1
|
Oppermann J, Rozenberg A, Fabrin T, González-Cabrera C, Parker R, Béjà O, Prigge M, Hegemann P. Robust optogenetic inhibition with red-light-sensitive anion-conducting channelrhodopsins. eLife 2024; 12:RP90100. [PMID: 39401075 PMCID: PMC11473104 DOI: 10.7554/elife.90100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2024] Open
Abstract
Channelrhodopsins (ChRs) are light-gated ion channels widely used to optically activate or silence selected electrogenic cells, such as individual brain neurons. Here, we describe identifying and characterizing a set of anion-conducting ChRs (ACRs) from diverse taxa and representing various branches of the ChR phylogenetic tree. The Mantoniella squamata ACR (MsACR1) showed high sensitivity to yellow-green light (λmax at 555 nm) and was further engineered for optogenetic applications. A single amino-acid substitution that mimicked red-light-sensitive rhodopsins like Chrimson shifted the photosensitivity 20 nm toward red light and accelerated photocurrent kinetics. Hence, it was named red and accelerated ACR, raACR. Both wild-type and mutant are capable optical silencers at low light intensities in mouse neurons in vitro and in vivo, while raACR offers a higher temporal resolution.
Collapse
Affiliation(s)
- Johannes Oppermann
- Institut für Biologie, Experimentelle Biophysik, Humboldt-Universität zu BerlinBerlinGermany
| | - Andrey Rozenberg
- Faculty of Biology, Technion – Israel Institute of TechnologyHaifaIsrael
| | - Thomaz Fabrin
- Research Group Neuromodulatory Networks, Leibniz Institute for NeurobiologyMagdeburgGermany
| | - Cristian González-Cabrera
- Research Group Neuromodulatory Networks, Leibniz Institute for NeurobiologyMagdeburgGermany
- Aligning Science Across Parkinson's (ASAP) Collaborative Research NetworkChevy ChaseUnited States
| | - Rafael Parker
- Research Group Neuromodulatory Networks, Leibniz Institute for NeurobiologyMagdeburgGermany
- Aligning Science Across Parkinson's (ASAP) Collaborative Research NetworkChevy ChaseUnited States
| | - Oded Béjà
- Faculty of Biology, Technion – Israel Institute of TechnologyHaifaIsrael
| | - Matthias Prigge
- Research Group Neuromodulatory Networks, Leibniz Institute for NeurobiologyMagdeburgGermany
- Aligning Science Across Parkinson's (ASAP) Collaborative Research NetworkChevy ChaseUnited States
- Center for Behavioral Brain Sciences, CBBSMagdeburgGermany
| | - Peter Hegemann
- Institut für Biologie, Experimentelle Biophysik, Humboldt-Universität zu BerlinBerlinGermany
| |
Collapse
|
2
|
Gerhards J, Volkov LI, Corbo JC, Malan D, Sasse P. Enzymatic vitamin A 2 production enables red-shifted optogenetics. Pflugers Arch 2023; 475:1409-1419. [PMID: 37987804 PMCID: PMC10730639 DOI: 10.1007/s00424-023-02880-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 10/20/2023] [Accepted: 11/03/2023] [Indexed: 11/22/2023]
Abstract
Optogenetics is a technology using light-sensitive proteins to control signaling pathways and physiological processes in cells and organs and has been applied in neuroscience, cardiovascular sciences, and many other research fields. Most commonly used optogenetic actuators are sensitive to blue and green light, but red-light activation would allow better tissue penetration and less phototoxicity. Cyp27c1 is a recently deorphanized cytochrome P450 enzyme that converts vitamin A1 to vitamin A2, thereby red-shifting the spectral sensitivity of visual pigments and enabling near-infrared vision in some aquatic species.Here, we investigated the ability of Cyp27c1-generated vitamin A2 to induce a shift in spectral sensitivity of the light-gated ion channel Channelrhodopsin-2 (ChR2) and its red-shifted homolog ReaChR. We used patch clamp to measure photocurrents at specific wavelengths in HEK 293 cells expressing ChR2 or ReaChR. Vitamin A2 incubation red-shifted the wavelength for half-maximal currents (λ50%) by 6.8 nm for ChR2 and 12.4 nm for ReaChR. Overexpression of Cyp27c1 in HEK 293 cells showed mitochondrial localization, and HPLC analysis showed conversion of vitamin A1 to vitamin A2. Notably, the λ50% of ChR2 photocurrents was red-shifted by 10.5 nm, and normalized photocurrents at 550 nm were about twofold larger with Cyp27c1 expression. Similarly, Cyp27c1 shifted the λ50% of ReaChR photocurrents by 14.3 nm and increased normalized photocurrents at 650 nm almost threefold.Since vitamin A2 incubation is not a realistic option for in vivo applications and expression of Cyp27c1 leads to a greater red-shift in spectral sensitivity, we propose co-expression of this enzyme as a novel strategy for red-shifted optogenetics.
Collapse
Affiliation(s)
- Johanna Gerhards
- Institute of Physiology I, Medical Faculty, University of Bonn, 53125, Bonn, Germany
| | - Leo I Volkov
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Joseph C Corbo
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Daniela Malan
- Institute of Physiology I, Medical Faculty, University of Bonn, 53125, Bonn, Germany.
| | - Philipp Sasse
- Institute of Physiology I, Medical Faculty, University of Bonn, 53125, Bonn, Germany.
| |
Collapse
|
3
|
Fernandez Lahore RG, Pampaloni NP, Schiewer E, Heim MM, Tillert L, Vierock J, Oppermann J, Walther J, Schmitz D, Owald D, Plested AJR, Rost BR, Hegemann P. Calcium-permeable channelrhodopsins for the photocontrol of calcium signalling. Nat Commun 2022; 13:7844. [PMID: 36543773 PMCID: PMC9772239 DOI: 10.1038/s41467-022-35373-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 11/29/2022] [Indexed: 12/24/2022] Open
Abstract
Channelrhodopsins are light-gated ion channels used to control excitability of designated cells in large networks with high spatiotemporal resolution. While ChRs selective for H+, Na+, K+ and anions have been discovered or engineered, Ca2+-selective ChRs have not been reported to date. Here, we analyse ChRs and mutant derivatives with regard to their Ca2+ permeability and improve their Ca2+ affinity by targeted mutagenesis at the central selectivity filter. The engineered channels, termed CapChR1 and CapChR2 for calcium-permeable channelrhodopsins, exhibit reduced sodium and proton conductance in connection with strongly improved Ca2+ permeation at negative voltage and low extracellular Ca2+ concentrations. In cultured cells and neurons, CapChR2 reliably increases intracellular Ca2+ concentrations. Moreover, CapChR2 can robustly trigger Ca2+ signalling in hippocampal neurons. When expressed together with genetically encoded Ca2+ indicators in Drosophila melanogaster mushroom body output neurons, CapChRs mediate light-evoked Ca2+ entry in brain explants.
Collapse
Affiliation(s)
| | - Niccolò P Pampaloni
- Molecular Neuroscience and Biophysics, Leibniz-Institut für Molekulare Pharmakologie, Berlin, Germany
- Institute of Biology, Cellular Biophysics, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Enrico Schiewer
- Institute of Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Berlin, Germany
| | - M-Marcel Heim
- Institute of Neurophysiology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Linda Tillert
- Institute of Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Berlin, Germany
- Neuroscience Research Center, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Johannes Vierock
- Institute of Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Berlin, Germany
- Neuroscience Research Center, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Johannes Oppermann
- Institute of Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Jakob Walther
- Department of Neurology with Experimental Neurology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Dietmar Schmitz
- Neuroscience Research Center, Charité - Universitätsmedizin Berlin, Berlin, Germany
- German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany
| | - David Owald
- Institute of Neurophysiology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Andrew J R Plested
- Molecular Neuroscience and Biophysics, Leibniz-Institut für Molekulare Pharmakologie, Berlin, Germany
- Institute of Biology, Cellular Biophysics, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Benjamin R Rost
- German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany
| | - Peter Hegemann
- Institute of Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Berlin, Germany
| |
Collapse
|
4
|
QuasAr Odyssey: the origin of fluorescence and its voltage sensitivity in microbial rhodopsins. Nat Commun 2022; 13:5501. [PMID: 36127376 PMCID: PMC9489792 DOI: 10.1038/s41467-022-33084-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 08/26/2022] [Indexed: 11/29/2022] Open
Abstract
Rhodopsins had long been considered non-fluorescent until a peculiar voltage-sensitive fluorescence was reported for archaerhodopsin-3 (Arch3) derivatives. These proteins named QuasArs have been used for imaging membrane voltage changes in cell cultures and small animals. However due to the low fluorescence intensity, these constructs require use of much higher light intensity than other optogenetic tools. To develop the next generation of sensors, it is indispensable to first understand the molecular basis of the fluorescence and its modulation by the membrane voltage. Based on spectroscopic studies of fluorescent Arch3 derivatives, we propose a unique photo-reaction scheme with extended excited-state lifetimes and inefficient photoisomerization. Molecular dynamics simulations of Arch3, of the Arch3 fluorescent derivative Archon1, and of several its mutants have revealed different voltage-dependent changes of the hydrogen-bonding networks including the protonated retinal Schiff-base and adjacent residues. Experimental observations suggest that under negative voltage, these changes modulate retinal Schiff base deprotonation and promote a decrease in the populations of fluorescent species. Finally, we identified molecular constraints that further improve fluorescence quantum yield and voltage sensitivity. The authors present an in-depth investigation of excited state dynamics and molecular mechanism of the voltage sensing in microbial rhodopsins. Using a combination of spectroscopic investigations and molecular dynamics simulations, the study proposes the voltage-modulated deprotonation of the chromophore as the key event in the voltage sensing. Thus, molecular constraints that may further improve the fluorescence quantum yield and the voltage sensitivity are presented.
Collapse
|
5
|
Zhou Y, Ding M, Nagel G, Konrad KR, Gao S. Advances and prospects of rhodopsin-based optogenetics in plant research. PLANT PHYSIOLOGY 2021; 187:572-589. [PMID: 35237820 PMCID: PMC8491038 DOI: 10.1093/plphys/kiab338] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 07/05/2021] [Indexed: 05/20/2023]
Abstract
Microbial rhodopsins have advanced optogenetics since the discovery of channelrhodopsins almost two decades ago. During this time an abundance of microbial rhodopsins has been discovered, engineered, and improved for studies in neuroscience and other animal research fields. Optogenetic applications in plant research, however, lagged largely behind. Starting with light-regulated gene expression, optogenetics has slowly expanded into plant research. The recently established all-trans retinal production in plants now enables the use of many microbial opsins, bringing extra opportunities to plant research. In this review, we summarize the recent advances of rhodopsin-based plant optogenetics and provide a perspective for future use, combined with fluorescent sensors to monitor physiological parameters.
Collapse
Affiliation(s)
- Yang Zhou
- Institute of Physiology, Department of Neurophysiology, Biocenter, University of Wuerzburg, Wuerzburg 97070, Germany
| | - Meiqi Ding
- Institute for Molecular Plant Physiology and Biophysics, Julius-von-Sachs-Institute, Biocenter, University of Wuerzburg, Wuerzburg 97082, Germany
| | - Georg Nagel
- Institute of Physiology, Department of Neurophysiology, Biocenter, University of Wuerzburg, Wuerzburg 97070, Germany
| | - Kai R. Konrad
- Institute for Molecular Plant Physiology and Biophysics, Julius-von-Sachs-Institute, Biocenter, University of Wuerzburg, Wuerzburg 97082, Germany
| | - Shiqiang Gao
- Institute of Physiology, Department of Neurophysiology, Biocenter, University of Wuerzburg, Wuerzburg 97070, Germany
| |
Collapse
|
6
|
Kaufmann JCD, Krause BS, Adam S, Ritter E, Schapiro I, Hegemann P, Bartl FJ. Modulation of Light Energy Transfer from Chromophore to Protein in the Channelrhodopsin ReaChR. Biophys J 2020; 119:705-716. [PMID: 32697975 DOI: 10.1016/j.bpj.2020.06.031] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 06/10/2020] [Accepted: 06/26/2020] [Indexed: 10/23/2022] Open
Abstract
The function of photoreceptors relies on efficient transfer of absorbed light energy from the chromophore to the protein to drive conformational changes that ultimately generate an output signal. In retinal-binding proteins, mainly two mechanisms exist to store the photon energy after photoisomerization: 1) conformational distortion of the prosthetic group retinal, and 2) charge separation between the protonated retinal Schiff base (RSBH+) and its counterion complex. Accordingly, energy transfer to the protein is achieved by chromophore relaxation and/or reduction of the charge separation in the RSBH+-counterion complex. Combining FTIR and UV-Vis spectroscopy along with molecular dynamics simulations, we show here for the widely used, red-activatable Volvox carteri channelrhodopsin-1 derivate ReaChR that energy storage and transfer into the protein depends on the protonation state of glutamic acid E163 (Ci1), one of the counterions of the RSBH+. Ci1 retains a pKa of 7.6 so that both its protonated and deprotonated forms equilibrate at physiological conditions. Protonation of Ci1 leads to a rigid hydrogen-bonding network in the active-site region. This stabilizes the distorted conformation of the retinal after photoactivation and decelerates energy transfer into the protein by impairing the release of the strain energy. In contrast, with deprotonated Ci1 or removal of the Ci1 glutamate side chain, the hydrogen-bonded system is less rigid, and energy transfer by chromophore relaxation is accelerated. Based on the hydrogen out-of-plane (HOOP) band decay kinetics, we determined the activation energy for these processes in dependence of the Ci1 protonation state.
Collapse
Affiliation(s)
- Joel C D Kaufmann
- Institut für Biologie, Biophysikalische Chemie, Humboldt-Universität zu Berlin, Berlin, Germany; Institut für Medizinische Physik und Biophysik, Charité Berlin, Berlin, Germany
| | - Benjamin S Krause
- Institut für Biologie, Experimentelle Biophysik, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Suliman Adam
- Fritz Haber Center for Molecular Dynamics Research at the Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Eglof Ritter
- Institut für Biologie, Biophysikalische Chemie, Humboldt-Universität zu Berlin, Berlin, Germany; Institut für Biologie, Experimentelle Biophysik, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Igor Schapiro
- Fritz Haber Center for Molecular Dynamics Research at the Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Peter Hegemann
- Institut für Biologie, Experimentelle Biophysik, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Franz J Bartl
- Institut für Biologie, Biophysikalische Chemie, Humboldt-Universität zu Berlin, Berlin, Germany.
| |
Collapse
|
7
|
Oppermann J, Fischer P, Silapetere A, Liepe B, Rodriguez-Rozada S, Flores-Uribe J, Schiewer E, Keidel A, Vierock J, Kaufmann J, Broser M, Luck M, Bartl F, Hildebrandt P, Wiegert JS, Béjà O, Hegemann P, Wietek J. MerMAIDs: a family of metagenomically discovered marine anion-conducting and intensely desensitizing channelrhodopsins. Nat Commun 2019; 10:3315. [PMID: 31346176 PMCID: PMC6658528 DOI: 10.1038/s41467-019-11322-6] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 06/24/2019] [Indexed: 01/07/2023] Open
Abstract
Channelrhodopsins (ChRs) are algal light-gated ion channels widely used as optogenetic tools for manipulating neuronal activity. ChRs desensitize under continuous bright-light illumination, resulting in a significant decline of photocurrents. Here we describe a metagenomically identified family of phylogenetically distinct anion-conducting ChRs (designated MerMAIDs). MerMAIDs almost completely desensitize during continuous illumination due to accumulation of a late non-conducting photointermediate that disrupts the ion permeation pathway. MerMAID desensitization can be fully explained by a single photocycle in which a long-lived desensitized state follows the short-lived conducting state. A conserved cysteine is the critical factor in desensitization, as its mutation results in recovery of large stationary photocurrents. The rapid desensitization of MerMAIDs enables their use as optogenetic silencers for transient suppression of individual action potentials without affecting subsequent spiking during continuous illumination. Our results could facilitate the development of optogenetic tools from metagenomic databases and enhance general understanding of ChR function.
Collapse
Affiliation(s)
- Johannes Oppermann
- Institute for Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115, Berlin, Germany
| | - Paul Fischer
- Institute for Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115, Berlin, Germany
| | - Arita Silapetere
- Institute for Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115, Berlin, Germany
| | - Bernhard Liepe
- Institute for Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115, Berlin, Germany
| | - Silvia Rodriguez-Rozada
- Research Group Synaptic Wiring and Information Processing, Center for Molecular Neurobiology Hamburg, Falkenried 94, 20251, Hamburg, Germany
| | - José Flores-Uribe
- Technion-Israel Institute of Technology, 32000, Haifa, Israel
- Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, Cologne, 50829, Germany
| | - Enrico Schiewer
- Institute for Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115, Berlin, Germany
| | - Anke Keidel
- Institute for Chemistry, Physical Chemistry/Biophysical Chemistry, Technische Universität Berlin, Straße des 17. Juni 135, 10623, Berlin, Germany
| | - Johannes Vierock
- Institute for Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115, Berlin, Germany
| | - Joel Kaufmann
- Institute for Biology, Biophysical Chemistry, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115, Berlin, Germany
| | - Matthias Broser
- Institute for Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115, Berlin, Germany
| | - Meike Luck
- Institute for Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115, Berlin, Germany
| | - Franz Bartl
- Institute for Biology, Biophysical Chemistry, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115, Berlin, Germany
| | - Peter Hildebrandt
- Institute for Chemistry, Physical Chemistry/Biophysical Chemistry, Technische Universität Berlin, Straße des 17. Juni 135, 10623, Berlin, Germany
| | - J Simon Wiegert
- Research Group Synaptic Wiring and Information Processing, Center for Molecular Neurobiology Hamburg, Falkenried 94, 20251, Hamburg, Germany
| | - Oded Béjà
- Technion-Israel Institute of Technology, 32000, Haifa, Israel
| | - Peter Hegemann
- Institute for Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115, Berlin, Germany.
| | - Jonas Wietek
- Institute for Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115, Berlin, Germany.
- Department of Neurobiology, Weizmann Institute of Science, 7610001, Rehovot, Israel.
| |
Collapse
|
8
|
Structural basis for ion selectivity and engineering in channelrhodopsins. Curr Opin Struct Biol 2019; 57:176-184. [PMID: 31174050 DOI: 10.1016/j.sbi.2019.04.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 04/24/2019] [Accepted: 04/25/2019] [Indexed: 01/03/2023]
Abstract
Channelrhodopsins have become an integral part of modern neuroscience approaches due to their ability to control neuronal activity in targeted cell populations. The recent determination of several channelrhodopsin X-ray structures now enables us to study their function with unprecedented molecular precision. We will discuss how these insights can guide the engineering of the ion conducting pathway to increase its selectivity for Cl-, Ca2+, and K+ ions and improve the overall conductance. Engineering such channelrhodopsins would further increase their utility in neuroscience research and beyond by controlling a wider range of physiological events. To thoroughly address this issue, we compare channelrhodopsin structures with structural features of voltage and ligand-gated K+, Cl- and Ca2+ channels and discuss how these could be implemented in channelrhodopsins.
Collapse
|
9
|
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.
Collapse
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.
| |
Collapse
|
10
|
Krause BS, Kaufmann JCD, Kuhne J, Vierock J, Huber T, Sakmar TP, Gerwert K, Bartl FJ, Hegemann P. Tracking Pore Hydration in Channelrhodopsin by Site-Directed Infrared-Active Azido Probes. Biochemistry 2019; 58:1275-1286. [DOI: 10.1021/acs.biochem.8b01211] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Benjamin S. Krause
- Institut für Biologie, Experimentelle Biophysik, Humboldt-Universität zu Berlin, Invalidenstrasse 42, 10115 Berlin, Germany
| | - Joel C. D. Kaufmann
- Institut für Biologie, Biophysikalische Chemie, Humboldt-Universität zu Berlin, Invalidenstrasse 42, 10115 Berlin, Germany
- Institut für medizinische Physik und Biophysik, Charité-Universitätsmedizin, Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Jens Kuhne
- Lehrstuhl für Biophysik, Ruhr-Universität Bochum, Universitätsstrasse 150, 44801 Bochum, Germany
| | - Johannes Vierock
- Institut für Biologie, Experimentelle Biophysik, Humboldt-Universität zu Berlin, Invalidenstrasse 42, 10115 Berlin, Germany
| | - Thomas Huber
- Laboratory of Chemical Biology & Signal Transduction, The Rockefeller University, 1230 York Avenue, New York, New York 10065, United States
| | - Thomas P. Sakmar
- Laboratory of Chemical Biology & Signal Transduction, The Rockefeller University, 1230 York Avenue, New York, New York 10065, United States
- Department of Neurobiology, Care Sciences and Society, Division for Neurogeriatrics, Center for Alzheimer Research, Karolinska Institutet, Alfred Nobels Allé 23, 141 57 Huddinge, Sweden
| | - Klaus Gerwert
- Lehrstuhl für Biophysik, Ruhr-Universität Bochum, Universitätsstrasse 150, 44801 Bochum, Germany
| | - Franz J. Bartl
- Institut für Biologie, Biophysikalische Chemie, Humboldt-Universität zu Berlin, Invalidenstrasse 42, 10115 Berlin, Germany
- Institut für medizinische Physik und Biophysik, Charité-Universitätsmedizin, Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Peter Hegemann
- Institut für Biologie, Experimentelle Biophysik, Humboldt-Universität zu Berlin, Invalidenstrasse 42, 10115 Berlin, Germany
| |
Collapse
|
11
|
Inoue K, Tahara S, Kato Y, Takeuchi S, Tahara T, Kandori H. Spectroscopic Study of Proton-Transfer Mechanism of Inward Proton-Pump Rhodopsin, Parvularcula oceani Xenorhodopsin. J Phys Chem B 2018; 122:6453-6461. [DOI: 10.1021/acs.jpcb.8b01279] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Keiichi Inoue
- PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Shinya Tahara
- Molecular Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako 351-0198, Japan
| | | | - Satoshi Takeuchi
- Molecular Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako 351-0198, Japan
- Ultrafast Spectroscopy Research Team, RIKEN Center for Advanced Photonics (RAP), RIKEN, 2-1 Hirosawa, Wako 351-0198, Japan
| | - Tahei Tahara
- Molecular Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako 351-0198, Japan
- Ultrafast Spectroscopy Research Team, RIKEN Center for Advanced Photonics (RAP), RIKEN, 2-1 Hirosawa, Wako 351-0198, Japan
| | | |
Collapse
|
12
|
Wietek J, Rodriguez-Rozada S, Tutas J, Tenedini F, Grimm C, Oertner TG, Soba P, Hegemann P, Wiegert JS. Anion-conducting channelrhodopsins with tuned spectra and modified kinetics engineered for optogenetic manipulation of behavior. Sci Rep 2017; 7:14957. [PMID: 29097684 PMCID: PMC5668261 DOI: 10.1038/s41598-017-14330-y] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 10/09/2017] [Indexed: 12/20/2022] Open
Abstract
Genetic engineering of natural light-gated ion channels has proven a powerful way to generate optogenetic tools for a wide variety of applications. In recent years, blue-light activated engineered anion-conducting channelrhodopsins (eACRs) have been developed, improved, and were successfully applied in vivo. We asked whether the approaches used to create eACRs can be transferred to other well-characterized cation-conducting channelrhodopsins (CCRs) to obtain eACRs with a broad spectrum of biophysical properties. We generated 22 variants using two conversion strategies applied to 11 CCRs and screened them for membrane expression, photocurrents and anion selectivity. We obtained two novel eACRs, Phobos and Aurora, with blue- and red-shifted action spectra and photocurrents similar to existing eACRs. Furthermore, step-function mutations greatly enhanced the cellular operational light sensitivity due to a slowed-down photocycle. These bi-stable eACRs can be reversibly toggled between open and closed states with brief light pulses of different wavelengths. All new eACRs reliably inhibited action potential firing in pyramidal CA1 neurons. In Drosophila larvae, eACRs conveyed robust and specific light-dependent inhibition of locomotion and nociception.
Collapse
Affiliation(s)
- Jonas Wietek
- Institute for Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115, Berlin, Germany
| | - Silvia Rodriguez-Rozada
- Research Group Synaptic Wiring and Information Processing, Center for Molecular Neurobiology Hamburg, Falkenried 94, 20251, Hamburg, Germany
| | - Janine Tutas
- Research Group Neuronal Patterning and Connectivity, Center for Molecular Neurobiology Hamburg, Falkenried 94, 20251, Hamburg, Germany
| | - Federico Tenedini
- Research Group Neuronal Patterning and Connectivity, Center for Molecular Neurobiology Hamburg, Falkenried 94, 20251, Hamburg, Germany
| | - Christiane Grimm
- Institute for Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115, Berlin, Germany
| | - Thomas G Oertner
- Institute for Synaptic Physiology, Center for Molecular Neurobiology Hamburg, Falkenried 94, 20251, Hamburg, Germany
| | - Peter Soba
- Research Group Neuronal Patterning and Connectivity, Center for Molecular Neurobiology Hamburg, Falkenried 94, 20251, Hamburg, Germany
| | - Peter Hegemann
- Institute for Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Invalidenstraße 42, 10115, Berlin, Germany
| | - J Simon Wiegert
- Institute for Synaptic Physiology, Center for Molecular Neurobiology Hamburg, Falkenried 94, 20251, Hamburg, Germany.
- Research Group Synaptic Wiring and Information Processing, Center for Molecular Neurobiology Hamburg, Falkenried 94, 20251, Hamburg, Germany.
| |
Collapse
|
13
|
Kaufmann JCD, Krause BS, Grimm C, Ritter E, Hegemann P, Bartl FJ. Proton transfer reactions in the red light-activatable channelrhodopsin variant ReaChR and their relevance for its function. J Biol Chem 2017; 292:14205-14216. [PMID: 28659342 PMCID: PMC5572910 DOI: 10.1074/jbc.m117.779629] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 06/27/2017] [Indexed: 11/06/2022] Open
Abstract
Channelrhodopsins (ChRs) are light-gated ion channels widely used for activating selected cells in large cellular networks. ChR variants with a red-shifted absorption maximum, such as the modified Volvox carteri ChR1 red-activatable channelrhodopsin ("ReaChR," λmax = 527 nm), are of particular interest because longer wavelengths allow optical excitation of cells in deeper layers of organic tissue. In all ChRs investigated so far, proton transfer reactions and hydrogen bond changes are crucial for the formation of the ion-conducting pore and the selectivity for protons versus cations, such as Na+, K+, and Ca2+ (1). By using a combination of electrophysiological measurements and UV-visible and FTIR spectroscopy, we characterized the proton transfer events in the photocycle of ReaChR and describe their relevance for its function. 1) The central gate residue Glu130 (Glu90 in Chlamydomonas reinhardtii (Cr) ChR2) (i) undergoes a hydrogen bond change in D → K transition and (ii) deprotonates in K → M transition. Its negative charge in the open state is decisive for proton selectivity. 2) The counter-ion Asp293 (Asp253 in CrChR2) receives the retinal Schiff base proton during M-state formation. Starting from M, a photocycle branching occurs involving (i) a direct M → D transition and (ii) formation of late photointermediates N and O. 3) The DC pair residue Asp196 (Asp156 in CrChR2) deprotonates in N → O transition. Interestingly, the D196N mutation increases 15-syn-retinal at the expense of 15-anti, which is the predominant isomer in the wild type, and abolishes the peak current in electrophysiological measurements. This suggests that the peak current is formed by 15-anti species, whereas 15-syn species contribute only to the stationary current.
Collapse
Affiliation(s)
- Joel C D Kaufmann
- From the Institut für medizinische Physik und Biophysik, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany,.
| | | | | | | | | | - Franz J Bartl
- From the Institut für medizinische Physik und Biophysik, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany,; Institut für Biologie, Biophysikalische Chemie, Humboldt-Universität zu Berlin, Invalidenstrasse 42, 10115 Berlin, Germany.
| |
Collapse
|