1
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Fujimoto KJ, Tsuzuki YA, Inoue K, Yanai T. Molecular Mechanisms behind Circular Dichroism Spectral Variations between Channelrhodopsin and Heliorhodopsin Dimers. J Phys Chem Lett 2024; 15:5788-5794. [PMID: 38780133 PMCID: PMC11145647 DOI: 10.1021/acs.jpclett.4c00879] [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] [Received: 03/24/2024] [Revised: 05/08/2024] [Accepted: 05/14/2024] [Indexed: 05/25/2024]
Abstract
Channelrhodopsin (ChR) and heliorhodopsin (HeR) are microbial rhodopsins with similar structures but different circular dichroism (CD) spectra: ChR shows biphasic negative and positive bands, whereas HeR shows a single positive band. We explored the physicochemical factors underlying these differences through computational methods. Using the exciton model based on first-principles computations, we obtained the CD spectra of ChR and HeR. The obtained spectra indicate that the protein dimer structures and the quantum mechanical treatment of the retinal chromophore and its interacting amino acids are crucial for accurately reproducing the experimental spectra. Further calculations revealed that the sign of the excitonic coupling was opposite between the ChR and HeR dimers, which was attributed to the contrasting second term of the orientation factor between the two retinal chromophores. These findings demonstrate that slight variations in the intermolecular orientation of the two chromophores can result in significant differences in the CD spectral shape.
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Affiliation(s)
- Kazuhiro J. Fujimoto
- Institute
of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furocho, Chikusa, Nagoya, Aichi 464-8601, Japan
- Department
of Chemistry, Graduate School of Science, Nagoya University, Furocho, Chikusa, Nagoya, Aichi 464-8601, Japan
| | - Yuta A. Tsuzuki
- Department
of Chemistry, Graduate School of Science, Nagoya University, Furocho, Chikusa, Nagoya, Aichi 464-8601, Japan
| | - Keiichi Inoue
- The
Institute for Solid State Physics, The University
of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
| | - Takeshi Yanai
- Institute
of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furocho, Chikusa, Nagoya, Aichi 464-8601, Japan
- Department
of Chemistry, Graduate School of Science, Nagoya University, Furocho, Chikusa, Nagoya, Aichi 464-8601, Japan
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2
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Bestsennaia E, Maslov I, Balandin T, Alekseev A, Yudenko A, Abu Shamseye A, Zabelskii D, Baumann A, Catapano C, Karathanasis C, Gordeliy V, Heilemann M, Gensch T, Borshchevskiy V. Channelrhodopsin-2 Oligomerization in Cell Membrane Revealed by Photo-Activated Localization Microscopy. Angew Chem Int Ed Engl 2024; 63:e202307555. [PMID: 38226794 DOI: 10.1002/anie.202307555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 01/03/2024] [Accepted: 01/15/2024] [Indexed: 01/17/2024]
Abstract
Microbial rhodopsins are retinal membrane proteins that found a broad application in optogenetics. The oligomeric state of rhodopsins is important for their functionality and stability. Of particular interest is the oligomeric state in the cellular native membrane environment. Fluorescence microscopy provides powerful tools to determine the oligomeric state of membrane proteins directly in cells. Among these methods is quantitative photoactivated localization microscopy (qPALM) allowing the investigation of molecular organization at the level of single protein clusters. Here, we apply qPALM to investigate the oligomeric state of the first and most used optogenetic tool Channelrhodopsin-2 (ChR2) in the plasma membrane of eukaryotic cells. ChR2 appeared predominantly as a dimer in the cell membrane and did not form higher oligomers. The disulfide bonds between Cys34 and Cys36 of adjacent ChR2 monomers were not required for dimer formation and mutations disrupting these bonds resulted in only partial monomerization of ChR2. The monomeric fraction increased when the total concentration of mutant ChR2 in the membrane was low. The dissociation constant was estimated for this partially monomerized mutant ChR2 as 2.2±0.9 proteins/μm2 . Our findings are important for understanding the mechanistic basis of ChR2 activity as well as for improving existing and developing future optogenetic tools.
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Affiliation(s)
- Ekaterina Bestsennaia
- Institute of Biological Information Processing 1, IBI-1 (Molecular and Cellular Physiology), Forschungszentrum Jülich, 52428, Jülich, Germany
| | - Ivan Maslov
- Dynamic Bioimaging Lab, Advanced Optical Microscopy Centre and the Biomedical Research Institute, Hasselt University, B3590, Diepenbeek, Belgium
- Laboratory for Photochemistry and Spectroscopy, Division for Molecular Imaging and Photonics, Department of Chemistry, KU Leuven, 3001, Leuven, Belgium
| | - Taras Balandin
- Institute of Biological Information Processing 7, IBI-7 (Structural Biochemistry), Forschungszentrum Jülich, 52428, Jülich, Germany
| | - Alexey Alekseev
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37075, Göttingen, Germany
| | - Anna Yudenko
- Department of Biomedical Sciences, University Medical Center Groningen, University of Groningen, 9713 AV, Groningen, The Netherlands
| | - Assalla Abu Shamseye
- Institute of Biological Information Processing 1, IBI-1 (Molecular and Cellular Physiology), Forschungszentrum Jülich, 52428, Jülich, Germany
- Institute of Biological Information Processing 7, IBI-7 (Structural Biochemistry), Forschungszentrum Jülich, 52428, Jülich, Germany
| | - Dmitrii Zabelskii
- Institute of Biological Information Processing 7, IBI-7 (Structural Biochemistry), Forschungszentrum Jülich, 52428, Jülich, Germany
- European XFEL, 22869, Schenefeld, Germany
| | - Arnd Baumann
- Institute of Biological Information Processing 1, IBI-1 (Molecular and Cellular Physiology), Forschungszentrum Jülich, 52428, Jülich, Germany
| | - Claudia Catapano
- Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt, 60438, Frankfurt, Germany
| | - Christos Karathanasis
- Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt, 60438, Frankfurt, Germany
| | - Valentin Gordeliy
- Institute of Biological Information Processing 7, IBI-7 (Structural Biochemistry), Forschungszentrum Jülich, 52428, Jülich, Germany
| | - Mike Heilemann
- Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt, 60438, Frankfurt, Germany
| | - Thomas Gensch
- Institute of Biological Information Processing 1, IBI-1 (Molecular and Cellular Physiology), Forschungszentrum Jülich, 52428, Jülich, Germany
| | - Valentin Borshchevskiy
- Institute of Biological Information Processing 7, IBI-7 (Structural Biochemistry), Forschungszentrum Jülich, 52428, Jülich, Germany
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3
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Petrovskaya LE, Lukashev EP, Lyukmanova EN, Shulepko MA, Kryukova EA, Ziganshin RH, Dolgikh DA, Maksimov EG, Rubin AB, Kirpichnikov MP, Lanyi JK, Balashov SP. Expression of Xanthorhodopsin in Escherichia coli. Protein J 2023:10.1007/s10930-023-10109-5. [DOI: 10.1007/s10930-023-10109-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/23/2023] [Indexed: 04/03/2023]
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4
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Davison PA, Tu W, Xu J, Della Valle S, Thompson IP, Hunter CN, Huang WE. Engineering a Rhodopsin-Based Photo-Electrosynthetic System in Bacteria for CO 2 Fixation. ACS Synth Biol 2022; 11:3805-3816. [PMID: 36264158 PMCID: PMC9680020 DOI: 10.1021/acssynbio.2c00397] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A key goal of synthetic biology is to engineer organisms that can use solar energy to convert CO2 to biomass, chemicals, and fuels. We engineered a light-dependent electron transfer chain by integrating rhodopsin and an electron donor to form a closed redox loop, which drives rhodopsin-dependent CO2 fixation. A light-driven proton pump comprising Gloeobacter rhodopsin (GR) and its cofactor retinal have been assembled in Ralstonia eutropha (Cupriavidus necator) H16. In the presence of light, this strain fixed inorganic carbon (or bicarbonate) leading to 20% growth enhancement, when formate was used as an electron donor. We found that an electrode from a solar panel can replace organic compounds to serve as the electron donor, mediated by the electron shuttle molecule riboflavin. In this new autotrophic and photo-electrosynthetic system, GR is augmented by an external photocell for reductive CO2 fixation. We demonstrated that this hybrid photo-electrosynthetic pathway can drive the engineered R. eutropha strain to grow using CO2 as the sole carbon source. In this system, a bioreactor with only two inputs, light and CO2, enables the R. eutropha strain to perform a rhodopsin-dependent autotrophic growth. Light energy alone, supplied by a solar panel, can drive the conversion of CO2 into biomass with a maximum electron transfer efficiency of 20%.
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Affiliation(s)
- Paul A. Davison
- Plants,
Photosynthesis and Soil, School of Biosciences, University of Sheffield, SheffieldS10 2TN, United Kingdom
| | - Weiming Tu
- Department
of Engineering Science, University of Oxford, OxfordOX1 3PJ, United Kingdom
| | - Jiabao Xu
- Department
of Engineering Science, University of Oxford, OxfordOX1 3PJ, United Kingdom
| | - Simona Della Valle
- Department
of Engineering Science, University of Oxford, OxfordOX1 3PJ, United Kingdom
| | - Ian P. Thompson
- Department
of Engineering Science, University of Oxford, OxfordOX1 3PJ, United Kingdom
| | - C. Neil Hunter
- Plants,
Photosynthesis and Soil, School of Biosciences, University of Sheffield, SheffieldS10 2TN, United Kingdom
| | - Wei E. Huang
- Department
of Engineering Science, University of Oxford, OxfordOX1 3PJ, United Kingdom,. Tel: +44 1865 283786
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5
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Shionoya T, Mizuno M, Kandori H, Mizutani Y. Contact-Mediated Retinal-Opsin Coupling Enables Proton Pumping in Gloeobacter Rhodopsin. J Phys Chem B 2022; 126:7857-7869. [PMID: 36173382 DOI: 10.1021/acs.jpcb.2c04208] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
When a chromophore embedded in a photoreceptive protein undergoes a reaction upon photoexcitation, the photoreaction triggers structural changes in the protein moiety that are necessary for the function of the protein. It is thus essential to elucidate the coupling between the chromophore and protein moiety to understand the functional mechanism for photoreceptive proteins, but the mechanism by which this coupling occurs remains poorly understood. Here, we show that nonbonded atomic contacts play an essential role in driving functionally important structural changes following photoisomerization of the chromophore in Gloeobacter rhodopsin (GR). Time-resolved ultraviolet resonance Raman spectroscopy revealed that the substitution of Trp222, which contacts with methyl groups of the retinal chromophore, with a Phe residue reduced the extent of structural change. The proton-pumping activity of the GR mutant was as small as 9% of that of the wild type. Time-resolved visible absorption and resonance Raman spectra showed that the photocycle of the mutant proceeded to the L intermediate following the all-trans to 13-cis photoisomerization step but did not result in the deprotonation of the chromophore. The present results demonstrate that the atomic contacts between the chromophore and the Trp222 side chain induce the structural changes necessary for proton transfer. The requirement for dense atomic packing in a protein structure for the efficient propagation of structural changes through a coupling mechanism is discussed.
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Affiliation(s)
- Tomomi Shionoya
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Misao Mizuno
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Hideki Kandori
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya, Aichi 466-8555, Japan
| | - Yasuhisa Mizutani
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
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6
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Brown LS. Light-driven proton transfers and proton transport by microbial rhodopsins - A biophysical perspective. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183867. [PMID: 35051382 DOI: 10.1016/j.bbamem.2022.183867] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 12/30/2021] [Accepted: 01/10/2022] [Indexed: 12/31/2022]
Abstract
In the last twenty years, our understanding of the rules and mechanisms for the outward light-driven proton transport (and underlying proton transfers) by microbial rhodopsins has been changing dramatically. It transitioned from a very detailed atomic-level understanding of proton transport by bacteriorhodopsin, the prototypical proton pump, to a confounding variety of sequence motifs, mechanisms, directions, and modes of transport in its newly found homologs. In this review, we will summarize and discuss experimental data obtained on new microbial rhodopsin variants, highlighting their contribution to the refinement and generalization of the ideas crystallized in the previous century. In particular, we will focus on the proton transport (and transfers) vectoriality and their structural determinants, which, in many cases, remain unidentified.
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Affiliation(s)
- Leonid S Brown
- Department of Physics and Biophysics Interdepartmental Group, University of Guelph, Ontario N1G 2W1, Canada.
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7
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Chi H, Zhou Q, Tutol JN, Phelps SM, Lee J, Kapadia P, Morcos F, Dodani SC. Coupling a Live Cell Directed Evolution Assay with Coevolutionary Landscapes to Engineer an Improved Fluorescent Rhodopsin Chloride Sensor. ACS Synth Biol 2022; 11:1627-1638. [PMID: 35389621 PMCID: PMC9184236 DOI: 10.1021/acssynbio.2c00033] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Our understanding of chloride in biology has been accelerated through the application of fluorescent protein-based sensors in living cells. These sensors can be generated and diversified to have a range of properties using laboratory-guided evolution. Recently, we established that the fluorescent proton-pumping rhodopsin wtGR from Gloeobacter violaceus can be converted into a fluorescent sensor for chloride. To unlock this non-natural function, a single point mutation at the Schiff counterion position (D121V) was introduced into wtGR fused to cyan fluorescent protein (CFP) resulting in GR1-CFP. Here, we have integrated coevolutionary analysis with directed evolution to understand how the rhodopsin sequence space can be explored and engineered to improve this starting point. We first show how evolutionary couplings are predictive of functional sites in the rhodopsin family and how a fitness metric based on a sequence can be used to quantify the known proton-pumping activities of GR-CFP variants. Then, we couple this ability to predict potential functional outcomes with a screening and selection assay in live Escherichia coli to reduce the mutational search space of five residues along the proton-pumping pathway in GR1-CFP. This iterative selection process results in GR2-CFP with four additional mutations: E132K, A84K, T125C, and V245I. Finally, bulk and single fluorescence measurements in live E. coli reveal that GR2-CFP is a reversible, ratiometric fluorescent sensor for extracellular chloride with an improved dynamic range. We anticipate that our framework will be applicable to other systems, providing a more efficient methodology to engineer fluorescent protein-based sensors with desired properties.
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8
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Fujimoto KJ. Electronic Couplings and Electrostatic Interactions Behind the Light Absorption of Retinal Proteins. Front Mol Biosci 2021; 8:752700. [PMID: 34604313 PMCID: PMC8480471 DOI: 10.3389/fmolb.2021.752700] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 09/02/2021] [Indexed: 11/13/2022] Open
Abstract
The photo-functional chromophore retinal exhibits a wide variety of optical absorption properties depending on its intermolecular interactions with surrounding proteins and other chromophores. By utilizing these properties, microbial and animal rhodopsins express biological functions such as ion-transport and signal transduction. In this review, we present the molecular mechanisms underlying light absorption in rhodopsins, as revealed by quantum chemical calculations. Here, symmetry-adapted cluster-configuration interaction (SAC-CI), combined quantum mechanical and molecular mechanical (QM/MM), and transition-density-fragment interaction (TDFI) methods are used to describe the electronic structure of the retinal, the surrounding protein environment, and the electronic coupling between chromophores, respectively. These computational approaches provide successful reproductions of experimentally observed absorption and circular dichroism (CD) spectra, as well as insights into the mechanisms of unique optical properties in terms of chromophore-protein electrostatic interactions and chromophore-chromophore electronic couplings. On the basis of the molecular mechanisms revealed in these studies, we also discuss strategies for artificial design of the optical absorption properties of rhodopsins.
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Affiliation(s)
- Kazuhiro J Fujimoto
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Nagoya, Japan.,Department of Chemistry, Graduate School of Science, Nagoya University, Nagoya, Japan
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9
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Tutol JN, Lee J, Chi H, Faizuddin FN, Abeyrathna SS, Zhou Q, Morcos F, Meloni G, Dodani SC. A single point mutation converts a proton-pumping rhodopsin into a red-shifted, turn-on fluorescent sensor for chloride. Chem Sci 2021; 12:5655-5663. [PMID: 34163777 PMCID: PMC8179538 DOI: 10.1039/d0sc06061e] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Accepted: 03/08/2021] [Indexed: 12/11/2022] Open
Abstract
The visualization of chloride in living cells with fluorescent sensors is linked to our ability to design hosts that can overcome the energetic penalty of desolvation to bind chloride in water. Fluorescent proteins can be used as biological supramolecular hosts to address this fundamental challenge. Here, we showcase the power of protein engineering to convert the fluorescent proton-pumping rhodopsin GR from Gloeobacter violaceus into GR1, a red-shifted, turn-on fluorescent sensor for chloride in detergent micelles and in live Escherichia coli. This non-natural function was unlocked by mutating D121, which serves as the counterion to the protonated retinylidene Schiff base chromophore. Substitution from aspartate to valine at this position (D121V) creates a binding site for chloride. The binding of chloride tunes the pK a of the chromophore towards the protonated, fluorescent state to generate a pH-dependent response. Moreover, ion pumping assays combined with bulk fluorescence and single-cell fluorescence microscopy experiments with E. coli, expressing a GR1 fusion with a cyan fluorescent protein, show that GR1 does not pump ions nor sense membrane potential but instead provides a reversible, ratiometric readout of changes in extracellular chloride at the membrane. This discovery sets the stage to use natural and laboratory-guided evolution to build a family of rhodopsin-based fluorescent chloride sensors with improved properties for cellular applications and learn how proteins can evolve and adapt to bind anions in water.
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Affiliation(s)
- Jasmine N Tutol
- Department of Chemistry and Biochemistry, The University of Texas at Dallas Richardson TX 75080 USA
| | - Jessica Lee
- Department of Chemistry and Biochemistry, The University of Texas at Dallas Richardson TX 75080 USA
- Department of Biological Sciences, The University of Texas at Dallas Richardson TX 75080 USA
| | - Hsichuan Chi
- Department of Chemistry and Biochemistry, The University of Texas at Dallas Richardson TX 75080 USA
- Department of Biological Sciences, The University of Texas at Dallas Richardson TX 75080 USA
| | - Farah N Faizuddin
- Department of Chemistry and Biochemistry, The University of Texas at Dallas Richardson TX 75080 USA
- Department of Biological Sciences, The University of Texas at Dallas Richardson TX 75080 USA
| | - Sameera S Abeyrathna
- Department of Chemistry and Biochemistry, The University of Texas at Dallas Richardson TX 75080 USA
| | - Qin Zhou
- Department of Biological Sciences, The University of Texas at Dallas Richardson TX 75080 USA
| | - Faruck Morcos
- Department of Biological Sciences, The University of Texas at Dallas Richardson TX 75080 USA
- Department of Bioengineering, The University of Texas at Dallas Richardson TX 75080 USA
| | - Gabriele Meloni
- Department of Chemistry and Biochemistry, The University of Texas at Dallas Richardson TX 75080 USA
| | - Sheel C Dodani
- Department of Chemistry and Biochemistry, The University of Texas at Dallas Richardson TX 75080 USA
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10
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His57 controls the efficiency of ESR, a light-driven proton pump from Exiguobacterium sibiricum at low and high pH. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1862:148328. [PMID: 33075275 DOI: 10.1016/j.bbabio.2020.148328] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 10/06/2020] [Accepted: 10/13/2020] [Indexed: 12/13/2022]
Abstract
ESR, a light-driven proton pump from Exiguobacterium sibiricum, contains a lysine residue (Lys96) in the proton donor site. Substitution of Lys96 with a nonionizable residue greatly slows reprotonation of the retinal Schiff base. The recent study of electrogenicity of the K96A mutant revealed that overall efficiency of proton transport is decreased in the mutant due to back reactions (Siletsky et al., BBA, 2019). Similar to members of the proteorhodopsin and xanthorhodopsin families, in ESR the primary proton acceptor from the Schiff base, Asp85, closely interacts with His57. To examine the role of His57 in the efficiency of proton translocation by ESR, we studied the effects of H57N and H57N/K96A mutations on the pH dependence of light-induced pH changes in suspensions of Escherichia coli cells, kinetics of absorption changes and electrogenic proton transfer reactions during the photocycle. We found that at low pH (<5) the proton pumping efficiency of the H57N mutant in E. coli cells and its electrogenic efficiency in proteoliposomes is substantially higher than in the WT, suggesting that interaction of His57 with Asp85 sets the low pH limit for H+ pumping in ESR. The electrogenic components that correspond to proton uptake were strongly accelerated at low pH in the mutant indicating that Lys96 functions as a very efficient proton donor at low pH. In the H57N/K96A mutant, a higher H+ pumping efficiency compared with K96A was observed especially at high pH, apparently from eliminating back reactions between Asp85 and the Schiff base by the H57N mutation.
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11
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The chirality origin of retinal-carotenoid complex in gloeobacter rhodopsin: a temperature-dependent excitonic coupling. Sci Rep 2020; 10:13992. [PMID: 32814821 PMCID: PMC7438509 DOI: 10.1038/s41598-020-70697-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Accepted: 07/29/2020] [Indexed: 11/08/2022] Open
Abstract
Retinal proteins play significant roles in light-induced protons/ions transport across the cell membrane. A recent studied retinal protein, gloeobacter rhodopsin (gR), functions as a proton pump, and binds the carotenoid salinixanthin (sal) in addition to the retinal chromophore. We have studied the interactions between the two chromophores as reflected in the circular dichroism (CD) spectrum of gR complex. gR exhibits a weak CD spectrum but following binding of sal, it exhibits a significant enhancement of the CD bands. To examine the CD origin, we have substituted the retinal chromophore of gR by synthetic retinal analogues, and have concluded that the CD bands originated from excitonic interaction between sal and the retinal chromophore as well as the sal chirality induced by binding to the protein. Temperature increase significantly affected the CD spectra, due to vanishing of excitonic coupling. A similar phenomenon of excitonic interaction lose between chromophores was recently reported for a photosynthetic pigment-protein complex (Nature Commmun, 9, 2018, 99). We propose that the excitonic interaction in gR is weaker due to protein conformational alterations. The excitonic interaction is further diminished following reduction of the retinal protonated Schiff base double bond. Furthermore, the intact structure of the retinal ring is necessary for obtaining the excitonic interaction.
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12
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Fujimoto KJ, Inoue K. Excitonic coupling effect on the circular dichroism spectrum of sodium-pumping rhodopsin KR2. J Chem Phys 2020; 153:045101. [DOI: 10.1063/5.0013642] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Affiliation(s)
- Kazuhiro J. Fujimoto
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furocho, Chikusa, Nagoya 464-8601, Japan
| | - Keiichi Inoue
- The Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa-shi, Chiba 277-8581, Japan
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13
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Ban X, Wu J, Kaustubh B, Lahiri P, Dhoble AS, Gu Z, Li C, Cheng L, Hong Y, Tong Y, Li Z. Additional salt bridges improve the thermostability of 1,4-α-glucan branching enzyme. Food Chem 2020; 316:126348. [DOI: 10.1016/j.foodchem.2020.126348] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 02/02/2020] [Accepted: 02/02/2020] [Indexed: 01/05/2023]
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14
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Ganapathy S, Opdam L, Hontani Y, Frehan S, Chen Q, Hellingwerf KJ, de Groot HJ, Kennis JT, de Grip WJ. Membrane matters: The impact of a nanodisc-bilayer or a detergent microenvironment on the properties of two eubacterial rhodopsins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183113. [DOI: 10.1016/j.bbamem.2019.183113] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 10/20/2019] [Accepted: 10/22/2019] [Indexed: 12/29/2022]
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15
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Otomo A, Mizuno M, Inoue K, Kandori H, Mizutani Y. Allosteric Communication with the Retinal Chromophore upon Ion Binding in a Light-Driven Sodium Ion-Pumping Rhodopsin. Biochemistry 2020; 59:520-529. [PMID: 31887021 DOI: 10.1021/acs.biochem.9b01062] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Krokinobacter rhodopsin 2 (KR2) serves as a light-driven sodium ion pump in the presence of sodium ion and works as a proton pump in the presence of larger monovalent cations such as potassium ion, rubidium ion, and cesium ion. Recent crystallographic studies revealed that KR2 forms a pentamer and possesses an ion binding site at the subunit interface. It is assumed that sodium ion bound at this binding site is not transported but contributes to the thermal stability. Because KR2 can convert its function in response to coexisting cation species, this ion binding site is likely to be involved in ion transport selectively. However, how sodium ion binding affects the structure of the retinal chromophore, which plays a crucial role in ion transport, remains poorly understood. Here, we observed the structure of the retinal chromophore under a wide range of cation concentrations using visible absorption and resonance Raman spectroscopy. We discovered that the hydrogen bond formed between the Schiff base of the retinal chromophore and its counterion, Asp116, is weakened upon binding of sodium ion. This allosteric communication between the Schiff base and the ion binding site at the subunit interface likely increases the apparent efficiency of sodium ion transport. In addition, this study demonstrates the significance of sodium ion binding: even though sodium ion is not transported, binding regulates the structure around the Schiff base and stabilizes the oligomeric structure.
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Affiliation(s)
- Akihiro Otomo
- Department of Chemistry, Graduate School of Science , Osaka University , 1-1 Machikaneyama , Toyonaka , Osaka 560-0043 , Japan
| | - Misao Mizuno
- Department of Chemistry, Graduate School of Science , Osaka University , 1-1 Machikaneyama , Toyonaka , Osaka 560-0043 , Japan
| | - Keiichi Inoue
- The Institute for Solid State Physics, The University of Tokyo , Kashiwa 277-8581 , Japan
| | - Hideki Kandori
- Department of Life Science and Applied Chemistry , Nagoya Institute of Technology , Showa-ku, Nagoya 466-8555 , Japan.,OptoBio Technology Research Center , Nagoya Institute of Technology , Showa-Ku, Nagoya 466-8555 , Japan
| | - Yasuhisa Mizutani
- Department of Chemistry, Graduate School of Science , Osaka University , 1-1 Machikaneyama , Toyonaka , Osaka 560-0043 , Japan
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16
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Morizumi T, Ou WL, Van Eps N, Inoue K, Kandori H, Brown LS, Ernst OP. X-ray Crystallographic Structure and Oligomerization of Gloeobacter Rhodopsin. Sci Rep 2019; 9:11283. [PMID: 31375689 PMCID: PMC6677831 DOI: 10.1038/s41598-019-47445-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 06/24/2019] [Indexed: 01/27/2023] Open
Abstract
Gloeobacter rhodopsin (GR) is a cyanobacterial proton pump which can be potentially applied to optogenetics. We solved the crystal structure of GR and found that it has overall similarity to the homologous proton pump from Salinibacter ruber, xanthorhodopsin (XR). We identified distinct structural characteristics of GR’s hydrogen bonding network in the transmembrane domain as well as the displacement of extracellular sides of the transmembrane helices relative to those of XR. Employing Raman spectroscopy and flash-photolysis, we found that GR in the crystals exists in a state which displays retinal conformation and photochemical cycle similar to the functional form observed in lipids. Based on the crystal structure of GR, we selected a site for spin labeling to determine GR’s oligomerization state using double electron–electron resonance (DEER) spectroscopy and demonstrated the pH-dependent pentamer formation of GR. Determination of the structure of GR as well as its pentamerizing propensity enabled us to reveal the role of structural motifs (extended helices, 3-omega motif and flipped B-C loop) commonly found among light-driven bacterial pumps in oligomer formation. Here we propose a new concept to classify these pumps based on the relationship between their oligomerization propensities and these structural determinants.
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Affiliation(s)
- Takefumi Morizumi
- Department of Biochemistry, University of Toronto, Toronto, Ontario, M5S 1A8, Canada
| | - Wei-Lin Ou
- Department of Biochemistry, University of Toronto, Toronto, Ontario, M5S 1A8, Canada
| | - Ned Van Eps
- Department of Biochemistry, University of Toronto, Toronto, Ontario, M5S 1A8, Canada
| | - Keiichi Inoue
- The Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
| | - Hideki Kandori
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya, 464-8555, Japan.,OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Nagoya, 464-8555, Japan
| | - Leonid S Brown
- Department of Physics, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
| | - Oliver P Ernst
- Department of Biochemistry, University of Toronto, Toronto, Ontario, M5S 1A8, Canada. .,Department of Molecular Genetics, University of Toronto, Ontario, M5S 1A8, Canada.
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17
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Iizuka A, Kajimoto K, Fujisawa T, Tsukamoto T, Aizawa T, Kamo N, Jung KH, Unno M, Demura M, Kikukawa T. Functional importance of the oligomer formation of the cyanobacterial H + pump Gloeobacter rhodopsin. Sci Rep 2019; 9:10711. [PMID: 31341208 PMCID: PMC6656774 DOI: 10.1038/s41598-019-47178-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 07/11/2019] [Indexed: 02/07/2023] Open
Abstract
Many microbial rhodopsins self-oligomerize, but the functional consequences of oligomerization have not been well clarified. We examined the effects of oligomerization of a H+ pump, Gloeobacter rhodopsin (GR), by using nanodisc containing trimeric and monomeric GR. The monomerization did not appear to affect the unphotolyzed GR. However, we found a significant impact on the photoreaction: The monomeric GR showed faint M intermediate formation and negligible H+ transfer reactions. These changes reflected the elevated pKa of the Asp121 residue, whose deprotonation is a prerequisite for the functional photoreaction. Here, we focused on His87, which is a neighboring residue of Asp121 and conserved among eubacterial H+ pumps but replaced by Met in an archaeal H+ pump. We found that the H87M mutation removes the “monomerization effects”: Even in the monomeric state, H87M contained the deprotonated Asp121 and showed both M formation and distinct H+ transfer reactions. Thus, for wild-type GR, monomerization probably strengthens the Asp121-His87 interaction and thereby elevates the pKa of Asp121 residue. This strong interaction might occur due to the loosened protein structure and/or the disruption of the interprotomer interaction of His87. Thus, the trimeric assembly of GR enables light-induced H+ transfer reactions through adjusting the positions of key residues.
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Affiliation(s)
- Azusa Iizuka
- Faculty of Advanced Life Science, Hokkaido University, Sapporo, 060-0810, Japan
| | - Kousuke Kajimoto
- Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University, Saga, 840-8502, Japan
| | - Tomotsumi Fujisawa
- Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University, Saga, 840-8502, Japan
| | - Takashi Tsukamoto
- Faculty of Advanced Life Science, Hokkaido University, Sapporo, 060-0810, Japan.,Global Station for Soft Matter, Global Institution for Collaborative Research and Education, Hokkaido University, Sapporo, 001-0021, Japan
| | - Tomoyasu Aizawa
- Faculty of Advanced Life Science, Hokkaido University, Sapporo, 060-0810, Japan.,Global Station for Soft Matter, Global Institution for Collaborative Research and Education, Hokkaido University, Sapporo, 001-0021, Japan
| | - Naoki Kamo
- Faculty of Advanced Life Science, Hokkaido University, Sapporo, 060-0810, Japan
| | - Kwang-Hwan Jung
- Department of Life Science and Institute of Biological Interfaces, Sogang University, Seoul, 04107, Republic of Korea
| | - Masashi Unno
- Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University, Saga, 840-8502, Japan
| | - Makoto Demura
- Faculty of Advanced Life Science, Hokkaido University, Sapporo, 060-0810, Japan.,Global Station for Soft Matter, Global Institution for Collaborative Research and Education, Hokkaido University, Sapporo, 001-0021, Japan
| | - Takashi Kikukawa
- Faculty of Advanced Life Science, Hokkaido University, Sapporo, 060-0810, Japan. .,Global Station for Soft Matter, Global Institution for Collaborative Research and Education, Hokkaido University, Sapporo, 001-0021, Japan.
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18
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Shionoya T, Mizuno M, Tsukamoto T, Ikeda K, Seki H, Kojima K, Shibata M, Kawamura I, Sudo Y, Mizutani Y. High Thermal Stability of Oligomeric Assemblies of Thermophilic Rhodopsin in a Lipid Environment. J Phys Chem B 2018; 122:6945-6953. [PMID: 29893559 DOI: 10.1021/acs.jpcb.8b04894] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Thermophilic rhodopsin (TR) is a light-driven proton pump from the extreme thermophile Thermus thermophilus JL-18. Previous studies on TR solubilized with detergent showed that the protein exhibits high thermal stability and forms a trimer at room temperature but irreversibly dissociates into monomers when incubated at physiological temperature (75 °C). In the present study, we used resonance Raman (RR) spectroscopy, solid-state NMR spectroscopy, and high-speed atomic force microscopy to analyze the oligomeric structure of TR in a lipid environment. The obtained spectra and microscopic images demonstrate that TR adopts a pentameric form in a lipid environment and that this assembly is stable at the physiological temperature, in contrast to the behavior of the protein in the solubilized state. These results indicate that the thermal stability of the oligomeric assembly of TR is higher in a lipid environment than in detergent micelles. The observed RR spectra also showed that the retinal chromophore is strongly hydrogen bonded to an internal water molecule via a protonated Schiff base, which is characteristic of proton-pumping rhodopsins. The obtained data strongly suggest that TR functions in the pentameric form at physiological temperature in the extreme thermophile T. thermophilus JL-18. We utilized the high thermal stability of the monomeric form of solubilized TR and here report the first RR spectra of the monomeric form of a microbial rhodopsin. The observed RR spectra revealed that the monomerization of TR alters the chromophore structure: there are changes in the bond alternation of the polyene chain and in the hydrogen-bond strength of the protonated Schiff base. The present study revealed the high thermal stability of oligomeric assemblies of TR in the lipid environment and suggested the importance of using TR embedded in lipid membrane for elucidation of its functional mechanism.
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Affiliation(s)
- Tomomi Shionoya
- Department of Chemistry, Graduate School of Science , Osaka University , 1-1 Machikaneyama , Toyonaka , Osaka 560-0043 , Japan
| | - Misao Mizuno
- Department of Chemistry, Graduate School of Science , Osaka University , 1-1 Machikaneyama , Toyonaka , Osaka 560-0043 , Japan
| | - Takashi Tsukamoto
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences , Okayama University , 1-1-1 Tsushima-naka , Kita-ku, Okayama 700-8530 , Japan
| | | | - Hayato Seki
- Graduate School of Engineering , Yokohama National University , Hodogaya-ku, Yokohama 240-8501 , Japan
| | - Keiichi Kojima
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences , Okayama University , 1-1-1 Tsushima-naka , Kita-ku, Okayama 700-8530 , Japan
| | | | - Izuru Kawamura
- Graduate School of Engineering , Yokohama National University , Hodogaya-ku, Yokohama 240-8501 , Japan
| | - Yuki Sudo
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences , Okayama University , 1-1-1 Tsushima-naka , Kita-ku, Okayama 700-8530 , Japan
| | - Yasuhisa Mizutani
- Department of Chemistry, Graduate School of Science , Osaka University , 1-1 Machikaneyama , Toyonaka , Osaka 560-0043 , Japan
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19
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Oligomeric states of microbial rhodopsins determined by high-speed atomic force microscopy and circular dichroic spectroscopy. Sci Rep 2018; 8:8262. [PMID: 29844455 PMCID: PMC5974397 DOI: 10.1038/s41598-018-26606-y] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 05/15/2018] [Indexed: 01/05/2023] Open
Abstract
Oligomeric assembly is a common feature of membrane proteins and often relevant to their physiological functions. Determining the stoichiometry and the oligomeric state of membrane proteins in a lipid bilayer is generally challenging because of their large size, complexity, and structural alterations under experimental conditions. Here, we use high-speed atomic force microscopy (HS-AFM) to directly observe the oligomeric states in the lipid membrane of various microbial rhodopsins found within eubacteria to archaea. HS-AFM images show that eubacterial rhodopsins predominantly exist as pentamer forms, while archaeal rhodopsins are trimers in the lipid membrane. In addition, circular dichroism (CD) spectroscopy reveals that pentameric rhodopsins display inverted CD couplets compared to those of trimeric rhodopsins, indicating different types of exciton coupling of the retinal chromophore in each oligomer. The results clearly demonstrate that the stoichiometry of the fundamental oligomer of microbial rhodopsins strongly correlate with the phylogenetic tree, providing a new insight into the relationship between the oligomeric structure and function-structural evolution of microbial rhodopsins.
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20
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Nakajima Y, Tsukamoto T, Kumagai Y, Ogura Y, Hayashi T, Song J, Kikukawa T, Demura M, Kogure K, Sudo Y, Yoshizawa S. Presence of a Haloarchaeal Halorhodopsin-Like Cl - Pump in Marine Bacteria. Microbes Environ 2018; 33:89-97. [PMID: 29553064 PMCID: PMC5877348 DOI: 10.1264/jsme2.me17197] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Light-driven ion-pumping rhodopsins are widely distributed among bacteria, archaea, and eukaryotes in the euphotic zone of the aquatic environment. H+-pumping rhodopsin (proteorhodopsin: PR), Na+-pumping rhodopsin (NaR), and Cl--pumping rhodopsin (ClR) have been found in marine bacteria, which suggests that these genes evolved independently in the ocean. Putative microbial rhodopsin genes were identified in the genome sequences of marine Cytophagia. In the present study, one of these genes was heterologously expressed in Escherichia coli cells and the rhodopsin protein named Rubricoccus marinus halorhodopsin (RmHR) was identified as a light-driven inward Cl- pump. Spectroscopic assays showed that the estimated dissociation constant (Kd,int.) of this rhodopsin was similar to that of haloarchaeal halorhodopsin (HR), while the Cl--transporting photoreaction mechanism of this rhodopsin was similar to that of HR, but different to that of the already-known marine bacterial ClR. This amino acid sequence similarity also suggested that this rhodopsin is similar to haloarchaeal HR and cyanobacterial HRs (e.g., SyHR and MrHR). Additionally, a phylogenetic analysis revealed that retinal biosynthesis pathway genes (blh and crtY) belong to a phylogenetic lineage of haloarchaea, indicating that these marine Cytophagia acquired rhodopsin-related genes from haloarchaea by lateral gene transfer. Based on these results, we concluded that inward Cl--pumping rhodopsin is present in genera of the class Cytophagia and may have the same evolutionary origins as haloarchaeal HR.
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Affiliation(s)
- Yu Nakajima
- Atmosphere and Ocean research Institute (AORI), The University of Tokyo.,Department of Natural Environmental Studies, Graduate School of Frontier Sciences, the University of Tokyo
| | - Takashi Tsukamoto
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University
| | - Yohei Kumagai
- Atmosphere and Ocean research Institute (AORI), The University of Tokyo.,Department of Natural Environmental Studies, Graduate School of Frontier Sciences, the University of Tokyo
| | - Yoshitoshi Ogura
- Department of Bacteriology, Faculty of Medical Sciences, Kyushu University
| | - Tetsuya Hayashi
- Department of Bacteriology, Faculty of Medical Sciences, Kyushu University
| | - Jaeho Song
- Department of Biological Sciences, Inha University
| | - Takashi Kikukawa
- Faculty of Advanced Life Science, Hokkaido University.,Global Station for Soft Matter, Global Institution for Collaborative Research and Education, Hokkaido University
| | - Makoto Demura
- Faculty of Advanced Life Science, Hokkaido University.,Global Station for Soft Matter, Global Institution for Collaborative Research and Education, Hokkaido University
| | - Kazuhiro Kogure
- Atmosphere and Ocean research Institute (AORI), The University of Tokyo.,Department of Natural Environmental Studies, Graduate School of Frontier Sciences, the University of Tokyo
| | - Yuki Sudo
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University
| | - Susumu Yoshizawa
- Atmosphere and Ocean research Institute (AORI), The University of Tokyo.,Department of Natural Environmental Studies, Graduate School of Frontier Sciences, the University of Tokyo
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21
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Jana S, Eliash T, Jung KH, Sheves M. Retinal Binding to Apo-Gloeobacter Rhodopsin: The Role of pH and Retinal-Carotenoid Interaction. J Phys Chem B 2017; 121:10759-10769. [PMID: 29111729 DOI: 10.1021/acs.jpcb.7b07523] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Over the past few decades, the structure, functions, properties, and molecular mechanisms of retinal proteins have been studied extensively. The newly studied retinal protein Gloeobacter rhodopsin (gR) acts as a light-driven proton pump, transferring a proton from the cytoplasmic region to the extracellular region of a cell following light absorption. It was previously shown that gR can bind the carotenoid salinixanthin (sal). In the present study, we report the effect of pH on the binding of retinal to the apo-protein of gR, in the presence and absence of sal, to form the gR pigment. We found that binding at different pH levels reflects the titration of two different protein residues, one at the lower pKa 3.5 and another at the higher pKa 8.4, that affect the pigment's formation. The maximum amount of pigment was formed at pH 5, both with and without the presence of sal. The introduction of sal accelerates the rate of pigment formation by a factor of 190. Furthermore, it is suggested that occupation of the binding site by the retinal chromophore induces protein conformational alterations which in turn affect the carotenoid conformation, which precedes the formation of the retinal-protein covalent bond. Our examination of synthetic retinal analogues in which the ring structure was modified revealed that, in the absence of sal, the retinal ring structure affects the rate of pigment formation and that the intact structure is needed for efficient pigment formation. However, the presence of sal abolishes this effect, and all-trans retinal and its modified ring analogues bind at a similar rate.
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Affiliation(s)
- Sankar Jana
- Department of Organic Chemistry, Weizmann Institute of Science , Rehovot 76100, Israel
| | - Tamar Eliash
- Department of Organic Chemistry, Weizmann Institute of Science , Rehovot 76100, Israel
| | - Kwang-Hwan Jung
- Department of Life Science and Institute of Biological Interfaces, Sogang University , Shinsu-Dong 1, Mapo-Gu, Seoul 121-742, South Korea
| | - Mordechai Sheves
- Department of Organic Chemistry, Weizmann Institute of Science , Rehovot 76100, Israel
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22
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Recent advances in biophysical studies of rhodopsins - Oligomerization, folding, and structure. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2017; 1865:1512-1521. [PMID: 28844743 DOI: 10.1016/j.bbapap.2017.08.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2017] [Revised: 08/06/2017] [Accepted: 08/11/2017] [Indexed: 12/19/2022]
Abstract
Retinal-binding proteins, mainly known as rhodopsins, function as photosensors and ion transporters in a wide range of organisms. From halobacterial light-driven proton pump, bacteriorhodopsin, to bovine photoreceptor, visual rhodopsin, they have served as prototypical α-helical membrane proteins in a large number of biophysical studies and aided in the development of many cutting-edge techniques of structural biology and biospectroscopy. In the last decade, microbial and animal rhodopsin families have expanded significantly, bringing into play a number of new interesting structures and functions. In this review, we will discuss recent advances in biophysical approaches to retinal-binding proteins, primarily microbial rhodopsins, including those in optical spectroscopy, X-ray crystallography, nuclear magnetic resonance, and electron paramagnetic resonance, as applied to such fundamental biological aspects as protein oligomerization, folding, and structure.
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23
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Chen Q, Arents J, Ganapathy S, de Grip WJ, Hellingwerf KJ. Functional Expression of Gloeobacter Rhodopsin inSynechocystissp. PCC6803. Photochem Photobiol 2017; 93:772-781. [DOI: 10.1111/php.12745] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 01/07/2017] [Indexed: 12/22/2022]
Affiliation(s)
- Que Chen
- Molecular Microbial Physiology; Swammerdam Institute for Life Sciences; University of Amsterdam; Amsterdam The Netherlands
| | - Jos Arents
- Molecular Microbial Physiology; Swammerdam Institute for Life Sciences; University of Amsterdam; Amsterdam The Netherlands
| | - Srividya Ganapathy
- Biophysical Organic Chemistry; Leiden Institute of Chemistry; Leiden University; Leiden The Netherlands
| | - Willem J. de Grip
- Biophysical Organic Chemistry; Leiden Institute of Chemistry; Leiden University; Leiden The Netherlands
| | - Klaas J. Hellingwerf
- Molecular Microbial Physiology; Swammerdam Institute for Life Sciences; University of Amsterdam; Amsterdam The Netherlands
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24
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Smolensky Koganov E, Leitus G, Rozin R, Weiner L, Friedman N, Sheves M. Cation Binding to Xanthorhodopsin: Electron Paramagnetic Resonance and Magnetic Studies. J Phys Chem B 2017; 121:4333-4340. [PMID: 28379004 DOI: 10.1021/acs.jpcb.6b12670] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Xanthorhodopsin (xR) is a member of the retinal protein family and acts as a proton pump in the cell membranes of the extremely halophilic eubacterium Salinibacter ruber. In addition to the retinal chromophore, xR contains a carotenoid, which acts as a light-harvesting antenna as it transfers 40% of the quanta it absorbs to the retinal. Our previous studies have shown that the CD and absorption spectra of xR are dramatically affected due to the protonation of two different residues. It is still unclear whether xR can bind cations. Electron paramagnetic resonance (EPR) spectroscopy used in the present study revealed that xR can bind divalent cations, such as Mn2+ and Ca2+, to deionized xR (DI-xR). We also demonstrate that xR can bind 1 equiv of Mn2+ to a high-affinity binding site followed by binding of ∼40 equiv in cooperative manner and ∼100 equiv of Mn2+ that are weakly bound. SQUID magnetic studies suggest that the high cooperative binding of Mn2+ cations to xR is due to the formation of Mn2+ clusters. Our data demonstrate that Ca2+ cations bind to DI-xR with a lower affinity than Mn2+, supporting the assumption that binding of Mn2+ occurs through cluster formation, because Ca2+ cations cannot form clusters in contrast to Mn2+.
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Affiliation(s)
- Elena Smolensky Koganov
- Department of Organic Chemistry and ‡Department of Chemical Research Support, Weizmann Institute of Science , Rehovot 76100, Israel
| | - Gregory Leitus
- Department of Organic Chemistry and ‡Department of Chemical Research Support, Weizmann Institute of Science , Rehovot 76100, Israel
| | - Rinat Rozin
- Department of Organic Chemistry and ‡Department of Chemical Research Support, Weizmann Institute of Science , Rehovot 76100, Israel
| | - Lev Weiner
- Department of Organic Chemistry and ‡Department of Chemical Research Support, Weizmann Institute of Science , Rehovot 76100, Israel
| | - Noga Friedman
- Department of Organic Chemistry and ‡Department of Chemical Research Support, Weizmann Institute of Science , Rehovot 76100, Israel
| | - Mordechai Sheves
- Department of Organic Chemistry and ‡Department of Chemical Research Support, Weizmann Institute of Science , Rehovot 76100, Israel
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25
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Niho A, Yoshizawa S, Tsukamoto T, Kurihara M, Tahara S, Nakajima Y, Mizuno M, Kuramochi H, Tahara T, Mizutani Y, Sudo Y. Demonstration of a Light-Driven SO42– Transporter and Its Spectroscopic Characteristics. J Am Chem Soc 2017; 139:4376-4389. [DOI: 10.1021/jacs.6b12139] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Akiko Niho
- Faculty
of Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan
| | - Susumu Yoshizawa
- Atmosphere
and Ocean Research Institute, The University of Tokyo, Chiba 277-8564, Japan
| | - Takashi Tsukamoto
- Faculty
of Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan
- Graduate
School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan
| | - Marie Kurihara
- Graduate
School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan
| | - Shinya Tahara
- Molecular
Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako 351-0198, Japan
| | - Yu Nakajima
- Atmosphere
and Ocean Research Institute, The University of Tokyo, Chiba 277-8564, Japan
| | - Misao Mizuno
- Department
of Chemistry, Graduate School of Science, Osaka University, 1-1
Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Hikaru Kuramochi
- Molecular
Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako 351-0198, Japan
- Ultrafast
Spectroscopy Research Team, RIKEN Center for Advanced Photonics (RAP), 2-1 Hirosawa, Wako 351-0198, Japan
| | - Tahei Tahara
- Molecular
Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako 351-0198, Japan
- Ultrafast
Spectroscopy Research Team, RIKEN Center for Advanced Photonics (RAP), 2-1 Hirosawa, Wako 351-0198, Japan
| | - Yasuhisa Mizutani
- Department
of Chemistry, Graduate School of Science, Osaka University, 1-1
Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Yuki Sudo
- Faculty
of Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan
- Graduate
School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan
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26
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N-H···N Hydrogen Bonds Involving Histidine Imidazole Nitrogen Atoms: A New Structural Role for Histidine Residues in Proteins. Biochemistry 2016; 55:3774-83. [PMID: 27305350 DOI: 10.1021/acs.biochem.6b00253] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The amino acid histidine can play a significant role in the structure and function of proteins. Its various functions include enzyme catalysis, metal binding activity, and involvement in cation-π, π-π, salt-bridge, and other types of noncovalent interactions. Although histidine's imidazole nitrogens (Nδ and Nε) are known to participate in hydrogen bond (HB) interactions as an acceptor or a donor, a systematic study of N-H···N HBs with the Nδ/Nε atom as the acceptor has not been conducted. In this study, we have examined two data sets of ultra-high-resolution (data set I) and very high-resolution (data set II) protein structures and identified 28 and 4017 examples of HBs of the N-H···Nδ/Nε type from both data sets involving histidine imidazole nitrogen as the acceptor. In nearly 70% of them, the main-chain N-H bond is the HB donor, and a majority of the examples are from the N-H group separated by two residues (Ni+2-Hi+2) from histidine. Quantum chemical calculations using model compounds were performed with imidazole and N-methylacetamide, and they assumed conformations from 19 examples from data set I with N-H···Nδ/Nε HBs. Basis set superposition error-corrected interaction energies varied from -5.0 to -6.78 kcal/mol. We also found that the imidazole nitrogen of 9% of histidine residues forming N-H···Nδ/Nε interactions in data set II participate in bifurcated HBs. Natural bond orbital analyses of model compounds indicate that the strength of each HB is mutually influenced by the other. Histidine residues involved in Ni+2-Hi+2···Nδi/Nεi HBs are frequently observed in a specific N-terminal capping position giving rise to a novel helix-capping motif. Along with their predominant occurrence in loop segments, we propose a new structural role for histidines in protein structures.
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27
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Tsukamoto T, Mizutani K, Hasegawa T, Takahashi M, Honda N, Hashimoto N, Shimono K, Yamashita K, Yamamoto M, Miyauchi S, Takagi S, Hayashi S, Murata T, Sudo Y. X-ray Crystallographic Structure of Thermophilic Rhodopsin: IMPLICATIONS FOR HIGH THERMAL STABILITY AND OPTOGENETIC FUNCTION. J Biol Chem 2016; 291:12223-32. [PMID: 27129243 DOI: 10.1074/jbc.m116.719815] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Indexed: 01/01/2023] Open
Abstract
Thermophilic rhodopsin (TR) is a photoreceptor protein with an extremely high thermal stability and the first characterized light-driven electrogenic proton pump derived from the extreme thermophile Thermus thermophilus JL-18. In this study, we confirmed its high thermal stability compared with other microbial rhodopsins and also report the potential availability of TR for optogenetics as a light-induced neural silencer. The x-ray crystal structure of TR revealed that its overall structure is quite similar to that of xanthorhodopsin, including the presence of a putative binding site for a carotenoid antenna; but several distinct structural characteristics of TR, including a decreased surface charge and a larger number of hydrophobic residues and aromatic-aromatic interactions, were also clarified. Based on the crystal structure, the structural changes of TR upon thermal stimulation were investigated by molecular dynamics simulations. The simulations revealed the presence of a thermally induced structural substate in which an increase of hydrophobic interactions in the extracellular domain, the movement of extracellular domains, the formation of a hydrogen bond, and the tilting of transmembrane helices were observed. From the computational and mutational analysis, we propose that an extracellular LPGG motif between helices F and G plays an important role in the thermal stability, acting as a "thermal sensor." These findings will be valuable for understanding retinal proteins with regard to high protein stability and high optogenetic performance.
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Affiliation(s)
- Takashi Tsukamoto
- From the Division of Pharmaceutical Sciences, Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan
| | - Kenji Mizutani
- the Department of Chemistry, Graduate School of Science, Chiba University, Chiba 263-8522, Japan, the Molecular Chirality Research Center, Chiba University, Chiba 263-8522, Japan
| | - Taisuke Hasegawa
- the Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Megumi Takahashi
- the Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan
| | - Naoya Honda
- From the Division of Pharmaceutical Sciences, Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan
| | - Naoki Hashimoto
- the Department of Chemistry, Graduate School of Science, Chiba University, Chiba 263-8522, Japan
| | - Kazumi Shimono
- the Faculty of Pharmaceutical Sciences, Toho University, Funabashi 274-8510, Japan, and
| | | | | | - Seiji Miyauchi
- the Faculty of Pharmaceutical Sciences, Toho University, Funabashi 274-8510, Japan, and
| | - Shin Takagi
- the Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan
| | - Shigehiko Hayashi
- the Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Takeshi Murata
- the Department of Chemistry, Graduate School of Science, Chiba University, Chiba 263-8522, Japan, the Molecular Chirality Research Center, Chiba University, Chiba 263-8522, Japan,
| | - Yuki Sudo
- From the Division of Pharmaceutical Sciences, Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan,
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Inoue K, Kato Y, Kandori H. Light-driven ion-translocating rhodopsins in marine bacteria. Trends Microbiol 2015; 23:91-8. [PMID: 25432080 DOI: 10.1016/j.tim.2014.10.009] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Revised: 10/14/2014] [Accepted: 10/27/2014] [Indexed: 12/25/2022]
Abstract
Microbial rhodopsins are the photoreceptive membrane proteins found in diverse microorganisms from within Archaea, Eubacteria, and eukaryotes. They have a hep-tahelical transmembrane structure that binds to an all-trans retinal chromophore. Since 2000, thousands of proteorhodopsins, genes of light-driven proton pump rhodopsins, have been identified from various species of marine bacteria. This suggests that they are used for the conversion of light into chemical energy, contribut-ing to carbon circulation related to ATP synthesis in the ocean. Furthermore, novel types of rhodopsin (sodium and chloride pumps) have recently been discovered. Here, we review recent progress in our understanding of ion-transporting rhodopsins of marine bacteria, based mainly on biophysical and biochemical research.
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29
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Maciejko J, Mehler M, Kaur J, Lieblein T, Morgner N, Ouari O, Tordo P, Becker-Baldus J, Glaubitz C. Visualizing Specific Cross-Protomer Interactions in the Homo-Oligomeric Membrane Protein Proteorhodopsin by Dynamic-Nuclear-Polarization-Enhanced Solid-State NMR. J Am Chem Soc 2015; 137:9032-43. [DOI: 10.1021/jacs.5b03606] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
| | | | | | | | | | - Olivier Ouari
- Aix-Marseille Université,
CNRS, ICR, UMR 7273, 13013 Marseille, France
| | - Paul Tordo
- Aix-Marseille Université,
CNRS, ICR, UMR 7273, 13013 Marseille, France
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30
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Petrovskaya LE, Balashov SP, Lukashev EP, Imasheva ES, Gushchin IY, Dioumaev AK, Rubin AB, Dolgikh DA, Gordeliy VI, Lanyi JK, Kirpichnikov MP. ESR — A retinal protein with unusual properties from Exiguobacterium sibiricum. BIOCHEMISTRY (MOSCOW) 2015; 80:688-700. [DOI: 10.1134/s000629791506005x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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31
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Characterization of an Unconventional Rhodopsin from the Freshwater Actinobacterium Rhodoluna lacicola. J Bacteriol 2015; 197:2704-12. [PMID: 26055118 DOI: 10.1128/jb.00386-15] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 06/04/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Rhodopsin-encoding microorganisms are common in many environments. However, knowing that rhodopsin genes are present provides little insight into how the host cells utilize light. The genome of the freshwater actinobacterium Rhodoluna lacicola encodes a rhodopsin of the uncharacterized actinorhodopsin family. We hypothesized that actinorhodopsin was a light-activated proton pump and confirmed this by heterologously expressing R. lacicola actinorhodopsin in retinal-producing Escherichia coli. However, cultures of R. lacicola did not pump protons, even though actinorhodopsin mRNA and protein were both detected. Proton pumping in R. lacicola was induced by providing exogenous retinal, suggesting that the cells lacked the retinal cofactor. We used high-performance liquid chromatography (HPLC) and oxidation of accessory pigments to confirm that R. lacicola does not synthesize retinal. These results suggest that in some organisms, the actinorhodopsin gene is constitutively expressed, but rhodopsin-based light capture may require cofactors obtained from the environment. IMPORTANCE Up to 70% of microbial genomes in some environments are predicted to encode rhodopsins. Because most microbial rhodopsins are light-activated proton pumps, the prevalence of this gene suggests that in some environments, most microorganisms respond to or utilize light energy. Actinorhodopsins were discovered in an analysis of freshwater metagenomic data and subsequently identified in freshwater actinobacterial cultures. We hypothesized that actinorhodopsin from the freshwater actinobacterium Rhodoluna lacicola was a light-activated proton pump and confirmed this by expressing actinorhodopsin in retinal-producing Escherichia coli. Proton pumping in R. lacicola was induced only after both light and retinal were provided, suggesting that the cells lacked the retinal cofactor. These results indicate that photoheterotrophy in this organism and others may require cofactors obtained from the environment.
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32
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Smolensky Koganov E, Brumfeld V, Friedman N, Sheves M. Origin of Circular Dichroism of Xanthorhodopsin. A Study with Artificial Pigments. J Phys Chem B 2014; 119:456-64. [DOI: 10.1021/jp510534s] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | - Vlad Brumfeld
- Department
of Chemical Research Support, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Noga Friedman
- Department
of Organic Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Mordechai Sheves
- Department
of Organic Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel
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33
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Tsukamoto T, Demura M, Sudo Y. Irreversible trimer to monomer transition of thermophilic rhodopsin upon thermal stimulation. J Phys Chem B 2014; 118:12383-94. [PMID: 25279934 DOI: 10.1021/jp507374q] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Assembly is one of the keys to understand biological molecules, and it takes place in spatial and temporal domains upon stimulation. Microbial rhodopsin (also called retinal protein) is a membrane-embedded protein that has a retinal chromophore within seven-transmembrane α-helices and shows homo-, di-, tri-, penta-, and hexameric assemblies. Those assemblies are closely related to critical physiological properties such as stabilizing the protein structure and regulating their photoreaction dynamics. Here we investigated the assembly and disassembly of thermophilic rhodopsin (TR), which is a novel proton-pumping rhodopsin derived from a thermophile living at 75 °C. TR was characterized using size-exclusion chromatography and circular dichroism spectroscopy, and formed a trimer at 25 °C, but irreversibly dissociated into monomers upon thermal stimulation. The transition temperature was estimated to be 68 °C. The irreversible nature made it possible to investigate the photochemical properties of both the trimer and the monomer independently. Compared with the trimer, the absorption maximum of the monomer is blue-shifted by 6 nm without any changes in the retinal composition, pKa value for the counterion or the sequence of the proton movement. The photocycling rate of the monomeric TR was similar to that of the trimeric TR. A similar trimer-monomer transition upon thermal stimulation was observed for another eubacterial rhodopsin GR but not for the archaeal rhodopsins AR3 and HwBR, suggesting that the transition is conserved in bacterial rhodopsins. Thus, the thermal stimulation of TR induces the irreversible disassembly of the trimer.
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Affiliation(s)
- Takashi Tsukamoto
- Division of Pharmaceutical Sciences, Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University , 1-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
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Chan SK, Kitajima-Ihara T, Fujii R, Gotoh T, Murakami M, Ihara K, Kouyama T. Crystal structure of Cruxrhodopsin-3 from Haloarcula vallismortis. PLoS One 2014; 9:e108362. [PMID: 25268964 PMCID: PMC4182453 DOI: 10.1371/journal.pone.0108362] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Accepted: 08/26/2014] [Indexed: 01/09/2023] Open
Abstract
Cruxrhodopsin-3 (cR3), a retinylidene protein found in the claret membrane of Haloarcula vallismortis, functions as a light-driven proton pump. In this study, the membrane fusion method was applied to crystallize cR3 into a crystal belonging to space group P321. Diffraction data at 2.1 Å resolution show that cR3 forms a trimeric assembly with bacterioruberin bound to the crevice between neighboring subunits. Although the structure of the proton-release pathway is conserved among proton-pumping archaeal rhodopsins, cR3 possesses the following peculiar structural features: 1) The DE loop is long enough to interact with a neighboring subunit, strengthening the trimeric assembly; 2) Three positive charges are distributed at the cytoplasmic end of helix F, affecting the higher order structure of cR3; 3) The cytoplasmic vicinity of retinal is more rigid in cR3 than in bacteriorhodopsin, affecting the early reaction step in the proton-pumping cycle; 4) the cytoplasmic part of helix E is greatly bent, influencing the proton uptake process. Meanwhile, it was observed that the photobleaching of retinal, which scarcely occurred in the membrane state, became significant when the trimeric assembly of cR3 was dissociated into monomers in the presence of an excess amount of detergent. On the basis of these observations, we discuss structural factors affecting the photostabilities of ion-pumping rhodopsins.
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Affiliation(s)
- Siu Kit Chan
- Department of Physics, Graduate School of Science, Nagoya University, Nagoya, Japan
| | | | - Ryudoh Fujii
- Department of Physics, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Toshiaki Gotoh
- Department of Physics, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Midori Murakami
- Department of Physics, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Kunio Ihara
- Center for Gene Research, Nagoya University, Nagoya, Japan
| | - Tsutomu Kouyama
- Department of Physics, Graduate School of Science, Nagoya University, Nagoya, Japan
- RIKEN Harima Institute/SPring-8, Mikazuki, Sayo, Hyogo, Japan
- * E-mail:
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35
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Claassens NJ, Volpers M, dos Santos VAPM, van der Oost J, de Vos WM. Potential of proton-pumping rhodopsins: engineering photosystems into microorganisms. Trends Biotechnol 2013; 31:633-42. [PMID: 24120288 DOI: 10.1016/j.tibtech.2013.08.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2013] [Revised: 08/19/2013] [Accepted: 08/27/2013] [Indexed: 01/04/2023]
Abstract
A wide range of proton-pumping rhodopsins (PPRs) have been discovered in recent years. Using a synthetic biology approach, PPR photosystems with different features can be easily introduced in nonphotosynthetic microbial hosts. PPRs can provide hosts with the ability to harvest light and drive the sustainable production of biochemicals or biofuels. PPRs use light energy to generate an outward proton flux, and the resulting proton motive force can subsequently power cellular processes. Recently, the introduction of PPRs in microbial production hosts has successfully led to light-driven biotechnological conversions. In this review, we discuss relevant features of natural PPRs, evaluate reported biotechnological applications of microbial production hosts equipped with PPRs, and provide an outlook on future developments.
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Affiliation(s)
- Nico J Claassens
- Laboratory of Microbiology, Wageningen University, Wageningen, The Netherlands
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36
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Bamann C, Bamberg E, Wachtveitl J, Glaubitz C. Proteorhodopsin. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2013; 1837:614-25. [PMID: 24060527 DOI: 10.1016/j.bbabio.2013.09.010] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 09/11/2013] [Accepted: 09/13/2013] [Indexed: 10/26/2022]
Abstract
Proteorhodopsins are the most abundant retinal based photoreceptors and their phototrophic function might be relevant in marine ecosystems. Here, we describe their remarkable molecular properties with a special focus on the green absorbing variant. Its distinct features include a high pKa value of the primary proton acceptor stabilized through an interaction with a conserved histidine, a long-range interaction between the cytoplasmic EF loop and the chromophore entailing a particular mode of color tuning and a variable proton pumping vectoriality with complex voltage-dependence. The proteorhodopsin family represents a profound example for structure-function relationships. Especially the development of a biophysical understanding of green proteorhodopsin is an excellent example for the unique opportunities offered by a combined approach of advanced spectroscopic and electrophysiological methods. This article is part of a Special Issue entitled: Retinal Proteins-You can teach an old dog new tricks.
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Affiliation(s)
- Christian Bamann
- Max Planck Institute of Biophysics, Max-von-Laue Straße 3, 60438 Frankfurt am Main, Germany.
| | - Ernst Bamberg
- Max Planck Institute of Biophysics, Max-von-Laue Straße 3, 60438 Frankfurt am Main, Germany
| | - Josef Wachtveitl
- Johann Wolfgang Goethe University, Institute for Physical and Theoretical Chemistry, Max-von-Laue Straße 7, 60438 Frankfurt am Main, Germany
| | - Clemens Glaubitz
- Johann Wolfgang Goethe University, Institute for Biophysical Chemistry & Centre for Biomolecular Magnetic Resonance, Max-von-Laue Straße 9, 60438 Frankfurt am Main, Germany
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37
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Brown LS. Eubacterial rhodopsins - unique photosensors and diverse ion pumps. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2013; 1837:553-61. [PMID: 23748216 DOI: 10.1016/j.bbabio.2013.05.006] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Revised: 05/27/2013] [Accepted: 05/29/2013] [Indexed: 10/26/2022]
Abstract
Since the discovery of proteorhodopsins, the ubiquitous marine light-driven proton pumps of eubacteria, a large number of other eubacterial rhodopsins with diverse structures and functions have been characterized. Here, we review the body of knowledge accumulated on the four major groups of eubacterial rhodopsins, with the focus on their biophysical characterization. We discuss advances and controversies on the unique eubacterial sensory rhodopsins (as represented by Anabaena sensory rhodopsin), proton-pumping proteorhodopsins and xanthorhodopsins, as well as novel non-proton ion pumps. This article is part of a Special Issue entitled: Retinal Proteins - You can teach an old dog new tricks.
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Affiliation(s)
- Leonid S Brown
- Department of Physics and Biophysics Interdepartmental Group, University of Guelph, Ontario N1G 2W1, Canada.
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38
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Tsukamoto T, Inoue K, Kandori H, Sudo Y. Thermal and spectroscopic characterization of a proton pumping rhodopsin from an extreme thermophile. J Biol Chem 2013; 288:21581-92. [PMID: 23740255 DOI: 10.1074/jbc.m113.479394] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
So far retinylidene proteins (∼rhodopsin) have not been discovered in thermophilic organisms. In this study we investigated and characterized a microbial rhodopsin derived from the extreme thermophilic bacterium Thermus thermophilus, which lives in a hot spring at around 75 °C. The gene for the retinylidene protein, named thermophilic rhodopsin (TR), was chemically synthesized with codon optimization. The codon optimized TR protein was functionally expressed in the cell membranes of Escherichia coli cells and showed active proton transport upon photoillumination. Spectroscopic measurements revealed that the purified TR bound only all-trans-retinal as a chromophore and showed an absorption maximum at 530 nm. In addition, TR exhibited both photocycle kinetics and pH-dependent absorption changes, which are characteristic of rhodopsins. Of note, time-dependent thermal denaturation experiments revealed that TR maintained its absorption even at 75 °C, and the denaturation rate constant of TR was much lower than those of other proton pumping rhodopsins such as archaerhodopsin-3 (200 ×), Haloquadratum walsbyi bacteriorhodopsin (by 10-times), and Gloeobacter rhodopsin (100 ×). Thus, these results suggest that microbial rhodopsins are also distributed among thermophilic organisms and have high stability. TR should allow the investigation of the molecular mechanisms of ion transport and protein folding.
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Affiliation(s)
- Takashi Tsukamoto
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan
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39
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Inoue K, Tsukamoto T, Sudo Y. Molecular and evolutionary aspects of microbial sensory rhodopsins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2013; 1837:562-77. [PMID: 23732219 DOI: 10.1016/j.bbabio.2013.05.005] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Revised: 05/14/2013] [Accepted: 05/16/2013] [Indexed: 02/03/2023]
Abstract
Retinal proteins (~rhodopsins) are photochemically reactive membrane-embedded proteins, with seven transmembrane α-helices which bind the chromophore retinal (vitamin A aldehyde). They are widely distributed through all three biological kingdoms, eukarya, bacteria and archaea, indicating the biological significance of the retinal proteins. Light absorption by the retinal proteins triggers a photoisomerization of the chromophore, leading to the biological function, light-energy conversion or light-signal transduction. This article reviews molecular and evolutionary aspects of the light-signal transduction by microbial sensory receptors and their related proteins. This article is part of a Special Issue entitled: Retinal Proteins - You can teach an old dog new tricks.
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Affiliation(s)
- Keiichi Inoue
- Department of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan; Japan Science and Technology Agency (JST), PRESTO, 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan
| | - Takashi Tsukamoto
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, 464-8602, Japan
| | - Yuki Sudo
- Japan Science and Technology Agency (JST), PRESTO, 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan; Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, 464-8602, Japan; Department of Life and Coordination-Complex Molecular Science, Institute for Molecular Science, 38 Nishigo-Naka, Myodaiji, Okazaki, Japan.
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