1
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Leighton RE, Frontiera RR. Quantifying Bacteriorhodopsin Activity as a Function of its Local Environment with a Raman-Based Assay. J Phys Chem B 2023; 127:8833-8841. [PMID: 37812499 DOI: 10.1021/acs.jpcb.3c04802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/11/2023]
Abstract
Bacteriorhodopsin (bR) is a transmembrane protein that functions as a light-driven proton pump in halophilic archaea. The bR photocycle has been well-characterized; however, these measurements almost exclusively measured purified bR, outside of its native membrane. To investigate what effect the cellular environment has on the bR photocycle, we have developed a Raman-based assay that can monitor the activity of the bR in a variety of conditions, including in its native membrane. The assay uses two continuous-wave lasers, one to initiate photochemistry and one to monitor bR activity. The excitation leads to the steady-state depletion of ground-state bR, which directly relates to the population of photocycle intermediate states. We have used this assay to monitor bR activity both in vitro and in vivo. Our in vitro measurements confirm that our assay is sensitive to bulk environmental changes reported in the literature. Our in vivo measurements show a decrease in bR activity with increasing extracellular pH for bR in its native membrane. The difference in activity with increasing pH indicates that the native membrane environment affects the function of bR. This assay opens the door to future measurements into understanding how the local environment of this transmembrane protein affects function.
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Affiliation(s)
- Ryan E Leighton
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Renee R Frontiera
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
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2
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Meng X, Ganapathy S, van Roemburg L, Post M, Brinks D. Voltage Imaging with Engineered Proton-Pumping Rhodopsins: Insights from the Proton Transfer Pathway. ACS PHYSICAL CHEMISTRY AU 2023; 3:320-333. [PMID: 37520318 PMCID: PMC10375888 DOI: 10.1021/acsphyschemau.3c00003] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 04/13/2023] [Accepted: 04/13/2023] [Indexed: 08/01/2023]
Abstract
Voltage imaging using genetically encoded voltage indicators (GEVIs) has taken the field of neuroscience by storm in the past decade. Its ability to create subcellular and network level readouts of electrical dynamics depends critically on the kinetics of the response to voltage of the indicator used. Engineered microbial rhodopsins form a GEVI subclass known for their high voltage sensitivity and fast response kinetics. Here we review the essential aspects of microbial rhodopsin photocycles that are critical to understanding the mechanisms of voltage sensitivity in these proteins and link them to insights from efforts to create faster, brighter and more sensitive microbial rhodopsin-based GEVIs.
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Affiliation(s)
- Xin Meng
- Department
of Imaging Physics, Delft University of
Technology, 2628 CJ Delft, The
Netherlands
| | - Srividya Ganapathy
- Department
of Imaging Physics, Delft University of
Technology, 2628 CJ Delft, The
Netherlands
- Department
of Pediatrics & Cellular and Molecular Medicine, UCSD School of Medicine, La Jolla, California 92093, United States
| | - Lars van Roemburg
- Department
of Imaging Physics, Delft University of
Technology, 2628 CJ Delft, The
Netherlands
| | - Marco Post
- Department
of Imaging Physics, Delft University of
Technology, 2628 CJ Delft, The
Netherlands
| | - Daan Brinks
- Department
of Imaging Physics, Delft University of
Technology, 2628 CJ Delft, The
Netherlands
- Department
of Molecular Genetics, Erasmus University
Medical Center, 3015 GD Rotterdam, The Netherlands
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3
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Archaeal Lipids Regulating the Trimeric Structure Dynamics of Bacteriorhodopsin for Efficient Proton Release and Uptake. Int J Mol Sci 2022; 23:ijms23136913. [PMID: 35805918 PMCID: PMC9278134 DOI: 10.3390/ijms23136913] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 06/19/2022] [Accepted: 06/20/2022] [Indexed: 11/30/2022] Open
Abstract
S-TGA-1 and PGP-Me are native archaeal lipids associated with the bacteriorhodopsin (bR) trimer and contribute to protein stabilization and native dynamics for proton transfer. However, little is known about the underlying molecular mechanism of how these lipids regulate bR trimerization and efficient photocycling. Here, we explored the specific binding of S-TGA-1 and PGP-Me with the bR trimer and elucidated how specific interactions modulate the bR trimeric structure and proton release and uptake using long-term atomistic molecular dynamic simulations. Our results showed that S-TGA-1 and PGP-Me are essential for stabilizing the bR trimer and maintaining the coherent conformational dynamics necessary for proton transfer. The specific binding of S-TGA-1 with W80 and K129 regulates proton release on the extracellular surface by forming a “Glu-shared” model. The interaction of PGP-Me with K40 ensures proton uptake by accommodating the conformation of the helices to recruit enough water molecules on the cytoplasmic side. The present study results could fill in the theoretical gaps of studies on the functional role of archaeal lipids and could provide a reference for other membrane proteins containing similar archaeal lipids.
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4
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Dynamic Coupling of Tyrosine 185 with the Bacteriorhodopsin Photocycle, as Revealed by Chemical Shifts, Assisted AF-QM/MM Calculations and Molecular Dynamic Simulations. Int J Mol Sci 2021; 22:ijms222413587. [PMID: 34948384 PMCID: PMC8709120 DOI: 10.3390/ijms222413587] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 12/14/2021] [Accepted: 12/16/2021] [Indexed: 11/23/2022] Open
Abstract
Aromatic residues are highly conserved in microbial photoreceptors and play crucial roles in the dynamic regulation of receptor functions. However, little is known about the dynamic mechanism of the functional role of those highly conserved aromatic residues during the receptor photocycle. Tyrosine 185 (Y185) is one of the highly conserved aromatic residues within the retinal binding pocket of bacteriorhodopsin (bR). In this study, we explored the molecular mechanism of its dynamic coupling with the bR photocycle by automated fragmentation quantum mechanics/molecular mechanics (AF-QM/MM) calculations and molecular dynamic (MD) simulations based on chemical shifts obtained by 2D solid-state NMR correlation experiments. We observed that Y185 plays a significant role in regulating the retinal cis–trans thermal equilibrium, stabilizing the pentagonal H-bond network, participating in the orientation switch of Schiff Base (SB) nitrogen, and opening the F42 gate by interacting with the retinal and several key residues along the proton translocation channel. Our findings provide a detailed molecular mechanism of the dynamic couplings of Y185 and the bR photocycle from a structural perspective. The method used in this paper may be applied to the study of other microbial photoreceptors.
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5
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Zimányi L, Sipos Á, Sarlós F, Nagypál R, Groma GI. Machine-learning model selection and parameter estimation from kinetic data of complex first-order reaction systems. PLoS One 2021; 16:e0255675. [PMID: 34370771 PMCID: PMC8352076 DOI: 10.1371/journal.pone.0255675] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 07/22/2021] [Indexed: 11/28/2022] Open
Abstract
Dealing with a system of first-order reactions is a recurrent issue in chemometrics, especially in the analysis of data obtained by spectroscopic methods applied on complex biological systems. We argue that global multiexponential fitting, the still common way to solve such problems, has serious weaknesses compared to contemporary methods of sparse modeling. Combining the advantages of group lasso and elastic net-the statistical methods proven to be very powerful in other areas-we created an optimization problem tunable from very sparse to very dense distribution over a large pre-defined grid of time constants, fitting both simulated and experimental multiwavelength spectroscopic data with high computational efficiency. We found that the optimal values of the tuning hyperparameters can be selected by a machine-learning algorithm based on a Bayesian optimization procedure, utilizing widely used or novel versions of cross-validation. The derived algorithm accurately recovered the true sparse kinetic parameters of an extremely complex simulated model of the bacteriorhodopsin photocycle, as well as the wide peak of hypothetical distributed kinetics in the presence of different noise levels. It also performed well in the analysis of the ultrafast experimental fluorescence kinetics data detected on the coenzyme FAD in a very wide logarithmic time window. We conclude that the primary application of the presented algorithms-implemented in available software-covers a wide area of studies on light-induced physical, chemical, and biological processes carried out with different spectroscopic methods. The demand for this kind of analysis is expected to soar due to the emerging ultrafast multidimensional infrared and electronic spectroscopic techniques that provide very large and complex datasets. In addition, simulations based on our methods could help in designing the technical parameters of future experiments for the verification of particular hypothetical models.
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Affiliation(s)
- László Zimányi
- Institute of Biophysics, Biological Research Centre, Eötvös Loránd Research Network, Szeged, Hungary
| | - Áron Sipos
- Institute of Biophysics, Biological Research Centre, Eötvös Loránd Research Network, Szeged, Hungary
| | - Ferenc Sarlós
- Institute of Biophysics, Biological Research Centre, Eötvös Loránd Research Network, Szeged, Hungary
| | - Rita Nagypál
- Institute of Biophysics, Biological Research Centre, Eötvös Loránd Research Network, Szeged, Hungary
- Doctoral School of Physics, University of Szeged, Szeged, Hungary
| | - Géza I. Groma
- Institute of Biophysics, Biological Research Centre, Eötvös Loránd Research Network, Szeged, Hungary
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6
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Apell HJ, Roudna M. Partial Reactions of the Na,K-ATPase: Determination of Activation Energies and an Approach to Mechanism. J Membr Biol 2020; 253:631-645. [PMID: 33184678 PMCID: PMC7688194 DOI: 10.1007/s00232-020-00153-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 11/05/2020] [Indexed: 11/26/2022]
Abstract
Abstract Kinetic experiments were performed with preparations of kidney Na,K-ATPase in isolated membrane fragments or reconstituted in vesicles to obtain information of the activation energies under turnover conditions and for selected partial reactions of the Post-Albers pump cycle. The ion transport activities were detected with potential or conformation sensitive fluorescent dyes in steady-state or time-resolved experiments. The activation energies were derived from Arrhenius plots of measurements in the temperature range between 5 °C and 37 °C. The results were used to elaborate indications of the respective underlying rate-limiting reaction steps and allowed conclusions to be drawn about possible molecular reaction mechanisms. The observed consequent alteration between ligand-induced reaction and conformational relaxation steps when the Na,K-ATPase performs the pump cycle, together with constraints set by thermodynamic principles, provided restrictions which have to be met when mechanistic models are proposed. A model meeting such requirements is presented for discussion. Graphic Abstract ![]()
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Affiliation(s)
- Hans-Jürgen Apell
- Department of Biology, University of Konstanz, 78464, Konstanz, Germany.
| | - Milena Roudna
- Department of Biology, University of Konstanz, 78464, Konstanz, Germany
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7
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Ono J, Imai M, Nishimura Y, Nakai H. Hydroxide Ion Carrier for Proton Pumps in Bacteriorhodopsin: Primary Proton Transfer. J Phys Chem B 2020; 124:8524-8539. [DOI: 10.1021/acs.jpcb.0c05507] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Junichi Ono
- Waseda Research Institute for Science and Engineering (WISE), Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, Japan
- Elements Strategy Initiative for Catalysts & Batteries (ESICB), Kyoto University, 1-30 Goryo-Ohara, Nishikyo-ku, Kyoto 615-8245, Japan
| | - Minori Imai
- Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, Japan
| | - Yoshifumi Nishimura
- Waseda Research Institute for Science and Engineering (WISE), Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, Japan
| | - Hiromi Nakai
- Waseda Research Institute for Science and Engineering (WISE), Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, Japan
- Elements Strategy Initiative for Catalysts & Batteries (ESICB), Kyoto University, 1-30 Goryo-Ohara, Nishikyo-ku, Kyoto 615-8245, Japan
- Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, Japan
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8
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Wickstrand C, Nogly P, Nango E, Iwata S, Standfuss J, Neutze R. Bacteriorhodopsin: Structural Insights Revealed Using X-Ray Lasers and Synchrotron Radiation. Annu Rev Biochem 2019; 88:59-83. [DOI: 10.1146/annurev-biochem-013118-111327] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Directional transport of protons across an energy transducing membrane—proton pumping—is ubiquitous in biology. Bacteriorhodopsin (bR) is a light-driven proton pump that is activated by a buried all- trans retinal chromophore being photoisomerized to a 13- cis conformation. The mechanism by which photoisomerization initiates directional proton transport against a proton concentration gradient has been studied by a myriad of biochemical, biophysical, and structural techniques. X-ray free electron lasers (XFELs) have created new opportunities to probe the structural dynamics of bR at room temperature on timescales from femtoseconds to milliseconds using time-resolved serial femtosecond crystallography (TR-SFX). Wereview these recent developments and highlight where XFEL studies reveal new details concerning the structural mechanism of retinal photoisomerization and proton pumping. We also discuss the extent to which these insights were anticipated by earlier intermediate trapping studies using synchrotron radiation. TR-SFX will open up the field for dynamical studies of other proteins that are not naturally light-sensitive.
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Affiliation(s)
- Cecilia Wickstrand
- Department of Chemistry and Molecular Biology, University of Gothenburg, SE-40530 Gothenburg, Sweden
| | - Przemyslaw Nogly
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zürich, 8093 Zürich, Switzerland
| | - Eriko Nango
- RIKEN SPring-8 Center, Hyogo 679-5148, Japan
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Yoshidakonoe-cho, Sakyo-ku, Kyoto, 606-8501, Japan
| | - So Iwata
- RIKEN SPring-8 Center, Hyogo 679-5148, Japan
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Yoshidakonoe-cho, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Jörg Standfuss
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institut, 5232 Villigen, Switzerland
| | - Richard Neutze
- Department of Chemistry and Molecular Biology, University of Gothenburg, SE-40530 Gothenburg, Sweden
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9
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Miyahara T, Nakatsuji H. Light-Driven Proton, Sodium Ion, and Chloride Ion Transfer Mechanisms in Rhodopsins: SAC-CI Study. J Phys Chem A 2019; 123:1766-1784. [DOI: 10.1021/acs.jpca.8b10203] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Tomoo Miyahara
- Quantum Chemistry Research Institute, Kyoto Technoscience Center 16, 14 Yoshida Kawara-machi, Sakyou-ku, Kyoto 606-8305, Japan
| | - Hiroshi Nakatsuji
- Quantum Chemistry Research Institute, Kyoto Technoscience Center 16, 14 Yoshida Kawara-machi, Sakyou-ku, Kyoto 606-8305, Japan
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10
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Abstract
Channelrhodopsin-2 (ChR2) is a light-sensitive ion channel widely used in optogenetics. Photoactivation triggers a trans-to-cis isomerization of a covalently bound retinal. Ensuing conformational changes open a cation-selective channel. We explore the structural dynamics in the early photocycle leading to channel opening by classical (MM) and quantum mechanical (QM) molecular simulations. With QM/MM simulations, we generated a protein-adapted force field for the retinal chromophore, which we validated against absorption spectra. In a 4-µs MM simulation of a dark-adapted ChR2 dimer, water entered the vestibules of the closed channel. Retinal all-trans to 13-cis isomerization, simulated with metadynamics, triggered a major restructuring of the charge cluster forming the channel gate. On a microsecond time scale, water penetrated the gate to form a membrane-spanning preopen pore between helices H1, H2, H3, and H7. This influx of water into an ion-impermeable preopen pore is consistent with time-resolved infrared spectroscopy and electrophysiology experiments. In the retinal 13-cis state, D253 emerged as the proton acceptor of the Schiff base. Upon proton transfer from the Schiff base to D253, modeled by QM/MM simulations, we obtained an early-M/P2390-like intermediate. Rapid rotation of the unprotonated Schiff base toward the cytosolic side effectively prevents its reprotonation from the extracellular side. From MM and QM simulations, we gained detailed insight into the mechanism of ChR2 photoactivation and early events in pore formation. By rearranging the network of charges and hydrogen bonds forming the gate, water emerges as a key player in light-driven ChR2 channel opening.
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Affiliation(s)
- Albert Ardevol
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany;
| | - Gerhard Hummer
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany;
- Department of Physics, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
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11
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Elghobashi-Meinhardt N, Phatak P, Bondar AN, Elstner M, Smith JC. Catalysis of Ground State cis[Formula: see text] trans Isomerization of Bacteriorhodopsin's Retinal Chromophore by a Hydrogen-Bond Network. J Membr Biol 2018. [PMID: 29516110 DOI: 10.1007/s00232-018-0027-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
For the photocycle of the membrane protein bacteriorhodopsin to proceed efficiently, the thermal 13-cis to all-trans back-isomerization of the retinal chromophore must return the protein to its resting state on a time-scale of milliseconds. Here, we report on quantum mechanical/molecular mechanical energy calculations examining the structural and energetic determinants of the retinal cis-trans isomerization in the protein environment. The results suggest that a hydrogen-bonded network consisting of the retinal Schiff base, active site amino acid residues, and water molecules can stabilize the twisted retinal, thus reducing the intrinsic energy cost of the cis-trans thermal isomerization barrier.
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Affiliation(s)
- Nadia Elghobashi-Meinhardt
- Department of Physical and Theoretical Chemistry, Theoretical Molecular Biophysics, Institute for Chemistry und Biochemistry, Freie Universität Berlin, Fabeckstr. 36a, Berlin, 14169, Germany.
| | - Prasad Phatak
- Institute of Physical and Theoretical Chemistry, TU Braunschweig, 38106, Braunschweig, Germany.,BASF SE, Carl-Bosch Strasse 38, 67056, Ludwigshafen am Rhein, Germany
| | - Ana-Nicoleta Bondar
- Department of Physics, Theoretical Molecular Biophysics, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
| | - Marcus Elstner
- Department of Theoretical Chemical Biology, Institute for Physical Chemistry, Karlsruhe Institut of Technology, Kaiserstrasse 12, 76131, Karlsruhe, Germany
| | - Jeremy C Smith
- Oak Ridge National Laboratory, Center for Molecular Biophysics, P.O. Box 2008 MS6309, Oak Ridge, TN, 37831-6309, USA.,Department of Biochemistry and Molecular and Cellular Biology, University of Tennessee, Knoxville, USA
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12
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Li YT, Tian H, Zhao HM, Jian MQ, Lv YJ, Tian Y, Wang Q, Yang Y, Xiang Y, Zhang Y, Ren TL. A novel cell-scale bio-nanogenerator based on electron-ion interaction for fast light power conversion. NANOSCALE 2018; 10:526-532. [PMID: 29255823 DOI: 10.1039/c7nr07671a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Natural energy haversting devices serve as an alternative candidate for power supply in many micro-/nano-systems. However, traditional nanogenerators based on piezoelectricity or triboelectric power generation face challenges in terms of biocompatibility and stability in various biological systems. The bacteriorhodopsin (bR) protein in Halobacterium halobium is an ideal biocompatible material for photoelectric conversion. Conventional bR systems based on ion transport or enhanced light absorption layers have a limited light power conversion speed. On the other hand, bR-based biohybrid devices have a great potential for sensitive light power conversion as compared to conventional nanogenerators. Herein, we present a biohybrid nanogenerator made of bR and horizontally aligned-long carbon nanotubes (CNTs) with electron-ion interaction for the first time for sensitive light power conversion. The bR layer serves as the proton pump, whereas CNTs are utilized to enhance the photocurrent; thus, the photocurrent frequency response improves significantly because of the effect of the electron-ion interaction. The photocurrent shows a linear relationship with the intensity of light and can still obtain a stable signal at a light intensity of 0.03 mW cm-2. With regard to the influence of the light on-off period, the photocurrent initially increases and then decreases with an increase in flickering frequency up to 360 Hz; this can be ascribed to the combinational influence of light switch speed and photocycle decay time. The photocurrent shows highest value (99 nA cm-2) at a frequency of about 50 Hz at a light intensity of 0.43 mW cm-2, which matches well with the frequency standard of the electrical power supply system. Moreover, we found that a higher density of CNTs contributed to improve performance of the nanogenerators. Furthermore, a H+ ion releasing model was proposed to interpret the operating mechanism of the biohybrid nanogenerator. The biohybrid nanogenerator shows great potential for applications as a power source for bio-nanosystems.
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Affiliation(s)
- Yu-Tao Li
- Institute of Microelectronics & Tsinghua National Laboratory for Information Science and Technology (TNList), Tsinghua University, Beijing 10084, China.
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13
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Krause BS, Grimm C, Kaufmann JCD, Schneider F, Sakmar TP, Bartl FJ, Hegemann P. Complex Photochemistry within the Green-Absorbing Channelrhodopsin ReaChR. Biophys J 2017; 112:1166-1175. [PMID: 28355544 PMCID: PMC5374998 DOI: 10.1016/j.bpj.2017.02.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Revised: 12/29/2016] [Accepted: 02/01/2017] [Indexed: 11/26/2022] Open
Abstract
Channelrhodopsins (ChRs) are light-activated ion channels widely employed for photostimulation of excitable cells. This study focuses on ReaChR, a chimeric ChR variant with optimal properties for optogenetic applications. We combined electrophysiological recordings with infrared and UV-visible spectroscopic measurements to investigate photocurrents and photochemical properties of ReaChR. Our data imply that ReaChR is green-light activated (λmax = 532 nm) with a non-rhodopsin-like action spectrum peaking at 610 nm for stationary photocurrents. This unusual spectral feature is associated with photoconversion of a previously unknown light-sensitive, blue-shifted photocycle intermediate L (λmax = 495 nm), which is accumulated under continuous illumination. To explain the complex photochemical reactions, we propose a symmetrical two-cycle-model based on the two C15=N isomers of the retinal cofactor with either syn- or anti-configuration, each comprising six consecutive states D, K, L, M, N, and O. Ion conduction involves two states per cycle, the late M- (M2) with a deprotonated retinal Schiff base and the consecutive green-absorbing N-state that both equilibrate via reversible reprotonation. In our model, a fraction of the deprotonated M-intermediate of the anti-cycle may be photoconverted-as the L-state-back to its inherent dark state, or to its M-state pendant (M') of the syn-cycle. The latter reaction pathway requires a C13=C14, C15=N double-isomerization of the retinal chromophore, whereas the intracircular photoconversion of M back to D involves only one C13=C14 double-bond isomerization.
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Affiliation(s)
- Benjamin S Krause
- Institute of Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Berlin, Germany.
| | - Christiane Grimm
- Institute of Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Joel C D Kaufmann
- Institute for Medical Physics and Biophysics, Charité Berlin, Berlin, Germany
| | - Franziska Schneider
- Institute of Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Thomas P Sakmar
- Laboratory of Chemical Biology and Signal Transduction, Rockefeller University, New York, New York
| | - Franz J Bartl
- Institute for Medical Physics and Biophysics, Charité Berlin, Berlin, Germany
| | - Peter Hegemann
- Institute of Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Berlin, Germany.
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14
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Lu Z, Wang J, Li R, Qiao Y, Zhou M, Li CM. Controllable stationary photocurrents generated from a bacteriorhodopsin/upconversion nanoparticle-based bionanosystem under NIR illumination. NANOSCALE 2016; 8:18524-18530. [PMID: 27782261 DOI: 10.1039/c6nr06930d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
In the past few decades, tremendous effort has been dedicated to develop bacteriorhodopsin (bR)-based photo-electronic devices for generating a stationary photocurrent and further for use as a component of artificial retinas in constant illumination sensing. However, an IR-triggered stationary photocurrent with controllable amplitudes has never been realized to date. Herein, NaYF4:Yb,Er and NaYF4:Yb,Tm upconversion nanoparticles (UCNPs) with green and blue emissions, respectively, were synthesized and further incorporated with bR to build a bionanosystem. Under 980 nm NIR irradiation the UCNPs function as internal green and blue light sources to initiate the photocycle and speed up the transition of bR from M410 to the ground state, consequently accelerating the bR photocycle for the generation of a stationary photocurrent. Moreover, the photocurrent profile could be tailored by changing the blue/green emission intensity ratio. The mechanism is analysed to explore the scientific insights. The system consisting of controllable blue and green light sources may not only hold great promise to construct new types of bR-based optical devices, but also offers a useful setup to investigate the fundamental science underlying the bR photoresponse.
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Affiliation(s)
- Zhisong Lu
- Institute for Clean Energy & Advance Materials, Southwest University, 1 Tiansheng Road, Chongqing 400715, P. R. China and Chongqing Key Laboratory for Advanced Materials & Technologies of Clean Energies, Southwest University, 1 Tiansheng Road, Chongqing 400715, P. R. China.
| | - Jing Wang
- Institute for Clean Energy & Advance Materials, Southwest University, 1 Tiansheng Road, Chongqing 400715, P. R. China and Chongqing Key Laboratory for Advanced Materials & Technologies of Clean Energies, Southwest University, 1 Tiansheng Road, Chongqing 400715, P. R. China.
| | - Rui Li
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan 430079, P. R. China
| | - Yan Qiao
- Institute for Clean Energy & Advance Materials, Southwest University, 1 Tiansheng Road, Chongqing 400715, P. R. China and Chongqing Key Laboratory for Advanced Materials & Technologies of Clean Energies, Southwest University, 1 Tiansheng Road, Chongqing 400715, P. R. China.
| | - Mengyao Zhou
- Institute for Clean Energy & Advance Materials, Southwest University, 1 Tiansheng Road, Chongqing 400715, P. R. China and Chongqing Key Laboratory for Advanced Materials & Technologies of Clean Energies, Southwest University, 1 Tiansheng Road, Chongqing 400715, P. R. China.
| | - Chang Ming Li
- Institute for Clean Energy & Advance Materials, Southwest University, 1 Tiansheng Road, Chongqing 400715, P. R. China and Chongqing Key Laboratory for Advanced Materials & Technologies of Clean Energies, Southwest University, 1 Tiansheng Road, Chongqing 400715, P. R. China. and Institute for Materials Science and Devices, Suzhou University of Science and Technology, Suzhou 215011, P.R. China
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15
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Hontani Y, Inoue K, Kloz M, Kato Y, Kandori H, Kennis JTM. The photochemistry of sodium ion pump rhodopsin observed by watermarked femto- to submillisecond stimulated Raman spectroscopy. Phys Chem Chem Phys 2016; 18:24729-36. [PMID: 27550793 DOI: 10.1039/c6cp05240a] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Krokinobacter rhodopsin 2 (KR2) is a recently discovered light-driven Na(+) pump that holds significant promise for application as a neural silencer in optogenetics. KR2 transports Na(+) (in NaCl solution) or H(+) (in larger cation solution, e.g. in CsCl) during its photocycle. Here, we investigate the photochemistry of KR2 with the recently developed watermarked, baseline-free femto- to submillisecond transient stimulated Raman spectroscopy (TSRS), which enables us to investigate retinal chromophore dynamics in real time with high spectral resolution over a large time range. We propose a new photocycle from femtoseconds to submilliseconds: J (formed in ∼200 fs) → K (∼3 ps) → K/L1 (∼20 ps) → K/L2 (∼30 ns) → L/M (∼20 μs). KR2 binds a Na(+) ion that is not transported on the extracellular side, of which the function is unclear. We demonstrate with TSRS that for the D102N mutant in NaCl (with Na(+) unbound, Na(+) transport) and for WT KR2 in CsCl (with Na(+) unbound, H(+) transport), the extracellular Na(+) binding significantly influences the intermediate K/L/M state equilibrium on the photocycle, while the identity of the transported ion, Na(+) or H(+), does not affect the photocycle. Our findings will contribute to further elucidation of the molecular mechanisms of KR2.
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Affiliation(s)
- Yusaku Hontani
- Department of Physics and Astronomy, Faculty of Sciences, VU University Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands.
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16
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Kim S, Kimleng C, Jang H, Sohn H, Kim GJ, Lee GR, Kim KS, Choi A, Jung KH. Isolation and characterization of proteorhodopsin homologue from Yellow Sea of Korea. Genes Genomics 2016. [DOI: 10.1007/s13258-016-0392-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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17
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Ge X, Gunner MR. Unraveling the mechanism of proton translocation in the extracellular half-channel of bacteriorhodopsin. Proteins 2016; 84:639-54. [DOI: 10.1002/prot.25013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2015] [Revised: 01/24/2016] [Accepted: 02/04/2016] [Indexed: 01/06/2023]
Affiliation(s)
- Xiaoxia Ge
- Physics Department; City College of New York; New York NY 10031
| | - M. R. Gunner
- Physics Department; City College of New York; New York NY 10031
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18
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McIsaac RS, Bedbrook CN, Arnold FH. Recent advances in engineering microbial rhodopsins for optogenetics. Curr Opin Struct Biol 2015; 33:8-15. [PMID: 26038227 PMCID: PMC4641784 DOI: 10.1016/j.sbi.2015.05.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Revised: 04/08/2015] [Accepted: 05/03/2015] [Indexed: 01/29/2023]
Abstract
Protein engineering of microbial rhodopsins has been successful in generating variants with improved properties for applications in optogenetics. Members of this membrane protein family can act as both actuators and sensors of neuronal activity. Chimeragenesis, structure-guided mutagenesis, and directed evolution have proven effective strategies for tuning absorption wavelength, altering ion specificity and increasing fluorescence. These approaches facilitate the development of useful optogenetic tools and, in some cases, have yielded insights into rhodopsin structure-function relationships.
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Affiliation(s)
- R. Scott McIsaac
- Division of Chemistry and Chemical Engineering, Mail Code 210-41, California Institute of Technology, Pasadena, California, United States of America
- Calico Life Sciences, South San Francisco, California, United States of America
| | - Claire N. Bedbrook
- Division of Biology and Biological Engineering, Mail Code 156-29, California Institute of Technology, Pasadena, California, United States of America
| | - Frances H. Arnold
- Division of Chemistry and Chemical Engineering, Mail Code 210-41, California Institute of Technology, Pasadena, California, United States of America
- Division of Biology and Biological Engineering, Mail Code 156-29, California Institute of Technology, Pasadena, California, United States of America
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19
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Tatum LA, Foy JT, Aprahamian I. Waste Management of Chemically Activated Switches: Using a Photoacid To Eliminate Accumulation of Side Products. J Am Chem Soc 2014; 136:17438-41. [DOI: 10.1021/ja511135k] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Luke A. Tatum
- Department of Chemistry, Dartmouth College, 6128 Burke Laboratory, Hanover, New Hampshire 03755, United States
| | - Justin T. Foy
- Department of Chemistry, Dartmouth College, 6128 Burke Laboratory, Hanover, New Hampshire 03755, United States
| | - Ivan Aprahamian
- Department of Chemistry, Dartmouth College, 6128 Burke Laboratory, Hanover, New Hampshire 03755, United States
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20
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Kouyama T, Fujii R, Kanada S, Nakanishi T, Chan SK, Murakami M. Structure of archaerhodopsin-2 at 1.8 Å resolution. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2014; 70:2692-701. [PMID: 25286853 PMCID: PMC4188009 DOI: 10.1107/s1399004714017313] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Accepted: 07/28/2014] [Indexed: 11/10/2022]
Abstract
Archaerhodopsin-2 (aR2), the sole protein found in the claret membrane of Halorubrum sp. Aus-2, functions as a light-driven proton pump. In this study, structural analysis of aR2 was performed using a novel three-dimensional crystal prepared by the successive fusion of claret membranes. The crystal is made up of stacked membranes, in each of which aR2 trimers are arranged on a hexagonal lattice. This lattice structure resembles that found in the purple membrane of H. salinarum, except that lipid molecules trapped within the trimeric structure are not distributed with perfect threefold symmetry. Nonetheless, diffraction data at 1.8 Å resolution provide accurate structural information about functionally important residues. It is shown that two glutamates in the proton-release channel form a paired structure that is maintained by a low-barrier hydrogen bond. Although the structure of the proton-release pathway is highly conserved among proton-pumping archaeal rhodopsins, aR2 possesses the following peculiar structural features: (i) the motional freedom of the tryptophan residue that makes contact with the C13 methyl group of retinal is restricted, affecting the formation/decay kinetics of the L state, and (ii) the N-terminal polypeptide folds into an Ω-loop, which may play a role in organizing the higher-order structure.
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Affiliation(s)
- Tsutomu Kouyama
- Department of Physics, Graduate School of Science, Nagoya University, Nagoya, Japan
- RIKEN Harima Institute/SPring-8, 1-1-1 Kouto, Mikazuki, Sayo, Hyogo, Japan
| | - Ryudo Fujii
- Department of Physics, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Soun Kanada
- Department of Physics, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Taichi Nakanishi
- Department of Physics, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Siu Kit Chan
- Department of Physics, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Midori Murakami
- Department of Physics, Graduate School of Science, Nagoya University, Nagoya, Japan
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21
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Tavanti F, Tozzini V. A multi-scale-multi-stable model for the rhodopsin photocycle. Molecules 2014; 19:14961-78. [PMID: 25237751 PMCID: PMC6271392 DOI: 10.3390/molecules190914961] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Revised: 08/28/2014] [Accepted: 09/08/2014] [Indexed: 11/19/2022] Open
Abstract
We report a multi-scale simulation study of the photocycle of the rhodopsins. The quasi-atomistic representation ("united atoms" UA) of retinal is combined with a minimalist coarse grained (CG, one-bead-per amino acid) representation of the protein, in a hybrid UA/CG approach, which is the homolog of QM/MM, but at lower resolution. An accurate multi-stable parameterization of the model allows simulating each state and transition among them, and the combination of different scale representation allows addressing the entire photocycle. We test the model on bacterial rhodopsin, for which more experimental data are available, and then also report results for mammalian rhodopsins. In particular, the analysis of simulations reveals the spontaneous appearance of meta-stable states in quantitative agreement with experimental data.
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Affiliation(s)
- Francesco Tavanti
- NEST-Istituto Nanoscienze, CNR, Piazza San Silvestro 12, 56127 Pisa, Italy
| | - Valentina Tozzini
- NEST-Istituto Nanoscienze, CNR, Piazza San Silvestro 12, 56127 Pisa, Italy.
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22
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Wickstrand C, Dods R, Royant A, Neutze R. Bacteriorhodopsin: Would the real structural intermediates please stand up? Biochim Biophys Acta Gen Subj 2014; 1850:536-53. [PMID: 24918316 DOI: 10.1016/j.bbagen.2014.05.021] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Revised: 05/23/2014] [Accepted: 05/29/2014] [Indexed: 11/18/2022]
Abstract
BACKGROUND Bacteriorhodopsin (bR) is the simplest known light driven proton pump and has been heavily studied using structural methods: eighty four X-ray diffraction, six electron diffraction and three NMR structures of bR are deposited within the protein data bank. Twenty one X-ray structures report light induced structural changes and changes induced by mutation, changes in pH, thermal annealing or X-ray induced photo-reduction have also been examined. SCOPE OF REVIEW We argue that light-induced structural changes that are replicated across several studies by independent research groups are those most likely to represent what is happening in reality. We present both internal distance matrix analyses that sort deposited bR structures into hierarchal trees, and difference Fourier analysis of deposited X-ray diffraction data. MAJOR CONCLUSIONS An internal distance matrix analysis separates most wild-type bR structures according to their different crystal forms, indicating how the protein's structure is influenced by crystallization conditions. A similar analysis clusters eleven studies of illuminated bR crystals as one branch of a hierarchal tree with reproducible movements of the extracellular portion of helix C towards helix G, and of the cytoplasmic portion of helix F away from helices A, B and G. All crystallographic data deposited for illuminated crystals show negative difference density on a water molecule (Wat402) that forms H-bonds to the retinal Schiff Base and two aspartate residues (Asp85, Asp212) in the bR resting state. Other recurring difference density features indicated reproducible side-chain, backbone and water molecule displacements. X-ray induced radiation damage also disorders Wat402 but acts via cleaving the head-groups of Asp85 and Asp212. GENERAL SIGNIFICANCE A remarkable level of agreement exists when deposited structures and crystallographic observations are viewed as a whole. From this agreement a unified picture of the structural mechanism of light-induced proton pumping by bR emerges. This article is part of a Special Issue entitled Structural biochemistry and biophysics of membrane proteins.
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Affiliation(s)
- Cecilia Wickstrand
- Department of Chemistry and Molecular Biology, University of Gothenburg, Box 462, SE-40530 Gothenburg, Sweden
| | - Robert Dods
- Department of Chemistry and Molecular Biology, University of Gothenburg, Box 462, SE-40530 Gothenburg, Sweden
| | - Antoine Royant
- Univ. Grenoble Alpes, IBS, F-38044 Grenoble, France; CNRS, IBS, F-38044 Grenoble, France; CEA, IBS, F-38044 Grenoble, France; European Synchrotron Radiation Facility, F-38043 Grenoble, France.
| | - Richard Neutze
- Department of Chemistry and Molecular Biology, University of Gothenburg, Box 462, SE-40530 Gothenburg, Sweden.
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23
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Álvarez R, Vaz B, Gronemeyer H, de Lera ÁR. Functions, therapeutic applications, and synthesis of retinoids and carotenoids. Chem Rev 2013; 114:1-125. [PMID: 24266866 DOI: 10.1021/cr400126u] [Citation(s) in RCA: 151] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Rosana Álvarez
- Departamento de Química Orgánica, Centro de Investigación Biomédica (CINBIO), and Instituto de Investigación Biomédica de Vigo (IBIV), Universidade de Vigo , 36310 Vigo, Spain
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24
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Yamashita H, Inoue K, Shibata M, Uchihashi T, Sasaki J, Kandori H, Ando T. Role of trimer-trimer interaction of bacteriorhodopsin studied by optical spectroscopy and high-speed atomic force microscopy. J Struct Biol 2013; 184:2-11. [PMID: 23462099 DOI: 10.1016/j.jsb.2013.02.011] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Revised: 12/22/2012] [Accepted: 02/12/2013] [Indexed: 10/27/2022]
Abstract
Bacteriorhodopsin (bR) trimers form a two-dimensional hexagonal lattice in the purple membrane of Halobacterium salinarum. However, the physiological significance of forming the lattice has long been elusive. Here, we study this issue by comparing properties of assembled and non-assembled bR trimers using directed mutagenesis, high-speed atomic force microscopy (HS-AFM), optical spectroscopy, and a proton pumping assay. First, we show that the bonds formed between W12 and F135 amino acid residues are responsible for trimer-trimer association that leads to lattice assembly; the lattice is completely disrupted in both W12I and F135I mutants. HS-AFM imaging reveals that both crystallized D96N and non-crystallized D96N/W12I mutants undergo a large conformational change (i.e., outward E-F loop displacement) upon light-activation. However, lattice disruption significantly reduces the rate of conformational change under continuous light illumination. Nevertheless, the quantum yield of M-state formation, measured by low-temperature UV-visible spectroscopy, and proton pumping efficiency are unaffected by lattice disruption. From these results, we conclude that trimer-trimer association plays essential roles in providing bound retinal with an appropriate environment to maintain its full photo-reactivity and in maintaining the natural photo-reaction pathway.
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Affiliation(s)
- Hayato Yamashita
- Department of Physics, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
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25
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Wolter T, Welke K, Phatak P, Bondar AN, Elstner M. Excitation energies of a water-bridged twisted retinal structure in the bacteriorhodopsin proton pump: a theoretical investigation. Phys Chem Chem Phys 2013; 15:12582-90. [DOI: 10.1039/c3cp44280b] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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26
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Zhang J, Yamazaki Y, Hikake M, Murakami M, Ihara K, Kouyama T. Crystal structure of the O intermediate of the Leu93→Ala mutant of bacteriorhodopsin. Proteins 2012; 80:2384-96. [DOI: 10.1002/prot.24124] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Revised: 05/05/2012] [Accepted: 05/14/2012] [Indexed: 12/23/2022]
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27
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Inoue K, Reissig L, Sakai M, Kobayashi S, Homma M, Fujii M, Kandori H, Sudo Y. Absorption Spectra and Photochemical Reactions in a Unique Photoactive Protein, Middle Rhodopsin MR. J Phys Chem B 2012; 116:5888-99. [DOI: 10.1021/jp302357m] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Keiichi Inoue
- Department of Frontier
Materials, Nagoya Institute of Technology, Showa-ku, Nagoya, 466-8555,
Japan
| | - Louisa Reissig
- Division of Biological
Science,
Graduate School of Science, Nagoya University, Nagoya, 464-8602, Japan
| | - Makoto Sakai
- Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta-cho,
Midori-ku, Yokohama 226-8503, Japan
| | - Shiori Kobayashi
- Division of Biological
Science,
Graduate School of Science, Nagoya University, Nagoya, 464-8602, Japan
| | - Michio Homma
- Division of Biological
Science,
Graduate School of Science, Nagoya University, Nagoya, 464-8602, Japan
| | - Masaaki Fujii
- Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta-cho,
Midori-ku, Yokohama 226-8503, Japan
| | - Hideki Kandori
- Department of Frontier
Materials, Nagoya Institute of Technology, Showa-ku, Nagoya, 466-8555,
Japan
| | - Yuki Sudo
- Division of Biological
Science,
Graduate School of Science, Nagoya University, Nagoya, 464-8602, Japan
- PRESTO, Japan Science and Technology Agency (JST), 4-1-8 Honcho Kawaguchi,
Saitama, 332-0012, Japan
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28
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Krishnamani V, Hegde BG, Langen R, Lanyi JK. Secondary and Tertiary Structure of Bacteriorhodopsin in the SDS Denatured State. Biochemistry 2012; 51:1051-60. [DOI: 10.1021/bi201769z] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Venkatramanan Krishnamani
- Department
of Physiology and Biophysics, University of California, Irvine, Irvine, California 92697, United States
| | - Balachandra G. Hegde
- Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, California
90033, United States
| | - Ralf Langen
- Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, California
90033, United States
| | - Janos K. Lanyi
- Department
of Physiology and Biophysics, University of California, Irvine, Irvine, California 92697, United States
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29
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Klimacek M, Brunsteiner M, Nidetzky B. Dynamic mechanism of proton transfer in mannitol 2-dehydrogenase from Pseudomonas fluorescens: mobile GLU292 controls proton relay through a water channel that connects the active site with bulk solvent. J Biol Chem 2011; 287:6655-67. [PMID: 22194597 PMCID: PMC3307286 DOI: 10.1074/jbc.m111.289223] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The active site of mannitol 2-dehydrogenase from Pseudomonas fluorescens (PfM2DH) is connected with bulk solvent through a narrow protein channel that shows structural resemblance to proton channels utilized by redox-driven proton pumps. A key element of the PfM2DH channel is the "mobile" Glu(292), which was seen crystallographically to adopt distinct positions up and down the channel. It was suggested that the "down → up" conformational change of Glu(292) could play a proton relay function in enzymatic catalysis, through direct proton shuttling by the Glu or because the channel is opened for water molecules forming a chain along which the protons flow. We report evidence from site-directed mutagenesis (Glu(292) → Ala) substantiated by data from molecular dynamics simulations that support a role for Glu(292) as a gate in a water chain (von Grotthuss-type) mechanism of proton translocation. Occupancy of the up and down position of Glu(292) is influenced by the bonding and charge state of the catalytic acid base Lys(295), suggesting that channel opening/closing motions of the Glu are synchronized to the reaction progress. Removal of gatekeeper control in the E292A mutant resulted in a selective, up to 120-fold slowing down of microscopic steps immediately preceding catalytic oxidation of mannitol, consistent with the notion that formation of the productive enzyme-NAD(+)-mannitol complex is promoted by a corresponding position change of Glu(292), which at physiological pH is associated with obligatory deprotonation of Lys(295) to solvent. These results underscore the important role of conformational dynamics in the proton transfer steps of alcohol dehydrogenase catalysis.
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Affiliation(s)
- Mario Klimacek
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, A-8010 Graz, Austria
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30
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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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31
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Krishnamani V, Lanyi JK. Structural changes in bacteriorhodopsin during in vitro refolding from a partially denatured state. Biophys J 2011; 100:1559-67. [PMID: 21402039 DOI: 10.1016/j.bpj.2011.02.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2010] [Revised: 02/03/2011] [Accepted: 02/04/2011] [Indexed: 10/18/2022] Open
Abstract
We report on the formation of the secondary and tertiary structure of bacteriorhodopsin during its in vitro refolding from an SDS-denatured state. We used the mobility of single spin labels in seven samples, attached at various locations to six of the seven helical segments to engineered cysteine residues, to follow coil-to-helix formation. Distance measurements obtained by spin dipolar quenching in six samples labeled at either the cytoplasmic or extracellular ends of pairs of helices revealed the time dependence of the recovery of the transmembrane helical bundle. The secondary structure in the majority of the helical segments refolds with a time constant of <100-140 ms. Recovery of the tertiary structure is achieved by sequential association of the helices and occurs in at least three distinct steps with time constants of 1), well below 1 s; 2), 3-4 s; and 3), 60-130 s (the latter depending on the helical pair). The slowest of these processes occurs in concert with recovery of the retinal chromophore.
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32
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Clemens M, Phatak P, Cui Q, Bondar AN, Elstner M. Role of Arg82 in the early steps of the bacteriorhodopsin proton-pumping cycle. J Phys Chem B 2011; 115:7129-35. [PMID: 21561116 DOI: 10.1021/jp201865k] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Proton-transfer reactions in the bacteriorhodopsin light-driven proton pump are coupled with structural rearrangements of protein amino acids and internal water molecules. It is generally thought that the first proton-transfer step from retinal Schiff base to the nearby Asp85 is coupled with movement of the Arg82 side chain away from Asp85 and toward the extracellular proton release group. This movement of Arg82 likely triggers the release of the proton from the proton release group to the extracellular bulk. The exact timing of the movement of Arg82 and how this movement is coupled with proton transfer are still not understood in molecular detail. Here, we address these questions by computing the free energy for the movement of the Arg82 side chain. The calculations indicate that protonation of Asp85 leads to a fast reorientation of the Arg82 side chain toward the extracellular proton release group.
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Affiliation(s)
- Maike Clemens
- Department of Theoretical and Computational Biophysics, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany
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33
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Borshchevskiy VI, Round ES, Popov AN, Büldt G, Gordeliy VI. X-ray-radiation-induced changes in bacteriorhodopsin structure. J Mol Biol 2011; 409:813-25. [PMID: 21530535 DOI: 10.1016/j.jmb.2011.04.038] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2011] [Revised: 04/12/2011] [Accepted: 04/13/2011] [Indexed: 11/29/2022]
Abstract
Bacteriorhodopsin (bR) provides light-driven vectorial proton transport across a cell membrane. Creation of electrochemical potential at the membrane is a universal step in energy transformation in a cell. Published atomic crystallographic models of early intermediate states of bR show a significant difference between them, and conclusions about pumping mechanisms have been contradictory. Here, we present a quantitative high-resolution crystallographic study of conformational changes in bR induced by X-ray absorption. It is shown that X-ray doses that are usually accumulated during data collection for intermediate-state studies are sufficient to significantly alter the structure of the protein. X-ray-induced changes occur primarily in the active site of bR. Structural modeling showed that X-ray absorption triggers retinal isomerization accompanied by the disappearance of electron densities corresponding to the water molecule W402 bound to the Schiff base. It is demonstrated that these and other X-ray-induced changes may mimic functional conformational changes of bR leading to misinterpretation of the earlier obtained X-ray crystallographic structures of photointermediates.
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Affiliation(s)
- Valentin I Borshchevskiy
- Laboratoire des Protéines Membranaires, Institut de Biologie Structurale J.-P. Ebel, UMR5075 CEA-CNRS-UJF, Grenoble 38027, France
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Mizuno M, Sudo Y, Homma M, Mizutani Y. Direct Observation of the Structural Change of Tyr174 in the Primary Reaction of Sensory Rhodopsin II. Biochemistry 2011; 50:3170-80. [DOI: 10.1021/bi101817y] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Misao Mizuno
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Yuki Sudo
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
- PRESTO, Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Michio Homma
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
| | - Yasuhisa Mizutani
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
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35
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Bondar AN, Fischer S, Smith JC. Water Pathways in the Bacteriorhodopsin Proton Pump. J Membr Biol 2010; 239:73-84. [DOI: 10.1007/s00232-010-9329-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Accepted: 11/05/2010] [Indexed: 01/18/2023]
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36
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Yokoyama Y, Negishi L, Kitoh T, Sonoyama M, Asami Y, Mitaku S. Effect of Lipid Phase Transition on Molecular Assembly and Structural Stability of Bacteriorhodopsin Reconstituted into Phosphatidylcholine Liposomes with Different Acyl-Chain Lengths. J Phys Chem B 2010; 114:15706-11. [DOI: 10.1021/jp108034n] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yasunori Yokoyama
- Department of Applied Physics, Graduate School of Engineering, Nagoya University, Nagoya, 464-8603 Japan, and TA Instruments Japan, Inc., Tokyo, 141-0031 Japan
| | - Lumi Negishi
- Department of Applied Physics, Graduate School of Engineering, Nagoya University, Nagoya, 464-8603 Japan, and TA Instruments Japan, Inc., Tokyo, 141-0031 Japan
| | - Taku Kitoh
- Department of Applied Physics, Graduate School of Engineering, Nagoya University, Nagoya, 464-8603 Japan, and TA Instruments Japan, Inc., Tokyo, 141-0031 Japan
| | - Masashi Sonoyama
- Department of Applied Physics, Graduate School of Engineering, Nagoya University, Nagoya, 464-8603 Japan, and TA Instruments Japan, Inc., Tokyo, 141-0031 Japan
| | - Yasuo Asami
- Department of Applied Physics, Graduate School of Engineering, Nagoya University, Nagoya, 464-8603 Japan, and TA Instruments Japan, Inc., Tokyo, 141-0031 Japan
| | - Shigeki Mitaku
- Department of Applied Physics, Graduate School of Engineering, Nagoya University, Nagoya, 464-8603 Japan, and TA Instruments Japan, Inc., Tokyo, 141-0031 Japan
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Aborted double bicycle-pedal isomerization with hydrogen bond breaking is the primary event of bacteriorhodopsin proton pumping. Proc Natl Acad Sci U S A 2010; 107:20172-7. [PMID: 21048087 DOI: 10.1073/pnas.1007000107] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Quantum mechanics/molecular mechanics calculations based on ab initio multiconfigurational second order perturbation theory are employed to construct a computer model of Bacteriorhodopsin that reproduces the observed static and transient electronic spectra, the dipole moment changes, and the energy stored in the photocycle intermediate K. The computed reaction coordinate indicates that the isomerization of the retinal chromophore occurs via a complex motion accounting for three distinct regimes: (i) production of the excited state intermediate I, (ii) evolution of I toward a conical intersection between the excited state and the ground state, and (iii) formation of K. We show that, during stage ii, a space-saving mechanism dominated by an asynchronous double bicycle-pedal deformation of the C10═C11─C12═C13─C14═N moiety of the chromophore dominates the isomerization. On this same stage a N─H/water hydrogen bond is weakened and initiates a breaking process that is completed during stage iii.
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Matsuoka D, Nakasako M. Prediction of Hydration Structures around Hydrophilic Surfaces of Proteins by Using the Empirical Hydration Distribution Functions from a Database Analysis. J Phys Chem B 2010; 114:4652-63. [DOI: 10.1021/jp9100224] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Daisuke Matsuoka
- Department of Physics, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522, Japan, and RIKEN Harima Institute, 1-1-1 Kouto, Mikaduki, Sayo, Hyogo, Japan
| | - Masayoshi Nakasako
- Department of Physics, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522, Japan, and RIKEN Harima Institute, 1-1-1 Kouto, Mikaduki, Sayo, Hyogo, Japan
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39
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Chu LK, El-Sayed MA. Kinetics of the M-Intermediate in the Photocycle of Bacteriorhodopsin upon Chemical Modification with Surfactants. Photochem Photobiol 2010; 86:316-23. [DOI: 10.1111/j.1751-1097.2009.00666.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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40
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Yokoyama Y, Sonoyama M, Mitaku S. Structural Changes in Bacteriorhodopsin in Purple Membranes Induced by Irreversible Photobleaching with Heterogeneous and Homogeneous Stability. Photochem Photobiol 2010; 86:297-301. [DOI: 10.1111/j.1751-1097.2009.00651.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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41
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Excitation of the M intermediates of wild-type bacteriorhodopsin and mutant D96N: temperature dependence of absorbance, electric responses and proton movements. Theor Chem Acc 2010. [DOI: 10.1007/s00214-009-0632-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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42
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Westenhoff S, Nazarenko E, Malmerberg E, Davidsson J, Katona G, Neutze R. Time-resolved structural studies of protein reaction dynamics: a smorgasbord of X-ray approaches. Acta Crystallogr A 2010; 66:207-19. [PMID: 20164644 PMCID: PMC2824530 DOI: 10.1107/s0108767309054361] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2009] [Accepted: 12/16/2009] [Indexed: 11/26/2022] Open
Abstract
Time-resolved structural studies of proteins have undergone several significant developments during the last decade. Recent developments using time-resolved X-ray methods, such as time-resolved Laue diffraction, low-temperature intermediate trapping, time-resolved wide-angle X-ray scattering and time-resolved X-ray absorption spectroscopy, are reviewed. Proteins undergo conformational changes during their biological function. As such, a high-resolution structure of a protein’s resting conformation provides a starting point for elucidating its reaction mechanism, but provides no direct information concerning the protein’s conformational dynamics. Several X-ray methods have been developed to elucidate those conformational changes that occur during a protein’s reaction, including time-resolved Laue diffraction and intermediate trapping studies on three-dimensional protein crystals, and time-resolved wide-angle X-ray scattering and X-ray absorption studies on proteins in the solution phase. This review emphasizes the scope and limitations of these complementary experimental approaches when seeking to understand protein conformational dynamics. These methods are illustrated using a limited set of examples including myoglobin and haemoglobin in complex with carbon monoxide, the simple light-driven proton pump bacteriorhodopsin, and the superoxide scavenger superoxide reductase. In conclusion, likely future developments of these methods at synchrotron X-ray sources and the potential impact of emerging X-ray free-electron laser facilities are speculated upon.
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Affiliation(s)
- Sebastian Westenhoff
- Department of Chemistry, Biochemistry and Biophysics, University of Gothenburg, Box 462, SE-40530 Gothenburg, Sweden
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Bajaj VS, Mak-Jurkauskas ML, Belenky M, Herzfeld J, Griffin RG. DNP enhanced frequency-selective TEDOR experiments in bacteriorhodopsin. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2010; 202:9-13. [PMID: 19854082 PMCID: PMC2818331 DOI: 10.1016/j.jmr.2009.09.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2009] [Revised: 08/27/2009] [Accepted: 09/03/2009] [Indexed: 05/06/2023]
Abstract
We describe a new approach to multiple (13)C-(15)N distance measurements in uniformly labeled solids, frequency-selective (FS) TEDOR. The method shares features with FS-REDOR and ZF- and BASE-TEDOR, which also provide quantitative (15)N-(13)C spectral assignments and distance measurements in U-[(13)C,(15)N] samples. To demonstrate the validity of the FS-TEDOR sequence, we measured distances in [U-(13)C,(15)N]-asparagine which are in good agreement with other methods. In addition, we integrate high frequency dynamic nuclear polarization (DNP) into the experimental protocol and use FS-TEDOR to record a resolved correlation spectrum of the Arg-(13)C(gamma)-(15)N(epsilon) region in [U-(13)C,(15)N]-bacteriorhodopsin. We resolve six of the seven cross-peaks expected based on the primary sequence of this membrane protein.
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Affiliation(s)
- Vikram S Bajaj
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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Borshchevskiy V, Efremov R, Moiseeva E, Büldt G, Gordeliy V. Overcoming merohedral twinning in crystals of bacteriorhodopsin grown in lipidic mesophase. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2009; 66:26-32. [PMID: 20057046 DOI: 10.1107/s0907444909042838] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2009] [Accepted: 10/18/2009] [Indexed: 11/11/2022]
Abstract
Twinning is one of the most common crystal-growth defects in protein crystallography. There are neither efficient rational approaches for the growth of nontwinned protein crystals nor are there examples of systematic studies of the dependence of the twinning-ratio distribution on crystallization conditions. The description of the twinning phenomenon has been covered even less for membrane-protein crystals and is non-existent for crystals grown using lipidic phases (in meso). In the present work, possibilities for overcoming merohedral twinning are investigated for crystals of the membrane protein bacteriorhodopsin (bR) grown in meso. It is shown that traditional crystallization additives are not effective in the case of the in meso crystallization of bR. The twinning ratio was determined for 310 crystals grown under different crystallization conditions. A correlation of the twinning ratio with the growth rate of the crystals was observed. Slow growth indicated that crystals had a noticeable chance of avoiding twinning. Model calculations were performed in order to rationalize this observation. The calculations confirmed the experimental observation that most crystals consist of two twin domains and showed that under this condition small changes in the probability of twin-domain formation lead to dramatic changes in the number of nontwinned crystals, which explains why slow crystal growth results in a considerable number of nontwinned crystals.
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Affiliation(s)
- Valentin Borshchevskiy
- Laboratoire des Protéines Membranaires, Institute de Biologie Structurale J.-P. Ebel, UMR5075 CEA-CNRS-UJF, Grenoble 38027, France
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45
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Andersson M, Malmerberg E, Westenhoff S, Katona G, Cammarata M, Wöhri AB, Johansson LC, Ewald F, Eklund M, Wulff M, Davidsson J, Neutze R. Structural Dynamics of Light-Driven Proton Pumps. Structure 2009; 17:1265-75. [DOI: 10.1016/j.str.2009.07.007] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2009] [Revised: 07/07/2009] [Accepted: 07/09/2009] [Indexed: 10/20/2022]
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46
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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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47
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Mizuno M, Shibata M, Yamada J, Kandori H, Mizutani Y. Picosecond Time-Resolved Ultraviolet Resonance Raman Spectroscopy of Bacteriorhodopsin: Primary Protein Response to the Photoisomerization of Retinal. J Phys Chem B 2009; 113:12121-8. [DOI: 10.1021/jp904388w] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Misao Mizuno
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan, and Department of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya 454-8555, Japan
| | - Mikihiro Shibata
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan, and Department of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya 454-8555, Japan
| | - Junya Yamada
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan, and Department of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya 454-8555, Japan
| | - Hideki Kandori
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan, and Department of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya 454-8555, Japan
| | - Yasuhisa Mizutani
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan, and Department of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya 454-8555, Japan
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48
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Hirai T, Subramaniam S, Lanyi JK. Structural snapshots of conformational changes in a seven-helix membrane protein: lessons from bacteriorhodopsin. Curr Opin Struct Biol 2009; 19:433-9. [PMID: 19643594 DOI: 10.1016/j.sbi.2009.07.009] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2009] [Revised: 07/09/2009] [Accepted: 07/10/2009] [Indexed: 11/28/2022]
Abstract
Recent advances in crystallizing integral membrane proteins have led to atomic models for the structures of several seven-helix membrane proteins, including those in the G-protein-coupled receptor family. Further steps toward exploring structure-function relationships will undoubtedly involve determination of the structural changes that occur during the various stages of receptor activation and deactivation. We expect that these efforts will bear many parallels to the studies of conformational changes in bacteriorhodopsin, which still remains the best-studied seven-helix membrane protein. Here, we provide a brief review of some of the lessons learned, the challenges faced, and the controversies over the last decade with determining conformational changes in bacteriorhodopsin. Our hope is that this analysis will be instructive for similar structural studies, especially of other seven-helix membrane proteins, in the coming decade.
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Affiliation(s)
- Teruhisa Hirai
- Three-dimensional Microscopy Research Team, RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan.
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49
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Abstract
Recent advances in the crystallography of bacteriorhodopsin, the light-driven proton pump, have yielded structural models for all intermediates of the photochemical cycle. For seven of the species, X-ray diffraction data were collected from trapped photostationary states in crystals, and for the two remaining ones the structures of selected mutants are available. The changes of the retinal chromophore, protein and bound water describe, at an atomic level, how accommodation of the twisted photoisomerized retinal to its binding site causes de-protonation of the retinal Schiff base and initiates cascades of gradual conformational rearrangements of the protein. One cascade propagates in the extracellular direction and results in proton release, and the other in the cytoplasmic direction and results in side-chain and main-chain rearrangements, formation of a chain of hydrogen-bonded water, and proton uptake from the bulk. Such local-global conformational coupling, with gradual spreading of a local perturbation over the rest of the protein, might be the uniting principle of transporters and receptors.
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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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50
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Babitzki G, Mathias G, Tavan P. The Infrared Spectra of the Retinal Chromophore in Bacteriorhodopsin Calculated by a DFT/MM Approach. J Phys Chem B 2009; 113:10496-508. [DOI: 10.1021/jp902432e] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- G. Babitzki
- Theoretische Biophysik, Lehrstuhl für Biomolekulare Optik, Ludwig-Maximilians-Universität Oettingenstr. 67, 80538 München, Germany
| | - G. Mathias
- Theoretische Biophysik, Lehrstuhl für Biomolekulare Optik, Ludwig-Maximilians-Universität Oettingenstr. 67, 80538 München, Germany
| | - P. Tavan
- Theoretische Biophysik, Lehrstuhl für Biomolekulare Optik, Ludwig-Maximilians-Universität Oettingenstr. 67, 80538 München, Germany
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