1
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Okuyama A, Hososhima S, Kandori H, Tsunoda SP. Driving forces of proton-pumping rhodopsins. Biophys J 2024; 123:4274-4284. [PMID: 39243129 DOI: 10.1016/j.bpj.2024.09.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2024] [Revised: 08/22/2024] [Accepted: 09/04/2024] [Indexed: 09/09/2024] Open
Abstract
Proton-pumping rhodopsins are light-driven proton transporters that have been discovered from various microbiota. They are categorized into two groups: outward-directed and inward-directed proton pumps. Although the directions of transport are opposite, they are active proton transporters that create an H+ gradient across a membrane. Here, we aimed to study the driving force of the proton-pumping rhodopsins and the effect of ΔΨ and ΔpH on their pumping functions. We systematically characterized the H+ transport properties of nine different rhodopsins, six outward-directed H+ pumps and three inward-directed pumps, by patch-clamp measurements after expressing them in mammalian cells. The driving force of each pump was estimated from the slope of the current-voltage relations (I-V plot). Notably, among the tested rhodopsins, we found a large variation in driving forces, ranging from 83 to 399 mV. The driving force and decay rate of each pump current exhibited a good correlation. We determined driving forces under various pHs. pH dependency was less than predicted by the Nernst potential in most of the rhodopsins. Our study demonstrates that the H+-pumping rhodopsins from different organisms exhibit various pumping properties in terms of driving force, kinetics, and pH dependency, which could be evolutionarily derived from adaptations to their environments.
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Affiliation(s)
- Akari Okuyama
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Aichi, Japan
| | - Shoko Hososhima
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Aichi, Japan; OptoBioTechnology Research Center, Nagoya Institute of Technology, Nagoya, Aichi, Japan
| | - Hideki Kandori
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Aichi, Japan; OptoBioTechnology Research Center, Nagoya Institute of Technology, Nagoya, Aichi, Japan
| | - Satoshi P Tsunoda
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Aichi, Japan; OptoBioTechnology Research Center, Nagoya Institute of Technology, Nagoya, Aichi, Japan.
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2
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de Grip WJ, Ganapathy S. Rhodopsins: An Excitingly Versatile Protein Species for Research, Development and Creative Engineering. Front Chem 2022; 10:879609. [PMID: 35815212 PMCID: PMC9257189 DOI: 10.3389/fchem.2022.879609] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2022] [Accepted: 05/16/2022] [Indexed: 01/17/2023] Open
Abstract
The first member and eponym of the rhodopsin family was identified in the 1930s as the visual pigment of the rod photoreceptor cell in the animal retina. It was found to be a membrane protein, owing its photosensitivity to the presence of a covalently bound chromophoric group. This group, derived from vitamin A, was appropriately dubbed retinal. In the 1970s a microbial counterpart of this species was discovered in an archaeon, being a membrane protein also harbouring retinal as a chromophore, and named bacteriorhodopsin. Since their discovery a photogenic panorama unfolded, where up to date new members and subspecies with a variety of light-driven functionality have been added to this family. The animal branch, meanwhile categorized as type-2 rhodopsins, turned out to form a large subclass in the superfamily of G protein-coupled receptors and are essential to multiple elements of light-dependent animal sensory physiology. The microbial branch, the type-1 rhodopsins, largely function as light-driven ion pumps or channels, but also contain sensory-active and enzyme-sustaining subspecies. In this review we will follow the development of this exciting membrane protein panorama in a representative number of highlights and will present a prospect of their extraordinary future potential.
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Affiliation(s)
- Willem J. de Grip
- Leiden Institute of Chemistry, Department of Biophysical Organic Chemistry, Leiden University, Leiden, Netherlands
- Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, Netherlands
| | - Srividya Ganapathy
- Department of Imaging Physics, Delft University of Technology, Netherlands
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3
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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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4
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Suzuki K, Del Carmen Marín M, Konno M, Bagherzadeh R, Murata T, Inoue K. Structural characterization of proton-pumping rhodopsin lacking a cytoplasmic proton donor residue by X-ray crystallography. J Biol Chem 2022; 298:101722. [PMID: 35151692 PMCID: PMC8927995 DOI: 10.1016/j.jbc.2022.101722] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 02/05/2022] [Accepted: 02/08/2022] [Indexed: 01/10/2023] Open
Abstract
DTG/DTS rhodopsin, which was named based on a three-residue motif (DTG or DTS) that is important for its function, is a light-driven proton-pumping microbial rhodopsin using a retinal chromophore. In contrast to other light-driven ion-pumping rhodopsins, DTG/DTS rhodopsin does not have a cytoplasmic proton donor residue, such as Asp, Glu, or Lys. Because of the lack of cytoplasmic proton donor residue, proton directly binds to the retinal chromophore from the cytoplasmic solvent. However, mutational experiments that showed the complicated effects of mutations were not able to clarify the roles played by each residue, and the detail of proton uptake pathway is unclear because of the lack of structural information. To understand the proton transport mechanism of DTG/DTS rhodopsin, here we report the three-dimensional structure of one of the DTG/DTS rhodopsins, PspR from Pseudomonas putida, by X-ray crystallography. We show that the structure of the cytoplasmic side of the protein is significantly different from that of bacteriorhodopsin, the best-characterized proton-pumping rhodopsin, and large cytoplasmic cavities were observed. We propose that these hydrophilic cytoplasmic cavities enable direct proton uptake from the cytoplasmic solvent without the need for a specialized cytoplasmic donor residue. The introduction of carboxylic residues homologous to the cytoplasmic donors in other proton-pumping rhodopsins resulted in higher pumping activity with less pH dependence, suggesting that DTG/DTS rhodopsins are advantageous for producing energy and avoiding intracellular alkalization in soil and plant-associated bacteria.
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Affiliation(s)
- Kano Suzuki
- Department of Chemistry, Graduate School of Science, Chiba University, Inage, Chiba, Japan
| | | | - Masae Konno
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba, Japan; PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan
| | - Reza Bagherzadeh
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba, Japan
| | - Takeshi Murata
- Department of Chemistry, Graduate School of Science, Chiba University, Inage, Chiba, Japan; Membrane Protein Research and Molecular Chirality Research Centers, Chiba University, Inage, Chiba, Japan.
| | - Keiichi Inoue
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba, Japan.
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5
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Kishi KE, Kim YS, Fukuda M, Inoue M, Kusakizako T, Wang PY, Ramakrishnan C, Byrne EFX, Thadhani E, Paggi JM, Matsui TE, Yamashita K, Nagata T, Konno M, Quirin S, Lo M, Benster T, Uemura T, Liu K, Shibata M, Nomura N, Iwata S, Nureki O, Dror RO, Inoue K, Deisseroth K, Kato HE. Structural basis for channel conduction in the pump-like channelrhodopsin ChRmine. Cell 2022; 185:672-689.e23. [PMID: 35114111 PMCID: PMC7612760 DOI: 10.1016/j.cell.2022.01.007] [Citation(s) in RCA: 59] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Revised: 12/13/2021] [Accepted: 01/11/2022] [Indexed: 12/24/2022]
Abstract
ChRmine, a recently discovered pump-like cation-conducting channelrhodopsin, exhibits puzzling properties (large photocurrents, red-shifted spectrum, and extreme light sensitivity) that have created new opportunities in optogenetics. ChRmine and its homologs function as ion channels but, by primary sequence, more closely resemble ion pump rhodopsins; mechanisms for passive channel conduction in this family have remained mysterious. Here, we present the 2.0 Å resolution cryo-EM structure of ChRmine, revealing architectural features atypical for channelrhodopsins: trimeric assembly, a short transmembrane-helix 3, a twisting extracellular-loop 1, large vestibules within the monomer, and an opening at the trimer interface. We applied this structure to design three proteins (rsChRmine and hsChRmine, conferring further red-shifted and high-speed properties, respectively, and frChRmine, combining faster and more red-shifted performance) suitable for fundamental neuroscience opportunities. These results illuminate the conduction and gating of pump-like channelrhodopsins and point the way toward further structure-guided creation of channelrhodopsins for applications across biology.
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Affiliation(s)
- Koichiro E Kishi
- Komaba Institute for Science, The University of Tokyo, Meguro, Tokyo, Japan
| | - Yoon Seok Kim
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Masahiro Fukuda
- Komaba Institute for Science, The University of Tokyo, Meguro, Tokyo, Japan
| | - Masatoshi Inoue
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Tsukasa Kusakizako
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo, Tokyo, Japan
| | - Peter Y Wang
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | | | - Eamon F X Byrne
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Elina Thadhani
- Department of Bioengineering, Stanford University, Stanford, CA, USA; Department of Computer Science, Stanford University, Stanford, CA, USA
| | - Joseph M Paggi
- Department of Computer Science, Stanford University, Stanford, CA, USA
| | - Toshiki E Matsui
- Komaba Institute for Science, The University of Tokyo, Meguro, Tokyo, Japan
| | - Keitaro Yamashita
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
| | - Takashi Nagata
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Japan; PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan
| | - Masae Konno
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Japan; PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan
| | - Sean Quirin
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Maisie Lo
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Tyler Benster
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Tomoko Uemura
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Kyoto, Sakyo, Japan
| | - Kehong Liu
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Kyoto, Sakyo, Japan
| | - Mikihiro Shibata
- WPI Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma, Kanazawa, Japan; High-Speed AFM for Biological Application Unit, Institute for Frontier Science Initiative, Kanazawa University, Kakuma, Kanazawa, Japan
| | - Norimichi Nomura
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Kyoto, Sakyo, Japan
| | - So Iwata
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Kyoto, Sakyo, Japan; RIKEN SPring-8 Center, Kouto, Sayo-cho, Sayo-gun, Hyogo, Japan
| | - Osamu Nureki
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo, Tokyo, Japan
| | - Ron O Dror
- Department of Computer Science, Stanford University, Stanford, CA, USA; Institute for Computational and Mathematical Engineering, Stanford University, Stanford, CA, USA
| | - Keiichi Inoue
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Japan
| | - Karl Deisseroth
- Department of Bioengineering, Stanford University, Stanford, CA, USA; CNC Program, Stanford University, Palo Alto, CA, USA; Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA; Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, USA.
| | - Hideaki E Kato
- Komaba Institute for Science, The University of Tokyo, Meguro, Tokyo, Japan; Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo, Tokyo, Japan; PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan; FOREST, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan.
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6
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Bondar AN. Mechanisms of long-distance allosteric couplings in proton-binding membrane transporters. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2022; 128:199-239. [PMID: 35034719 DOI: 10.1016/bs.apcsb.2021.09.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Membrane transporters that use proton binding and proton transfer for function couple local protonation change with changes in protein conformation and water dynamics. Changes of protein conformation might be required to allow transient formation of hydrogen-bond networks that bridge proton donor and acceptor pairs separated by long distances. Inter-helical hydrogen-bond networks adjust rapidly to protonation change, and ensure rapid response of the protein structure and dynamics. Membrane transporters with known three-dimensional structures and proton-binding groups inform on general principles of protonation-coupled protein conformational dynamics. Inter-helical hydrogen bond motifs between proton-binding carboxylate groups and a polar sidechain are observed in unrelated membrane transporters, suggesting common principles of coupling protonation change with protein conformational dynamics.
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Affiliation(s)
- Ana-Nicoleta Bondar
- University of Bucharest, Faculty of Physics, Măgurele, Romania; Forschungszentrum Jülich, Institute of Computational Biomedicine, Jülich, Germany.
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7
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Panzer S, Zhang C, Konte T, Bräuer C, Diemar A, Yogendran P, Yu-Strzelczyk J, Nagel G, Gao S, Terpitz U. Modified Rhodopsins From Aureobasidium pullulans Excel With Very High Proton-Transport Rates. Front Mol Biosci 2021; 8:750528. [PMID: 34790700 PMCID: PMC8591190 DOI: 10.3389/fmolb.2021.750528] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 09/16/2021] [Indexed: 11/19/2022] Open
Abstract
Aureobasidium pullulans is a black fungus that can adapt to various stressful conditions like hypersaline, acidic, and alkaline environments. The genome of A. pullulans exhibits three genes coding for putative opsins ApOps1, ApOps2, and ApOps3. We heterologously expressed these genes in mammalian cells and Xenopus oocytes. Localization in the plasma membrane was greatly improved by introducing additional membrane trafficking signals at the N-terminus and the C-terminus. In patch-clamp and two-electrode-voltage clamp experiments, all three proteins showed proton pump activity with maximal activity in green light. Among them, ApOps2 exhibited the most pronounced proton pump activity with current amplitudes occasionally extending 10 pA/pF at 0 mV. Proton pump activity was further supported in the presence of extracellular weak organic acids. Furthermore, we used site-directed mutagenesis to reshape protein functions and thereby implemented light-gated proton channels. We discuss the difference to other well-known proton pumps and the potential of these rhodopsins for optogenetic applications.
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Affiliation(s)
- Sabine Panzer
- Department of Biotechnology and Biophysics, Theodor-Boveri-Institute, Julius Maximilian University of Wuerzburg, Wuerzburg, Germany
| | - Chong Zhang
- Department of Neurophysiology, Physiological Institute, Julius Maximilian University of Wuerzburg, Wuerzburg, Germany
| | - Tilen Konte
- Faculty of Medicine, Institute of Biochemistry, University of Ljubljana, Ljubljana, Slovenia
| | - Celine Bräuer
- Department of Biotechnology and Biophysics, Theodor-Boveri-Institute, Julius Maximilian University of Wuerzburg, Wuerzburg, Germany
| | - Anne Diemar
- Department of Biotechnology and Biophysics, Theodor-Boveri-Institute, Julius Maximilian University of Wuerzburg, Wuerzburg, Germany
| | - Parathy Yogendran
- Department of Biotechnology and Biophysics, Theodor-Boveri-Institute, Julius Maximilian University of Wuerzburg, Wuerzburg, Germany
| | - Jing Yu-Strzelczyk
- Department of Neurophysiology, Physiological Institute, Julius Maximilian University of Wuerzburg, Wuerzburg, Germany
| | - Georg Nagel
- Department of Neurophysiology, Physiological Institute, Julius Maximilian University of Wuerzburg, Wuerzburg, Germany
| | - Shiqiang Gao
- Department of Neurophysiology, Physiological Institute, Julius Maximilian University of Wuerzburg, Wuerzburg, Germany
| | - Ulrich Terpitz
- Department of Biotechnology and Biophysics, Theodor-Boveri-Institute, Julius Maximilian University of Wuerzburg, Wuerzburg, Germany
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8
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Hososhima S, Kandori H, Tsunoda SP. Ion transport activity and optogenetics capability of light-driven Na+-pump KR2. PLoS One 2021; 16:e0256728. [PMID: 34506508 PMCID: PMC8432791 DOI: 10.1371/journal.pone.0256728] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Accepted: 08/13/2021] [Indexed: 01/26/2023] Open
Abstract
KR2 from marine bacteria Krokinobacter eikastus is a light-driven Na+ pumping rhodopsin family (NaRs) member that actively transports Na+ and/or H+ depending on the ionic state. We here report electrophysiological studies on KR2 to address ion-transport properties under various electrochemical potentials of Δ[Na+], ΔpH, membrane voltage and light quality, because the contributions of these on the pumping activity were less understood so far. After transient expression of KR2 in mammalian cultured cells (ND7/23 cells), photocurrents were measured by whole-cell patch clamp under various intracellular Na+ and pH conditions. When KR2 was continuously illuminated with LED light, two distinct time constants were obtained depending on the Na+ concentration. KR2 exhibited slow ion transport (τoff of 28 ms) below 1.1 mM NaCl and rapid transport (τoff of 11 ms) above 11 mM NaCl. This indicates distinct transporting kinetics of H+ and Na+. Photocurrent amplitude (current density) depends on the intracellular Na+ concentration, as is expected for a Na+ pump. The M-intermediate in the photocycle of KR2 could be transferred into the dark state without net ion transport by blue light illumination on top of green light. The M intermediate was stabilized by higher membrane voltage. Furthermore, we assessed the optogenetic silencing effect of rat cortical neurons after expressing KR2. Light power dependency revealed that action potential was profoundly inhibited by 1.5 mW/mm2 green light illumination, confirming the ability to apply KR2 as an optogenetics silencer.
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Affiliation(s)
- Shoko Hososhima
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya, Japan
| | - Hideki Kandori
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya, Japan
- OptoBio Technology Research Center, Nagoya Institute of Technology, Showa-ku, Nagoya, Japan
| | - Satoshi P. Tsunoda
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya, Japan
- PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan
- * E-mail:
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9
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Discovery of a microbial rhodopsin that is the most stable in extreme environments. iScience 2021; 24:102620. [PMID: 34151231 PMCID: PMC8188555 DOI: 10.1016/j.isci.2021.102620] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 04/28/2021] [Accepted: 05/19/2021] [Indexed: 12/18/2022] Open
Abstract
Microbial rhodopsin is a retinal protein that functions as an ion pump, channel, and sensory transducer, as well as a light sensor, as in biosensors and biochips. Tara76 rhodopsin is a typical proton-pumping rhodopsin that exhibits strong stability against extreme pH, detergent, temperature, salt stress, and dehydration stress and even under dual and triple conditions. Tara76 rhodopsin has a thermal stability approximately 20 times higher than that of thermal rhodopsin at 80°C and is even stable at 85°C. Tara76 rhodopsin is also stable at pH 0.02 to 13 and exhibits strong resistance in detergent, including Triton X-100 and SDS. We tested the current flow that electrical current flow across dried proteins on the paper at high temperatures using an electrode device, which was measured stably from 25°C up to 120°C. These properties suggest that this Tara76 rhodopsin is suitable for many applications in the fields of bioengineering and biotechnology.
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10
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Inoue K. Diversity, Mechanism, and Optogenetic Application of Light-Driven Ion Pump Rhodopsins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1293:89-126. [PMID: 33398809 DOI: 10.1007/978-981-15-8763-4_6] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Ion-transporting microbial rhodopsins are widely used as major molecular tools in optogenetics. They are categorized into light-gated ion channels and light-driven ion pumps. While the former passively transport various types of cations and anions in a light-dependent manner, light-driven ion pumps actively transport specific ions, such as H+, Na+, Cl-, against electrophysiological potential by using light energy. Since the ion transport by these pumps induces hyperpolarization of membrane potential and inhibit neural firing, light-driven ion-pumping rhodopsins are mostly applied as inhibitory optogenetics tools. Recent progress in genome and metagenome sequencing identified more than several thousands of ion-pumping rhodopsins from a wide variety of microbes, and functional characterization studies has been revealing many new types of light-driven ion pumps one after another. Since light-gated channels were reviewed in other chapters in this book, here the rapid progress in functional characterization, molecular mechanism study, and optogenetic application of ion-pumping rhodopsins were reviewed.
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Affiliation(s)
- Keiichi Inoue
- The Institute for Solid State Physics, The University of Tokyo, Chiba, Japan.
- PRESTO, Japan Science and Technology Agency, Saitama, Japan.
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11
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Derr JB, Tamayo J, Clark JA, Morales M, Mayther MF, Espinoza EM, Rybicka-Jasińska K, Vullev VI. Multifaceted aspects of charge transfer. Phys Chem Chem Phys 2020; 22:21583-21629. [PMID: 32785306 PMCID: PMC7544685 DOI: 10.1039/d0cp01556c] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Charge transfer and charge transport are by far among the most important processes for sustaining life on Earth and for making our modern ways of living possible. Involving multiple electron-transfer steps, photosynthesis and cellular respiration have been principally responsible for managing the energy flow in the biosphere of our planet since the Great Oxygen Event. It is impossible to imagine living organisms without charge transport mediated by ion channels, or electron and proton transfer mediated by redox enzymes. Concurrently, transfer and transport of electrons and holes drive the functionalities of electronic and photonic devices that are intricate for our lives. While fueling advances in engineering, charge-transfer science has established itself as an important independent field, originating from physical chemistry and chemical physics, focusing on paradigms from biology, and gaining momentum from solar-energy research. Here, we review the fundamental concepts of charge transfer, and outline its core role in a broad range of unrelated fields, such as medicine, environmental science, catalysis, electronics and photonics. The ubiquitous nature of dipoles, for example, sets demands on deepening the understanding of how localized electric fields affect charge transfer. Charge-transfer electrets, thus, prove important for advancing the field and for interfacing fundamental science with engineering. Synergy between the vastly different aspects of charge-transfer science sets the stage for the broad global impacts that the advances in this field have.
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Affiliation(s)
- James B Derr
- Department of Biochemistry, University of California, Riverside, CA 92521, USA.
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12
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Friedrich D, Brünig FN, Nieuwkoop AJ, Netz RR, Hegemann P, Oschkinat H. Collective exchange processes reveal an active site proton cage in bacteriorhodopsin. Commun Biol 2020; 3:4. [PMID: 31925324 PMCID: PMC6941954 DOI: 10.1038/s42003-019-0733-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 12/02/2019] [Indexed: 01/01/2023] Open
Abstract
Proton translocation across membranes is vital to all kingdoms of life. Mechanistically, it relies on characteristic proton flows and modifications of hydrogen bonding patterns, termed protonation dynamics, which can be directly observed by fast magic angle spinning (MAS) NMR. Here, we demonstrate that reversible proton displacement in the active site of bacteriorhodopsin already takes place in its equilibrated dark-state, providing new information on the underlying hydrogen exchange processes. In particular, MAS NMR reveals proton exchange at D85 and the retinal Schiff base, suggesting a tautomeric equilibrium and thus partial ionization of D85. We provide evidence for a proton cage and detect a preformed proton path between D85 and the proton shuttle R82. The protons at D96 and D85 exchange with water, in line with ab initio molecular dynamics simulations. We propose that retinal isomerization makes the observed proton exchange processes irreversible and delivers a proton towards the extracellular release site. Daniel Friedrich et al. show that reversible proton translocation occurs in the dark–state of bacteriorhodopsin, involving the retinal Schiff base and D85 exchanging protons with H2O. They find evidence of an active site proton cage and possible proton transfer via R82.
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Affiliation(s)
- Daniel Friedrich
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Str. 10, 13125, Berlin, Germany.,Freie Universität Berlin, Institut für Chemie und Biochemie, 14195, Berlin, Germany.,Department of Molecular and Cellular Biology, Harvard University, 52 Oxford Street, Cambridge, MA, 02138, USA.,Department of Cancer Biology, Dana-Farber Cancer Institute, 360 Longwood Avenue, Boston, MA, 02215, USA
| | - Florian N Brünig
- Freie Universität Berlin, Fachbereich Physik, 14195, Berlin, Germany
| | - Andrew J Nieuwkoop
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Str. 10, 13125, Berlin, Germany.,Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, 123 Bevier Road, Piscataway, NJ, 08854, USA
| | - Roland R Netz
- Freie Universität Berlin, Fachbereich Physik, 14195, Berlin, Germany
| | - Peter Hegemann
- Humboldt-Universität zu Berlin, Institut für Biologie, Invalidenstr. 42, 10115, Berlin, Germany
| | - Hartmut Oschkinat
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Str. 10, 13125, Berlin, Germany. .,Freie Universität Berlin, Institut für Chemie und Biochemie, 14195, Berlin, Germany.
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13
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Engineered Passive Potassium Conductance in the KR2 Sodium Pump. Biophys J 2019; 116:1941-1951. [PMID: 31036257 DOI: 10.1016/j.bpj.2019.04.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 03/31/2019] [Accepted: 04/03/2019] [Indexed: 11/23/2022] Open
Abstract
Light-driven sodium pumps (NaRs) are microbial rhodopsins that utilize light energy to actively transport sodium ions out of the cell. Here, we used targeted mutagenesis and electrophysiological methods in living cells to demonstrate that NaRs can be converted into light-activated cation channels by molecular engineering. Specifically, introduction of the R109Q mutation into the sodium ion pump of Dokdonia eikasta (KR2) results in passive ion conductance, with a high preference for potassium over sodium ions. However, in this mutant, residual active outward pumping of sodium ions competes with passive inward transport of potassium. Channel-like behavior could also be achieved by introduction of other mutations into the KR2 counterion complex, and further, these modifications were transferrable to other NaRs. Combining the R109Q replacement with modifications at position S70 removed the residual sodium pumping and greatly enhanced the channel-like activity. However, passive photocurrents were only observed in leak mutants if the KR2 counterions, D116 and D251, were deprotonated, which was only observed under alkaline conditions. Overall, our results reveal that interactions between R109 and the nearby residues, L75, S70, D116, and D251, prevent passive backflow during ion transport in NaRs.
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14
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Fudim R, Szczepek M, Vierock J, Vogt A, Schmidt A, Kleinau G, Fischer P, Bartl F, Scheerer P, Hegemann P. Design of a light-gated proton channel based on the crystal structure of Coccomyxa rhodopsin. Sci Signal 2019; 12:12/573/eaav4203. [PMID: 30890657 DOI: 10.1126/scisignal.aav4203] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The light-driven proton pump Coccomyxa subellipsoidea rhodopsin (CsR) provides-because of its high expression in heterologous host cells-an opportunity to study active proton transport under controlled electrochemical conditions. In this study, solving crystal structure of CsR at 2.0-Å resolution enabled us to identify distinct features of the membrane protein that determine ion transport directivity and voltage sensitivity. A specific hydrogen bond between the highly conserved Arg83 and the nearby nonconserved tyrosine (Tyr14) guided our structure-based transformation of CsR into an operational light-gated proton channel (CySeR) that could potentially be used in optogenetic assays. Time-resolved electrophysiological and spectroscopic measurements distinguished pump currents from channel currents in a single protein and emphasized the necessity of Arg83 mobility in CsR as a dynamic extracellular barrier to prevent passive conductance. Our findings reveal that molecular constraints that distinguish pump from channel currents are structurally more confined than was generally expected. This knowledge might enable the structure-based design of novel optogenetic tools, which derive from microbial pumps and are therefore ion specific.
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Affiliation(s)
- Roman Fudim
- Experimental Biophysics, Institute for Biology, Humboldt-Universität zu Berlin, Invalidenstr. 42, 10115 Berlin, Germany
| | - Michal Szczepek
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Institute for Medical Physics and Biophysics, Group Protein X-ray Crystallography & Signal Transduction, Charitéplatz 1, D-10117 Berlin, Germany
| | - Johannes Vierock
- Experimental Biophysics, Institute for Biology, Humboldt-Universität zu Berlin, Invalidenstr. 42, 10115 Berlin, Germany
| | - Arend Vogt
- Experimental Biophysics, Institute for Biology, Humboldt-Universität zu Berlin, Invalidenstr. 42, 10115 Berlin, Germany
| | - Andrea Schmidt
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Institute for Medical Physics and Biophysics, Group Protein X-ray Crystallography & Signal Transduction, Charitéplatz 1, D-10117 Berlin, Germany
| | - Gunnar Kleinau
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Institute for Medical Physics and Biophysics, Group Protein X-ray Crystallography & Signal Transduction, Charitéplatz 1, D-10117 Berlin, Germany
| | - Paul Fischer
- Experimental Biophysics, Institute for Biology, Humboldt-Universität zu Berlin, Invalidenstr. 42, 10115 Berlin, Germany
| | - Franz Bartl
- Biophysical Chemistry, Institute for Biology, Humboldt-Universität zu Berlin, Invalidenstr. 42, 10115 Berlin, Germany
| | - Patrick Scheerer
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Institute for Medical Physics and Biophysics, Group Protein X-ray Crystallography & Signal Transduction, Charitéplatz 1, D-10117 Berlin, Germany.
| | - Peter Hegemann
- Experimental Biophysics, Institute for Biology, Humboldt-Universität zu Berlin, Invalidenstr. 42, 10115 Berlin, Germany.
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15
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Electrical properties, substrate specificity and optogenetic potential of the engineered light-driven sodium pump eKR2. Sci Rep 2018; 8:9316. [PMID: 29915394 PMCID: PMC6006383 DOI: 10.1038/s41598-018-27690-w] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 05/24/2018] [Indexed: 01/22/2023] Open
Abstract
A new microbial rhodopsin class that actively transports sodium out of the cell upon illumination was described in 2013. However, poor membrane targeting of the first-identified sodium pump KR2 in mammalian cells has hindered the direct electrical investigation of its transport mechanism and optogenetic application to date. Accordingly, we designed enhanced KR2 (eKR2), which exhibits improved membrane targeting and higher photocurrents in mammalian cells to facilitate molecular characterization and future optogenetic applications. Our selectivity measurements revealed that stationary photocurrents are primarily carried by sodium, whereas protons only play a minor role, if any. Combining laser-induced photocurrent and absorption measurements, we found that spectral changes were not necessarily related to changes in transport activity. Finally, we showed that eKR2 can be expressed in cultured hippocampal mouse neurons and induce reversible inhibition of action potential firing with millisecond precision upon illumination with moderate green-light. Hence, the light-driven sodium pump eKR2 is a reliable inhibitory optogenetic tool applicable to situations in which the proton and chloride gradients should not be altered.
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16
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Takayama R, Kaneko A, Okitsu T, Tsunoda SP, Shimono K, Mizuno M, Kojima K, Tsukamoto T, Kandori H, Mizutani Y, Wada A, Sudo Y. Production of a Light-Gated Proton Channel by Replacing the Retinal Chromophore with Its Synthetic Vinylene Derivative. J Phys Chem Lett 2018; 9:2857-2862. [PMID: 29750864 DOI: 10.1021/acs.jpclett.8b00879] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Rhodopsin is widely distributed in organisms as a membrane-embedded photoreceptor protein, consisting of the apoprotein opsin and vitamin-A aldehyde retinal, A1-retinal and A2-retinal being the natural chromophores. Modifications of opsin (e.g., by mutations) have provided insight into the molecular mechanism of the light-induced functions of rhodopsins as well as providing tools in chemical biology to control cellular activity by light. Instead of the apoprotein opsin, in this study, we focused on the retinal chromophore and synthesized three vinylene derivatives of A2-retinal. One of them, C(14)-vinylene A2-retinal (14V-A2), was successfully incorporated into the opsin of a light-driven proton pump archaerhodopsin-3 (AR3). Electrophysiological experiments revealed that the opsin of AR3 (archaeopsin3, AO3) with 14V-A2 functions as a light-gated proton channel. The engineered proton channel showed characteristic photochemical properties, which are significantly different from those of AR3. Thus, we successfully produced a proton channel by replacing the chromophore of AR3.
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Affiliation(s)
- Riho Takayama
- Faculty of Pharmaceutical Sciences , Okayama University , Okayama 700-8530 , Japan
| | - Akimasa Kaneko
- Faculty of Pharmaceutical Sciences , Okayama University , Okayama 700-8530 , Japan
| | - Takashi Okitsu
- Laboratory of Organic Chemistry for Life Science , Kobe Pharmaceutical University , Kobe 658-8558 , Japan
| | - Satoshi P Tsunoda
- Department of Frontier Materials , Nagoya Institute of Technology , Nagoya 466-8555 , Japan
- PRESTO, Japan Science and Technology Agency , 4-1-8 Honcho , Kawaguchi , Saitama 332-0012 , Japan
| | - Kazumi Shimono
- Faculty of Pharmaceutical Sciences , Toho University , Funabashi 274-8510 , Japan
| | - Misao Mizuno
- Department of Chemistry , Graduate School of Science, Osaka University , Toyonaka 560-0043 , Japan
| | - Keiichi Kojima
- Faculty of Pharmaceutical Sciences , Okayama University , Okayama 700-8530 , Japan
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences , Okayama University , Okayama 700-8530 , 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
| | - Hideki Kandori
- Department of Frontier Materials , Nagoya Institute of Technology , Nagoya 466-8555 , Japan
| | - Yasuhisa Mizutani
- Department of Chemistry , Graduate School of Science, Osaka University , Toyonaka 560-0043 , Japan
| | - Akimori Wada
- Laboratory of Organic Chemistry for Life Science , Kobe Pharmaceutical University , Kobe 658-8558 , 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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17
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Volkov O, Kovalev K, Polovinkin V, Borshchevskiy V, Bamann C, Astashkin R, Marin E, Popov A, Balandin T, Willbold D, Büldt G, Bamberg E, Gordeliy V. Structural insights into ion conduction by channelrhodopsin 2. Science 2018; 358:358/6366/eaan8862. [PMID: 29170206 DOI: 10.1126/science.aan8862] [Citation(s) in RCA: 119] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Accepted: 10/30/2017] [Indexed: 11/02/2022]
Abstract
The light-gated ion channel channelrhodopsin 2 (ChR2) from Chlamydomonas reinhardtii is a major optogenetic tool. Photon absorption starts a well-characterized photocycle, but the structural basis for the regulation of channel opening remains unclear. We present high-resolution structures of ChR2 and the C128T mutant, which has a markedly increased open-state lifetime. The structure reveals two cavities on the intracellular side and two cavities on the extracellular side. They are connected by extended hydrogen-bonding networks involving water molecules and side-chain residues. Central is the retinal Schiff base that controls and synchronizes three gates that separate the cavities. Separate from this network is the DC gate that comprises a water-mediated bond between C128 and D156 and interacts directly with the retinal Schiff base. Comparison with the C128T structure reveals a direct connection of the DC gate to the central gate and suggests how the gating mechanism is affected by subtle tuning of the Schiff base's interactions.
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Affiliation(s)
- Oleksandr Volkov
- Institute of Complex Systems (ICS), ICS-6: Structural Biochemistry, Research Centre Juelich, Juelich, Germany
| | - Kirill Kovalev
- Institute of Complex Systems (ICS), ICS-6: Structural Biochemistry, Research Centre Juelich, Juelich, Germany.,Institut de Biologie Structurale Jean-Pierre Ebel, Université Grenoble Alpes-Commissariat à l'Energie Atomique et aux Energies Alternatives-CNRS, Grenoble, France.,Moscow Institute of Physics and Technology, Dolgoprudny, Russia.,Institute of Crystallography, University of Aachen, Aachen, Germany
| | - Vitaly Polovinkin
- Institute of Complex Systems (ICS), ICS-6: Structural Biochemistry, Research Centre Juelich, Juelich, Germany.,Institut de Biologie Structurale Jean-Pierre Ebel, Université Grenoble Alpes-Commissariat à l'Energie Atomique et aux Energies Alternatives-CNRS, Grenoble, France.,Moscow Institute of Physics and Technology, Dolgoprudny, Russia.,ELI Beamlines, Institute of Physics, Czech Academy of Sciences, 18221 Prague, Czech Republic
| | | | | | - Roman Astashkin
- Institut de Biologie Structurale Jean-Pierre Ebel, Université Grenoble Alpes-Commissariat à l'Energie Atomique et aux Energies Alternatives-CNRS, Grenoble, France.,Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - Egor Marin
- Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - Alexander Popov
- European Synchrotron Radiation Facility, 38027 Grenoble, France
| | - Taras Balandin
- Institute of Complex Systems (ICS), ICS-6: Structural Biochemistry, Research Centre Juelich, Juelich, Germany
| | - Dieter Willbold
- Institute of Complex Systems (ICS), ICS-6: Structural Biochemistry, Research Centre Juelich, Juelich, Germany.,Institut de Biologie Structurale Jean-Pierre Ebel, Université Grenoble Alpes-Commissariat à l'Energie Atomique et aux Energies Alternatives-CNRS, Grenoble, France.,Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Georg Büldt
- Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - Ernst Bamberg
- Max Planck Institute of Biophysics, Frankfurt am Main, Germany.
| | - Valentin Gordeliy
- Institute of Complex Systems (ICS), ICS-6: Structural Biochemistry, Research Centre Juelich, Juelich, Germany. .,Institut de Biologie Structurale Jean-Pierre Ebel, Université Grenoble Alpes-Commissariat à l'Energie Atomique et aux Energies Alternatives-CNRS, Grenoble, France.,Moscow Institute of Physics and Technology, Dolgoprudny, Russia
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18
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Kandori H, Inoue K, Tsunoda SP. Light-Driven Sodium-Pumping Rhodopsin: A New Concept of Active Transport. Chem Rev 2018. [DOI: 10.1021/acs.chemrev.7b00548] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
| | - Keiichi Inoue
- PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Satoshi P. Tsunoda
- PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
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19
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Ranjan P, Kateriya S. Localization and dimer stability of a newly identified microbial rhodopsin from a polar, non-motile green algae. BMC Res Notes 2018; 11:65. [PMID: 29361974 PMCID: PMC5781313 DOI: 10.1186/s13104-018-3181-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 01/16/2018] [Indexed: 11/10/2022] Open
Abstract
OBJECTIVE The eukaryotic plasma membrane localized light-gated proton-pumping rhodopsins possesses great optogenetic applications for repolarization (silencing) of the neuronal activity simply by light illumination. Very few plasma membrane localized proton-pumping rhodopsins of a eukaryotic origin are known that have optogenetic potential. Our objective was to identify and characterize microbial rhodopsin of an eukaryotic origin that expresses on plasma membrane. The plasma membrane localized light-gated proton pump of an eukaryotic origin hold great promise to be used as an optogenetic tools for the neurobiology. RESULTS Here, we had characterized the cellular expression and membrane localization of a new rhodopsin in Antarctican algae Coccomyxa subellipsoidea. It is the first algal ion pumping rhodopsin that localizes to the plasma membrane of the eukaryotic cells. Coccomyxa subellipsoidea rhodopsin exists in the monomeric and dimeric state both the in vivo and in vitro. The dimeric form of the Coccomyxa subellipsoidea rhodopsin is resistant to heat and detergent denaturants.
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Affiliation(s)
- Peeyush Ranjan
- Department of Biochemistry, University of Delhi South Campus, Benito Juarez Road, New Delhi, 110021, India.,Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, 20742, USA
| | - Suneel Kateriya
- Department of Biochemistry, University of Delhi South Campus, Benito Juarez Road, New Delhi, 110021, India. .,School of Biotechnology, Jawaharlal Nehru University, New Delhi, 110067, India.
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20
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Einav T, Phillips R. Monod-Wyman-Changeux Analysis of Ligand-Gated Ion Channel Mutants. J Phys Chem B 2017; 121:3813-3824. [PMID: 28134524 DOI: 10.1021/acs.jpcb.6b12672] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
We present a framework for computing the gating properties of ligand-gated ion channel mutants using the Monod-Wyman-Changeux (MWC) model of allostery. We derive simple analytic formulas for key functional properties such as the leakiness, dynamic range, half-maximal effective concentration ([EC50]), and effective Hill coefficient, and explore the full spectrum of phenotypes that are accessible through mutations. Specifically, we consider mutations in the channel pore of nicotinic acetylcholine receptor (nAChR) and the ligand binding domain of a cyclic nucleotide-gated (CNG) ion channel, demonstrating how each mutation can be characterized as only affecting a subset of the biophysical parameters. In addition, we show how the unifying perspective offered by the MWC model allows us, perhaps surprisingly, to collapse the plethora of dose-response data from different classes of ion channels into a universal family of curves.
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Affiliation(s)
- Tal Einav
- Department of Physics, California Institute of Technology , Pasadena, California 91125, United States
| | - Rob Phillips
- Department of Applied Physics and Division of Biology and Biological Engineering, California Institute of Technology , Pasadena, California 91125, United States
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21
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Fu W, Chaiboonchoe A, Khraiwesh B, Nelson DR, Al-Khairy D, Mystikou A, Alzahmi A, Salehi-Ashtiani K. Algal Cell Factories: Approaches, Applications, and Potentials. Mar Drugs 2016; 14:md14120225. [PMID: 27983586 PMCID: PMC5192462 DOI: 10.3390/md14120225] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 12/02/2016] [Accepted: 12/05/2016] [Indexed: 12/26/2022] Open
Abstract
With the advent of modern biotechnology, microorganisms from diverse lineages have been used to produce bio-based feedstocks and bioactive compounds. Many of these compounds are currently commodities of interest, in a variety of markets and their utility warrants investigation into improving their production through strain development. In this review, we address the issue of strain improvement in a group of organisms with strong potential to be productive “cell factories”: the photosynthetic microalgae. Microalgae are a diverse group of phytoplankton, involving polyphyletic lineage such as green algae and diatoms that are commonly used in the industry. The photosynthetic microalgae have been under intense investigation recently for their ability to produce commercial compounds using only light, CO2, and basic nutrients. However, their strain improvement is still a relatively recent area of work that is under development. Importantly, it is only through appropriate engineering methods that we may see the full biotechnological potential of microalgae come to fruition. Thus, in this review, we address past and present endeavors towards the aim of creating productive algal cell factories and describe possible advantageous future directions for the field.
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Affiliation(s)
- Weiqi Fu
- Division of Science and Math, New York University Abu Dhabi, P.O. Box 129188 Saadiyat Island, Abu Dhabi, UAE.
| | - Amphun Chaiboonchoe
- Division of Science and Math, New York University Abu Dhabi, P.O. Box 129188 Saadiyat Island, Abu Dhabi, UAE.
| | - Basel Khraiwesh
- Center for Genomics and Systems Biology (CGSB), New York University Abu Dhabi, P.O. Box 129188 Saadiyat Island, Abu Dhabi, UAE.
| | - David R Nelson
- Center for Genomics and Systems Biology (CGSB), New York University Abu Dhabi, P.O. Box 129188 Saadiyat Island, Abu Dhabi, UAE.
| | - Dina Al-Khairy
- Division of Science and Math, New York University Abu Dhabi, P.O. Box 129188 Saadiyat Island, Abu Dhabi, UAE.
| | - Alexandra Mystikou
- Division of Science and Math, New York University Abu Dhabi, P.O. Box 129188 Saadiyat Island, Abu Dhabi, UAE.
| | - Amnah Alzahmi
- Center for Genomics and Systems Biology (CGSB), New York University Abu Dhabi, P.O. Box 129188 Saadiyat Island, Abu Dhabi, UAE.
| | - Kourosh Salehi-Ashtiani
- Division of Science and Math, New York University Abu Dhabi, P.O. Box 129188 Saadiyat Island, Abu Dhabi, UAE.
- Center for Genomics and Systems Biology (CGSB), New York University Abu Dhabi, P.O. Box 129188 Saadiyat Island, Abu Dhabi, UAE.
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22
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Inoue K, Ito S, Kato Y, Nomura Y, Shibata M, Uchihashi T, Tsunoda SP, Kandori H. A natural light-driven inward proton pump. Nat Commun 2016; 7:13415. [PMID: 27853152 PMCID: PMC5118547 DOI: 10.1038/ncomms13415] [Citation(s) in RCA: 106] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 09/28/2016] [Indexed: 01/03/2023] Open
Abstract
Light-driven outward H+ pumps are widely distributed in nature, converting sunlight energy into proton motive force. Here we report the characterization of an oppositely directed H+ pump with a similar architecture to outward pumps. A deep-ocean marine bacterium, Parvularcula oceani, contains three rhodopsins, one of which functions as a light-driven inward H+ pump when expressed in Escherichia coli and mouse neural cells. Detailed mechanistic analyses of the purified proteins reveal that small differences in the interactions established at the active centre determine the direction of primary H+ transfer. Outward H+ pumps establish strong electrostatic interactions between the primary H+ donor and the extracellular acceptor. In the inward H+ pump these electrostatic interactions are weaker, inducing a more relaxed chromophore structure that leads to the long-distance transfer of H+ to the cytoplasmic side. These results demonstrate an elaborate molecular design to control the direction of H+ transfers in proteins.
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Affiliation(s)
- Keiichi Inoue
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
- OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
- PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Shota Ito
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
| | - Yoshitaka Kato
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
| | - Yurika Nomura
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
| | - Mikihiro Shibata
- Department of Physics, Kanazawa University, Kanazawa 920-1192, Japan
- Bio-AFM Frontier Research Center, Kanazawa University, Kanazawa 920-1192, Japan
| | - Takayuki Uchihashi
- Department of Physics, Kanazawa University, Kanazawa 920-1192, Japan
- Bio-AFM Frontier Research Center, Kanazawa University, Kanazawa 920-1192, Japan
| | - Satoshi P. Tsunoda
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
| | - Hideki Kandori
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
- OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
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23
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Copits BA, Pullen MY, Gereau RW. Spotlight on pain: optogenetic approaches for interrogating somatosensory circuits. Pain 2016; 157:2424-2433. [PMID: 27340912 PMCID: PMC5069102 DOI: 10.1097/j.pain.0000000000000620] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Bryan A Copits
- Washington University Pain Center, Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO, USA
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24
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Govorunova EG, Sineshchekov OA, Spudich JL. Structurally Distinct Cation Channelrhodopsins from Cryptophyte Algae. Biophys J 2016; 110:2302-2304. [PMID: 27233115 DOI: 10.1016/j.bpj.2016.05.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Revised: 04/20/2016] [Accepted: 05/02/2016] [Indexed: 02/08/2023] Open
Abstract
Microbial rhodopsins are remarkable for the diversity of their functional mechanisms based on the same protein scaffold. A class of rhodopsins from cryptophyte algae show close sequence homology with haloarchaeal rhodopsin proton pumps rather than with previously known channelrhodopsins from chlorophyte (green) algae. In particular, both aspartate residues that occupy the positions of the chromophore Schiff base proton acceptor and donor, a hallmark of rhodopsin proton pumps, are conserved in these cryptophyte proteins. We expressed the corresponding polynucleotides in human embryonic kidney (HEK293) cells and studied electrogenic properties of the encoded proteins with whole-cell patch-clamp recording. Despite their lack of residues characteristic of the chlorophyte cation channels, these proteins are cation-conducting channelrhodopsins that carry out light-gated passive transport of Na(+) and H(+). These findings show that channel function in rhodopsins has evolved via multiple routes.
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Affiliation(s)
- Elena G Govorunova
- Center for Membrane Biology and Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, McGovern Medical School, Houston, Texas
| | - Oleg A Sineshchekov
- Center for Membrane Biology and Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, McGovern Medical School, Houston, Texas
| | - John L Spudich
- Center for Membrane Biology and Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, McGovern Medical School, Houston, Texas.
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25
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Ferenczi EA, Vierock J, Atsuta-Tsunoda K, Tsunoda SP, Ramakrishnan C, Gorini C, Thompson K, Lee SY, Berndt A, Perry C, Minniberger S, Vogt A, Mattis J, Prakash R, Delp S, Deisseroth K, Hegemann P. Optogenetic approaches addressing extracellular modulation of neural excitability. Sci Rep 2016; 6:23947. [PMID: 27045897 PMCID: PMC4820717 DOI: 10.1038/srep23947] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 03/10/2016] [Indexed: 12/28/2022] Open
Abstract
The extracellular ionic environment in neural tissue has the capacity to influence, and be influenced by, natural bouts of neural activity. We employed optogenetic approaches to control and investigate these interactions within and between cells, and across spatial scales. We began by developing a temporally precise means to study microdomain-scale interactions between extracellular protons and acid-sensing ion channels (ASICs). By coupling single-component proton-transporting optogenetic tools to ASICs to create two-component optogenetic constructs (TCOs), we found that acidification of the local extracellular membrane surface by a light-activated proton pump recruited a slow inward ASIC current, which required molecular proximity of the two components on the membrane. To elicit more global effects of activity modulation on ‘bystander’ neurons not under direct control, we used densely-expressed depolarizing (ChR2) or hyperpolarizing (eArch3.0, eNpHR3.0) tools to create a slow non-synaptic membrane current in bystander neurons, which matched the current direction seen in the directly modulated neurons. Extracellular protons played contributory role but were insufficient to explain the entire bystander effect, suggesting the recruitment of other mechanisms. Together, these findings present a new approach to the engineering of multicomponent optogenetic tools to manipulate ionic microdomains, and probe the complex neuronal-extracellular space interactions that regulate neural excitability.
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Affiliation(s)
- Emily A Ferenczi
- Bioengineering, Stanford University, 318 Campus Drive, Stanford, CA 94305, USA.,Neurosciences, Stanford University, 318 Campus Drive, Stanford, CA 94305, USA
| | - Johannes Vierock
- Institute of Biology, Experimental Biophysics, Invalidenstraße 42, D-10115 Berlin, Germany
| | - Kyoko Atsuta-Tsunoda
- Institute of Biology, Experimental Biophysics, Invalidenstraße 42, D-10115 Berlin, Germany
| | - Satoshi P Tsunoda
- Institute of Biology, Experimental Biophysics, Invalidenstraße 42, D-10115 Berlin, Germany
| | - Charu Ramakrishnan
- Bioengineering, Stanford University, 318 Campus Drive, Stanford, CA 94305, USA
| | - Christopher Gorini
- Bioengineering, Stanford University, 318 Campus Drive, Stanford, CA 94305, USA
| | - Kimberly Thompson
- Bioengineering, Stanford University, 318 Campus Drive, Stanford, CA 94305, USA
| | - Soo Yeun Lee
- Bioengineering, Stanford University, 318 Campus Drive, Stanford, CA 94305, USA
| | - Andre Berndt
- Bioengineering, Stanford University, 318 Campus Drive, Stanford, CA 94305, USA
| | - Chelsey Perry
- Bioengineering, Stanford University, 318 Campus Drive, Stanford, CA 94305, USA
| | - Sonja Minniberger
- Institute of Biology, Experimental Biophysics, Invalidenstraße 42, D-10115 Berlin, Germany
| | - Arend Vogt
- Institute of Biology, Experimental Biophysics, Invalidenstraße 42, D-10115 Berlin, Germany
| | - Joanna Mattis
- Bioengineering, Stanford University, 318 Campus Drive, Stanford, CA 94305, USA.,Neurosciences, Stanford University, 318 Campus Drive, Stanford, CA 94305, USA
| | - Rohit Prakash
- Bioengineering, Stanford University, 318 Campus Drive, Stanford, CA 94305, USA.,Neurosciences, Stanford University, 318 Campus Drive, Stanford, CA 94305, USA
| | - Scott Delp
- Bioengineering, Stanford University, 318 Campus Drive, Stanford, CA 94305, USA
| | - Karl Deisseroth
- Bioengineering, Stanford University, 318 Campus Drive, Stanford, CA 94305, USA.,HHMI, Stanford University, 318 Campus Drive, Stanford, CA 94305, USA.,Department of Psychiatry &Behavioral Science, Stanford University, 401 Quarry Road, Stanford, CA 94305, USA
| | - Peter Hegemann
- Institute of Biology, Experimental Biophysics, Invalidenstraße 42, D-10115 Berlin, Germany
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