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Vlasova A, Polyakova A, Gromova A, Dolotova S, Bukhalovich S, Bagaeva D, Bondarev N, Tsybrov F, Kovalev K, Mikhailov A, Sidorov D, Bogorodskiy A, Ilyinsky N, Kuklin A, Vlasov A, Borshchevskiy V, Ivanovich V. Optogenetic cytosol acidification of mammalian cells using an inward proton-pumping rhodopsin. Int J Biol Macromol 2023:124949. [PMID: 37224908 DOI: 10.1016/j.ijbiomac.2023.124949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 05/14/2023] [Accepted: 05/15/2023] [Indexed: 05/26/2023]
Abstract
Ion gradients are a universal form of energy, information storage and conversion in living cells. Advances in optogenetics inspire the development of novel tools towards control of different cellular processes with light. Rhodopsins are perspective tools for optogenetic manipulation of ion gradients in cells and subcellular compartments, controlling pH of the cytosol and intracellular organelles. The key step of the development of new optogenetic tools is evaluation of their efficiency. Here, we used a high-throughput quantitative method for comparing efficiency of proton-pumping rhodopsins in Escherichia coli cells. This approach allowed us to show that an inward proton pump xenorhodopsin from Nanosalina sp. (NsXeR) is a powerful tool for optogenetic control of pH of mammalian subcellular compartments. Further, we demonstrate that NsXeR can be used for fast optogenetic acidification of the cytosol of mammalian cells. This is the first evidence of optogenetic cytosol acidification by an inward proton pump at physiological pH values. Our approach offers unique opportunities to study cellular metabolism at normal and pathological conditions and might help to understand the role of pH dysregulation in cellular dysfunctions.
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Affiliation(s)
- A Vlasova
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - A Polyakova
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - A Gromova
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - S Dolotova
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia; Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, Moscow, Russia
| | - S Bukhalovich
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - D Bagaeva
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - N Bondarev
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - F Tsybrov
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - K Kovalev
- European Molecular Biology Laboratory, Hamburg, Germany
| | - A Mikhailov
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - D Sidorov
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - A Bogorodskiy
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - N Ilyinsky
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - A Kuklin
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia; Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna, Russia
| | - A Vlasov
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia; Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna, Russia
| | - V Borshchevskiy
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia; Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna, Russia.
| | - V Ivanovich
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia.
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Westermann M, Hoischen C, Wöhlbrand L, Rabus R, Rhiel E. Light and prey influence the abundances of two rhodopsins in the dinoflagellate Oxyrrhis marina. Protoplasma 2023; 260:529-544. [PMID: 35871098 PMCID: PMC9931815 DOI: 10.1007/s00709-022-01795-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Accepted: 07/14/2022] [Indexed: 06/15/2023]
Abstract
Antisera were raised against the C-terminal amino acid sequences of the two rhodopsins ADY17806 and AEA49880 of Oxyrrhis marina. The antisera and affinity-purified antibodies thereof were used in western immunoblotting experiments of total cell protein fractions from cultures grown either in darkness or in white, red, green, or blue light. Furthermore, the rhodopsin abundances were profiled in cultures fed with yeast or the prasinophyte Pyramimonas grossii. The immunosignals of ADY17806 and AEA49880 were similar when O. marina was grown in white, green, or blue light. Signal intensities were lower under conditions of red light and lowest in darkness. Higher amounts were registered for both rhodopsins when O. marina was fed with yeast compared to P. grossii. Furthermore, total cell protein of cultures of O. marina grown under all cultivation conditions was separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis, followed by tryptic in-gel digestion and mass spectrometric analysis of the 25-kDa protein bands. The rhodopsin ADY17809 was detected in all samples of the light quality experiments and in 14 of the 16 samples of the prey quality experiments. The rhodopsin ABV22427 was not detected in one sample of the light quality experiments. It was detected in 15 of the 16 samples of the prey quality experiments. Peptide fragments of the other rhodopsins were detected less often, and no clear distribution pattern was evident with respect to the applied light quality or offered prey, indicating that none of them was exclusively formed under a distinct light regime or when feeding on yeast or the prasinophyte. Fluorescence light microscopy using the affinity-purified antibodies revealed significant labeling of the cell periphery and cell internal structures, which resembled vacuoles, tiny vesicles, and rather compact structures. Immunolabeling electron microscopy strengthened these results and showed that the cytoplasmic membrane, putative lysosome membranes, membranes encircling the food vacuole, and birefringent bodies became labeled.
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Affiliation(s)
- Martin Westermann
- Electron Microscopy Center of the Jena University Hospital, Friedrich-Schiller-University Jena, Ziegelmühlenweg 1, 07743, Jena, Germany
| | - Christian Hoischen
- CF Imaging, Leibniz Institute On Aging, Fritz-Lipmann-Institute (FLI), Beutenbergstraße 11, 07745, Jena, Germany
| | - Lars Wöhlbrand
- General and Molecular Microbiology, Institute for Chemistry and Biology of the Marine Environment, Carl Von Ossietzky University Oldenburg, P.O.B. 2503, 26129, Oldenburg, Germany
| | - Ralf Rabus
- General and Molecular Microbiology, Institute for Chemistry and Biology of the Marine Environment, Carl Von Ossietzky University Oldenburg, P.O.B. 2503, 26129, Oldenburg, Germany
| | - Erhard Rhiel
- Plankton Ecology, Institute for Chemistry and Biology of the Marine Environment, Carl Von Ossietzky University Oldenburg, P.O.B. 2503, 26129, Oldenburg, Germany.
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3
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Rhiel E, Hoischen C, Westermann M. Rhodopsins build up the birefringent bodies of the dinoflagellate Oxyrrhis marina. Protoplasma 2022; 259:1047-1060. [PMID: 34738175 PMCID: PMC9184458 DOI: 10.1007/s00709-021-01717-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 10/14/2021] [Indexed: 06/13/2023]
Abstract
The ultrastructure of the birefringent bodies of the dinoflagellate Oxyrrhis marina was investigated by transmission electron microscopy. Ultrathin sectioning revealed that the bodies consist of highly ordered and densely packed lamellae, which show a regular striation along their longitudinal axis. A lattice distance of 6.1 nm was measured for the densely packed lamellae by FFT (Fast Fourier Transformation) analysis. In addition, a rather faint and oblique running striation was registered. Lamellae sectioned rather oblique or almost close to the surface show a honeycombed structure with a periodicity of 7.2-7.8 nm. Freeze-fracture transmission electron microscopy revealed that the lamellae are composed of highly ordered, crystalline arrays of particles. Here, FFT analysis resulted in lattice distances of 7.0-7.6 nm. Freeze-fracture transmission electron microscopy further revealed that the bodies remained intact after cell rupture followed by ascending flotation of the membrane fractions on discontinuous sucrose gradients. The birefringent bodies most likely are formed by evaginations of membranes, which separate the cytoplasm from the food vacuoles. Distinct, slightly reddish-colored areas, which resembled the birefringent bodies with respect to size and morphology, were registered by bright field light microscopy within Oxyrrhis marina cells. An absorbance maximum at 540 nm was registered for these areas, indicating that they are composed of rhodopsins. This was finally proven by immuno-transmission electron microscopy, as antisera directed against the C-terminal amino acid sequences of the rhodopsins AEA49880 and ADY17806 intensely immunolabeled the birefringent bodies of Oxyrrhis marina.
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Affiliation(s)
- Erhard Rhiel
- Plankton Ecology, Institute for Chemistry and Biology of the Marine Environment, Carl Von Ossietzky University Oldenburg, Carl-von-Ossietzky-Straße 9-11, D-26129, Oldenburg, Germany.
| | - Christian Hoischen
- CF Imaging, Leibniz Institute On Aging, Fritz-Lipmann-Institute (FLI), Beutenbergstraße 11, D-07745, Jena, Germany
| | - Martin Westermann
- Electron Microscopy Center at the Jena University Hospital, Friedrich-Schiller-University Jena, Ziegelmühlenweg 1, D-07743, Jena, Germany
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4
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Pedraza-González L, Barneschi L, Padula D, De Vico L, Olivucci M. Evolution of the Automatic Rhodopsin Modeling (ARM) Protocol. Top Curr Chem (Cham) 2022; 380:21. [PMID: 35291019 PMCID: PMC8924150 DOI: 10.1007/s41061-022-00374-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 01/29/2022] [Indexed: 10/27/2022]
Abstract
In recent years, photoactive proteins such as rhodopsins have become a common target for cutting-edge research in the field of optogenetics. Alongside wet-lab research, computational methods are also developing rapidly to provide the necessary tools to analyze and rationalize experimental results and, most of all, drive the design of novel systems. The Automatic Rhodopsin Modeling (ARM) protocol is focused on providing exactly the necessary computational tools to study rhodopsins, those being either natural or resulting from mutations. The code has evolved along the years to finally provide results that are reproducible by any user, accurate and reliable so as to replicate experimental trends. Furthermore, the code is efficient in terms of necessary computing resources and time, and scalable in terms of both number of concurrent calculations as well as features. In this review, we will show how the code underlying ARM achieved each of these properties.
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Affiliation(s)
- Laura Pedraza-González
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, Via Aldo Moro 2, 53100, Siena, Italy. .,Department of Chemistry and Industrial Chemistry, University of Pisa, Via Moruzzi 13, 56124, Pisa, Italy.
| | - Leonardo Barneschi
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, Via Aldo Moro 2, 53100, Siena, Italy
| | - Daniele Padula
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, Via Aldo Moro 2, 53100, Siena, Italy
| | - Luca De Vico
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, Via Aldo Moro 2, 53100, Siena, Italy.
| | - Massimo Olivucci
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università degli Studi di Siena, Via Aldo Moro 2, 53100, Siena, Italy. .,Department of Chemistry, Bowling Green State University, Bowling Green, OH, 43403, USA.
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5
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Rokitskaya TI, Maliar NL, Siletsky SA, Gordeliy V, Antonenko YN. Electrophysiological Characterization of Microbial Rhodopsin Transport Properties: Electrometric and ΔpH Measurements Using Planar Lipid Bilayer, Collodion Film, and Fluorescent Probe Approaches. Methods Mol Biol 2022; 2501:259-275. [PMID: 35857232 DOI: 10.1007/978-1-0716-2329-9_12] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Electrophysiological approaches to the study of the activity of retinal-containing protein bacteriorhodopsin (bR) or other proteins of this family are based usually on measurements of electrical current through a planar bilayer lipid membrane (BLM) with proteoliposomes attached to the BLM surface at one side of the membrane. Here, we describe the measurements of the pumping activity of bR and channelrhodopsin 2 (ChR2) with special attention to the study of voltage dependence of the light-induced currents. Strong voltage dependence of ChR2 suggests light-triggered ion channel activity of ChR2. We also describe electrophysiological measurements with the help of collodion film instead of BLM for the measurements of fast stages of a rhodopsin photocycle as well as the estimation of the activity of proteoliposomes without a macro membrane using fluorescent probes such as oxonol VI or 9-aminoacridine.
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Affiliation(s)
- Tatyana I Rokitskaya
- Department of Bioenergetics, Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Nina L Maliar
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology (National Research University), Dolgoprudny, Russia
| | - Sergey A Siletsky
- Department of Molecular Energetics of Microorganisms, Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Valentin Gordeliy
- Institut de Biologie Structurale (IBS), Université Grenoble Alpes, CEA, CNRS, Grenoble, France
| | - Yuri N Antonenko
- Department of Bioenergetics, Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia.
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Munro RA, de Vlugt J, Ward ME, Kim SY, Lee KA, Jung KH, Ladizhansky V, Brown LS. Biosynthetic production of fully carbon-13 labeled retinal in E. coli for structural and functional studies of rhodopsins. J Biomol NMR 2019; 73:49-58. [PMID: 30719609 DOI: 10.1007/s10858-019-00225-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2018] [Accepted: 01/16/2019] [Indexed: 06/09/2023]
Abstract
The isomerization of a covalently bound retinal is an integral part of both microbial and animal rhodopsin function. As such, detailed structure and conformational changes in the retinal binding pocket are of significant interest and are studied in various NMR, FTIR, and Raman spectroscopy experiments, which commonly require isotopic labeling of retinal. Unfortunately, the de novo organic synthesis of an isotopically-labeled retinal is complex and often cost-prohibitive, especially for large scale expression required for solid-state NMR. We present the novel protocol for biosynthetic production of an isotopically labeled retinal ligand concurrently with an apoprotein in E. coli as a cost-effective alternative to the de novo organic synthesis. Previously, the biosynthesis of a retinal precursor, β-carotene, has been introduced into many different organisms. We extended this system to the prototrophic E. coli expression strain BL21 in conjunction with the inducible expression of a β-dioxygenase and proteo-opsin. To demonstrate the applicability of this system, we were able to assign several new carbon resonances for proteorhodopsin-bound retinal by using fully 13C-labeled glucose as the sole carbon source. Furthermore, we demonstrated that this biosynthetically produced retinal can be extracted from E. coli cells by applying a hydrophobic solvent layer to the growth medium and reconstituted into an externally produced opsin of any desired labeling pattern.
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Affiliation(s)
- Rachel A Munro
- Departments of Physics, and Biophysics Interdepartmental Group, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada
| | - Jeffrey de Vlugt
- Departments of Physics, and Biophysics Interdepartmental Group, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada
| | - Meaghan E Ward
- Departments of Physics, and Biophysics Interdepartmental Group, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada
| | - So Young Kim
- Deptartment of Life Science, Institute of Biological Interfaces, Sogang University, Shinsu-Dong 1, Mapo-Gu, Seoul, 121-742, Republic of Korea
- Division of Biotechnology, College of Environmental & Bioresource Sciences, Chonbuk National University, Jeonju, Republic of Korea
| | - Keon Ah Lee
- Deptartment of Life Science, Institute of Biological Interfaces, Sogang University, Shinsu-Dong 1, Mapo-Gu, Seoul, 121-742, Republic of Korea
| | - Kwang-Hwan Jung
- Deptartment of Life Science, Institute of Biological Interfaces, Sogang University, Shinsu-Dong 1, Mapo-Gu, Seoul, 121-742, Republic of Korea
| | - Vladimir Ladizhansky
- Departments of Physics, and Biophysics Interdepartmental Group, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada
| | - Leonid S Brown
- Departments of Physics, and Biophysics Interdepartmental Group, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada.
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Senthilan PR, Grebler R, Reinhard N, Rieger D, Helfrich-Förster C. Role of Rhodopsins as Circadian Photoreceptors in the Drosophila melanogaster. Biology (Basel) 2019; 8:biology8010006. [PMID: 30634679 PMCID: PMC6466219 DOI: 10.3390/biology8010006] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 12/14/2018] [Accepted: 01/04/2019] [Indexed: 12/19/2022]
Abstract
Light profoundly affects the circadian clock and the activity levels of animals. Along with the systematic changes in intensity and spectral composition, over the 24-h day, light shows considerable irregular fluctuations (noise). Using light as the Zeitgeber for the circadian clock is, therefore, a complex task and this might explain why animals utilize multiple photoreceptors to entrain their circadian clock. The fruit fly Drosophila melanogaster possesses light-sensitive Cryptochrome and seven Rhodopsins that all contribute to light detection. We review the role of Rhodopsins in circadian entrainment, and of direct light-effects on the activity, with a special emphasis on the newly discovered Rhodopsin 7 (Rh7). We present evidence that Rhodopsin 6 in receptor cells 8 of the compound eyes, as well as in the extra retinal Hofbauer-Buchner eyelets, plays a major role in entraining the fly’s circadian clock with an appropriate phase-to-light–dark cycles. We discuss recent contradictory findings regarding Rhodopsin 7 and report original data that support its role in the compound eyes and in the brain. While Rhodopsin 7 in the brain appears to have a minor role in entrainment, in the compound eyes it seems crucial for fine-tuning light sensitivity to prevent overshooting responses to bright light.
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Affiliation(s)
- Pingkalai R Senthilan
- Neurobiology & Genetics, Theodor-Boveri Institute, Biocenter, Julius-Maximilians University Würzburg, Am Hubland, 97074 Würzburg, Germany.
| | - Rudi Grebler
- Neurobiology & Genetics, Theodor-Boveri Institute, Biocenter, Julius-Maximilians University Würzburg, Am Hubland, 97074 Würzburg, Germany.
| | - Nils Reinhard
- Neurobiology & Genetics, Theodor-Boveri Institute, Biocenter, Julius-Maximilians University Würzburg, Am Hubland, 97074 Würzburg, Germany.
| | - Dirk Rieger
- Neurobiology & Genetics, Theodor-Boveri Institute, Biocenter, Julius-Maximilians University Würzburg, Am Hubland, 97074 Würzburg, Germany.
| | - Charlotte Helfrich-Förster
- Neurobiology & Genetics, Theodor-Boveri Institute, Biocenter, Julius-Maximilians University Würzburg, Am Hubland, 97074 Würzburg, Germany.
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8
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Brown LS, Ernst OP. Recent advances in biophysical studies of rhodopsins - Oligomerization, folding, and structure. Biochim Biophys Acta Proteins Proteom 2017; 1865:1512-21. [PMID: 28844743 DOI: 10.1016/j.bbapap.2017.08.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2017] [Revised: 08/06/2017] [Accepted: 08/11/2017] [Indexed: 12/19/2022]
Abstract
Retinal-binding proteins, mainly known as rhodopsins, function as photosensors and ion transporters in a wide range of organisms. From halobacterial light-driven proton pump, bacteriorhodopsin, to bovine photoreceptor, visual rhodopsin, they have served as prototypical α-helical membrane proteins in a large number of biophysical studies and aided in the development of many cutting-edge techniques of structural biology and biospectroscopy. In the last decade, microbial and animal rhodopsin families have expanded significantly, bringing into play a number of new interesting structures and functions. In this review, we will discuss recent advances in biophysical approaches to retinal-binding proteins, primarily microbial rhodopsins, including those in optical spectroscopy, X-ray crystallography, nuclear magnetic resonance, and electron paramagnetic resonance, as applied to such fundamental biological aspects as protein oligomerization, folding, and structure.
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9
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Grebler R, Kistenpfennig C, Rieger D, Bentrop J, Schneuwly S, Senthilan PR, Helfrich-Förster C. Drosophila Rhodopsin 7 can partially replace the structural role of Rhodopsin 1, but not its physiological function. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2017; 203:649-659. [PMID: 28500442 PMCID: PMC5537319 DOI: 10.1007/s00359-017-1182-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 05/03/2017] [Accepted: 05/05/2017] [Indexed: 11/25/2022]
Abstract
Rhodopsin 7 (Rh7), a new invertebrate Rhodopsin gene, was discovered in the genome of Drosophila melanogaster in 2000 and thought to encode for a functional Rhodopsin protein. Indeed, Rh7 exhibits most hallmarks of the known Rhodopsins, except for the G-protein-activating QAKK motif in the third cytoplasmic loop that is absent in Rh7. Here, we show that Rh7 can partially substitute Rh1 in the outer receptor cells (R1–6) for rhabdomere maintenance, but that it cannot activate the phototransduction cascade in these cells. This speaks against a role of Rh7 as photopigment in R1–6, but does not exclude that it works in the inner photoreceptor cells.
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Affiliation(s)
- Rudi Grebler
- Neurobiology and Genetics, Biocenter, Theodor Boveri Institute, University of Würzburg, 97074, Würzburg, Germany
| | - Christa Kistenpfennig
- Neurobiology and Genetics, Biocenter, Theodor Boveri Institute, University of Würzburg, 97074, Würzburg, Germany
- Oxitec Ltd, 71 Innovation Drive, Milton Park, Oxford, OX14 4RQ, UK
| | - Dirk Rieger
- Neurobiology and Genetics, Biocenter, Theodor Boveri Institute, University of Würzburg, 97074, Würzburg, Germany
| | - Joachim Bentrop
- Cell- and Neurobiology, Zoological Institute, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
| | - Stephan Schneuwly
- Developmental Biology, Institute of Zoology, University of Regensburg, Regensburg, Germany
| | - Pingkalai R Senthilan
- Neurobiology and Genetics, Biocenter, Theodor Boveri Institute, University of Würzburg, 97074, Würzburg, Germany
| | - Charlotte Helfrich-Förster
- Neurobiology and Genetics, Biocenter, Theodor Boveri Institute, University of Würzburg, 97074, Würzburg, Germany.
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10
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Abstract
Rhodopsins are the major photopigments in the fruit fly Drosophila melanogaster. Drosophila express six well-characterized Rhodopsins (Rh1–Rh6) with distinct absorption maxima and expression pattern. In 2000, when the Drosophila genome was published, a novel Rhodopsin gene was discovered: Rhodopsin 7 (Rh7). Rh7 is highly conserved among the Drosophila genus and is also found in other arthropods. Phylogenetic trees based on protein sequences suggest that the seven Drosophila Rhodopsins cluster in three different groups. While Rh1, Rh2 and Rh6 form a “vertebrate-melanopsin-type”–cluster, and Rh3, Rh4 and Rh5 form an “insect-type”-Rhodopsin cluster, Rh7 seem to form its own cluster. Although Rh7 has nearly all important features of a functional Rhodopsin, it differs from other Rhodopsins in its genomic and structural properties, suggesting it might have an overall different role than other known Rhodopsins.
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