1
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Bühl E, Resler T, Lam R, Asido M, Bamberg E, Schlesinger R, Bamann C, Heberle J, Wachtveitl J. Assessing the Role of R120 in the Gating of CrChR2 by Time-Resolved Spectroscopy from Femtoseconds to Seconds. J Am Chem Soc 2023; 145:21832-21840. [PMID: 37773976 DOI: 10.1021/jacs.3c05399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/01/2023]
Abstract
The light-gated ion channel channelrhodopsin-2 from Chlamydomonas reinhardtii (CrChR2) is the most frequently used optogenetic tool in neurosciences. However, the precise molecular mechanism of the channel opening and the correlation among retinal isomerization, the photocycle, and the channel activity of the protein are missing. Here, we present electrophysiological and spectroscopic investigations on the R120H variant of CrChR2. R120 is a key residue in an extended network linking the retinal chromophore to several gates of the ion channel. We show that despite the deficient channel activity, the photocycle of the variant is intact. In a comparative study for R120H and the wild type, we resolve the vibrational changes in the spectral range of the retinal and amide I bands across the time range from femtoseconds to seconds. Analysis of the amide I mode reveals a significant impairment of the ultrafast protein response after retinal excitation. We conclude that channel opening in CrChR2 is prepared immediately after retinal excitation. Additionally, chromophore isomerization is essential for both photocycle and channel activities, although both processes can occur independently.
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Affiliation(s)
- Elena Bühl
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt am Main, Max-von-Laue Strasse 7, 60438 Frankfurt, Germany
| | - Tom Resler
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Rebecca Lam
- Max Planck Institute of Biophysics, Max-von-Laue Strasse 3, 60438 Frankfurt am Main, Germany
| | - Marvin Asido
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt am Main, Max-von-Laue Strasse 7, 60438 Frankfurt, Germany
| | - Ernst Bamberg
- Max Planck Institute of Biophysics, Max-von-Laue Strasse 3, 60438 Frankfurt am Main, Germany
| | - Ramona Schlesinger
- Department of Physics, Genetic Biophysics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Christian Bamann
- Max Planck Institute of Biophysics, Max-von-Laue Strasse 3, 60438 Frankfurt am Main, Germany
| | - Joachim Heberle
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Josef Wachtveitl
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt am Main, Max-von-Laue Strasse 7, 60438 Frankfurt, Germany
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2
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QuasAr Odyssey: the origin of fluorescence and its voltage sensitivity in microbial rhodopsins. Nat Commun 2022; 13:5501. [PMID: 36127376 PMCID: PMC9489792 DOI: 10.1038/s41467-022-33084-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 08/26/2022] [Indexed: 11/29/2022] Open
Abstract
Rhodopsins had long been considered non-fluorescent until a peculiar voltage-sensitive fluorescence was reported for archaerhodopsin-3 (Arch3) derivatives. These proteins named QuasArs have been used for imaging membrane voltage changes in cell cultures and small animals. However due to the low fluorescence intensity, these constructs require use of much higher light intensity than other optogenetic tools. To develop the next generation of sensors, it is indispensable to first understand the molecular basis of the fluorescence and its modulation by the membrane voltage. Based on spectroscopic studies of fluorescent Arch3 derivatives, we propose a unique photo-reaction scheme with extended excited-state lifetimes and inefficient photoisomerization. Molecular dynamics simulations of Arch3, of the Arch3 fluorescent derivative Archon1, and of several its mutants have revealed different voltage-dependent changes of the hydrogen-bonding networks including the protonated retinal Schiff-base and adjacent residues. Experimental observations suggest that under negative voltage, these changes modulate retinal Schiff base deprotonation and promote a decrease in the populations of fluorescent species. Finally, we identified molecular constraints that further improve fluorescence quantum yield and voltage sensitivity. The authors present an in-depth investigation of excited state dynamics and molecular mechanism of the voltage sensing in microbial rhodopsins. Using a combination of spectroscopic investigations and molecular dynamics simulations, the study proposes the voltage-modulated deprotonation of the chromophore as the key event in the voltage sensing. Thus, molecular constraints that may further improve the fluorescence quantum yield and the voltage sensitivity are presented.
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3
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Vogl DP, Conibear AC, Becker CFW. Segmental and site-specific isotope labelling strategies for structural analysis of posttranslationally modified proteins. RSC Chem Biol 2021; 2:1441-1461. [PMID: 34704048 PMCID: PMC8496066 DOI: 10.1039/d1cb00045d] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Accepted: 08/11/2021] [Indexed: 01/02/2023] Open
Abstract
Posttranslational modifications can alter protein structures, functions and locations, and are important cellular regulatory and signalling mechanisms. Spectroscopic techniques such as nuclear magnetic resonance, infrared and Raman spectroscopy, as well as small-angle scattering, can provide insights into the structural and dynamic effects of protein posttranslational modifications and their impact on interactions with binding partners. However, heterogeneity of modified proteins from natural sources and spectral complexity often hinder analyses, especially for large proteins and macromolecular assemblies. Selective labelling of proteins with stable isotopes can greatly simplify spectra, as one can focus on labelled residues or segments of interest. Employing chemical biology tools for modifying and isotopically labelling proteins with atomic precision provides access to unique protein samples for structural biology and spectroscopy. Here, we review site-specific and segmental isotope labelling methods that are employed in combination with chemical and enzymatic tools to access posttranslationally modified proteins. We discuss illustrative examples in which these methods have been used to facilitate spectroscopic studies of posttranslationally modified proteins, providing new insights into biology.
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Affiliation(s)
- Dominik P Vogl
- University of Vienna, Faculty of Chemistry, Institute of Biological Chemistry Währinger Straße 38 1090 Vienna Austria +43-1-4277-870510 +43-1-4277-70510
| | - Anne C Conibear
- The University of Queensland, School of Biomedical Sciences St Lucia Brisbane 4072 QLD Australia
| | - Christian F W Becker
- University of Vienna, Faculty of Chemistry, Institute of Biological Chemistry Währinger Straße 38 1090 Vienna Austria +43-1-4277-870510 +43-1-4277-70510
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4
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Sorigué D, Hadjidemetriou K, Blangy S, Gotthard G, Bonvalet A, Coquelle N, Samire P, Aleksandrov A, Antonucci L, Benachir A, Boutet S, Byrdin M, Cammarata M, Carbajo S, Cuiné S, Doak RB, Foucar L, Gorel A, Grünbein M, Hartmann E, Hienerwadel R, Hilpert M, Kloos M, Lane TJ, Légeret B, Legrand P, Li-Beisson Y, Moulin SLY, Nurizzo D, Peltier G, Schirò G, Shoeman RL, Sliwa M, Solinas X, Zhuang B, Barends TRM, Colletier JP, Joffre M, Royant A, Berthomieu C, Weik M, Domratcheva T, Brettel K, Vos MH, Schlichting I, Arnoux P, Müller P, Beisson F. Mechanism and dynamics of fatty acid photodecarboxylase. Science 2021; 372:372/6538/eabd5687. [PMID: 33833098 DOI: 10.1126/science.abd5687] [Citation(s) in RCA: 80] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 02/17/2021] [Indexed: 12/21/2022]
Abstract
Fatty acid photodecarboxylase (FAP) is a photoenzyme with potential green chemistry applications. By combining static, time-resolved, and cryotrapping spectroscopy and crystallography as well as computation, we characterized Chlorella variabilis FAP reaction intermediates on time scales from subpicoseconds to milliseconds. High-resolution crystal structures from synchrotron and free electron laser x-ray sources highlighted an unusual bent shape of the oxidized flavin chromophore. We demonstrate that decarboxylation occurs directly upon reduction of the excited flavin by the fatty acid substrate. Along with flavin reoxidation by the alkyl radical intermediate, a major fraction of the cleaved carbon dioxide unexpectedly transformed in 100 nanoseconds, most likely into bicarbonate. This reaction is orders of magnitude faster than in solution. Two strictly conserved residues, R451 and C432, are essential for substrate stabilization and functional charge transfer.
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Affiliation(s)
- D Sorigué
- Aix-Marseille University, CEA, CNRS, Institute of Biosciences and Biotechnologies, BIAM Cadarache, 13108 Saint-Paul-lez-Durance, France
| | - K Hadjidemetriou
- Université Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale, 38000 Grenoble, France
| | - S Blangy
- Aix-Marseille University, CEA, CNRS, Institute of Biosciences and Biotechnologies, BIAM Cadarache, 13108 Saint-Paul-lez-Durance, France
| | - G Gotthard
- European Synchrotron Radiation Facility, 38043 Grenoble, France
| | - A Bonvalet
- LOB, CNRS, INSERM, Ecole Polytechnique, Institut Polytechnique de Paris, 91128 Palaiseau, France
| | - N Coquelle
- Large-Scale Structures Group, Institut Laue Langevin, 38042 Grenoble Cedex 9, France
| | - P Samire
- Aix-Marseille University, CEA, CNRS, Institute of Biosciences and Biotechnologies, BIAM Cadarache, 13108 Saint-Paul-lez-Durance, France.,Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
| | - A Aleksandrov
- LOB, CNRS, INSERM, Ecole Polytechnique, Institut Polytechnique de Paris, 91128 Palaiseau, France
| | - L Antonucci
- LOB, CNRS, INSERM, Ecole Polytechnique, Institut Polytechnique de Paris, 91128 Palaiseau, France
| | - A Benachir
- LOB, CNRS, INSERM, Ecole Polytechnique, Institut Polytechnique de Paris, 91128 Palaiseau, France
| | - S Boutet
- Linac Coherent Light Source (LCLS), SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - M Byrdin
- Université Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale, 38000 Grenoble, France
| | - M Cammarata
- Department of Physics, UMR UR1-CNRS 6251, University of Rennes 1, F-Rennes, France.
| | - S Carbajo
- Linac Coherent Light Source (LCLS), SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - S Cuiné
- Aix-Marseille University, CEA, CNRS, Institute of Biosciences and Biotechnologies, BIAM Cadarache, 13108 Saint-Paul-lez-Durance, France
| | - R B Doak
- Max-Planck-Institut für medizinische Forschung, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - L Foucar
- Max-Planck-Institut für medizinische Forschung, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - A Gorel
- Max-Planck-Institut für medizinische Forschung, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - M Grünbein
- Max-Planck-Institut für medizinische Forschung, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - E Hartmann
- Max-Planck-Institut für medizinische Forschung, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - R Hienerwadel
- Aix-Marseille University, CEA, CNRS, Institute of Biosciences and Biotechnologies, BIAM Cadarache, 13108 Saint-Paul-lez-Durance, France
| | - M Hilpert
- Max-Planck-Institut für medizinische Forschung, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - M Kloos
- Max-Planck-Institut für medizinische Forschung, Jahnstrasse 29, 69120 Heidelberg, Germany.
| | - T J Lane
- Linac Coherent Light Source (LCLS), SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - B Légeret
- Aix-Marseille University, CEA, CNRS, Institute of Biosciences and Biotechnologies, BIAM Cadarache, 13108 Saint-Paul-lez-Durance, France
| | - P Legrand
- Synchrotron SOLEIL. L'Orme des Merisiers Saint-Aubin, BP 48, 91192 Gif-sur-Yvette, France
| | - Y Li-Beisson
- Aix-Marseille University, CEA, CNRS, Institute of Biosciences and Biotechnologies, BIAM Cadarache, 13108 Saint-Paul-lez-Durance, France
| | - S L Y Moulin
- Aix-Marseille University, CEA, CNRS, Institute of Biosciences and Biotechnologies, BIAM Cadarache, 13108 Saint-Paul-lez-Durance, France
| | - D Nurizzo
- European Synchrotron Radiation Facility, 38043 Grenoble, France
| | - G Peltier
- Aix-Marseille University, CEA, CNRS, Institute of Biosciences and Biotechnologies, BIAM Cadarache, 13108 Saint-Paul-lez-Durance, France
| | - G Schirò
- Université Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale, 38000 Grenoble, France
| | - R L Shoeman
- Max-Planck-Institut für medizinische Forschung, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - M Sliwa
- Univ. Lille, CNRS, UMR 8516, LASIRE, LAboratoire de Spectroscopie pour les Interactions, la Réactivité et l'Environnement, 59000 Lille, France
| | - X Solinas
- LOB, CNRS, INSERM, Ecole Polytechnique, Institut Polytechnique de Paris, 91128 Palaiseau, France
| | - B Zhuang
- LOB, CNRS, INSERM, Ecole Polytechnique, Institut Polytechnique de Paris, 91128 Palaiseau, France.,Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
| | - T R M Barends
- Max-Planck-Institut für medizinische Forschung, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - J-P Colletier
- Université Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale, 38000 Grenoble, France
| | - M Joffre
- LOB, CNRS, INSERM, Ecole Polytechnique, Institut Polytechnique de Paris, 91128 Palaiseau, France
| | - A Royant
- Université Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale, 38000 Grenoble, France.,European Synchrotron Radiation Facility, 38043 Grenoble, France
| | - C Berthomieu
- Aix-Marseille University, CEA, CNRS, Institute of Biosciences and Biotechnologies, BIAM Cadarache, 13108 Saint-Paul-lez-Durance, France.
| | - M Weik
- Université Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale, 38000 Grenoble, France.
| | - T Domratcheva
- Max-Planck-Institut für medizinische Forschung, Jahnstrasse 29, 69120 Heidelberg, Germany. .,Department of Chemistry, Lomonosov Moscow State University, Moscow 119991, Russia
| | - K Brettel
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
| | - M H Vos
- LOB, CNRS, INSERM, Ecole Polytechnique, Institut Polytechnique de Paris, 91128 Palaiseau, France.
| | - I Schlichting
- Max-Planck-Institut für medizinische Forschung, Jahnstrasse 29, 69120 Heidelberg, Germany.
| | - P Arnoux
- Aix-Marseille University, CEA, CNRS, Institute of Biosciences and Biotechnologies, BIAM Cadarache, 13108 Saint-Paul-lez-Durance, France.
| | - P Müller
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France.
| | - F Beisson
- Aix-Marseille University, CEA, CNRS, Institute of Biosciences and Biotechnologies, BIAM Cadarache, 13108 Saint-Paul-lez-Durance, France.
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5
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Abstract
Infrared difference spectroscopy probes vibrational changes of proteins upon their perturbation. Compared with other spectroscopic methods, it stands out by its sensitivity to the protonation state, H-bonding, and the conformation of different groups in proteins, including the peptide backbone, amino acid side chains, internal water molecules, or cofactors. In particular, the detection of protonation and H-bonding changes in a time-resolved manner, not easily obtained by other techniques, is one of the most successful applications of IR difference spectroscopy. The present review deals with the use of perturbations designed to specifically change the protein between two (or more) functionally relevant states, a strategy often referred to as reaction-induced IR difference spectroscopy. In the first half of this contribution, I review the technique of reaction-induced IR difference spectroscopy of proteins, with special emphasis given to the preparation of suitable samples and their characterization, strategies for the perturbation of proteins, and methodologies for time-resolved measurements (from nanoseconds to minutes). The second half of this contribution focuses on the spectral interpretation. It starts by reviewing how changes in H-bonding, medium polarity, and vibrational coupling affect vibrational frequencies, intensities, and bandwidths. It is followed by band assignments, a crucial aspect mostly performed with the help of isotopic labeling and site-directed mutagenesis, and complemented by integration and interpretation of the results in the context of the studied protein, an aspect increasingly supported by spectral calculations. Selected examples from the literature, predominately but not exclusively from retinal proteins, are used to illustrate the topics covered in this review.
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6
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Uchida T, Dojun N, Ota K, Sekine Y, Nakamura Y, Umetsu S, Ishimori K. Role of conserved arginine in the heme distal site of HutZ from Vibrio cholerae in the heme degradation reaction. Arch Biochem Biophys 2019; 677:108165. [PMID: 31689379 DOI: 10.1016/j.abb.2019.108165] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 10/25/2019] [Accepted: 10/30/2019] [Indexed: 10/25/2022]
Abstract
HutZ from Vibrio cholerae is a dimeric enzyme that catalyzes degradation of heme. The highly conserved Arg92 residue in the HutZ family is proposed to interact with an iron-bound water molecule in the distal heme pocket. To clarify the specific role of Arg92 in the heme degradation reaction, the residue was substituted with alanine, leucine, histidine or lysine to modulate electrostatic interactions with iron-bound ligand. All four Arg92 mutants reacted with hydrogen peroxide to form verdoheme, a prominent intermediate in the heme degradation process. However, when ascorbic acid was used as an electron source, iron was not released even at pH 6.0 despite a decrease in the Soret band, indicating that non-enzymatic heme degradation occurred. Comparison of the rates of heme reduction, ligand binding and verdoheme formation suggested that proton transfer to the reduced oxyferrous heme, a potential rate-limiting step of heme degradation in HutZ, is hampered by mutation. In our previous study, we found that the increase in the distance between heme and Trp109 from 16 to 18 Å upon lowering the pH from 8.0 to 6.0 leads to activation of ascorbic acid-assisted heme degradation by HutZ. The distance in Arg92 mutants was >19 Å at pH 6.0, suggesting that subunit-subunit interactions at this pH are not suitable for heme degradation, similar to Asp132 and His63 mutants. These results suggest that interactions of Arg92 with heme-bound ligand induce alterations in the distance between subunits, which plays a key role in controlling the heme degradation activity of HutZ.
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Affiliation(s)
- Takeshi Uchida
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, 060-0810, Japan; Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, 060-8628, Japan.
| | - Nobuhiko Dojun
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, 060-0810, Japan
| | - Kazuki Ota
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, 060-0810, Japan
| | - Yukari Sekine
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, 060-0810, Japan
| | - Yuina Nakamura
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, 060-0810, Japan
| | - Sayaka Umetsu
- Division of Chemistry, School of Science, Hokkaido University, Sapporo, 060-0810, Japan
| | - Koichiro Ishimori
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, 060-0810, Japan; Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, 060-8628, Japan
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7
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Fudim R, Szczepek M, Vierock J, Vogt A, Schmidt A, Kleinau G, Fischer P, Bartl F, Scheerer P, Hegemann P. Design of a light-gated proton channel based on the crystal structure of Coccomyxa rhodopsin. Sci Signal 2019; 12:12/573/eaav4203. [PMID: 30890657 DOI: 10.1126/scisignal.aav4203] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The light-driven proton pump Coccomyxa subellipsoidea rhodopsin (CsR) provides-because of its high expression in heterologous host cells-an opportunity to study active proton transport under controlled electrochemical conditions. In this study, solving crystal structure of CsR at 2.0-Å resolution enabled us to identify distinct features of the membrane protein that determine ion transport directivity and voltage sensitivity. A specific hydrogen bond between the highly conserved Arg83 and the nearby nonconserved tyrosine (Tyr14) guided our structure-based transformation of CsR into an operational light-gated proton channel (CySeR) that could potentially be used in optogenetic assays. Time-resolved electrophysiological and spectroscopic measurements distinguished pump currents from channel currents in a single protein and emphasized the necessity of Arg83 mobility in CsR as a dynamic extracellular barrier to prevent passive conductance. Our findings reveal that molecular constraints that distinguish pump from channel currents are structurally more confined than was generally expected. This knowledge might enable the structure-based design of novel optogenetic tools, which derive from microbial pumps and are therefore ion specific.
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Affiliation(s)
- Roman Fudim
- Experimental Biophysics, Institute for Biology, Humboldt-Universität zu Berlin, Invalidenstr. 42, 10115 Berlin, Germany
| | - Michal Szczepek
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Institute for Medical Physics and Biophysics, Group Protein X-ray Crystallography & Signal Transduction, Charitéplatz 1, D-10117 Berlin, Germany
| | - Johannes Vierock
- Experimental Biophysics, Institute for Biology, Humboldt-Universität zu Berlin, Invalidenstr. 42, 10115 Berlin, Germany
| | - Arend Vogt
- Experimental Biophysics, Institute for Biology, Humboldt-Universität zu Berlin, Invalidenstr. 42, 10115 Berlin, Germany
| | - Andrea Schmidt
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Institute for Medical Physics and Biophysics, Group Protein X-ray Crystallography & Signal Transduction, Charitéplatz 1, D-10117 Berlin, Germany
| | - Gunnar Kleinau
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Institute for Medical Physics and Biophysics, Group Protein X-ray Crystallography & Signal Transduction, Charitéplatz 1, D-10117 Berlin, Germany
| | - Paul Fischer
- Experimental Biophysics, Institute for Biology, Humboldt-Universität zu Berlin, Invalidenstr. 42, 10115 Berlin, Germany
| | - Franz Bartl
- Biophysical Chemistry, Institute for Biology, Humboldt-Universität zu Berlin, Invalidenstr. 42, 10115 Berlin, Germany
| | - Patrick Scheerer
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Institute for Medical Physics and Biophysics, Group Protein X-ray Crystallography & Signal Transduction, Charitéplatz 1, D-10117 Berlin, Germany.
| | - Peter Hegemann
- Experimental Biophysics, Institute for Biology, Humboldt-Universität zu Berlin, Invalidenstr. 42, 10115 Berlin, Germany.
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8
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Improved production of bacteriorhodopsin from Halobacterium salinarum through direct amino acid supplement in the basal medium. Extremophiles 2018; 23:133-139. [DOI: 10.1007/s00792-018-1067-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2018] [Accepted: 11/14/2018] [Indexed: 12/28/2022]
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9
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Banyikwa A, Miller SE, Krebs RA, Xiao Y, Carney JM, Braiman MS. Anhydrous Monoalkylguanidines in Aprotic and Nonpolar Solvents: Models for Deprotonated Arginine Side Chains in Membrane Environments. ACS OMEGA 2017; 2:7239-7252. [PMID: 31457300 PMCID: PMC6645140 DOI: 10.1021/acsomega.7b00281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Accepted: 08/22/2017] [Indexed: 06/10/2023]
Abstract
In this study, the synthesis of crystalline dodecylguanidine free base and its spectroscopic characterization in nonpolar environments are described. IR as well as 1H and 15N NMR spectra of the free base dissolved in aprotic solvents are substantially different from the previously reported spectra of arginine, or other monoalkylguanidinium compounds, at high hydroxide concentrations. The current results provide improved modeling for the spectroscopic signals that would be expected from a deprotonated arginine in a nonpolar environment. On the basis of our spectra of the authentic dodecylguanidine free base, addition of large amounts of aqueous hydroxide to arginine or other monoalklyguanidinium salts does not deprotonate them. Instead, hydroxide addition leads to the formation of a guanidinium hydroxide complex, with a dissociation constant near ∼500 mM that accounts for the established arginine pK value of ∼13.7. We also report a method for synthesizing a compound containing both phenol and free-base guanidine groups, linked by a dodecyl chain that should be generalizable to other hydrocarbon linkers. Such alkyl-guanidine and phenolyl-alkyl-guanidine compounds can serve as small-molecule models for the conserved arginine-tyrosine groupings that have been observed in crystallographic structures of both microbial rhodopsins and G-protein-coupled receptors.
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10
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Banyikwa A, Goos A, Kiemle DJ, Foulkes MAC, Braiman MS. Experimental and Computational Modeling of H-Bonded Arginine-Tyrosine Groupings in Aprotic Environments. ACS OMEGA 2017; 2:5641-5659. [PMID: 31457828 PMCID: PMC6644469 DOI: 10.1021/acsomega.7b00282] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Accepted: 06/28/2017] [Indexed: 06/08/2023]
Abstract
H-bonds between neutral tyrosine and arginine in nonpolar environments are modeled by small-molecule phenol/guanidine complexes. From the temperature and concentration dependence of UV spectra, a value of ΔH° = -74 ± 4 kJ mol-1 is deduced for the formation of H-bonded p-cresol/dodecylguanidine in hexane. ΔE = -71 kJ mol-1 is computed with density functional theory (in vacuo). In dimethyl sulfoxide or crystals, (p-phenolyl)alkylguanidines form head-to-tail homodimers with two strong H-bonding interactions, as evidenced by UV, IR, and NMR spectral shifts, strong IR continuum absorbance bands, and short O···N distances in X-ray crystal structures. Phenol/alkylguanidine H-bonded complexes consist of polarizable rapidly interconverting tautomers, with the proton shift from phenol to guanidine increasing with increase in the polarity of the aprotic solvent. As measured by NMR, both groups in these strongly H-bonded neutral complexes can simultaneously appear to be predominantly protonated. These systems serve as models for the hypothetical hydrogen-Bonded Uncharged (aRginine + tYrosine), or "BU(RY)", motifs in membrane proteins.
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Affiliation(s)
- Andrew
Toyi Banyikwa
- Chemistry
Department, Center for Science & Technology, Syracuse University, Room 1-014, Syracuse, New
York 13244, United
States
| | - Alan Goos
- Chemistry
Department, Center for Science & Technology, Syracuse University, Room 1-014, Syracuse, New
York 13244, United
States
| | - David J. Kiemle
- Analytical
and Technical Services, SUNY College of
Environmental Science and Forestry, 123 Jahn Laboratory, Syracuse, New York 13210, United
States
| | - Michael A. C. Foulkes
- Chemistry
Department, Center for Science & Technology, Syracuse University, Room 1-014, Syracuse, New
York 13244, United
States
| | - Mark S. Braiman
- Chemistry
Department, Center for Science & Technology, Syracuse University, Room 1-014, Syracuse, New
York 13244, United
States
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11
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Yonezawa K, Shimizu N, Kurihara K, Yamazaki Y, Kamikubo H, Kataoka M. Neutron crystallography of photoactive yellow protein reveals unusual protonation state of Arg52 in the crystal. Sci Rep 2017; 7:9361. [PMID: 28839266 PMCID: PMC5570954 DOI: 10.1038/s41598-017-09718-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 07/28/2017] [Indexed: 11/09/2022] Open
Abstract
Because of its high pKa, arginine (Arg) is believed to be protonated even in the hydrophobic environment of the protein interior. However, our neutron crystallographic structure of photoactive yellow protein, a light sensor, demonstrated that Arg52 adopts an electrically neutral form. We also showed that the hydrogen bond between the chromophore and Glu46 is a so-called low barrier hydrogen bond (LBHB). Because both the neutral Arg and LBHB are unusual in proteins, these observations remain controversial. To validate our findings, we carried out neutron crystallographic analysis of the E46Q mutant of PYP. The resultant structure revealed that the proportion of the cationic form is higher in E46Q than in WT, although the cationic and neutral forms of Arg52 coexist in E46Q. These observations were confirmed by the occupancy of the deuterium atom bound to the N η1 atom combined with an alternative conformation of the N(η2)D2 group comprising sp2 hybridisation. Based on these results, we propose that the formation of the LBHB decreases the proton affinity of Arg52, stabilizing the neutral form in the crystal.
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Affiliation(s)
- Kento Yonezawa
- Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara, 630-0192, Japan
| | - Nobutaka Shimizu
- Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki, 305-0801, Japan
| | - Kazuo Kurihara
- National Institutes for Quantum and Radiological Science and Technology (QST), 2-4 Oaza- Shirakata, Tokai, Ibaraki, 319-1106, Japan
| | - Yoichi Yamazaki
- Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara, 630-0192, Japan
| | - Hironari Kamikubo
- Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara, 630-0192, Japan.
| | - Mikio Kataoka
- Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara, 630-0192, Japan. .,Comprehensive Research Organization for Science and Society, Research Center for Neutron Science and Technology, 162-1 Shirakata, Tokai, Ibaraki, 319-1106, Japan.
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12
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Yoshimura Y, Oktaviani NA, Yonezawa K, Kamikubo H, Mulder FAA. Unambiguous Determination of Protein Arginine Ionization States in Solution by NMR Spectroscopy. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201609605] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Yuichi Yoshimura
- Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry Aarhus University Gustav Wieds Vej 14 8000 Aarhus C Denmark
| | - Nur Alia Oktaviani
- Groningen Biomolecular Sciences and Biotechnology Institute University of Groningen The Netherlands
| | - Kento Yonezawa
- Graduate School of Materials Science Nara Institute of Science and Technology, Ikoma, Nara Japan
| | - Hironari Kamikubo
- Graduate School of Materials Science Nara Institute of Science and Technology, Ikoma, Nara Japan
| | - Frans A. A. Mulder
- Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry Aarhus University Gustav Wieds Vej 14 8000 Aarhus C Denmark
- Groningen Biomolecular Sciences and Biotechnology Institute University of Groningen The Netherlands
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13
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Avilés-Moreno JR, Berden G, Oomens J, Martínez-Haya B. Isolated complexes of the amino acid arginine with polyether and polyamine macrocycles, the role of proton transfer. Phys Chem Chem Phys 2017; 19:31345-31351. [DOI: 10.1039/c7cp04270a] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Protonated arginine interacts with 12-crown-4 through the guanidinium side group. In the complex with the N-substituted analog cyclen, the dominant conformation is the result of the proton transfer from the carboxylic acid group of the amino acid to the macrocycle.
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Affiliation(s)
- Juan Ramón Avilés-Moreno
- Department of Physical
- Chemical and Natural Systems
- Universidad Pablo de Olavide
- E-41013 Seville
- Spain
| | - Giel Berden
- Radboud University
- Institute for Molecules and Materials
- FELIX Laboratory
- 6525ED Nijmegen
- The Netherlands
| | - Jos Oomens
- Radboud University
- Institute for Molecules and Materials
- FELIX Laboratory
- 6525ED Nijmegen
- The Netherlands
| | - Bruno Martínez-Haya
- Department of Physical
- Chemical and Natural Systems
- Universidad Pablo de Olavide
- E-41013 Seville
- Spain
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14
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Yoshimura Y, Oktaviani NA, Yonezawa K, Kamikubo H, Mulder FAA. Unambiguous Determination of Protein Arginine Ionization States in Solution by NMR Spectroscopy. Angew Chem Int Ed Engl 2016; 56:239-242. [PMID: 27897362 DOI: 10.1002/anie.201609605] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Indexed: 11/09/2022]
Abstract
Because arginine residues in proteins are expected to be in their protonated form almost without exception, reports demonstrating that a protein arginine residue is charge-neutral are rare and potentially controversial. Herein, we present a 13 C-detected NMR experiment for probing individual arginine residues in proteins notwithstanding the presence of chemical and conformational exchange effects. In the experiment, the 15 Nη and 15 Nϵ chemical shifts of an arginine head group are correlated with that of the directly attached 13 Cζ . In the resulting spectrum, the number of protons in the arginine head group can be obtained directly from the 15 N-1 H scalar coupling splitting pattern. We applied this method to unambiguously determine the ionization state of the R52 side chain in the photoactive yellow protein from Halorhodospira halophila. Although only three Hη atoms were previously identified by neutron crystallography, we show that R52 is predominantly protonated in solution.
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Affiliation(s)
- Yuichi Yoshimura
- Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, Aarhus University, Gustav Wieds Vej 14, 8000, Aarhus C, Denmark
| | - Nur Alia Oktaviani
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, The Netherlands
| | - Kento Yonezawa
- Graduate School of Materials Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan
| | - Hironari Kamikubo
- Graduate School of Materials Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan
| | - Frans A A Mulder
- Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, Aarhus University, Gustav Wieds Vej 14, 8000, Aarhus C, Denmark.,Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, The Netherlands
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15
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Conversion of a light-driven proton pump into a light-gated ion channel. Sci Rep 2015; 5:16450. [PMID: 26597707 PMCID: PMC4657025 DOI: 10.1038/srep16450] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 10/14/2015] [Indexed: 12/19/2022] Open
Abstract
Interest in microbial rhodopsins with ion pumping activity has been revitalized in the context of optogenetics, where light-driven ion pumps are used for cell hyperpolarization and voltage sensing. We identified an opsin-encoding gene (CsR) in the genome of the arctic alga Coccomyxa subellipsoidea C-169 that can produce large photocurrents in Xenopus oocytes. We used this property to analyze the function of individual residues in proton pumping. Modification of the highly conserved proton shuttling residue R83 or its interaction partner Y57 strongly reduced pumping power. Moreover, this mutation converted CsR at moderate electrochemical load into an operational proton channel with inward or outward rectification depending on the amino acid substitution. Together with molecular dynamics simulations, these data demonstrate that CsR-R83 and its interacting partner Y57 in conjunction with water molecules forms a proton shuttle that blocks passive proton flux during the dark-state but promotes proton movement uphill upon illumination.
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16
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Koniev O, Wagner A. Developments and recent advancements in the field of endogenous amino acid selective bond forming reactions for bioconjugation. Chem Soc Rev 2015; 44:5495-551. [PMID: 26000775 DOI: 10.1039/c5cs00048c] [Citation(s) in RCA: 388] [Impact Index Per Article: 43.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Bioconjugation methodologies have proven to play a central enabling role in the recent development of biotherapeutics and chemical biology approaches. Recent endeavours in these fields shed light on unprecedented chemical challenges to attain bioselectivity, biocompatibility, and biostability required by modern applications. In this review the current developments in various techniques of selective bond forming reactions of proteins and peptides were highlighted. The utility of each endogenous amino acid-selective conjugation methodology in the fields of biology and protein science has been surveyed with emphasis on the most relevant among reported transformations; selectivity and practical use have been discussed.
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Affiliation(s)
- Oleksandr Koniev
- Laboratory of Functional Chemo-Systems (UMR 7199), Labex Medalis, University of Strasbourg, 74 Route du Rhin, 67401 Illkirch-Graffenstaden, France.
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17
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Fitch CA, Platzer G, Okon M, Garcia-Moreno BE, McIntosh LP. Arginine: Its pKa value revisited. Protein Sci 2015; 24:752-61. [PMID: 25808204 DOI: 10.1002/pro.2647] [Citation(s) in RCA: 216] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 01/23/2015] [Accepted: 01/26/2015] [Indexed: 12/25/2022]
Abstract
Using complementary approaches of potentiometry and NMR spectroscopy, we have determined that the equilibrium acid dissociation constant (pKa value) of the arginine guanidinium group is 13.8 ± 0.1. This is substantially higher than that of ∼ 12 often used in structure-based electrostatics calculations and cited in biochemistry textbooks. The revised intrinsic pKa value helps explains why arginine side chains in proteins are always predominantly charged, even at pH values as great as 10. The high pKa value also reinforces the observation that arginine side chains are invariably protonated under physiological conditions of near neutral pH. This occurs even when the guanidinium moiety is buried in a hydrophobic micro-environment, such as that inside a protein or a lipid membrane, thought to be incompatible with the presence of a charged group.
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Affiliation(s)
- Carolyn A Fitch
- Department of Biophysics, Johns Hopkins University, Baltimore, Maryland, 21218
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18
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Platzer G, Okon M, McIntosh LP. pH-dependent random coil (1)H, (13)C, and (15)N chemical shifts of the ionizable amino acids: a guide for protein pK a measurements. JOURNAL OF BIOMOLECULAR NMR 2014; 60:109-129. [PMID: 25239571 DOI: 10.1007/s10858-014-9862-y] [Citation(s) in RCA: 149] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 09/09/2014] [Indexed: 06/03/2023]
Abstract
The pK a values and charge states of ionizable residues in polypeptides and proteins are frequently determined via NMR-monitored pH titrations. To aid the interpretation of the resulting titration data, we have measured the pH-dependent chemical shifts of nearly all the (1)H, (13)C, and (15)N nuclei in the seven common ionizable amino acids (X = Asp, Glu, His, Cys, Tyr, Lys, and Arg) within the context of a blocked tripeptide, acetyl-Gly-X-Gly-amide. Alanine amide and N-acetyl alanine were used as models of the N- and C-termini, respectively. Together, this study provides an essentially complete set of pH-dependent intra-residue and nearest-neighbor reference chemical shifts to help guide protein pK a measurements. These data should also facilitate pH-dependent corrections in algorithms used to predict the chemical shifts of random coil polypeptides. In parallel, deuterium isotope shifts for the side chain (15)N nuclei of His, Lys, and Arg in their positively-charged and neutral states were also measured. Along with previously published results for Asp, Glu, Cys, and Tyr, these deuterium isotope shifts can provide complementary experimental evidence for defining the ionization states of protein residues.
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Affiliation(s)
- Gerald Platzer
- Department of Biochemistry and Molecular Biology, Life Sciences Centre, 2350 Health Sciences Mall, University of British Columbia, Vancouver, BC, V6T 1Z3, Canada
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19
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Gunner MR, Amin M, Zhu X, Lu J. Molecular mechanisms for generating transmembrane proton gradients. BIOCHIMICA ET BIOPHYSICA ACTA 2013; 1827:892-913. [PMID: 23507617 PMCID: PMC3714358 DOI: 10.1016/j.bbabio.2013.03.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 01/28/2013] [Accepted: 03/01/2013] [Indexed: 01/02/2023]
Abstract
Membrane proteins use the energy of light or high energy substrates to build a transmembrane proton gradient through a series of reactions leading to proton release into the lower pH compartment (P-side) and proton uptake from the higher pH compartment (N-side). This review considers how the proton affinity of the substrates, cofactors and amino acids are modified in four proteins to drive proton transfers. Bacterial reaction centers (RCs) and photosystem II (PSII) carry out redox chemistry with the species to be oxidized on the P-side while reduction occurs on the N-side of the membrane. Terminal redox cofactors are used which have pKas that are strongly dependent on their redox state, so that protons are lost on oxidation and gained on reduction. Bacteriorhodopsin is a true proton pump. Light activation triggers trans to cis isomerization of a bound retinal. Strong electrostatic interactions within clusters of amino acids are modified by the conformational changes initiated by retinal motion leading to changes in proton affinity, driving transmembrane proton transfer. Cytochrome c oxidase (CcO) catalyzes the reduction of O2 to water. The protons needed for chemistry are bound from the N-side. The reduction chemistry also drives proton pumping from N- to P-side. Overall, in CcO the uptake of 4 electrons to reduce O2 transports 8 charges across the membrane, with each reduction fully coupled to removal of two protons from the N-side, the delivery of one for chemistry and transport of the other to the P-side.
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Affiliation(s)
- M R Gunner
- Department of Physics, City College of New York, New York, NY 10031, USA.
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20
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Quinone-dependent proton transfer pathways in the photosynthetic cytochrome b6f complex. Proc Natl Acad Sci U S A 2013; 110:4297-302. [PMID: 23440205 DOI: 10.1073/pnas.1222248110] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
As much as two-thirds of the proton gradient used for transmembrane free energy storage in oxygenic photosynthesis is generated by the cytochrome b6f complex. The proton uptake pathway from the electrochemically negative (n) aqueous phase to the n-side quinone binding site of the complex, and a probable route for proton exit to the positive phase resulting from quinol oxidation, are defined in a 2.70-Å crystal structure and in structures with quinone analog inhibitors at 3.07 Å (tridecyl-stigmatellin) and 3.25-Å (2-nonyl-4-hydroxyquinoline N-oxide) resolution. The simplest n-side proton pathway extends from the aqueous phase via Asp20 and Arg207 (cytochrome b6 subunit) to quinone bound axially to heme c(n). On the positive side, the heme-proximal Glu78 (subunit IV), which accepts protons from plastosemiquinone, defines a route for H(+) transfer to the aqueous phase. These pathways provide a structure-based description of the quinone-mediated proton transfer responsible for generation of the transmembrane electrochemical potential gradient in oxygenic photosynthesis.
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21
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Morgan JE, Vakkasoglu AS, Lanyi JK, Lugtenburg J, Gennis RB, Maeda A. Structure changes upon deprotonation of the proton release group in the bacteriorhodopsin photocycle. Biophys J 2013; 103:444-452. [PMID: 22947860 DOI: 10.1016/j.bpj.2012.06.022] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2012] [Revised: 05/19/2012] [Accepted: 06/04/2012] [Indexed: 11/18/2022] Open
Abstract
In the photocycle of bacteriorhodopsin at pH 7, a proton is ejected to the extracellular medium during the protonation of Asp-85 upon formation of the M intermediate. The group that releases the ejected proton does not become reprotonated until the prephotolysis state is restored from the N and O intermediates. In contrast, at acidic pH, this proton release group remains protonated to the end of the cycle. Time-resolved Fourier transform infrared measurements obtained at pH 5 and 7 were fitted to obtain spectra of kinetic intermediates, from which the spectra of M and N/O versus unphotolyzed state were calculated. Vibrational features that appear in both M and N/O spectra at pH 7, but not at pH 5, are attributable to deprotonation from the proton release group and resulting structural alterations. Our results agree with the earlier conclusion that this group is a protonated internal water cluster, and provide a stronger experimental basis for this assignment. A decrease in local polarity at the N-C bond of the side chain of Lys-216 resulting from deprotonation of this water cluster may be responsible for the increase in the proton affinity of Asp-85 through M and N/O, which is crucial for maintaining the directionality of proton pumping.
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Affiliation(s)
- Joel E Morgan
- Department of Biology, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York
| | - Ahmet S Vakkasoglu
- Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Janos K Lanyi
- Department of Physiology and Biophysics, University of California, Irvine, California
| | - Johan Lugtenburg
- Department of Chemistry, University of Leiden, Leiden, The Netherlands
| | - Robert B Gennis
- Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois; Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Akio Maeda
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois.
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22
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Singh R, Grigg JC, Armstrong Z, Murphy MEP, Eltis LD. Distal heme pocket residues of B-type dye-decolorizing peroxidase: arginine but not aspartate is essential for peroxidase activity. J Biol Chem 2012; 287:10623-10630. [PMID: 22308037 DOI: 10.1074/jbc.m111.332171] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
DypB from Rhodococcus jostii RHA1 is a bacterial dye-decolorizing peroxidase (DyP) that oxidizes lignin and Mn(II). Three residues interact with the iron-bound solvent species in ferric DypB: Asn-246 and the conserved Asp-153 and Arg-244. Substitution of either Asp-153 or Asn-246 with alanine minimally affected the second order rate constant for Compound I formation (k(1) ∼ 10(5) M(-1)s(-1)) and the specificity constant (k(cat)/K(m)) for H(2)O(2). Even in the D153A/N246A double variant, these values were reduced less than 30-fold. However, these substitutions dramatically reduced the stability of Compound I (t(1/2) ∼ 0.13 s) as compared with the wild-type enzyme (540 s). By contrast, substitution of Arg-244 with leucine abolished the peroxidase activity, and heme iron of the variant showed a pH-dependent transition from high spin (pH 5) to low spin (pH 8.5). Two variants were designed to mimic the plant peroxidase active site: D153H, which was more than an order of magnitude less reactive with H(2)O(2), and N246H, which had no detectable peroxidase activity. X-ray crystallographic studies revealed that structural changes in the variants are confined to the distal heme environment. The data establish an essential role for Arg-244 in Compound I formation in DypB, possibly through charge stabilization and proton transfer. The principle roles of Asp-153 and Asn-246 appear to be in modulating the subsequent reactivity of Compound I. These results expand the range of residues known to catalyze Compound I formation in heme peroxidases.
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Affiliation(s)
- Rahul Singh
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Jason C Grigg
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Zachary Armstrong
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Michael E P Murphy
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Lindsay D Eltis
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada.
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23
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Clair ECS, Ogren JI, Mamaev S, Kralj JM, Rothschild KJ. Conformational changes in the archaerhodopsin-3 proton pump: detection of conserved strongly hydrogen bonded water networks. J Biol Phys 2011; 38:153-68. [PMID: 23277676 DOI: 10.1007/s10867-011-9246-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2011] [Accepted: 10/25/2011] [Indexed: 11/30/2022] Open
Abstract
Archaerhodopsin-3 (AR3) is a light-driven proton pump from Halorubrum sodomense, but little is known about its photocycle. Recent interest has focused on AR3 because of its ability to serve both as a high-performance, genetically-targetable optical silencer of neuronal activity and as a membrane voltage sensor. We examined light-activated structural changes of the protein, retinal chromophore, and internal water molecules during the photocycle of AR3. Low-temperature and rapid-scan time-resolved FTIR-difference spectroscopy revealed that conformational changes during formation of the K, M, and N photocycle intermediates are similar, although not identical, to bacteriorhodopsin (BR). Positive/negative bands in the region above 3,600 cm( - 1), which have previously been assigned to structural changes of weakly hydrogen bonded internal water molecules, were substantially different between AR3 and BR. This included the absence of positive bands recently associated with a chain of proton transporting water molecules in the cytoplasmic channel and a weakly hydrogen bonded water (W401), which is part of a hydrogen-bonded pentagonal cluster located near the retinal Schiff base. However, many of the broad IR continuum absorption changes below 3,000 cm( - 1) assigned to networks of water molecules involved in proton transport through cytoplasmic and extracellular portions in BR were very similar in AR3. This work and subsequent studies comparing BR and AR3 structural changes will help identify conserved elements in BR-like proton pumps as well as bioengineer AR3 to optimize neural silencing and voltage sensing.
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Affiliation(s)
- Erica C Saint Clair
- Department of Physics, Photonics Center and Molecular Biophysics Laboratory, Boston University, Boston, MA 02215 USA
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24
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Shimada Y, Suzuki H, Tsuchiya T, Mimuro M, Noguchi T. Structural Coupling of an Arginine Side Chain with the Oxygen-Evolving Mn4Ca Cluster in Photosystem II As Revealed by Isotope-Edited Fourier Transform Infrared Spectroscopy. J Am Chem Soc 2011; 133:3808-11. [DOI: 10.1021/ja200186h] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yuichiro Shimada
- Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501, Japan
| | - Hiroyuki Suzuki
- Institute of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573, Japan
| | - Tohru Tsuchiya
- Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501, Japan
| | - Mamoru Mimuro
- Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501, Japan
| | - Takumi Noguchi
- Institute of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573, Japan
- Division of Material Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
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25
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Morgan JE, Vakkasoglu AS, Lanyi JK, Gennis RB, Maeda A. Coordinating the structural rearrangements associated with unidirectional proton transfer in the bacteriorhodopsin photocycle induced by deprotonation of the proton-release group: a time-resolved difference FTIR spectroscopic study. Biochemistry 2010; 49:3273-81. [PMID: 20232848 DOI: 10.1021/bi901757y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In the photocycle of bacteriorhodopsin at pH 7, proton release from the proton releasing group (PRG) to the extracellular medium occurs during formation of the M intermediate. This proton release is inhibited at acidic pH, below the pK(a) of the PRG, approximately 6 in M, and instead occurs later in the cycle as the initial state is restored from the O intermediate. Here, structural changes related to deprotonation of the PRG have been investigated by time-resolved FTIR spectroscopy at 25 degrees C. The vibrational features at 2100-1790, 1730-1685, 1661, and 1130-1045 cm(-1) have greater negative intensity in the pure M-minus-BR spectrum and even in the M-minus-BR spectrum, that is present earlier together with the L-minus-BR spectrum, at pH 7, than in the corresponding M-minus-BR spectra at pH 5 or 4. The D212N mutation abolishes the decreases in the intensities of the broad feature between 1730 and 1685 cm(-1) and the band at 1661 cm(-1). The 1730-1685 cm(-1) feature may arise from transition dipole coupling of the backbone carbonyl groups of Glu204, Phe208, Asp212, and Lys216 interacting with Tyr57 and C(15)-H of the chromophore. The 1661 cm(-1) band, which is insensitive to D(2)O substitution, may arise by interaction of the backbone carbonyl of Asp212 with C(15)-H. The 2100-1790 cm(-1) feature with a trough at 1885 cm(-1) could be due to a water cluster. Depletion of these bands upon deprotonation of the PRG is attributable to disruption of a coordinated structure, held in place by interactions of Asp212. Deprotonation of the PRG is also accompanied by disruption of the interaction of the water molecule near Arg82. The liberated Asp212 may stabilize the protonated state of Asp85 and thus confer unidirectionality to the transport.
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Affiliation(s)
- Joel E Morgan
- Department of Biology, Center for Biotechnology and Interdisciplinary Studies, Room 2137, Rensselaer Polytechnic Institute, 110 Eighth Street, Troy, New York 12180, USA
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26
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Yamamoto M, Hayakawa N, Murakami M, Kouyama T. Crystal structures of different substrates of bacteriorhodopsin's M intermediate at various pH levels. J Mol Biol 2009; 393:559-73. [PMID: 19712684 DOI: 10.1016/j.jmb.2009.08.047] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2009] [Revised: 08/18/2009] [Accepted: 08/19/2009] [Indexed: 11/16/2022]
Abstract
The hexagonal P622 crystal of bacteriorhodopsin, which is made up of stacked membranes, is stable provided that the precipitant concentration in the soaking solution is higher than a critical value (i.e., 1.5 M ammonium sulfate). Diffraction data showed that the crystal lattice shrank linearly with increasing precipitant concentration, due primarily to narrowing of intermembrane spaces. Although the crystal shrinkage did not affect the rate of formation of the photoreaction M intermediate, its lifetime increased exponentially with the precipitant concentration. It was suggested that the energetic barrier of the M-to-N transition becomes higher when the motional freedom of the EF loop is reduced by crystal lattice force. As a result of this property, the M state accumulated predominantly when the crystal that was soaked at a high precipitant concentration was illuminated at room temperature. Structural data obtained at various pH levels showed that the overall structure of M is not strongly dependent on pH, except that Glu194 and Glu204 in the proton release complex are more separated at pH 7 than at pH 4.4. This result suggests that light-induced disruption of the paired structure of Glu194 and Glu204 is incomplete when external pH is lower than the pK(a) value of the proton release group in the M state.
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Affiliation(s)
- Masataka Yamamoto
- Department of Physics, Graduate School of Science, Nagoya University, Nagoya, Japan
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Seeger MA, von Ballmoos C, Verrey F, Pos KM. Crucial Role of Asp408 in the Proton Translocation Pathway of Multidrug Transporter AcrB: Evidence from Site-Directed Mutagenesis and Carbodiimide Labeling. Biochemistry 2009; 48:5801-12. [DOI: 10.1021/bi900446j] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Markus A. Seeger
- Institute of Physiology and Zurich Centre for Integrative Human Physiology (ZIHP), University of Zurich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
- Institute of Microbiology, Swiss Federal Institute of Technology (ETH), Wolfgang-Pauli-Strasse 10, CH-8093 Zürich, Switzerland
| | - Christoph von Ballmoos
- Institute of Microbiology, Swiss Federal Institute of Technology (ETH), Wolfgang-Pauli-Strasse 10, CH-8093 Zürich, Switzerland
| | - François Verrey
- Institute of Physiology and Zurich Centre for Integrative Human Physiology (ZIHP), University of Zurich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - Klaas M. Pos
- Institute of Physiology and Zurich Centre for Integrative Human Physiology (ZIHP), University of Zurich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
- Cluster of Excellence Frankfurt-Macromolecular Complexes, Institute of Biochemistry, Goethe-University Frankfurt am Main, Max-von-Laue-Strasse 9, D-60438 Frankfurt am Main, Germany
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28
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Affiliation(s)
- James P McEvoy
- Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520-8107, USA
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29
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Narváez AJ, Voevodskaya N, Thelander L, Gräslund A. The Involvement of Arg265 of Mouse Ribonucleotide Reductase R2 Protein in Proton Transfer and Catalysis. J Biol Chem 2006; 281:26022-8. [PMID: 16829694 DOI: 10.1074/jbc.m604598200] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ribonucleotide reductase class I enzymes consist of two non-identical subunits, R1 and R2, the latter containing a diiron carboxylate center and a stable tyrosyl radical (Tyr*), both essential for catalysis. Catalysis is known to involve highly conserved amino acid residues covering a range of approximately 35 A and a concerted mechanism involving long range electron transfer, probably coupled to proton transfer. A number of residues involved in electron transfer in both the R1 and R2 proteins have been identified, but no direct model has been presented regarding the proton transfer side of the process. Arg265 is conserved in all known sequences of class Ia R2. In this study we have used site-directed mutagenesis to gain insight into the role of this residue, which lies close to the catalytically essential Asp266 and Trp103. Mutants to Arg265 included replacement by Ala, Glu, Gln, and Tyr. All mutants of Arg265 were found to have no or low catalytic activity with the exception of Arg265 to Glu, which shows approximately 40% of the activity of native R2. We also found that the Arg mutants were capable of stable tyrosyl radical generation, with similar kinetics of radical formation and R1 binding as native R2. Our results, supported by molecular modeling, strongly suggest that Arg265 is involved in the proton-coupled electron transfer pathway and may act as a proton mediator during catalysis.
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Affiliation(s)
- Ana J Narváez
- Department of Biochemistry and Biophysics, Stockholm University, SE-10691 Stockholm, Sweden
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30
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Arkin IT. Isotope-edited IR spectroscopy for the study of membrane proteins. Curr Opin Chem Biol 2006; 10:394-401. [PMID: 16935550 PMCID: PMC7185810 DOI: 10.1016/j.cbpa.2006.08.013] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2006] [Accepted: 08/15/2006] [Indexed: 11/25/2022]
Abstract
Fourier transform infrared (FTIR) spectroscopy has long been a powerful tool for structural analysis of membrane proteins. However, because of difficulties in resolving contributions from individual residues, most of the derived measurements tend to yield average properties for the system under study. Isotope editing, through its ability to resolve individual vibrations, establishes FTIR as a method that is capable of yielding accurate structural data on individual sites in a protein.
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Affiliation(s)
- Isaiah T Arkin
- The Alexander Silberman Institute of Life Sciences, Department of Biological Chemistry, The Hebrew University of Jerusalem, Edmund J Safra Campus, Givat-Ram, Jerusalem, Israel.
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31
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Lanyi JK. Proton transfers in the bacteriorhodopsin photocycle. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2006; 1757:1012-8. [PMID: 16376293 DOI: 10.1016/j.bbabio.2005.11.003] [Citation(s) in RCA: 156] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2005] [Revised: 11/08/2005] [Accepted: 11/10/2005] [Indexed: 11/23/2022]
Abstract
The steps in the mechanism of proton transport in bacteriorhodopsin include examples for most kinds of proton transfer reactions that might occur in a transmembrane pump: proton transfer via a bridging water molecule, coupled protonation/deprotonation of two buried groups separated by a considerable distance, long-range proton migration over a hydrogen-bonded aqueous chain, and capture as well as release of protons at the membrane-water interface. The conceptual and technical advantages of this system have allowed close examination of many of these model reactions, some at an atomic level.
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Affiliation(s)
- Janos K Lanyi
- Department of Physiology and Biophysics, University of California, Irvine, CA 92697, USA.
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32
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Gunner MR, Mao J, Song Y, Kim J. Factors influencing the energetics of electron and proton transfers in proteins. What can be learned from calculations. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2006; 1757:942-68. [PMID: 16905113 PMCID: PMC2760439 DOI: 10.1016/j.bbabio.2006.06.005] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2006] [Revised: 06/07/2006] [Accepted: 06/13/2006] [Indexed: 11/15/2022]
Abstract
A protein structure should provide the information needed to understand its observed properties. Significant progress has been made in developing accurate calculations of acid/base and oxidation/reduction reactions in proteins. Current methods and their strengths and weaknesses are discussed. The distribution and calculated ionization states in a survey of proteins is described, showing that a significant minority of acidic and basic residues are buried in the protein and that most of these remain ionized. The electrochemistry of heme and quinones are considered. Proton transfers in bacteriorhodopsin and coupled electron and proton transfers in photosynthetic reaction centers, 5-coordinate heme binding proteins and cytochrome c oxidase are highlighted as systems where calculations have provided insight into the reaction mechanism.
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Affiliation(s)
- M R Gunner
- Physics Department City College of New York, New York, NY 10031, USA.
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33
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Ming M, Lu M, Balashov SP, Ebrey TG, Li Q, Ding J. pH dependence of light-driven proton pumping by an archaerhodopsin from Tibet: comparison with bacteriorhodopsin. Biophys J 2006; 90:3322-32. [PMID: 16473896 PMCID: PMC1432102 DOI: 10.1529/biophysj.105.076547] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2005] [Accepted: 01/19/2006] [Indexed: 11/18/2022] Open
Abstract
The pH-dependence of photocycle of archaerhodopsin 4 (AR4) was examined, and the underlying proton pumping mechanism investigated. AR4 is a retinal-containing membrane protein isolated from a strain of halobacteria from a Tibetan salt lake. It acts as a light-driven proton pump like bacteriorhodopsin (BR). However, AR4 exhibits an "abnormal" feature--the time sequence of proton release and uptake is reversed at neutral pH. We show here that the temporal sequence of AR4 reversed to "normal"--proton release preceding proton uptake--when the pH is increased above 8.6. We estimated the pK(a) of the proton release complex (PRC) in the M-intermediate to be approximately 8.4, much higher than 5.7 of wide-type BR. The pH-dependence of the rate constant of M-formation shows that the pK(a) of PRC in the initial state of AR4 is approximately 10.4, whereas it is 9.7 in BR. Thus in AR4, the chromophore photoisomerization and subsequent proton transport from the Schiff base to Asp-85 is coupled to a decrease in the pK(a) of PRC from 10.4 to 8.4, which is 2 pK units less than in BR (4 units). This weakened coupling accounts for the lack of early proton release at neutral pH and the reversed time sequence of proton release and uptake in AR4. Nevertheless the PRC in AR4 effectively facilitates deprotonation of primary proton acceptor and recovery of initial state at neutral pH. We found also that all pK(a)s of the key amino acid residues in AR4 were elevated compared to those of BR.
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Affiliation(s)
- Ming Ming
- Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai, China
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Brown LS, Jung KH. Bacteriorhodopsin-like proteins of eubacteria and fungi: the extent of conservation of the haloarchaeal proton-pumping mechanism. Photochem Photobiol Sci 2006; 5:538-46. [PMID: 16761082 DOI: 10.1039/b514537f] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A stereotypical image of a retinal-binding proton pump derived from extensive studies of halobacterial ion-transporting and sensory rhodopsins is a fast-cycling protein which possesses two strategically placed carboxylic acids serving as proton donor and acceptor for the retinal Schiff base. We review recent biophysical and bioinformatic data on the novel eubacterial and eucaryotic rhodopsins to analyze the extent of conservation of the haloarchaeal mechanism of transmembrane proton transport. We show that only the most essential elements of the haloarchaeal proton-pumping machinery are conserved universally, and that a mere presence of these elements in primary structures does not guarantee the proton-pumping ability.
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Affiliation(s)
- Leonid S Brown
- Department of Physics, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
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Garczarek F, Brown LS, Lanyi JK, Gerwert K. Proton binding within a membrane protein by a protonated water cluster. Proc Natl Acad Sci U S A 2005; 102:3633-8. [PMID: 15738416 PMCID: PMC553315 DOI: 10.1073/pnas.0500421102] [Citation(s) in RCA: 176] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Proton transfer is crucial for many enzyme reactions. Here, we show that in addition to protonatable amino acid side chains, water networks could constitute proton-binding sites in proteins. A broad IR continuum absorbance change during the proton pumping photocycle of bacteriorhodopsin (bR) indicates most likely deprotonation of a protonated water cluster at the proton release site close to the surface. We investigate the influence of several mutations on the proton release network and the continuum change, to gain information about the location and extent of the protonated water network and to reveal the participating residues necessary for its stabilization. We identify a protonated water cluster consisting in total of one proton and about five water molecules surrounded by six side chains and three backbone groups (Tyr-57, Arg-82, Tyr-83, Glu-204, Glu-194, Ser-193, Pro-77, Tyr-79, and Thr-205). The observed perturbation of proton release by many single-residue mutations is now explained by the influence of numerous side chains on the protonated H bonded network. In situ hydrogen/deuterium exchange Fourier transform IR measurements of the bR ground state, show that the proton of the release group becomes localized on Glu-204 and Asp-204 in the ground state of the mutants E194D and E204D, respectively, even though it is delocalized in the ground state of wild-type bR. Thus, the release mechanism switches between the wild-type and mutated proteins from a delocalized to a localized proton-binding site.
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Affiliation(s)
- Florian Garczarek
- Lehrstuhl für Biophysik, Ruhr-Universität Bochum, D-44780 Bochum, Germany
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