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Govorunova EG, Sineshchekov OA, Spudich JL. Emerging Diversity of Channelrhodopsins and Their Structure-Function Relationships. Front Cell Neurosci 2022; 15:800313. [PMID: 35140589 PMCID: PMC8818676 DOI: 10.3389/fncel.2021.800313] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 12/28/2021] [Indexed: 12/12/2022] Open
Abstract
Cation and anion channelrhodopsins (CCRs and ACRs, respectively) from phototactic algae have become widely used as genetically encoded molecular tools to control cell membrane potential with light. Recent advances in polynucleotide sequencing, especially in environmental samples, have led to identification of hundreds of channelrhodopsin homologs in many phylogenetic lineages, including non-photosynthetic protists. Only a few CCRs and ACRs have been characterized in detail, but there are indications that ion channel function has evolved within the rhodopsin superfamily by convergent routes. The diversity of channelrhodopsins provides an exceptional platform for the study of structure-function evolution in membrane proteins. Here we review the current state of channelrhodopsin research and outline perspectives for its further development.
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English AW, Berglund K, Carrasco D, Goebel K, Gross RE, Isaacson R, Mistretta OC, Wynans C. Bioluminescent Optogenetics: A Novel Experimental Therapy to Promote Axon Regeneration after Peripheral Nerve Injury. Int J Mol Sci 2021; 22:ijms22137217. [PMID: 34281270 PMCID: PMC8269199 DOI: 10.3390/ijms22137217] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 06/24/2021] [Accepted: 06/25/2021] [Indexed: 11/18/2022] Open
Abstract
Functional recovery after peripheral nerve injury (PNI) is poor, mainly due to the slow and incomplete regeneration of injured axons. Experimental therapies that increase the excitability of the injured axons have proven remarkably successful in promoting regeneration, but their clinical applicability has been limited. Bioluminescent optogenetics (BL-OG) uses luminopsins, fusion proteins of light-generating luciferase and light-sensing ion channels that could be used to increase neuronal excitability if exposed to a suitable substrate. Excitatory luminopsins were expressed in motoneurons of transgenic mice and in wildtype mice transduced with adeno-associated viral vectors. Intraperitoneal administration of coelenterazine (CTZ), a known luciferase substrate, generated intense bioluminescence in peripheral axons. This bioluminescence increased motoneuron excitability. A single administration of CTZ immediately after sciatic nerve transection and repair markedly enhanced motor axon regeneration. Compound muscle action potentials were 3–4 times larger than controls by 4 weeks after injury. The results observed with transgenic mice were comparable to those of mice in which the luminopsin was expressed using viral vectors. Significantly more motoneurons had successfully reinnervated muscle targets four weeks after nerve injury in BL-OG treated mice than in controls. Bioluminescent optogenetics is a promising therapeutic approach to enhancing axon regeneration after PNI.
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Affiliation(s)
- Arthur W. English
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA; (D.C.); (K.G.); (R.I.); (O.C.M.); (C.W.)
- Department of Rehabilitation Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA
- Correspondence:
| | - Ken Berglund
- Department of Neurosurgery, Emory University School of Medicine, Atlanta, GA 30322, USA; (K.B.); (R.E.G.)
| | - Dario Carrasco
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA; (D.C.); (K.G.); (R.I.); (O.C.M.); (C.W.)
| | - Katharina Goebel
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA; (D.C.); (K.G.); (R.I.); (O.C.M.); (C.W.)
| | - Robert E. Gross
- Department of Neurosurgery, Emory University School of Medicine, Atlanta, GA 30322, USA; (K.B.); (R.E.G.)
| | - Robin Isaacson
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA; (D.C.); (K.G.); (R.I.); (O.C.M.); (C.W.)
| | - Olivia C. Mistretta
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA; (D.C.); (K.G.); (R.I.); (O.C.M.); (C.W.)
| | - Carly Wynans
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA; (D.C.); (K.G.); (R.I.); (O.C.M.); (C.W.)
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Nagasaka Y, Hososhima S, Kubo N, Nagata T, Kandori H, Inoue K, Yawo H. Gate-keeper of ion transport-a highly conserved helix-3 tryptophan in a channelrhodopsin chimera, C1C2/ChRWR. Biophys Physicobiol 2020; 17:59-70. [PMID: 33173715 PMCID: PMC7593130 DOI: 10.2142/biophysico.bsj-2020007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 05/27/2020] [Indexed: 12/01/2022] Open
Abstract
Microbial rhodopsin is a large family of membrane proteins having seven transmembrane helices (TM1-7) with an all-trans retinal (ATR) chromophore that is covalently bound to Lys in the TM7. The Trp residue in the middle of TM3, which is homologous to W86 of bacteriorhodopsin (BR), is highly conserved among microbial rhodopsins with various light-driven functions. However, the significance of this Trp for the ion transport function of microbial rhodopsins has long remained unknown. Here, we replaced the W163 (BR W86 counterpart) of a channelrhodopsin (ChR), C1C2/ChRWR, which is a chimera between ChR1 and 2, with a smaller aromatic residue, Phe to verify its role in the ion transport. Under whole-cell patch clamp recordings from the ND7/23 cells that were transfected with the DNA plasmid coding human codon optimized C1C2/ChRWR (hWR) or its W163F mutant (hWR-W163F), the photocurrents were evoked by a pulsatile light at 475 nm. The ion-transporting activity of hWR was strongly altered by the W163F mutation in 3 points: (1) the H+ leak at positive membrane potential (Vm) and its light-adaptation, (2) the attenuation of cation channel activity and (3) the manifestation of outward H+ pump activity. All of these results strongly suggest that W163 has a role in stabilizing the structure involved in the gating-on and -off of the cation channel, the role of “gate keeper”. We can attribute the attenuation of cation channel activity to the incomplete gating-on and the H+ leak to the incomplete gating-off.
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Affiliation(s)
- Yujiro Nagasaka
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan.,Department of Advanced Materials Science, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Shoko Hososhima
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya 466-8555, Japan
| | - Naoko Kubo
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan.,Department of Physiology, Tohoku University Graduate School of Medicine, Sendai, Miyagi 980-8575, Japan
| | - Takashi Nagata
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan.,Precursory Research for Embryonic Science and Technology (PRESTO) , Japan Science and Technology Agency (JST), Kawaguchi, Saitama 332-0012, Japan
| | - Hideki Kandori
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya 466-8555, Japan.,OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
| | - Keiichi Inoue
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Hiromu Yawo
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
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Molecular Dynamics Simulation of Transmembrane Transport of Chloride Ions in Mutants of Channelrhodopsin. Biomolecules 2019; 9:biom9120852. [PMID: 31835536 PMCID: PMC6995576 DOI: 10.3390/biom9120852] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 12/01/2019] [Accepted: 12/06/2019] [Indexed: 01/12/2023] Open
Abstract
Channelrhodopsins (ChRs) are light-gated transmembrane cation channels which are widely used for optogenetic technology. Replacing glutamate located at the central gate of the ion channel with positively charged amino acid residues will reverse ion selectivity and allow anion conduction. The structures and properties of the ion channel, the transport of chloride, and potential of mean force (PMF) of the chimera protein (C1C2) and its mutants, EK-TC, ER-TC and iChloC, were investigated by molecular dynamics simulation. The results show that the five-fold mutation in E122Q-E129R-E140S-D195N-T198C (iChloC) increases the flexibility of the transmembrane channel protein better than the double mutations in EK-TC and ER-TC, and results in an expanded ion channel pore size and decreased steric resistance. The iChloC mutant was also found to have a higher affinity for chloride ions and, based on surface electrostatic potential analysis, provides a favorable electrostatic environment for anion conduction. The PMF free energy curves revealed that high affinity Cl- binding sites are generated near the central gate of the three mutant proteins. The energy barriers for the EK-TC and ER-TC were found to be much higher than that of iChloC. The results suggest that the transmembrane ion channel of iChloC protein is better at facilitating the capture and transport of chloride ions.
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Formation Mechanism of Ion Channel in Channelrhodopsin-2: Molecular Dynamics Simulation and Steering Molecular Dynamics Simulations. Int J Mol Sci 2019; 20:ijms20153780. [PMID: 31382458 PMCID: PMC6695816 DOI: 10.3390/ijms20153780] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Accepted: 07/30/2019] [Indexed: 01/19/2023] Open
Abstract
Channelrhodopsin-2 (ChR2) is a light-activated and non-selective cationic channel protein that can be easily expressed in specific neurons to control neuronal activity by light. Although ChR2 has been extensively used as an optogenetic tool in neuroscience research, the molecular mechanism of cation channel formation following retinal photoisomerization in ChR2 is not well understood. In this paper, studies of the closed and opened state ChR2 structures are presented. The formation of the cationic channel is elucidated in atomic detail using molecular dynamics simulations on the all-trans-retinal (ChR2-trans) configuration of ChR2 and its isomerization products, 13-cis-retinal (ChR2-cis) configuration, respectively. Photoisomerization of the retinal-chromophore causes the destruction of interactions among the crucial residues (e.g., E90, E82, N258, and R268) around the channel and the extended H-bond network mediated by numerous water molecules, which opens the pore. Steering molecular dynamics (SMD) simulations show that the electrostatic interactions at the binding sites in intracellular gate (ICG) and central gate (CG) can influence the transmembrane transport of Na+ in ChR2-cis obviously. Potential of mean force (PMF) constructed by SMD and umbrella sampling also found the existing energy wells at these two binding sites during the transportation of Na+. These wells partly hinder the penetration of Na+ into cytoplasm through the ion channel. This investigation provides a theoretical insight on the formation mechanism of ion channels and the mechanism of ion permeation.
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Berglund K, Fernandez AM, Gutekunst CAN, Hochgeschwender U, Gross RE. Step-function luminopsins for bimodal prolonged neuromodulation. J Neurosci Res 2019; 98:422-436. [PMID: 30957296 DOI: 10.1002/jnr.24424] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 02/26/2019] [Accepted: 03/14/2019] [Indexed: 11/09/2022]
Abstract
Although molecular tools for controlling neuronal activity by light have vastly expanded, there are still unmet needs which require development and refinement. For example, light delivery into the brain is still a major practical challenge that hinders potential translation of optogenetics in human patients. In addition, it would be advantageous to manipulate neuronal activity acutely and precisely as well as chronically and non-invasively, using the same genetic construct in animal models. We have previously addressed these challenges by employing bioluminescence and have created a new line of opto-chemogenetic probes termed luminopsins by fusing light-sensing opsins with light-emitting luciferases. In this report, we incorporated Chlamydomonas channelrhodopsin 2 with step-function mutations as the opsin moiety in the new luminopsin fusion protein termed step-function luminopsin (SFLMO). Bioluminescence-induced photocurrent lasted longer than the bioluminescence signal due to very slow deactivation of the mutated channel. In addition, bioluminescence was able to activate most of the channels on the cell surface due to the extremely high light sensitivity of the channel. This efficient channel activation was partly mediated by radiationless bioluminescence resonance energy transfer due to the proximity of luciferase and opsin. To test the utility of SFLMOs in vivo, we transduced the substantia nigra unilaterally via a viral vector in male rats. Injection of the luciferase substrate as well as conventional photostimulation via fiber optics elicited circling behaviors. Thus, SFLMOs expand the current approaches for manipulation of neuronal activity in the brain and add more versatility and practicality to optogenetics in freely behaving animals.
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Affiliation(s)
- Ken Berglund
- Department of Neurosurgery, Emory University School of Medicine, Atlanta, Georgia
| | | | | | - Ute Hochgeschwender
- Neuroscience Program and College of Medicine, Central Michigan University, Mt Pleasant, Michigan
| | - Robert E Gross
- Department of Neurosurgery, Emory University School of Medicine, Atlanta, Georgia
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7
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Vierock J, Grimm C, Nitzan N, Hegemann P. Molecular determinants of proton selectivity and gating in the red-light activated channelrhodopsin Chrimson. Sci Rep 2017; 7:9928. [PMID: 28855540 PMCID: PMC5577340 DOI: 10.1038/s41598-017-09600-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 07/21/2017] [Indexed: 12/15/2022] Open
Abstract
Channelrhodopsins are light-gated ion channels of green algae used for the precise temporal and spatial control of transmembrane ion fluxes. The channelrhodopsin Chrimson from Chlamydomonas noctigama allows unprecedented deep tissue penetration due to peak absorption at 590 nm. We demonstrate by electrophysiological recordings and imaging techniques that Chrimson is highly proton selective causing intracellular acidification in HEK cells that is responsible for slow photocurrent decline during prolonged illumination. We localized molecular determinants of both high proton selectivity and red light activation to the extracellular pore. Whereas exchange of Glu143 only drops proton conductance and generates an operational Na-channel with 590 nm activation, exchange of Glu139 in addition increased the open state lifetime and shifted the absorption hypsochromic by 70 nm. In conjunction with Glu300 in the center and Glu124 and Glu125 at the intracellular end of the pore, Glu139 contributes to a delocalized activation gate and stabilizes by long-range interaction counterion configuration involving protonation of Glu165 that we identified as a key determinant of the large opsin shift in Chrimson.
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Affiliation(s)
- Johannes Vierock
- Institute of Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, 10115, Berlin, Germany.
| | - Christiane Grimm
- Institute of Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, 10115, Berlin, Germany
| | - Noam Nitzan
- Institute of Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, 10115, Berlin, Germany.,Neuroscience Research Center, Charité - Universitätsmedizin Berlin, Charitéplatz 1, 10117, Berlin, Germany
| | - Peter Hegemann
- Institute of Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, 10115, Berlin, Germany
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8
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Zamani A, Sakuragi S, Ishizuka T, Yawo H. Kinetic characteristics of chimeric channelrhodopsins implicate the molecular identity involved in desensitization. Biophys Physicobiol 2017; 14:13-22. [PMID: 28409086 PMCID: PMC5289414 DOI: 10.2142/biophysico.14.0_13] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 12/29/2016] [Indexed: 12/01/2022] Open
Abstract
Channelrhodopsin (ChR)-1 and ChR2 were the first-identified members of ChRs which are a growing subfamily of microbial-type rhodopsins. Light absorption drives the generation of a photocurrent in cell membranes expressing ChR2. However, the photocurrent amplitude attenuates and becomes steady-state during prolonged irradiation. This process, called desensitization or inactivation, has been attributed to the accumulation of intermediates less conductive to cations. Here we provided evidence that the dark-adapted (DA) photocurrent before desensitization is kinetically different from the light-adapted (LA) one after desensitization, that is, the deceleration of both basal-to-conductive and conductive-to-basal transitions. When the kinetics were compared between the DA and LA photocurrents for the ChR1/2 chimeras, the transmembrane helices, TM1 and TM2, were the determinants of both basal-to-conductive and conductive-to-basal transitions, whereas TM4 may contribute to the basal-to-conductive transitions and TM5 may contribute to the conductive-to-basal transitions, respectively. The fact that the desensitization-dependent decrease of the basal-to-conductive and conductive-to-basal transitions was facilitated by the TM1 exchange from ChR2 to ChR1 and reversed by the further TM2 exchange suggests that the conformation change for the channel gating is predominantly regulated by the interaction between TM1 and TM2. Although the exchange of TM1 from ChR2 to ChR1 showed no obvious influence on the spectral sensitivity, this exchange significantly induced the desensitization-dependent blue shift. Therefore, the TM1 and 2 are the main structures involved in two features of the desensitization, the stabilization of protein conformation and the charge distribution around the retinal-Schiff base (RSB+).
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Affiliation(s)
- Alemeh Zamani
- Department of Developmental Biology and Neurosciences, Tohoku University Graduate School of Life Sciences, Sendai, Miyagi 980-8577, Japan
| | - Shigeo Sakuragi
- Department of Developmental Biology and Neurosciences, Tohoku University Graduate School of Life Sciences, Sendai, Miyagi 980-8577, Japan
| | - Toru Ishizuka
- Department of Developmental Biology and Neurosciences, Tohoku University Graduate School of Life Sciences, Sendai, Miyagi 980-8577, Japan
| | - Hiromu Yawo
- Department of Developmental Biology and Neurosciences, Tohoku University Graduate School of Life Sciences, Sendai, Miyagi 980-8577, Japan.,Center for Neuroscience, Tohoku University Graduate School of Medicine, Sendai, Miyagi 980-8575, Japan
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Watanabe S, Ishizuka T, Hososhima S, Zamani A, Hoque MR, Yawo H. The regulatory mechanism of ion permeation through a channelrhodopsin derived from Mesostigma viride (MvChR1). Photochem Photobiol Sci 2016; 15:365-74. [DOI: 10.1039/c5pp00290g] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
MvChR2 was rather insensitive to Gd3+ because of the absence of negativity at the 116th position, which is glutamate in the case of channelrhodopsin-2 (CrChR2) or the C1C2.
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Affiliation(s)
- Shota Watanabe
- Department of Developmental Biology and Neuroscience
- Tohoku University Graduate School of Life Sciences and JST
- CREST
- Sendai 980-8577
- Japan
| | - Toru Ishizuka
- Department of Developmental Biology and Neuroscience
- Tohoku University Graduate School of Life Sciences and JST
- CREST
- Sendai 980-8577
- Japan
| | - Shoko Hososhima
- Department of Developmental Biology and Neuroscience
- Tohoku University Graduate School of Life Sciences and JST
- CREST
- Sendai 980-8577
- Japan
| | - Alemeh Zamani
- Department of Developmental Biology and Neuroscience
- Tohoku University Graduate School of Life Sciences and JST
- CREST
- Sendai 980-8577
- Japan
| | - Mohammad Razuanul Hoque
- Department of Developmental Biology and Neuroscience
- Tohoku University Graduate School of Life Sciences and JST
- CREST
- Sendai 980-8577
- Japan
| | - Hiromu Yawo
- Department of Developmental Biology and Neuroscience
- Tohoku University Graduate School of Life Sciences and JST
- CREST
- Sendai 980-8577
- Japan
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Takemoto M, Kato HE, Koyama M, Ito J, Kamiya M, Hayashi S, Maturana AD, Deisseroth K, Ishitani R, Nureki O. Molecular Dynamics of Channelrhodopsin at the Early Stages of Channel Opening. PLoS One 2015; 10:e0131094. [PMID: 26114863 PMCID: PMC4482709 DOI: 10.1371/journal.pone.0131094] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Accepted: 05/28/2015] [Indexed: 11/25/2022] Open
Abstract
Channelrhodopsin (ChR) is a light-gated cation channel that responds to blue light. Since ChR can be readily expressed in specific neurons to precisely control their activities by light, it has become a powerful tool in neuroscience. Although the recently solved crystal structure of a chimeric ChR, C1C2, provided the structural basis for ChR, our understanding of the molecular mechanism of ChR still remains limited. Here we performed electrophysiological analyses and all-atom molecular dynamics (MD) simulations, to investigate the importance of the intracellular and central constrictions of the ion conducting pore observed in the crystal structure of C1C2. Our electrophysiological analysis revealed that two glutamate residues, Glu122 and Glu129, in the intracellular and central constrictions, respectively, should be deprotonated in the photocycle. The simulation results suggested that the deprotonation of Glu129 in the central constriction leads to ion leakage in the ground state, and implied that the protonation of Glu129 is important for preventing ion leakage in the ground state. Moreover, we modeled the 13-cis retinal bound; i.e., activated C1C2, and performed MD simulations to investigate the conformational changes in the early stage of the photocycle. Our simulations suggested that retinal photoisomerization induces the conformational change toward channel opening, including the movements of TM6, TM7 and TM2. These insights into the dynamics of the ground states and the early photocycle stages enhance our understanding of the channel function of ChR.
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Affiliation(s)
- Mizuki Takemoto
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113–0033, Japan
| | - Hideaki E. Kato
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113–0033, Japan
| | - Michio Koyama
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113–0033, Japan
| | - Jumpei Ito
- Department of Bioengineering Sciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464–8601, Japan
| | - Motoshi Kamiya
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606–8502, Japan
| | - Shigehiko Hayashi
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606–8502, Japan
| | - Andrés D. Maturana
- Department of Bioengineering Sciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464–8601, Japan
| | - Karl Deisseroth
- Department of Bioengineering and Howard Hughes Medical Institute, Stanford University, Stanford, California 94305, United States of America
| | - Ryuichiro Ishitani
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113–0033, Japan
- * E-mail: (ON); (RI)
| | - Osamu Nureki
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113–0033, Japan
- * E-mail: (ON); (RI)
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Arias-Darraz L, Colenso CK, Veliz LA, Vivar JP, Cardenas S, Brauchi S. A TRP conductance modulates repolarization after sensory-dependent depolarization in Chlamydomonas reinhardtii. PLANT SIGNALING & BEHAVIOR 2015; 10:e1052924. [PMID: 26186626 PMCID: PMC4622017 DOI: 10.1080/15592324.2015.1052924] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Revised: 05/13/2015] [Accepted: 05/15/2015] [Indexed: 05/26/2023]
Abstract
Sensory integration is vital for motile organisms constantly exposed to changing surroundings. Chlamydomonas reinhardtii is a single-celled green alga found swimming in freshwater. In this type of alga, sensory input is first detected by membrane receptors located in the cell body, and then transduced to the beating cilia by membrane depolarization. Many components of the machinery associated with sensory integration in C. reinhardtii, such as chemoreceptors and repolarization-associated channels, are yet uncharacterized. TRP channels are known mediators for cellular sensing in animal cells and it has been suggested that the C. reinhardtii genome encodes for a set of TRP proteins. Here, by combining behavioral studies with electrophysiological experiments conducted on both population and single alga, we test whether TRP channel blockers affect algal swimming behavior. Our results suggest that a TRP conductance is associated to the repolarization that follows a depolarizing receptor potential, highlighting a primitive function of TRP proteins.
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Affiliation(s)
- Luis Arias-Darraz
- Physiology Department; Faculty of Medicine; Universidad Austral de Chile; Campus Isla Teja, Valdivia, Chile
| | - Charlotte K Colenso
- Physiology Department; Faculty of Medicine; Universidad Austral de Chile; Campus Isla Teja, Valdivia, Chile
| | - Luis A Veliz
- Physiology Department; Faculty of Medicine; Universidad Austral de Chile; Campus Isla Teja, Valdivia, Chile
| | - Juan P Vivar
- Physiology Department; Faculty of Medicine; Universidad Austral de Chile; Campus Isla Teja, Valdivia, Chile
| | - Sylvana Cardenas
- Physiology Department; Faculty of Medicine; Universidad Austral de Chile; Campus Isla Teja, Valdivia, Chile
| | - Sebastian Brauchi
- Physiology Department; Faculty of Medicine; Universidad Austral de Chile; Campus Isla Teja, Valdivia, Chile
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Kuhne J, Eisenhauer K, Ritter E, Hegemann P, Gerwert K, Bartl F. Early formation of the ion-conducting pore in channelrhodopsin-2. Angew Chem Int Ed Engl 2014; 54:4953-7. [PMID: 25537168 DOI: 10.1002/anie.201410180] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Revised: 11/20/2014] [Indexed: 11/10/2022]
Abstract
Channelrhodopsins (ChRs) are light-gated ion channels that are widely used in optogenetics. They allow precise control of neuronal activity with light, but a detailed understanding of how the channel is gated and the ions are conducted is still lacking. The recent determination of the X-ray structural model in the closed state marks an important milestone. Herein the open state structure is presented and the early formation of the ion conducting pore is elucidated in atomic detail using time-resolved FTIR spectroscopy. Photo-isomerization of the retinal-chromophore causes a downward movement of the highly conserved E90, which opens the pore. Molecular dynamic (MD) simulations show that water molecules invade through this opened pore, Helix 2 tilts and the channel fully opens within ms. Since E90 is a highly conserved residue, the proposed E90-Helix2-tilt (EHT) model might describe a general activation mechanism and provides a new avenue for further mechanistic studies and engineering.
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Affiliation(s)
- Jens Kuhne
- Lehrstuhl für Biophysik, Ruhr Universität Bochum, Universitätsstrasse 150, 44780 Bochum (Germany)
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Kuhne J, Eisenhauer K, Ritter E, Hegemann P, Gerwert K, Bartl F. Die frühe Entstehung der ionenleitenden Pore in Channelrhodopsin-2. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201410180] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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14
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Ernst OP, Lodowski DT, Elstner M, Hegemann P, Brown L, Kandori H. Microbial and animal rhodopsins: structures, functions, and molecular mechanisms. Chem Rev 2014; 114:126-63. [PMID: 24364740 PMCID: PMC3979449 DOI: 10.1021/cr4003769] [Citation(s) in RCA: 759] [Impact Index Per Article: 75.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2013] [Indexed: 12/31/2022]
Affiliation(s)
- Oliver P. Ernst
- Departments
of Biochemistry and Molecular Genetics, University of Toronto, 1 King’s College Circle, Medical Sciences Building, Toronto, Ontario M5S 1A8, Canada
| | - David T. Lodowski
- Center
for Proteomics and Bioinformatics, Case
Western Reserve University School of Medicine, 10900 Euclid Avenue, Cleveland, Ohio 44106, United States
| | - Marcus Elstner
- Institute
for Physical Chemistry, Karlsruhe Institute
of Technology, Kaiserstrasse
12, 76131 Karlsruhe, Germany
| | - Peter Hegemann
- Institute
of Biology, Experimental Biophysics, Humboldt-Universität
zu Berlin, Invalidenstrasse
42, 10115 Berlin, Germany
| | - Leonid
S. Brown
- Department
of Physics and Biophysics Interdepartmental Group, University of Guelph, 50 Stone Road East, Guelph, Ontario N1G 2W1, Canada
| | - Hideki Kandori
- Department
of Frontier Materials, Nagoya Institute
of Technology, Showa-ku, Nagoya 466-8555, Japan
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15
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Yawo H, Asano T, Sakai S, Ishizuka T. Optogenetic manipulation of neural and non-neural functions. Dev Growth Differ 2013; 55:474-90. [PMID: 23550617 DOI: 10.1111/dgd.12053] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Revised: 02/25/2013] [Accepted: 02/26/2013] [Indexed: 01/22/2023]
Abstract
Optogenetic manipulation of the neuronal activity enables one to analyze the neuronal network both in vivo and in vitro with precise spatio-temporal resolution. Channelrhodopsins (ChRs) are light-sensitive cation channels that depolarize the cell membrane, whereas halorhodopsins and archaerhodopsins are light-sensitive Cl(-) and H(+) transporters, respectively, that hyperpolarize it when exogenously expressed. The cause-effect relationship between a neuron and its function in the brain is thus bi-directionally investigated with evidence of necessity and sufficiency. In this review we discuss the potential of optogenetics with a focus on three major requirements for its application: (i) selection of the light-sensitive proteins optimal for optogenetic investigation, (ii) targeted expression of these selected proteins in a specific group of neurons, and (iii) targeted irradiation with high spatiotemporal resolution. We also discuss recent progress in the application of optogenetics to studies of non-neural cells such as glial cells, cardiac and skeletal myocytes. In combination with stem cell technology, optogenetics may be key to successful research using embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) derived from human patients through optical regulation of differentiation-maturation, through optical manipulation of tissue transplants and, furthermore, through facilitating survival and integration of transplants.
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Affiliation(s)
- Hiromu Yawo
- Department of Developmental Biology and Neuroscience, Tohoku University Graduate School of Life Sciences, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan.
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Yawo H, Koizumi A, Hegemann P. Adventure beyond borders of scientific fields with optogenetics. Neurosci Res 2013; 75:1-2. [PMID: 23465316 DOI: 10.1016/j.neures.2013.02.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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