. [PMID: 32955491 PMCID: PMC7797162 DOI: 10.3791/61733] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Dynamic nuclear polarization (DNP) can dramatically increase the sensitivity of magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. These sensitivity gains increase as temperatures decrease and are large enough to enable the study of molecules at very low concentrations at the operating temperatures (~100 K) of most commercial DNP-equipped NMR spectrometers. This leads to the possibility of in-cell structural biology on cryopreserved cells for macromolecules at their endogenous levels in their native environments. However, the freezing rates required for cellular cryopreservation are exceeded during typical sample handling for DNP MAS NMR and this results in loss of cellular integrity and viability. This article describes a detailed protocol for the preparation and cryogenic transfer of a frozen sample of mammalian cells into a MAS NMR spectrometer.
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Affiliation(s)
- Rupam Ghosh
- Department of Biophysics, University of Texas Southwestern Medical Center
| | - Jaka Kragelj
- Department of Biophysics, University of Texas Southwestern Medical Center
| | - Yiling Xiao
- Department of Biophysics, University of Texas Southwestern Medical Center
| | - Kendra K Frederick
- Department of Biophysics, University of Texas Southwestern Medical Center; Center for Alzheimer's and Neurodegenerative Disease and Center for Systems Biology, University of Texas Southwestern Medical Center;
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8
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Schmidt T, Jeon J, Okuno Y, Chiliveri SC, Clore GM. Submillisecond Freezing Permits Cryoprotectant-Free EPR Double Electron-Electron Resonance Spectroscopy. Chemphyschem 2020; 21:1224-1229. [PMID: 32383308 DOI: 10.1002/cphc.202000312] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 05/06/2020] [Indexed: 01/22/2023]
Abstract
Double electron-electron resonance (DEER) EPR spectroscopy is a powerful method for obtaining distance distributions between pairs of engineered nitroxide spin-labels in proteins and other biological macromolecules. These measurements require the use of cryogenic temperatures (77 K or less) to prolong the phase memory relaxation time (Tm ) sufficiently to enable detection of a DEER echo curve. Generally, a cryoprotectant such as glycerol is added to protein samples to facilitate glass formation and avoid protein clustering (which can result in a large decrease in Tm ) during relatively slow flash freezing in liquid N2 . However, cryoprotectants are osmolytes and can influence protein folding/unfolding equilibria, as well as species populations in weak multimeric systems. Here we show that submillisecond rapid freezing, achieved by high velocity spraying of the sample onto a rapidly spinning, liquid nitrogen cooled copper disc obviates the requirement for cryoprotectants and permits high quality DEER data to be obtained in absence of glycerol. We demonstrate this approach on five different protein systems: protein A, the metastable drkN SH3 domain, urea-unfolded drkN SH3, HIV-1 reverse transcriptase, and the transmembrane domain of HIV-1 gp41 in lipid bicelles.
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Affiliation(s)
- Thomas Schmidt
- Laboratory of Chemical Physics, National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892-0520, USA
| | - Jaekyun Jeon
- Laboratory of Chemical Physics, National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892-0520, USA
| | - Yusuke Okuno
- Laboratory of Chemical Physics, National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892-0520, USA
| | - Sai C Chiliveri
- Laboratory of Chemical Physics, National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892-0520, USA
| | - G Marius Clore
- Laboratory of Chemical Physics, National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892-0520, USA
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9
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Panarelli EG, van der Meer H, Gast P, Groenen EJJ. Effective coupling of rapid freeze-quench to high-frequency electron paramagnetic resonance. PLoS One 2020; 15:e0232555. [PMID: 32392255 PMCID: PMC7213726 DOI: 10.1371/journal.pone.0232555] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 04/16/2020] [Indexed: 11/18/2022] Open
Abstract
We report an easy, efficient and reproducible way to prepare Rapid-Freeze-Quench samples in sub-millimeter capillaries and load these into the probe head of a 275 GHz Electron Paramagnetic Resonance spectrometer. Kinetic data obtained for the binding reaction of azide to myoglobin demonstrate the feasibility of the method for high-frequency EPR. Experiments on the same samples at 9.5 GHz show that only a single series of Rapid-Freeze-Quench samples is required for studies at multiple microwave frequencies.
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Affiliation(s)
- E Gabriele Panarelli
- Department of Physics, Huygens-Kamerlingh Onnes Laboratory, Leiden University, Leiden, The Netherlands
| | - Harmen van der Meer
- Department of Physics, Huygens-Kamerlingh Onnes Laboratory, Leiden University, Leiden, The Netherlands
| | - Peter Gast
- Department of Physics, Huygens-Kamerlingh Onnes Laboratory, Leiden University, Leiden, The Netherlands
| | - Edgar J J Groenen
- Department of Physics, Huygens-Kamerlingh Onnes Laboratory, Leiden University, Leiden, The Netherlands
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10
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Panarelli EG, Gast P, Groenen EJJ. Temperature-cycle electron paramagnetic resonance. Phys Chem Chem Phys 2020; 22:9487-9493. [PMID: 32314999 DOI: 10.1039/d0cp00664e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
We report on a novel approach to the study of rates and short-lived intermediates of (bio)chemical reactions that involve paramagnetic species. Temperature-cycle Electron Paramagnetic Resonance (EPR) concerns the repeated heating of a reaction mixture in the cavity of an EPR spectrometer by pulsed irradiation with a near-infrared diode laser combined with intermittent characterization of the sample by 275 GHz EPR at a lower temperature at which the reaction does not proceed. The new technique is demonstrated for the reduction of TEMPOL with sodium dithionite in aqueous solution down to the sub-second time scale. We show that a single sample suffices to obtain a complete kinetic trace. Variation of the length and power of the laser pulse offers great flexibility as regards the time scale of the experiment and the temperature at which the reaction can be studied. For water/glycerol mixtures we introduce a simple way to obtain and load an unreacted sample into the spectrometer at low temperature.
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Affiliation(s)
- E Gabriele Panarelli
- Department of Physics, Huygens-Kamerlingh Onnes Laboratory, Leiden University, PO Box 9504, 2300 RA Leiden, The Netherlands.
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11
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Accelerating structural life science by paramagnetic lanthanide probe methods. Biochim Biophys Acta Gen Subj 2020; 1864:129332. [DOI: 10.1016/j.bbagen.2019.03.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 03/18/2019] [Accepted: 03/20/2019] [Indexed: 02/08/2023]
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12
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Ju LC, Cheng Z, Fast W, Bonomo RA, Crowder MW. The Continuing Challenge of Metallo-β-Lactamase Inhibition: Mechanism Matters. Trends Pharmacol Sci 2018; 39:635-647. [PMID: 29680579 DOI: 10.1016/j.tips.2018.03.007] [Citation(s) in RCA: 100] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 03/16/2018] [Accepted: 03/22/2018] [Indexed: 01/16/2023]
Abstract
Metallo-β-lactamases (MBLs) are a significant clinical problem because they hydrolyze and inactivate nearly all β-lactam-containing antibiotics. These 'lifesaving drugs' constitute >50% of the available contemporary antibiotic arsenal. Despite the global spread of MBLs, MBL inhibitors have not yet appeared in clinical trials. Most MBL inhibitors target active site zinc ions and vary in mechanism from ternary complex formation to metal ion stripping. Importantly, differences in mechanism can impact pharmacology in terms of reversibility, target selectivity, and structure-activity relationship interpretation. This review surveys the mechanisms of MBL inhibitors and describes methods that determine the mechanism of inhibition to guide development of future therapeutics.
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Affiliation(s)
- Lin-Cheng Ju
- Department of Urology, Shengjing Hospital of China Medical University, Shenyang, Liaoning 110004, PR China; Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA.
| | - Zishuo Cheng
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA
| | - Walter Fast
- Division of Chemical Biology and Medicinal Chemistry, College of Pharmacy, University of Texas, Austin, TX 78712, USA
| | - Robert A Bonomo
- Research Services, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH 44106, USA; Departments of Medicine, Pharmacology, Molecular Biology and Microbiology, Biochemistry, Proteomics, and Bioinformatics and the CWRU-Cleveland VAMC Center for Antimicrobial Resistance and Epidemiology, Cleveland, OH 44106, USA
| | - Michael W Crowder
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA
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13
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Collauto A, DeBerg HA, Kaufmann R, Zagotta WN, Stoll S, Goldfarb D. Rates and equilibrium constants of the ligand-induced conformational transition of an HCN ion channel protein domain determined by DEER spectroscopy. Phys Chem Chem Phys 2018; 19:15324-15334. [PMID: 28569901 DOI: 10.1039/c7cp01925d] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ligand binding can induce significant conformational changes in proteins. The mechanism of this process couples equilibria associated with the ligand binding event and the conformational change. Here we show that by combining the application of W-band double electron-electron resonance (DEER) spectroscopy with microfluidic rapid freeze quench (μRFQ) it is possible to resolve these processes and obtain both equilibrium constants and reaction rates. We studied the conformational transition of the nitroxide labeled, isolated carboxy-terminal cyclic-nucleotide binding domain (CNBD) of the HCN2 ion channel upon binding of the ligand 3',5'-cyclic adenosine monophosphate (cAMP). Using model-based global analysis, the time-resolved data of the μRFQ DEER experiments directly provide fractional populations of the open and closed conformations as a function of time. We modeled the ligand-induced conformational change in the protein using a four-state model: apo/open (AO), apo/closed (AC), bound/open (BO), bound/closed (BC). These species interconvert according to AC + L ⇌ AO + L ⇌ BO ⇌ BC. By analyzing the concentration dependence of the relative contributions of the closed and open conformations at equilibrium, we estimated the equilibrium constants for the two conformational equilibria and the open-state ligand dissociation constant. Analysis of the time-resolved μRFQ DEER data gave estimates for the intrinsic rates of ligand binding and unbinding as well as the rates of the conformational change. This demonstrates that DEER can quantitatively resolve both the thermodynamics and the kinetics of ligand binding and the associated conformational change.
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Affiliation(s)
- Alberto Collauto
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot, 76100, Israel.
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14
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Nick TU, Ravichandran KR, Stubbe J, Kasanmascheff M, Bennati M. Spectroscopic Evidence for a H Bond Network at Y 356 Located at the Subunit Interface of Active E. coli Ribonucleotide Reductase. Biochemistry 2017. [PMID: 28640584 DOI: 10.1021/acs.biochem.7b00462] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The reaction catalyzed by E. coli ribonucleotide reductase (RNR) composed of α and β subunits that form an active α2β2 complex is a paradigm for proton-coupled electron transfer (PCET) processes in biological transformations. β2 contains the diferric tyrosyl radical (Y122·) cofactor that initiates radical transfer (RT) over 35 Å via a specific pathway of amino acids (Y122· ⇆ [W48] ⇆ Y356 in β2 to Y731 ⇆ Y730 ⇆ C439 in α2). Experimental evidence exists for colinear and orthogonal PCET in α2 and β2, respectively. No mechanistic model yet exists for the PCET across the subunit (α/β) interface. Here, we report unique EPR spectroscopic features of Y356·-β, the pathway intermediate generated by the reaction of 2,3,5-F3Y122·-β2/CDP/ATP with wt-α2, Y731F-α2, or Y730F-α2. High field EPR (94 and 263 GHz) reveals a dramatically perturbed g tensor. [1H] and [2H]-ENDOR reveal two exchangeable H bonds to Y356·: a moderate one almost in-plane with the π-system and a weak one. DFT calculation on small models of Y· indicates that two in-plane, moderate H bonds (rO-H ∼1.8-1.9 Å) are required to reproduce the gx value of Y356· (wt-α2). The results are consistent with a model, in which a cluster of two, almost symmetrically oriented, water molecules provide the two moderate H bonds to Y356· that likely form a hydrogen bond network of water molecules involved in either the reversible PCET across the subunit interface or in H+ release to the solvent during Y356 oxidation.
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Affiliation(s)
- Thomas U Nick
- Research Group Electron-Spin Resonance Spectroscopy, Max Planck Institute for Biophysical Chemistry , 37077 Göttingen, Germany
| | - Kanchana R Ravichandran
- Department of Chemistry, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - JoAnne Stubbe
- Department of Chemistry, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Müge Kasanmascheff
- Research Group Electron-Spin Resonance Spectroscopy, Max Planck Institute for Biophysical Chemistry , 37077 Göttingen, Germany
| | - Marina Bennati
- Research Group Electron-Spin Resonance Spectroscopy, Max Planck Institute for Biophysical Chemistry , 37077 Göttingen, Germany.,Department of Chemistry, University of Göttingen , 37077 Göttingen, Germany
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15
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Glaenzer J, Peter MF, Thomas GH, Hagelueken G. PELDOR Spectroscopy Reveals Two Defined States of a Sialic Acid TRAP Transporter SBP in Solution. Biophys J 2017; 112:109-120. [PMID: 28076802 DOI: 10.1016/j.bpj.2016.12.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Revised: 11/29/2016] [Accepted: 12/08/2016] [Indexed: 10/20/2022] Open
Abstract
The tripartite ATP-independent periplasmic (TRAP) transporters are a widespread class of membrane transporters in bacteria and archaea. Typical substrates for TRAP transporters are organic acids including the sialic acid N-acetylneuraminic acid. The substrate binding proteins (SBP) of TRAP transporters are the best studied component and are responsible for initial high-affinity substrate binding. To better understand the dynamics of the ligand binding process, pulsed electron-electron double resonance (PELDOR, also known as DEER) spectroscopy was applied to study the conformational changes in the N-acetylneuraminic acid-specific SBP VcSiaP. The protein is the SBP of VcSiaPQM, a sialic acid TRAP transporter from Vibrio cholerae. Spin-labeled double-cysteine mutants of VcSiaP were analyzed in the substrate-bound and -free state and the measured distances were compared to available crystal structures. The data were compatible with two clear states only, which are consistent with the open and closed forms seen in TRAP SBP crystal structures. Substrate titration experiments demonstrated the transition of the population from one state to the other with no other observed forms. Mutants of key residues involved in ligand binding and/or proposed to be involved in domain closure were produced and the corresponding PELDOR experiments reveal important insights into the open-closed transition. The results are in excellent agreement with previous in vivo sialylation experiments. The structure of the spin-labeled Q54R1/L173R1 R125A mutant was solved at 2.1 Å resolution, revealing no significant changes in the protein structure. Thus, the loss of domain closure appears to be solely due to loss of binding. In conclusion, these data are consistent with TRAP SBPs undergoing a simple two-state transition from an open-unliganded to closed-liganded state during the transport cycle.
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Affiliation(s)
- Janin Glaenzer
- Institute for Physical & Theoretical Chemistry, University of Bonn, Bonn, Germany
| | - Martin F Peter
- Institute for Physical & Theoretical Chemistry, University of Bonn, Bonn, Germany
| | | | - Gregor Hagelueken
- Institute for Physical & Theoretical Chemistry, University of Bonn, Bonn, Germany.
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16
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Nami F, Gast P, Groenen EJJ. Rapid Freeze-Quench EPR Spectroscopy: Improved Collection of Frozen Particles. APPLIED MAGNETIC RESONANCE 2016; 47:643-653. [PMID: 27340337 PMCID: PMC4875044 DOI: 10.1007/s00723-016-0783-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 04/18/2016] [Indexed: 05/22/2023]
Abstract
Rapid freeze-quench (RFQ) in combination with electron paramagnetic resonance (EPR) spectroscopy at X-band is a proven technique to trap and characterize paramagnetic intermediates of biochemical reactions. Preparation of suitable samples is still cumbersome, despite many attempts to remedy this problem, and limits the wide applicability of RFQ EPR. We present a method, which improves the collection of freeze-quench particles from isopentane and their packing in an EPR tube. The method is based on sucking the particle suspension into an EPR tube with a filter at the bottom. This procedure results in a significant reduction of the required volume of reactants, which allows the economical use of valuable reactants such as proteins. The approach also enables the successful collection of smaller frozen particles, which are generated at higher flow rates. The method provides for a reproducible, efficient and fast collection of the freeze-quench particles and can be easily adapted to RFQ EPR at higher microwave frequencies than X-band.
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Affiliation(s)
- Faezeh Nami
- Huygens-Kamerlingh Onnes Laboratory, Department of Physics, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands
| | - Peter Gast
- Huygens-Kamerlingh Onnes Laboratory, Department of Physics, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands
| | - Edgar J. J. Groenen
- Huygens-Kamerlingh Onnes Laboratory, Department of Physics, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands
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17
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Jhong SR, Li CY, Sung TC, Lan YJ, Chang KJ, Chiang YW. Evidence for an Induced-Fit Process Underlying the Activation of Apoptotic BAX by an Intrinsically Disordered BimBH3 Peptide. J Phys Chem B 2016; 120:2751-60. [PMID: 26913490 DOI: 10.1021/acs.jpcb.6b00909] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Apoptotic BAX protein functions as a critical gateway to mitochondria-mediated apoptosis. A diversity of stimuli has been implicated in initiating BAX activation, but the triggering mechanism remains elusive. Here we study the interaction of BAX with an intrinsically disordered BH3 motif of Bim protein (BimBH3) using ESR techniques. Upon incubation with BAX, BimBH3 binds to BAX at helices 1/6 trigger site to initiate conformational changes of BAX, which in turn promotes the formation of BAX oligomers. The study strategy is twofold: while BAX oligomerization was monitored through spectral changes of spin-labeled BAX, the binding kinetics was studied by observing time-dependent changes of spin-labeled BimBH3. Meanwhile, conformational transition between the unstructured and structured BimBH3 was measured. We show that helical propensity of the BimBH3 is increased upon binding to BAX but is then reduced after being released from the activated BAX; the release is due to the BimBH3-induced conformational change of BAX that is a prerequisite for the oligomer assembling. Intermediate states are identified, offering a key snapshot of the coupled folding and binding process. Our results provide a quantitative mechanistic description of the BAX activation and reveal new insights into the mechanism underlying the interactions between BAX and BH3-mimetic peptide.
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Affiliation(s)
- Siao-Ru Jhong
- Department of Chemistry, National Tsing Hua University , Hsinchu 30013, Taiwan
| | - Ching-Yu Li
- Department of Chemistry, National Tsing Hua University , Hsinchu 30013, Taiwan
| | - Tai-Ching Sung
- Department of Chemistry, National Tsing Hua University , Hsinchu 30013, Taiwan
| | - Yu-Jing Lan
- Department of Chemistry, National Tsing Hua University , Hsinchu 30013, Taiwan
| | - Kuo-Jung Chang
- Department of Chemistry, National Tsing Hua University , Hsinchu 30013, Taiwan
| | - Yun-Wei Chiang
- Department of Chemistry, National Tsing Hua University , Hsinchu 30013, Taiwan
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18
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Smith AN, Long JR. Dynamic Nuclear Polarization as an Enabling Technology for Solid State Nuclear Magnetic Resonance Spectroscopy. Anal Chem 2016; 88:122-32. [PMID: 26594903 PMCID: PMC5704910 DOI: 10.1021/acs.analchem.5b04376] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Adam N Smith
- Department of Chemistry, University of Florida , 214 Leigh Hall, Gainesville, Florida 32611-7200, United States
| | - Joanna R Long
- Department of Biochemistry and Molecular Biology, University of Florida , P. O. Box 100245, Gainesville, Florida 32610-0245, United States
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19
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Abou Fadel M, de Juan A, Touati N, Vezin H, Duponchel L. New chemometric approach MCR-ALS to unmix EPR spectroscopic data from complex mixtures. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2014; 248:27-35. [PMID: 25310877 DOI: 10.1016/j.jmr.2014.09.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 09/17/2014] [Accepted: 09/18/2014] [Indexed: 06/04/2023]
Abstract
Electron paramagnetic resonance (EPR) spectra of mixtures are often difficult to interpret due to the superposition of spectral contribution of various species present in the complex materials. It is challenging to accurately identify the number of pure compounds present and to extract their pure spectra. In this study, the powerful chemometric method, multivariate curve resolution-alternating least squares (MCR-ALS), is applied to identify different paramagnetic centers. This method is used to simultaneously extract, with no prior knowledge, the pure spectra and the corresponding concentration profiles of all the compounds in the unknown and unresolved mixtures. The goal of our work is to apply, for the first time, this new chemometrics methodology, MCR-ALS, on EPR spectroscopic data in order to characterize a series of distinct but strongly overlapping spectra of various paramagnetic species.
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Affiliation(s)
- Maya Abou Fadel
- LASIR CNRS UMR 8516, Université Lille 1, Sciences et Technologies, 59655 Villeneuve d'Ascq Cedex, France
| | - Anna de Juan
- Grup de Quimiometria, Quimica Analitica, Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain
| | - Nadia Touati
- LASIR CNRS UMR 8516, Université Lille 1, Sciences et Technologies, 59655 Villeneuve d'Ascq Cedex, France
| | - Hervé Vezin
- LASIR CNRS UMR 8516, Université Lille 1, Sciences et Technologies, 59655 Villeneuve d'Ascq Cedex, France
| | - Ludovic Duponchel
- LASIR CNRS UMR 8516, Université Lille 1, Sciences et Technologies, 59655 Villeneuve d'Ascq Cedex, France.
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