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Govorunova EG, Sineshchekov OA. Channelrhodopsins: From Phototaxis to Optogenetics. BIOCHEMISTRY. BIOKHIMIIA 2023; 88:1555-1570. [PMID: 38105024 DOI: 10.1134/s0006297923100115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2023] [Revised: 07/09/2023] [Accepted: 07/09/2023] [Indexed: 12/19/2023]
Abstract
Channelrhodopsins stand out among other retinal proteins because of their capacity to generate passive ionic currents following photoactivation. Owing to that, channelrhodopsins are widely used in neuroscience and cardiology as instruments for optogenetic manipulation of the activity of excitable cells. Photocurrents generated by channelrhodopsins were first discovered in the cells of green algae in the 1970s. In this review we describe this discovery and discuss the current state of research in the field.
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2
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Filiba O, Borin VA, Schapiro I. The involvement of triplet states in the isomerization of retinaloids. Phys Chem Chem Phys 2022; 24:26223-26231. [PMID: 36278932 DOI: 10.1039/d2cp03791b] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Rhodopsins form a family of photoreceptor proteins which utilize the retinal chromophore for light energy conversion. Upon light absorption the retinal chromophore undergoes a photoisomerization. This reaction involves a non-radiative relaxation through a conical intersection between the singlet excited state and the ground state. In this work we studied the possible involvement of triplet states in the photoisomerization of retinaloids using the extended multistate (XMS) version of CASPT2. To this end, truncated models of three retinaloids were considered: protonated Schiff base, deprotonated Schiff base and the aldehyde form. The optimized geometries of the reactant, the product and the conical intersection were connected by a linear interpolation of internal coordinates to describe the isomerization. The energetic position of the low-lying singlet and triplet states as well as their spin-orbit coupling matrix elements (SOCME) were calculated along the isomerization profile. The SOCME values peaked in vicinity of the conical intersection for all the retinaloids. Furthermore, the magnitude of SOCME is invariant to the number of double bonds in the model. The SOCME for the protonated Schiff base is negligible (1.5 cm-1) which renders the involvement of the triplet state as improbable. However, the largest SOCME value of 30 cm-1 was found for the aldehyde form, followed by 15 cm-1 for the deprotonated Schiff base.
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Affiliation(s)
- Ofer Filiba
- Fritz Haber Research Center for Molecular Dynamics and Institute of Chemistry, The Hebrew University of Jerusalem, 9190401, Jerusalem, Israel.
| | - Veniamin A Borin
- Fritz Haber Research Center for Molecular Dynamics and Institute of Chemistry, The Hebrew University of Jerusalem, 9190401, Jerusalem, Israel.
| | - Igor Schapiro
- Fritz Haber Research Center for Molecular Dynamics and Institute of Chemistry, The Hebrew University of Jerusalem, 9190401, Jerusalem, Israel.
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3
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Rozenberg A, Kaczmarczyk I, Matzov D, Vierock J, Nagata T, Sugiura M, Katayama K, Kawasaki Y, Konno M, Nagasaka Y, Aoyama M, Das I, Pahima E, Church J, Adam S, Borin VA, Chazan A, Augustin S, Wietek J, Dine J, Peleg Y, Kawanabe A, Fujiwara Y, Yizhar O, Sheves M, Schapiro I, Furutani Y, Kandori H, Inoue K, Hegemann P, Béjà O, Shalev-Benami M. Rhodopsin-bestrophin fusion proteins from unicellular algae form gigantic pentameric ion channels. Nat Struct Mol Biol 2022; 29:592-603. [PMID: 35710843 DOI: 10.1038/s41594-022-00783-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 04/27/2022] [Indexed: 11/09/2022]
Abstract
Many organisms sense light using rhodopsins, photoreceptive proteins containing a retinal chromophore. Here we report the discovery, structure and biophysical characterization of bestrhodopsins, a microbial rhodopsin subfamily from marine unicellular algae, in which one rhodopsin domain of eight transmembrane helices or, more often, two such domains in tandem, are C-terminally fused to a bestrophin channel. Cryo-EM analysis of a rhodopsin-rhodopsin-bestrophin fusion revealed that it forms a pentameric megacomplex (~700 kDa) with five rhodopsin pseudodimers surrounding the channel in the center. Bestrhodopsins are metastable and undergo photoconversion between red- and green-absorbing or green- and UVA-absorbing forms in the different variants. The retinal chromophore, in a unique binding pocket, photoisomerizes from all-trans to 11-cis form. Heterologously expressed bestrhodopsin behaves as a light-modulated anion channel.
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Affiliation(s)
- Andrey Rozenberg
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa, Israel
| | - Igor Kaczmarczyk
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Donna Matzov
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Johannes Vierock
- Institute for Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Takashi Nagata
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Japan.,PRESTO, Japan Science and Technology Agency, Kawaguchi, Japan
| | - Masahiro Sugiura
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Japan
| | - Kota Katayama
- PRESTO, Japan Science and Technology Agency, Kawaguchi, Japan.,Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Japan.,OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Japan
| | - Yuma Kawasaki
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Japan
| | - Masae Konno
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Japan.,PRESTO, Japan Science and Technology Agency, Kawaguchi, Japan
| | - Yujiro Nagasaka
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Japan
| | - Mako Aoyama
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Japan
| | - Ishita Das
- Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot, Israel
| | - Efrat Pahima
- Fritz Haber Center for Molecular Dynamics Research Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Jonathan Church
- Fritz Haber Center for Molecular Dynamics Research Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Suliman Adam
- Fritz Haber Center for Molecular Dynamics Research Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Veniamin A Borin
- Fritz Haber Center for Molecular Dynamics Research Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Ariel Chazan
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa, Israel
| | - Sandra Augustin
- Institute for Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Jonas Wietek
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel
| | - Julien Dine
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel
| | - Yoav Peleg
- Structural Proteomics Unit (SPU), Life Sciences Core Facilities (LSCF), Weizmann Institute of Science, Rehovot, Israel
| | - Akira Kawanabe
- Laboratory of Molecular Physiology & Biophysics, Faculty of Medicine, Kagawa University, Miki-cho, Japan
| | - Yuichiro Fujiwara
- Laboratory of Molecular Physiology & Biophysics, Faculty of Medicine, Kagawa University, Miki-cho, Japan
| | - Ofer Yizhar
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel
| | - Mordechai Sheves
- Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot, Israel
| | - Igor Schapiro
- Fritz Haber Center for Molecular Dynamics Research Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Yuji Furutani
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Japan.,OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Japan
| | - Hideki Kandori
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Japan.,OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Japan
| | - Keiichi Inoue
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Japan
| | - Peter Hegemann
- Institute for Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Oded Béjà
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa, Israel.
| | - Moran Shalev-Benami
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel.
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4
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Broser M. Far-Red Absorbing Rhodopsins, Insights From Heterodimeric Rhodopsin-Cyclases. Front Mol Biosci 2022; 8:806922. [PMID: 35127823 PMCID: PMC8815786 DOI: 10.3389/fmolb.2021.806922] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 12/27/2021] [Indexed: 11/13/2022] Open
Abstract
The recently discovered Rhodopsin-cyclases from Chytridiomycota fungi show completely unexpected properties for microbial rhodopsins. These photoreceptors function exclusively as heterodimers, with the two subunits that have very different retinal chromophores. Among them is the bimodal photoswitchable Neorhodopsin (NeoR), which exhibits a near-infrared absorbing, highly fluorescent state. These are features that have never been described for any retinal photoreceptor. Here these properties are discussed in the context of color-tuning approaches of retinal chromophores, which have been extensively studied since the discovery of the first microbial rhodopsin, bacteriorhodopsin, in 1971 (Oesterhelt et al., Nature New Biology, 1971, 233 (39), 149–152). Further a brief review about the concept of heterodimerization is given, which is widely present in class III cyclases but is unknown for rhodopsins. NIR-sensitive retinal chromophores have greatly expanded our understanding of the spectral range of natural retinal photoreceptors and provide a novel perspective for the development of optogenetic tools.
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Tian Y, Gao S, Nagel G. In Vivo and In Vitro Characterization of Cyclase and Phosphodiesterase Rhodopsins. Methods Mol Biol 2022; 2501:325-338. [PMID: 35857236 DOI: 10.1007/978-1-0716-2329-9_16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Rhodopsins with enzymatic activity were found in microbes, in 2004 hypothetically from sequence data and since 2014 by experimental proof. So far three different types are known: light-activated guanylyl cyclase opsins (Cyclop) in fungi, light-inhibited two-component guanylyl cyclase opsins (2c-Cyclop) in green algae, and rhodopsin phosphodiesterases (RhoPDE) in choanoflagellates. They are integral membrane proteins with eight transmembrane helices (TM), different to the other microbial (type I) rhodopsins with 7 TM. Therefore, we propose a classification as type Ib rhodopsins for opsins with 8 TM and type Ia for the ones with 7 TM. To characterize those rhodopsins or their mutants, the expression in Xenopus laevis oocytes proved to be an efficient strategy. Functional analysis was initially performed "in oocyte" (in vivo), but more detailed characterization can be obtained with an in vitro assay. In this chapter, we describe procedures how to extract membranes from oocytes after cRNA microinjection and heterologous protein expression. Enzymatic activity of these membranes is then analyzed under different illumination conditions. In addition, fluorescent labeling of the rhodopsins is employed to quantify the expression level and the absolute activity of designed mutants. We discuss strengths and pitfalls, associated with this expression system, and strategies for selecting potentially useful optogenetic tools.
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Affiliation(s)
- Yuehui Tian
- Department of Neurophysiology, Institute of Physiology, Biocenter, University of Wuerzburg, Wuerzburg, Germany
- Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Guangzhou, China
| | - Shiqiang Gao
- Department of Neurophysiology, Institute of Physiology, Biocenter, University of Wuerzburg, Wuerzburg, Germany
| | - Georg Nagel
- Department of Neurophysiology, Institute of Physiology, Biocenter, University of Wuerzburg, Wuerzburg, Germany.
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6
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Abstract
Rhodopsins are photoreceptive membrane proteins consisting of a common heptahelical transmembrane architecture that contains a retinal chromophore. Rhodopsin was first discovered in the animal retina in 1876, but a different type of rhodopsin, bacteriorhodopsin, was reported to be present in the cell membrane of an extreme halophilic archaeon, Halobacterium salinarum, 95 years later. Although these findings were made by physiological observation of pigmented tissue and cell bodies, recent progress in genomic and metagenomic analyses has revealed that there are more than 10,000 microbial rhodopsins and 9000 animal rhodopsins with large diversity and tremendous new functionality. In this Cell Science at a Glance article and accompanying poster, we provide an overview of the diversity of functions, structures, color discrimination mechanisms and optogenetic applications of these two rhodopsin families, and will also highlight the third distinctive rhodopsin family, heliorhodopsin.
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Affiliation(s)
- Takashi Nagata
- The Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan.,PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Keiichi Inoue
- The Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
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7
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Gallot-Lavallée L, Archibald JM. Evolutionary Biology: Viral Rhodopsins Illuminate Algal Evolution. Curr Biol 2021; 30:R1469-R1471. [PMID: 33352125 DOI: 10.1016/j.cub.2020.10.080] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A new metagenomics study has shown that marine viruses recently acquired genes encoding light-gated ion channels from green algae. These so-called channelrhodopsin genes may allow the viruses to manipulate the swimming behavior of the algae they infect.
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Affiliation(s)
- Lucie Gallot-Lavallée
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, Canada
| | - John M Archibald
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, Canada.
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Miyamura S, Nakayama T, Mitsuhashi F, Nagumo T, Sato T, Motomura T, Hori T. Sex-specific Positioning of the Mating Structure in Scale-bearing Gametes of Monostroma angicava and Collinsiella cava (Ulvophyceae, Chlorophyta): A Possible Widespread Difference between Male and Female Gametes. JOURNAL OF PHYCOLOGY 2021; 57:510-527. [PMID: 33150600 DOI: 10.1111/jpy.13096] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 10/02/2020] [Accepted: 10/10/2020] [Indexed: 06/11/2023]
Abstract
The gametes of chlorophytes can be divided into two morphological types (types α and β) based on the position of the mating structure relative to the flagella and eyespot. To elucidate the relationship between the morphological types and the sexes, we studied spatial relationships between the flagellar apparatus-eyespot-mating structures in biflagellate male and female gametes and their fate after fertilization in the anisogamous (Monostroma angicava) and the slightly anisogamous species (Collinsiella cava) using field emission scanning electron microscopy and transmission electron microscopy. The smaller male and larger female gametes of M. angicava had two basal bodies arranged at a 180° angle and the cell surface coated with square-shaped body scales, except for the flagella and mating structures. The mating structure of the female gamete was located on the same side of the flagellar beat plane as the eyespot (type β), whereas that of the male gamete was located on the opposite side (type α). This mating structure arrangement was also confirmed in C. cava. The initial fusion when male and female gametes were mixed involved the mating structures. In a fusing pair of gametes, each flagellum of one gamete lay alongside one flagellum of the other gamete. As fusion proceeded, the gamete pair transformed into a quadriflagellate planozygote, in which the four basal bodies were arranged in a cruciate pattern. The eyespots were positioned side-by-side on the same side of the cell. These results suggest that the two morphological types of gametes are intimately correlated with the particular sexes.
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Affiliation(s)
- Shinichi Miyamura
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8572, Japan
| | - Takeshi Nakayama
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8572, Japan
| | | | - Tamotsu Nagumo
- Echigo Natural History Laboratory, Ojiya, Niigata, 947-9941, Japan
| | - Tomonori Sato
- Muroran Marine Station, Field Science Center for Northern Biosphere, Hokkaido University, Muroran, 051-0013, Japan
| | - Taizo Motomura
- Muroran Marine Station, Field Science Center for Northern Biosphere, Hokkaido University, Muroran, 051-0013, Japan
| | - Terumitsu Hori
- Laboratory for Ginkgo Sciences, 2-5-23 Higashi, Tsukuba, Ibaraki, 305-0046, Japan
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9
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Tian Y, Nagel G, Gao S. An engineered membrane-bound guanylyl cyclase with light-switchable activity. BMC Biol 2021; 19:54. [PMID: 33775243 PMCID: PMC8006352 DOI: 10.1186/s12915-021-00978-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 02/09/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Microbial rhodopsins vary in their chemical properties, from light sensitive ion transport to different enzymatic activities. Recently, a novel family of two-component Cyclase (rhod)opsins (2c-Cyclop) from the green algae Chlamydomonas reinhardtii and Volvox carteri was characterized, revealing a light-inhibited guanylyl cyclase (GC) activity. More genes similar to 2c-Cyclop exist in algal genomes, but their molecular and physiological functions remained uncharacterized. RESULTS Chlamyopsin-5 (Cop5) from C. reinhardtii is related to Cr2c-Cyclop1 (Cop6) and can be expressed in Xenopus laevis oocytes, but shows no GC activity. Here, we exchanged parts of Cop5 with the corresponding ones of Cr2c-Cyclop1. When exchanging the opsin part of Cr2c-Cyclop1 with that of Cop5, we obtained a bi-stable guanylyl cyclase (switch-Cyclop1) whose activity can be switched by short light flashes. The GC activity of switch-Cyclop1 is increased for hours by a short 380 nm illumination and switched off (20-fold decreased) by blue or green light. switch-Cyclop1 is very light-sensitive and can half-maximally be activated by ~ 150 photons/nm2 of 380 nm (~ 73 J/m2) or inhibited by ~ 40 photons/nm2 of 473 nm (~ 18 J/m2). CONCLUSIONS This engineered guanylyl cyclase is the first light-switchable enzyme for cGMP level regulation. Light-regulated cGMP production with high light-sensitivity is a promising technique for the non-invasive investigation of the effects of cGMP signaling in many different tissues.
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Affiliation(s)
- Yuehui Tian
- Department of Neurophysiology, Institute of Physiology, Biocenter, University of Wuerzburg, 97070, Wuerzburg, Germany.,Present address: Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Guangzhou, 510006, China
| | - Georg Nagel
- Department of Neurophysiology, Institute of Physiology, Biocenter, University of Wuerzburg, 97070, Wuerzburg, Germany.
| | - Shiqiang Gao
- Department of Neurophysiology, Institute of Physiology, Biocenter, University of Wuerzburg, 97070, Wuerzburg, Germany.
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Tsunoda SP, Sugiura M, Kandori H. Molecular Properties and Optogenetic Applications of Enzymerhodopsins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1293:153-165. [PMID: 33398812 DOI: 10.1007/978-981-15-8763-4_9] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The cyclic nucleotides cAMP and cGMP are ubiquitous secondary messengers that regulate multiple biological functions including gene expression, differentiation, proliferation, and cell survival. In sensory neurons, cyclic nucleotides are responsible for signal modulation, amplification, and encoding. For spatial and temporal manipulation of cyclic nucleotide dynamics, optogenetics have a great advantage over pharmacological approaches. Enzymerhodopsins are a unique family of microbial rhodopsins. These molecules are made up of a membrane-embedded rhodopsin domain, which binds an all trans-retinal to form a chromophore, and a cytoplasmic water-soluble catalytic domain. To date, three kinds of molecules have been identified from lower eukaryotes such as fungi, algae, and flagellates. Among these, histidine kinase rhodopsin (HKR) is a light-inhibited guanylyl cyclase. Rhodopsin GC (Rh-GC) functions as a light-activated guanylyl cyclase, while rhodopsin PDE (Rh-PDE) functions as a light-activated phosphodiesterase that degrades cAMP and cGMP. These enzymerhodopsins have great potential in optogenetic applications for manipulating the intracellular cyclic nucleotide dynamics of living cells. Here we introduce the molecular function and applicability of these molecules.
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Affiliation(s)
- Satoshi P Tsunoda
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan. .,JST PRESTO, Saitama, Japan.
| | - Masahiro Sugiura
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan
| | - Hideki Kandori
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan
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11
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Javadi A, Arrieta J, Tuval I, Polin M. Photo-bioconvection: towards light control of flows in active suspensions. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2020; 378:20190523. [PMID: 32762429 PMCID: PMC7422871 DOI: 10.1098/rsta.2019.0523] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The persistent motility of individual constituents in microbial suspensions represents a prime example of the so-called active matter systems. Cells consume energy, exert forces and move, overall releasing the constraints of equilibrium statistical mechanics of passive elements and allowing for complex spatio-temporal patterns to emerge. Moreover, when subject to physico-chemical stimuli their collective behaviour often drives large-scale instabilities of a hydrodynamic nature, with implications for biomixing in natural environments and incipient industrial applications. In turn, our ability to exert external control of these driving stimuli could be used to govern the emerging patterns. Light, being easily manipulable and, at the same time, an important stimulus for a wide variety of microorganisms, is particularly well suited to this end. In this paper, we will discuss the current state, developments and some of the emerging advances in the fundamentals and applications of light-induced bioconvection with a focus on recent experimental realizations and modelling efforts. This article is part of the theme issue 'Stokes at 200 (part 2)'.
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Affiliation(s)
- A. Javadi
- Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK
- e-mail:
| | - J. Arrieta
- Instituto Mediterráneo de Estudios Avanzados, IMEDEA, UIB-CSIC, 07190 Esporles, Spain
| | - I. Tuval
- Instituto Mediterráneo de Estudios Avanzados, IMEDEA, UIB-CSIC, 07190 Esporles, Spain
- Departamento de Física, Universitat de les Illes Balears, 07122 Palma de Mallorca, Spain
| | - M. Polin
- Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK
- Centre for Mechanochemical Cell Biology, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK
- e-mail:
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12
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Arrieta J, Polin M, Saleta-Piersanti R, Tuval I. Light Control of Localized Photobioconvection. PHYSICAL REVIEW LETTERS 2019; 123:158101. [PMID: 31702314 DOI: 10.1103/physrevlett.123.158101] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Revised: 07/04/2019] [Indexed: 05/12/2023]
Abstract
Microorganismal motility is often characterized by complex responses to environmental physico-chemical stimuli. Although the biological basis of these responses is often not well understood, their exploitation already promises novel avenues to directly control the motion of living active matter at both the individual and collective level. Here we leverage the phototactic ability of the model microalga Chlamydomonas reinhardtii to precisely control the timing and position of localized cell photoaccumulation, leading to the controlled development of isolated bioconvective plumes. This novel form of photobioconvection allows a precise, fast, and reconfigurable control of the spatiotemporal dynamics of the instability and the ensuing global recirculation, which can be activated and stopped in real time. A simple continuum model accounts for the phototactic response of the suspension and demonstrates how the spatiotemporal dynamics of the illumination field can be used as a simple external switch to produce efficient bio mixing.
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Affiliation(s)
- Jorge Arrieta
- Instituto Mediterráneo de Estudios Avanzados, IMEDEA, UIB-CSIC, Esporles, 07190, Spain
| | - Marco Polin
- Physics Department and Centre for Mechanochemical Cell Biology, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, United Kingdom
| | | | - Idan Tuval
- Instituto Mediterráneo de Estudios Avanzados, IMEDEA, UIB-CSIC, Esporles, 07190, Spain
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13
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Luck M, Velázquez Escobar F, Glass K, Sabotke MI, Hagedorn R, Corellou F, Siebert F, Hildebrandt P, Hegemann P. Photoreactions of the Histidine Kinase Rhodopsin Ot-HKR from the Marine Picoalga Ostreococcus tauri. Biochemistry 2019; 58:1878-1891. [PMID: 30768260 DOI: 10.1021/acs.biochem.8b01200] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The tiny picoalga, Ostreococcus tauri, originating from the Thau Lagoon is a member of the marine phytoplankton. Because of its highly reduced genome and small cell size, while retaining the fundamental requirements of a eukaryotic photosynthetic cell, it became a popular model organism for studying photosynthesis or circadian clock-related processes. We analyzed the spectroscopic properties of the photoreceptor domain of the histidine kinase rhodopsin Ot-HKR that is suggested to be involved in the light-induced entrainment of the Ostreococcus circadian clock. We found that the rhodopsin, Ot-Rh, dark state absorbs maximally at 505 nm. Exposure to green-orange light led to the accumulation of a blue-shifted M-state-like absorbance form with a deprotonated Schiff base. This Ot-Rh P400 state had an unusually long lifetime of several minutes. A second long-living photoproduct with a red-shifted absorbance, P560, accumulated upon illumination with blue/UVA light. The resulting photochromicity of the rhodopsin is expected to be advantageous to its function as a molecular control element of the signal transducing HKR domains. The light intensity and the ratio of blue vs green light are reflected by the ratio of rhodopsin molecules in the long-living absorbance forms. Furthermore, dark-state absorbance and the photocycle kinetics vary with the salt content of the environment substantially. This observation is attributed to anion binding in the dark state and a transient anion release during the photocycle, indicating that the salinity affects the photoinduced processes.
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Affiliation(s)
- Meike Luck
- Institute of Biology, Experimental Biophysics, Humboldt-Universität zu Berlin , Berlin 10115 , Germany
| | | | - Kathrin Glass
- Institute of Biology, Experimental Biophysics, Humboldt-Universität zu Berlin , Berlin 10115 , Germany
| | - Mareike-Isabel Sabotke
- Institute of Biology, Experimental Biophysics, Humboldt-Universität zu Berlin , Berlin 10115 , Germany
| | - Rolf Hagedorn
- Institute of Biology, Experimental Biophysics, Humboldt-Universität zu Berlin , Berlin 10115 , Germany
| | - Florence Corellou
- Laboratoire d'Oceanographie Microbienne , Université Pierre et Marie Curie (Paris 6), Centre National de la Recherche Scientifique, Unité Mixte de Recherche , 7621 , Observatoire Oceanologique, Banyuls/mer , France
| | - Friedrich Siebert
- Institute of Chemistry, Technische Universität Berlin , Berlin 10623 , Germany.,Institut für Molekulare Medizin und Zellforschung, Sektion Biophysik , Albert-Ludwigs-Universität Freiburg , Freiburg 79104 , Germany
| | - Peter Hildebrandt
- Institute of Chemistry, Technische Universität Berlin , Berlin 10623 , Germany
| | - Peter Hegemann
- Institute of Biology, Experimental Biophysics, Humboldt-Universität zu Berlin , Berlin 10115 , Germany
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14
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Kabbara S, Hérivaux A, Dugé de Bernonville T, Courdavault V, Clastre M, Gastebois A, Osman M, Hamze M, Cock JM, Schaap P, Papon N. Diversity and Evolution of Sensor Histidine Kinases in Eukaryotes. Genome Biol Evol 2019; 11:86-108. [PMID: 30252070 PMCID: PMC6324907 DOI: 10.1093/gbe/evy213] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/24/2018] [Indexed: 12/20/2022] Open
Abstract
Histidine kinases (HKs) are primary sensor proteins that act in cell signaling pathways generically referred to as "two-component systems" (TCSs). TCSs are among the most widely distributed transduction systems used by both prokaryotic and eukaryotic organisms to detect and respond to a broad range of environmental cues. The structure and distribution of HK proteins are now well documented in prokaryotes, but information is still fragmentary for eukaryotes. Here, we have taken advantage of recent genomic resources to explore the structural diversity and the phylogenetic distribution of HKs in the prominent eukaryotic supergroups. Searches of the genomes of 67 eukaryotic species spread evenly throughout the phylogenetic tree of life identified 748 predicted HK proteins. Independent phylogenetic analyses of predicted HK proteins were carried out for each of the major eukaryotic supergroups. This allowed most of the compiled sequences to be categorized into previously described HK groups. Beyond the phylogenetic analysis of eukaryotic HKs, this study revealed some interesting findings: 1) characterization of some previously undescribed eukaryotic HK groups with predicted functions putatively related to physiological traits; 2) discovery of HK groups that were previously believed to be restricted to a single kingdom in additional supergroups, and 3) indications that some evolutionary paths have led to the appearance, transfer, duplication, and loss of HK genes in some phylogenetic lineages. This study provides an unprecedented overview of the structure and distribution of HKs in the Eukaryota and represents a first step toward deciphering the evolution of TCS signaling in living organisms.
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Affiliation(s)
- Samar Kabbara
- Groupe d’Etude des Interactions Hôte-Pathogène, GEIHP, EA3142, Université d’Angers, SFR 4208 ICAT, France
| | - Anaïs Hérivaux
- Groupe d’Etude des Interactions Hôte-Pathogène, GEIHP, EA3142, Université d’Angers, SFR 4208 ICAT, France
| | | | - Vincent Courdavault
- Biomolécules et Biotechnologies Végétales, BBV, EA2106, Université François Rabelais de Tours, France
| | - Marc Clastre
- Biomolécules et Biotechnologies Végétales, BBV, EA2106, Université François Rabelais de Tours, France
| | - Amandine Gastebois
- Groupe d’Etude des Interactions Hôte-Pathogène, GEIHP, EA3142, Université d’Angers, SFR 4208 ICAT, France
| | - Marwan Osman
- Laboratoire Microbiologie Santé et Environnement, Faculté de Santé Publique, Université Libanaise, Tripoli, Lebanon
| | - Monzer Hamze
- Laboratoire Microbiologie Santé et Environnement, Faculté de Santé Publique, Université Libanaise, Tripoli, Lebanon
| | - J Mark Cock
- Algal Genetics Group, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, Sorbonne Université, UPMC Université Paris 06, CNRS, Roscoff, France
| | - Pauline Schaap
- School of Life Sciences, University of Dundee, United Kingdom
| | - Nicolas Papon
- Groupe d’Etude des Interactions Hôte-Pathogène, GEIHP, EA3142, Université d’Angers, SFR 4208 ICAT, France
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15
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Tian Y, Gao S, von der Heyde EL, Hallmann A, Nagel G. Two-component cyclase opsins of green algae are ATP-dependent and light-inhibited guanylyl cyclases. BMC Biol 2018; 16:144. [PMID: 30522480 PMCID: PMC6284317 DOI: 10.1186/s12915-018-0613-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Accepted: 11/20/2018] [Indexed: 11/10/2022] Open
Abstract
Background The green algae Chlamydomonas reinhardtii and Volvox carteri are important models for studying light perception and response, expressing many different photoreceptors. More than 10 opsins were reported in C. reinhardtii, yet only two—the channelrhodopsins—were functionally characterized. Characterization of new opsins would help to understand the green algae photobiology and to develop new tools for optogenetics. Results Here we report the characterization of a novel opsin family from these green algae: light-inhibited guanylyl cyclases regulated through a two-component-like phosphoryl transfer, called “two-component cyclase opsins” (2c-Cyclops). We prove the existence of such opsins in C. reinhardtii and V. carteri and show that they have cytosolic N- and C-termini, implying an eight-transmembrane helix structure. We also demonstrate that cGMP production is both light-inhibited and ATP-dependent. The cyclase activity of Cr2c-Cyclop1 is kept functional by the ongoing phosphorylation and phosphoryl transfer from the histidine kinase to the response regulator in the dark, proven by mutagenesis. Absorption of a photon inhibits the cyclase activity, most likely by inhibiting the phosphoryl transfer. Overexpression of Vc2c-Cyclop1 protein in V. carteri leads to significantly increased cGMP levels, demonstrating guanylyl cyclase activity of Vc2c-Cyclop1 in vivo. Live cell imaging of YFP-tagged Vc2c-Cyclop1 in V. carteri revealed a development-dependent, layer-like structure at the immediate periphery of the nucleus and intense spots in the cell periphery. Conclusions Cr2c-Cyclop1 and Vc2c-Cyclop1 are light-inhibited and ATP-dependent guanylyl cyclases with an unusual eight-transmembrane helix structure of the type I opsin domain which we propose to classify as type Ib, in contrast to the 7 TM type Ia opsins. Overexpression of Vc2c-Cyclop1 protein in V. carteri led to a significant increase of cGMP, demonstrating enzyme functionality in the organism of origin. Fluorescent live cell imaging revealed that Vc2c-Cyclop1 is located in the periphery of the nucleus and in confined areas at the cell periphery. Electronic supplementary material The online version of this article (10.1186/s12915-018-0613-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Yuehui Tian
- Botanik I, Julius-Maximilians-Universität Würzburg, Biozentrum, Julius-von-Sachs-Platz 2, 97082, Würzburg, Germany
| | - Shiqiang Gao
- Botanik I, Julius-Maximilians-Universität Würzburg, Biozentrum, Julius-von-Sachs-Platz 2, 97082, Würzburg, Germany.
| | - Eva Laura von der Heyde
- Department of Cellular and Developmental Biology of Plants, University of Bielefeld, Universitätsstr. 25, 33615, Bielefeld, Germany
| | - Armin Hallmann
- Department of Cellular and Developmental Biology of Plants, University of Bielefeld, Universitätsstr. 25, 33615, Bielefeld, Germany.
| | - Georg Nagel
- Botanik I, Julius-Maximilians-Universität Würzburg, Biozentrum, Julius-von-Sachs-Platz 2, 97082, Würzburg, Germany.
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16
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Canales J, Henriquez-Valencia C, Brauchi S. The Integration of Electrical Signals Originating in the Root of Vascular Plants. FRONTIERS IN PLANT SCIENCE 2018; 8:2173. [PMID: 29375591 PMCID: PMC5767606 DOI: 10.3389/fpls.2017.02173] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 12/12/2017] [Indexed: 05/07/2023]
Abstract
Plants have developed different signaling systems allowing for the integration of environmental cues to coordinate molecular processes associated to both early development and the physiology of the adult plant. Research on systemic signaling in plants has traditionally focused on the role of phytohormones as long-distance signaling molecules, and more recently the importance of peptides and miRNAs in building up this communication process has also been described. However, it is well-known that plants have the ability to generate different types of long-range electrical signals in response to different stimuli such as light, temperature variations, wounding, salt stress, or gravitropic stimulation. Presently, it is unclear whether short or long-distance electrical communication in plants is linked to nutrient uptake. This review deals with aspects of sensory input in plant roots and the propagation of discrete signals to the plant body. We discuss the physiological role of electrical signaling in nutrient uptake and how nutrient variations may become an electrical signal propagating along the plant.
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Affiliation(s)
- Javier Canales
- Facultad de Ciencias, Instituto de Bioquimica y Microbiologia, Universidad Austral de Chile, Valdivia, Chile
- Millennium Institute for Integrative Systems and Synthetic Biology, Santiago, Chile
| | - Carlos Henriquez-Valencia
- Facultad de Ciencias, Instituto de Bioquimica y Microbiologia, Universidad Austral de Chile, Valdivia, Chile
| | - Sebastian Brauchi
- Facultad de Medicina, Instituto de Fisiologia, Universidad Austral de Chile, Valdivia, Chile
- Millennium Nucleus of Ion Channels-Associated Diseases, Valdivia, Chile
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17
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Abstract
Microbial rhodopsins (MRs) are a large family of photoactive membrane proteins, found in microorganisms belonging to all kingdoms of life, with new members being constantly discovered. Among the MRs are light-driven proton, cation and anion pumps, light-gated cation and anion channels, and various photoreceptors. Due to their abundance and amenability to studies, MRs served as model systems for a great variety of biophysical techniques, and recently found a great application as optogenetic tools. While the basic aspects of microbial rhodopsins functioning have been known for some time, there is still a plenty of unanswered questions. This chapter presents and summarizes the available knowledge, focusing on the functional and structural studies.
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Affiliation(s)
- Ivan Gushchin
- Moscow Institute of Physics and Technology, Dolgoprudniy, Russia.
| | - Valentin Gordeliy
- Moscow Institute of Physics and Technology, Dolgoprudniy, Russia.
- University of Grenoble Alpes, CEA, CNRS, IBS, Grenoble, France.
- Institute of Complex Systems (ICS), ICS-6: Structural Biochemistry, Research Centre Jülich, Jülich, Germany.
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18
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Absorption and Emission Spectroscopic Investigation of Thermal Dynamics and Photo-Dynamics of the Rhodopsin Domain of the Rhodopsin-Guanylyl Cyclase from the Nematophagous Fungus Catenaria anguillulae. Int J Mol Sci 2017; 18:ijms18102099. [PMID: 28981475 PMCID: PMC5666781 DOI: 10.3390/ijms18102099] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 09/27/2017] [Accepted: 09/28/2017] [Indexed: 11/16/2022] Open
Abstract
The rhodopsin-guanylyl cyclase from the nematophagous fungus Catenaria anguillulae belongs to a recently discovered class of enzymerhodopsins and may find application as a tool in optogenetics. Here the rhodopsin domain CaRh of the rhodopsin-guanylyl cyclase from Catenaria anguillulae was studied by absorption and emission spectroscopic methods. The absorption cross-section spectrum and excitation wavelength dependent fluorescence quantum distributions of CaRh samples were determined (first absorption band in the green spectral region). The thermal stability of CaRh was studied by long-time attenuation measurements at room temperature (20.5 °C) and refrigerator temperature of 3.5 °C. The apparent melting temperature of CaRh was determined by stepwise sample heating up and cooling down (obtained apparent melting temperature: 62 ± 2 °C). The photocycle dynamics of CaRh was investigated by sample excitation to the first inhomogeneous absorption band of the CaRhda dark-adapted state around 590 nm (long-wavelength tail), 530 nm (central region) and 470 nm (short-wavelength tail) and following the absorption spectra development during exposure and after exposure (time resolution 0.0125 s). The original protonated retinal Schiff base PRSBall-trans in CaRhda photo-converted reversibly to protonated retinal Schiff base PRSBall-trans,la1 with restructured surroundings (CaRhla₁ light-adapted state, slightly blue-shifted and broadened first absorption band, recovery to CaRhda with time constant of 0.8 s) and deprotonated retinal Schiff base RSB13-cis (CaRhla₂ light-adapted state, first absorption band in violet to near ultraviolet spectral region, recovery to CaRhda with time constant of 0.35 s). Long-time light exposure of light-adapted CaRhla₁ around 590, 530 and 470 nm caused low-efficient irreversible degradation to photoproducts CaRhprod. Schemes of the primary photocycle dynamics of CaRhda and the secondary photocycle dynamics of CaRhla1 are developed.
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19
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Luck M, Hegemann P. The two parallel photocycles of the Chlamydomonas sensory photoreceptor histidine kinase rhodopsin 1. JOURNAL OF PLANT PHYSIOLOGY 2017; 217:77-84. [PMID: 28784569 DOI: 10.1016/j.jplph.2017.07.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 07/10/2017] [Accepted: 07/11/2017] [Indexed: 06/07/2023]
Abstract
Histidine kinase rhodopsins (HKRs) belong to a class of unexplored sensory photoreceptors that share a similar modular architecture. The light sensing rhodopsin domain is covalently linked to signal-transducing modules and in some cases to a C-terminal guanylyl-cyclase effector. In spite of their wide distribution in unicellular organisms, very little is known about their physiological role and mechanistic functioning. We investigated the photochemical properties of the recombinant rhodopsin-fragment of Cr-HKR1 originating from Chlamydomonas reinhardtii. Our spectroscopic studies revealed an unusual thermal stability of the photoproducts with the deprotonated retinal Schiff base (RSB). Upon UV-irradiation these Rh-UV states with maximal absorbance in the UVA-region (Rh-UV) photochemically convert to stable blue light absorbing rhodopsin (Rh-Bl) with protonated chromophore. The heterogeneity of the sample is based on two parallel photocycles with the chromophore in C15=N-syn- or -anti-configuration. This report represents an attempt to decipher the underlying reaction schemes and interconversions of the two coexisting photocycles.
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Affiliation(s)
- Meike Luck
- Institute for Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Germany.
| | - Peter Hegemann
- Institute for Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Germany
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20
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Govorunova EG, Sineshchekov OA, Li H, Spudich JL. Microbial Rhodopsins: Diversity, Mechanisms, and Optogenetic Applications. Annu Rev Biochem 2017; 86:845-872. [PMID: 28301742 PMCID: PMC5747503 DOI: 10.1146/annurev-biochem-101910-144233] [Citation(s) in RCA: 229] [Impact Index Per Article: 32.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Microbial rhodopsins are a family of photoactive retinylidene proteins widespread throughout the microbial world. They are notable for their diversity of function, using variations of a shared seven-transmembrane helix design and similar photochemical reactions to carry out distinctly different light-driven energy and sensory transduction processes. Their study has contributed to our understanding of how evolution modifies protein scaffolds to create new protein chemistry, and their use as tools to control membrane potential with light is fundamental to optogenetics for research and clinical applications. We review the currently known functions and present more in-depth assessment of three functionally and structurally distinct types discovered over the past two years: (a) anion channelrhodopsins (ACRs) from cryptophyte algae, which enable efficient optogenetic neural suppression; (b) cryptophyte cation channelrhodopsins (CCRs), structurally distinct from the green algae CCRs used extensively for neural activation and from cryptophyte ACRs; and
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Affiliation(s)
- Elena G Govorunova
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas 77030; , , ,
| | - Oleg A Sineshchekov
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas 77030; , , ,
| | - Hai Li
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas 77030; , , ,
| | - John L Spudich
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas 77030; , , ,
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21
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Phototaxis beyond turning: persistent accumulation and response acclimation of the microalga Chlamydomonas reinhardtii. Sci Rep 2017; 7:3447. [PMID: 28615673 PMCID: PMC5471259 DOI: 10.1038/s41598-017-03618-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Accepted: 05/02/2017] [Indexed: 11/08/2022] Open
Abstract
Phototaxis is an important reaction to light displayed by a wide range of motile microorganisms. Flagellated eukaryotic microalgae in particular, like the model organism Chlamydomonas reinhardtii, steer either towards or away from light by a rapid and precisely timed modulation of their flagellar activity. Cell steering, however, is only the beginning of a much longer process which ultimately allows cells to determine their light exposure history. This process is not well understood. Here we present a first quantitative study of the long timescale phototactic motility of Chlamydomonas at both single cell and population levels. Our results reveal that the phototactic strategy adopted by these microorganisms leads to an efficient exposure to light, and that the phototactic response is modulated over typical timescales of tens of seconds. The adaptation dynamics for phototaxis and chlorophyll fluorescence show a striking quantitative agreement, suggesting that photosynthesis controls quantitatively how cells navigate a light field.
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22
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The trafficking of bacterial type rhodopsins into the Chlamydomonas eyespot and flagella is IFT mediated. Sci Rep 2016; 6:34646. [PMID: 27694882 PMCID: PMC5046144 DOI: 10.1038/srep34646] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Accepted: 09/14/2016] [Indexed: 11/08/2022] Open
Abstract
The bacterial type rhodopsins are present in all the three domains of life. In contrast to the animal type rhodopsin that performs mainly sensory functions in higher eukaryotes, the bacterial type rhodopsin could function as ion channel, pumps and as sensory proteins. The functioning of rhodopsin in higher eukaryotes requires the transport of rhodopsin from its site of synthesis to the ciliated outer segment of the photoreceptive cells. However, the trafficking of bacterial type rhodopsin from its site of synthesis to the position of action is not characterized. Here we present the first report for the existence of an IFT-interactome mediated trafficking of the bacterial type rhodopsins into eyespot and flagella of the Chlamydomonas. We show that there is a light-dependent, dynamic localization of rhodopsins between flagella and eyespot of Chlamydomonas. The involvement of IFT components in the rhodopsin trafficking was elucidated by the use of conditional IFT mutants. We found that rhodopsin can be co-immunoprecipitated with the components of IFT machinery and with other protein components required for the IFT-cargo complex formation. These findings show that light-regulated localization of rhodopsin is not restricted to animals thereby suggesting that rhodopsin trafficking is an IFT dependent ancient process.
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23
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Sarto-Jackson I, Tomaska L. How to bake a brain: yeast as a model neuron. Curr Genet 2016; 62:347-70. [PMID: 26782173 DOI: 10.1007/s00294-015-0554-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 12/09/2015] [Accepted: 12/10/2015] [Indexed: 12/14/2022]
Abstract
More than 30 years ago Dan Koshland published an inspirational essay presenting the bacterium as a model neuron (Koshland, Trends Neurosci 6:133-137, 1983). In the article he argued that there are several similarities between neurons and bacterial cells in "how signals are processed within a cell or how this processing machinery can be modified to produce plasticity". He then explored the bacterial chemosensory system to emphasize its attributes that are analogous to information processing in neurons. In this review, we wish to expand Koshland's original idea by adding the yeast cell to the list of useful models of a neuron. The fact that yeasts and neurons are specialized versions of the eukaryotic cell sharing all principal components sets the stage for a grand evolutionary tinkering where these components are employed in qualitatively different tasks, but following analogous molecular logic. By way of example, we argue that evolutionarily conserved key components involved in polarization processes (from budding or mating in Saccharomyces cervisiae to neurite outgrowth or spinogenesis in neurons) are shared between yeast and neurons. This orthologous conservation of modules makes S. cervisiae an excellent model organism to investigate neurobiological questions. We substantiate this claim by providing examples of yeast models used for studying neurological diseases.
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Affiliation(s)
- Isabella Sarto-Jackson
- Konrad Lorenz Institute for Evolution and Cognition Research, Martinstraße 12, 3400, Klosterneuburg, Austria.
| | - Lubomir Tomaska
- Department of Genetics, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynska dolina B-1, Ilkovicova 6, 842 15, Bratislava, Slovak Republic.
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24
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Gao S, Nagpal J, Schneider MW, Kozjak-Pavlovic V, Nagel G, Gottschalk A. Optogenetic manipulation of cGMP in cells and animals by the tightly light-regulated guanylyl-cyclase opsin CyclOp. Nat Commun 2015; 6:8046. [PMID: 26345128 PMCID: PMC4569695 DOI: 10.1038/ncomms9046] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2015] [Accepted: 07/11/2015] [Indexed: 12/28/2022] Open
Abstract
Cyclic GMP (cGMP) signalling regulates multiple biological functions through activation of protein kinase G and cyclic nucleotide-gated (CNG) channels. In sensory neurons, cGMP permits signal modulation, amplification and encoding, before depolarization. Here we implement a guanylyl cyclase rhodopsin from Blastocladiella emersonii as a new optogenetic tool (BeCyclOp), enabling rapid light-triggered cGMP increase in heterologous cells (Xenopus oocytes, HEK293T cells) and in Caenorhabditis elegans. Among five different fungal CyclOps, exhibiting unusual eight transmembrane topologies and cytosolic N-termini, BeCyclOp is the superior optogenetic tool (light/dark activity ratio: 5,000; no cAMP production; turnover (20 °C) ∼17 cGMP s−1). Via co-expressed CNG channels (OLF in oocytes, TAX-2/4 in C. elegans muscle), BeCyclOp photoactivation induces a rapid conductance increase and depolarization at very low light intensities. In O2/CO2 sensory neurons of C. elegans, BeCyclOp activation evokes behavioural responses consistent with their normal sensory function. BeCyclOp therefore enables precise and rapid optogenetic manipulation of cGMP levels in cells and animals. Cyclic guanosine monophosphate (cGMP) is a cellular second messenger involved in many processes including regulation of neuronal excitability and vascular tone. Gao, Nagpal et al., employ a fungal rhodopsin to optogenetically control cGMP levels in multiple systems including C. elegans sensory neurons.
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Affiliation(s)
- Shiqiang Gao
- Department of Biology, Institute for Molecular Plant Physiology and Biophysics, Biocenter, Julius-Maximilians-University of Würzburg, Julius-von-Sachs-Platz 2, D-97082 Würzburg, Germany
| | - Jatin Nagpal
- Buchmann Institute for Molecular Life Sciences, Goethe University, Max von Laue Strasse 15, D-60438 Frankfurt, Germany.,Department for Biochemistry, Chemistry and Pharmacy, Institute of Biochemistry, Goethe University, Max von Laue Strasse 9, D-60438 Frankfurt, Germany
| | - Martin W Schneider
- Buchmann Institute for Molecular Life Sciences, Goethe University, Max von Laue Strasse 15, D-60438 Frankfurt, Germany.,Department for Biochemistry, Chemistry and Pharmacy, Institute of Biochemistry, Goethe University, Max von Laue Strasse 9, D-60438 Frankfurt, Germany
| | - Vera Kozjak-Pavlovic
- Department of Microbiology, Biocenter, Julius-Maximilians-University of Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Georg Nagel
- Department of Biology, Institute for Molecular Plant Physiology and Biophysics, Biocenter, Julius-Maximilians-University of Würzburg, Julius-von-Sachs-Platz 2, D-97082 Würzburg, Germany
| | - Alexander Gottschalk
- Buchmann Institute for Molecular Life Sciences, Goethe University, Max von Laue Strasse 15, D-60438 Frankfurt, Germany.,Department for Biochemistry, Chemistry and Pharmacy, Institute of Biochemistry, Goethe University, Max von Laue Strasse 9, D-60438 Frankfurt, Germany.,Cluster of Excellence Frankfurt-Macromolecular Complexes (CEF-MC), Goethe University, Max von Laue Strasse 15, D-60438 Frankfurt, Germany
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25
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Transcriptional analysis of Volvox photoreceptors suggests the existence of different cell-type specific light-signaling pathways. Curr Genet 2014; 61:3-18. [PMID: 25117716 DOI: 10.1007/s00294-014-0440-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Revised: 07/10/2014] [Accepted: 07/25/2014] [Indexed: 12/14/2022]
Abstract
Photosynthetic organisms, e.g., plants including green algae, use a sophisticated light-sensing system, composed of primary photoreceptors and additional downstream signaling components, to monitor changes in the ambient light environment towards adjust their growth and development. Although a variety of cellular processes, e.g., initiation of cleavage division and final cellular differentiation, have been shown to be light-regulated in the green alga Volvox carteri, little is known about the underlying light perception and signaling pathways. This multicellular alga possesses at least 12 photoreceptors, i.e., one phototropin (VcPhot), four cryptochromes (VcCRYa, VcCRYp, VcCRYd1, and VcCRYd2), and seven members of rhodopsin-like photoreceptors (VR1, VChR1, VChR2, VcHKR1, VcHKR2, VcHKR3, and VcHKR4), which display distinct light-dependent chemical processes based on their protein architectures and associated chromophores. Gene expression analyses could show that the transcript levels of some of the photoreceptor genes (e.g., VChR1 and VcHKR1) accumulate during division cleavages, while others (e.g., VcCRYa, VcCRYp, and VcPhot) accumulate during final cellular differentiation. However, the pattern of transcript accumulation changes when the alga switches to the sexual development. Eight photoreceptor genes, e.g., VcPhot, VcCRYp, and VcHKR1, are highly expressed in the somatic cells, while only the animal-type rhodopsin VR1 was found to be highly expressed in the reproductive cells/embryos during both asexual and sexual life cycles. Moreover, accumulation of VChR1 and VcCRYa transcripts is more sensitive to light and changes in response to more than one light quality. Obviously, different regulatory mechanisms underlying gene expression control transcript accumulation of photoreceptors not only during development, but also in a cell-type specific way and in response to various external signals such as light quality. The transcriptional patterns described in this study show that Volvox photoreceptors are mostly expressed in a cell-type specific manner. This gives reason to believe that cell-type specific light-signaling pathways allow differential regulation of cellular and developmental processes in response to the environmental light cues.
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Luck M, Mathes T, Bruun S, Fudim R, Hagedorn R, Tran Nguyen TM, Kateriya S, Kennis JTM, Hildebrandt P, Hegemann P. A photochromic histidine kinase rhodopsin (HKR1) that is bimodally switched by ultraviolet and blue light. J Biol Chem 2012; 287:40083-90. [PMID: 23027869 DOI: 10.1074/jbc.m112.401604] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Rhodopsins are light-activated chromoproteins that mediate signaling processes via transducer proteins or promote active or passive ion transport as ion pumps or directly light-activated channels. Here, we provide spectroscopic characterization of a rhodopsin from the Chlamydomonas eyespot. It belongs to a recently discovered but so far uncharacterized family of histidine kinase rhodopsins (HKRs). These are modular proteins consisting of rhodopsin, a histidine kinase, a response regulator, and in some cases an effector domain such as an adenylyl or guanylyl cyclase, all encoded in a single protein as a two-component system. The recombinant rhodopsin fragment, Rh, of HKR1 is a UVA receptor (λ(max) = 380 nm) that is photoconverted by UV light into a stable blue light-absorbing meta state Rh-Bl (λ(max) = 490 nm). Rh-Bl is converted back to Rh-UV by blue light. Raman spectroscopy revealed that the Rh-UV chromophore is in an unusual 13-cis,15-anti configuration, which explains why the chromophore is deprotonated. The excited state lifetime of Rh-UV is exceptionally stable, probably caused by a relatively unpolar retinal binding pocket, converting into the photoproduct within about 100 ps, whereas the blue form reacts 100 times faster. We propose that the photochromic HKR1 plays a role in the adaptation of behavioral responses in the presence of UVA light.
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Affiliation(s)
- Meike Luck
- Institute of Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, 10115 Berlin, Germany
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27
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Ji ZG, Ito S, Honjoh T, Ohta H, Ishizuka T, Fukazawa Y, Yawo H. Light-evoked somatosensory perception of transgenic rats that express channelrhodopsin-2 in dorsal root ganglion cells. PLoS One 2012; 7:e32699. [PMID: 22412908 PMCID: PMC3295764 DOI: 10.1371/journal.pone.0032699] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Accepted: 01/29/2012] [Indexed: 11/18/2022] Open
Abstract
In vertebrate somatosensory systems, each mode of touch-pressure, temperature or pain is sensed by sensory endings of different dorsal root ganglion (DRG) neurons, which conducted to the specific cortical loci as nerve impulses. Therefore, direct electrical stimulation of the peripheral nerve endings causes an erroneous sensation to be conducted by the nerve. We have recently generated several transgenic lines of rat in which channelrhodopsin-2 (ChR2) transgene is driven by the Thy-1.2 promoter. In one of them, W-TChR2V4, some neurons were endowed with photosensitivity by the introduction of the ChR2 gene, coding an algal photoreceptor molecule. The DRG neurons expressing ChR2 were immunohistochemically identified using specific antibodies to the markers of mechanoreceptive or nociceptive neurons. Their peripheral nerve endings in the plantar skin as well as the central endings in the spinal cord were also examined. We identified that ChR2 is expressed in a certain population of large neurons in the DRG of W-TChR2V4. On the basis of their morphology and molecular markers, these neurons were classified as mechanoreceptive but not nociceptive. ChR2 was also distributed in their peripheral sensory nerve endings, some of which were closely associated with CK20-positive cells to form Merkel cell-neurite complexes or with S-100-positive cells to form structures like Meissner's corpuscles. These nerve endings are thus suggested to be involved in the sensing of touch. Each W-TChR2V4 rat showed a sensory-evoked behavior in response to blue LED flashes on the plantar skin. It is thus suggested that each rat acquired an unusual sensory modality of sensing blue light through the skin as touch-pressure. This light-evoked somatosensory perception should facilitate study of how the complex tactile sense emerges in the brain.
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Affiliation(s)
- Zhi-Gang Ji
- Department of Developmental Biology and Neuroscience, Tohoku University Graduate School of Life Sciences and JST, CREST, Sendai, Japan
- Tohoku University Basic and Translational Research Centre for Global Brain Science, Sendai, Japan
| | - Shin Ito
- Department of Developmental Biology and Neuroscience, Tohoku University Graduate School of Life Sciences and JST, CREST, Sendai, Japan
- Tohoku University Basic and Translational Research Centre for Global Brain Science, Sendai, Japan
| | - Tatsuya Honjoh
- Department of Developmental Biology and Neuroscience, Tohoku University Graduate School of Life Sciences and JST, CREST, Sendai, Japan
- Tohoku University Basic and Translational Research Centre for Global Brain Science, Sendai, Japan
| | - Hiroyuki Ohta
- Department of Developmental Biology and Neuroscience, Tohoku University Graduate School of Life Sciences and JST, CREST, Sendai, Japan
- Department of Physiology, National Defense Medical College, Tokorozawa, Japan
| | - Toru Ishizuka
- Department of Developmental Biology and Neuroscience, Tohoku University Graduate School of Life Sciences and JST, CREST, Sendai, Japan
| | - Yugo Fukazawa
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Hiromu Yawo
- Department of Developmental Biology and Neuroscience, Tohoku University Graduate School of Life Sciences and JST, CREST, Sendai, Japan
- Tohoku University Basic and Translational Research Centre for Global Brain Science, Sendai, Japan
- Center for Neuroscience, Tohoku University Graduate School of Medicine, Sendai, Japan
- * E-mail:
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Zhang F, Vierock J, Yizhar O, Fenno LE, Tsunoda S, Kianianmomeni A, Prigge M, Berndt A, Cushman J, Polle J, Magnuson J, Hegemann P, Deisseroth K. The microbial opsin family of optogenetic tools. Cell 2012; 147:1446-57. [PMID: 22196724 PMCID: PMC4166436 DOI: 10.1016/j.cell.2011.12.004] [Citation(s) in RCA: 403] [Impact Index Per Article: 33.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Revised: 11/17/2011] [Accepted: 12/05/2011] [Indexed: 11/24/2022]
Abstract
The capture and utilization of light is an exquisitely evolved process. The single-component microbial opsins, although more limited than multicomponent cascades in processing, display unparalleled compactness and speed. Recent advances in understanding microbial opsins have been driven by molecular engineering for optogenetics and by comparative genomics. Here we provide a Primer on these light-activated ion channels and pumps, describe a group of opsins bridging prior categories, and explore the convergence of molecular engineering and genomic discovery for the utilization and understanding of these remarkable molecular machines.
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Affiliation(s)
- Feng Zhang
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA.
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Baluska F, Mancuso S. Deep evolutionary origins of neurobiology: Turning the essence of 'neural' upside-down. Commun Integr Biol 2011; 2:60-5. [PMID: 19513267 DOI: 10.4161/cib.2.1.7620] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2008] [Accepted: 12/15/2008] [Indexed: 01/17/2023] Open
Abstract
It is generally assumed, both in common-sense argumentations and scientific concepts, that brains and neurons represent late evolutionary achievements which are present only in more advanced animals. Here we overview recently published data clearly revealing that our understanding of bacteria, unicellular eukaryotic organisms, plants, brains and neurons, rooted in the Aristotelian philosophy is flawed. Neural aspects of biological systems are obvious already in bacteria and unicellular biological units such as sexual gametes and diverse unicellular eukaryotic organisms. Altogether, processes and activities thought to represent evolutionary 'recent' specializations of the nervous system emerge rather to represent ancient and fundamental cell survival processes.
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Mittelmeier TM, Boyd JS, Lamb MR, Dieckmann CL. Asymmetric properties of the Chlamydomonas reinhardtii cytoskeleton direct rhodopsin photoreceptor localization. J Cell Biol 2011; 193:741-53. [PMID: 21555459 PMCID: PMC3166873 DOI: 10.1083/jcb.201009131] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Accepted: 04/06/2011] [Indexed: 11/22/2022] Open
Abstract
The eyespot of the unicellular green alga Chlamydomonas reinhardtii is a photoreceptive organelle required for phototaxis. Relative to the anterior flagella, the eyespot is asymmetrically positioned adjacent to the daughter four-membered rootlet (D4), a unique bundle of acetylated microtubules extending from the daughter basal body toward the posterior of the cell. Here, we detail the relationship between the rhodopsin eyespot photoreceptor Channelrhodopsin 1 (ChR1) and acetylated microtubules. In wild-type cells, ChR1 was observed in an equatorial patch adjacent to D4 near the end of the acetylated microtubules and along the D4 rootlet. In cells with cytoskeletal protein mutations, supernumerary ChR1 patches remained adjacent to acetylated microtubules. In mlt1 (multieyed) mutant cells, supernumerary photoreceptor patches were not restricted to the D4 rootlet, and more anterior eyespots correlated with shorter acetylated microtubule rootlets. The data suggest a model in which photoreceptor localization is dependent on microtubule-based trafficking selective for the D4 rootlet, which is perturbed in mlt1 mutant cells.
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Affiliation(s)
- Telsa M. Mittelmeier
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721
| | - Joseph S. Boyd
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721
| | - Mary Rose Lamb
- Department of Biology, University of Puget Sound, Tacoma, WA 98416
| | - Carol L. Dieckmann
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721
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31
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Panneels V, Kock I, Krijnse-Locker J, Rezgaoui M, Sinning I. Drosophila photoreceptor cells exploited for the production of eukaryotic membrane proteins: receptors, transporters and channels. PLoS One 2011; 6:e18478. [PMID: 21494623 PMCID: PMC3072989 DOI: 10.1371/journal.pone.0018478] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2010] [Accepted: 03/01/2011] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Membrane proteins (MPs) play key roles in signal transduction. However, understanding their function at a molecular level is mostly hampered by the lack of protein in suitable amount and quality. Despite impressive developments in the expression of prokaryotic MPs, eukaryotic MP production has lagged behind and there is a need for new expression strategies. In a pilot study, we produced a Drosophila glutamate receptor specifically in the eyes of transgenic flies, exploiting the naturally abundant membrane stacks in the photoreceptor cells (PRCs). Now we address the question whether the PRCs also process different classes of medically relevant target MPs which were so far notoriously difficult to handle with conventional expression strategies. PRINCIPAL FINDINGS We describe the homologous and heterologous expression of 10 different targets from the three major MP classes--G protein-coupled receptors (GPCRs), transporters and channels in Drosophila eyes. PRCs offered an extraordinary capacity to produce, fold and accommodate massive amounts of MPs. The expression of some MPs reached similar levels as the endogenous rhodopsin, indicating that the PRC membranes were almost unsaturable. Expression of endogenous rhodopsin was not affected by the target MPs and both could coexist in the membrane stacks. Heterologous expression levels reached about 270 to 500 pmol/mg total MP, resulting in 0.2-0.4 mg purified target MP from 1 g of fly heads. The metabotropic glutamate receptor and human serotonin transporter--both involved in synaptic transmission--showed native pharmacological characteristics and could be purified to homogeneity as a prerequisite for further studies. SIGNIFICANCE We demonstrate expression in Drosophila PRCs as an efficient and inexpensive tool for the large scale production of functional eukaryotic MPs. The fly eye system offers a number of advantages over conventional expression systems and paves the way for in-depth analyses of eukaryotic MPs that have so far not been accessible to biochemical and biophysical studies.
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Affiliation(s)
- Valérie Panneels
- Department of Structural Biology, Heidelberg University Biochemistry Center (BZH), Heidelberg, Germany
| | - Ines Kock
- Department of Structural Biology, Heidelberg University Biochemistry Center (BZH), Heidelberg, Germany
| | - Jacomine Krijnse-Locker
- Department of Infectious Diseases and Core Facility Electron Microscopy (EMCF), University of Heidelberg, Heidelberg, Germany
| | - Meriem Rezgaoui
- Department of Structural Biology, Heidelberg University Biochemistry Center (BZH), Heidelberg, Germany
| | - Irmgard Sinning
- Department of Structural Biology, Heidelberg University Biochemistry Center (BZH), Heidelberg, Germany
- * E-mail:
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Sineshchekov OA, Govorunova EG, Spudich JL. Photosensory functions of channelrhodopsins in native algal cells. Photochem Photobiol 2009; 85:556-63. [PMID: 19222796 DOI: 10.1111/j.1751-1097.2008.00524.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Photomotility responses in flagellate alga are mediated by two types of sensory rhodopsins (A and B). Upon photoexcitation they trigger a cascade of transmembrane currents which provide sensory transduction of light stimuli. Both types of algal sensory rhodopsins demonstrate light-gated ion channel activities when heterologously expressed in animal cells, and therefore they have been given the alternative names channelrhodopsin 1 and 2. In recent publications their channel activity has been assumed to initiate the transduction chain in the native algal cells. Here we present data showing that: (1) the modes of action of both types of sensory rhodopsins are different in native cells such as Chlamydomonas reinhardtii than in heterologous expression systems, and also differ between the two types of rhodopsins; (2) the primary function of Type B sensory rhodopsin (channelrhodopsin-2) is biochemical activation of secondary Ca(2+)-channels with evidence for amplification and a diffusible messenger, sufficient for mediating phototaxis and photophobic responses; (3) Type A sensory rhodopsin (channelrhodopsin-1) mediates avoidance responses by direct channel activity under high light intensities and exhibits low-efficiency amplification. These dual functions of algal sensory rhodopsins enable the highly sophisticated photobehavior of algal cells.
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Affiliation(s)
- Oleg A Sineshchekov
- Department of Biochemistry and Molecular Biology, University of Texas Medical School, Houston, TX, USA.
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33
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Abstract
Studies of ion channels have for long been dominated by the animalcentric, if not anthropocentric, view of physiology. The structures and activities of ion channels had, however, evolved long before the appearance of complex multicellular organisms on earth. The diversity of ion channels existing in cellular membranes of prokaryotes is a good example. Although at first it may appear as a paradox that most of what we know about the structure of eukaryotic ion channels is based on the structure of bacterial channels, this should not be surprising given the evolutionary relatedness of all living organisms and suitability of microbial cells for structural studies of biological macromolecules in a laboratory environment. Genome sequences of the human as well as various microbial, plant, and animal organisms unambiguously established the evolutionary links, whereas crystallographic studies of the structures of major types of ion channels published over the last decade clearly demonstrated the advantage of using microbes as experimental organisms. The purpose of this review is not only to provide an account of acquired knowledge on microbial ion channels but also to show that the study of microbes and their ion channels may also hold a key to solving unresolved molecular mysteries in the future.
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Affiliation(s)
- Boris Martinac
- School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia.
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34
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Govorunova EG, Voytsekh OO, Sineshchekov OA. Changes in photoreceptor currents and their sensitivity to the chemoeffector tryptone during gamete mating in Chlamydomonas reinhardtii. PLANTA 2007; 225:441-9. [PMID: 16896790 DOI: 10.1007/s00425-006-0357-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2006] [Accepted: 07/07/2006] [Indexed: 05/11/2023]
Abstract
Chlamydomonas reinhardtii Dangeard generates photoreceptor currents (PCs) upon light excitation. These currents play a key role in the signal transduction chain for photomotility responses. We have previously found that inhibition of PCs by tryptone occurs only in gametes that display chemotaxis toward this agent, and is not observed in chemotactically insensitive vegetative cells. Here we show that the sensitivity to tryptone is characteristic of gametes of both mating types, and examine the influence of gamete mating on PCs and their sensitivity to tryptone. The amplitude of PCs increases after cell fusion, but the sensitivity of these currents to tryptone decreases upon flagellar adhesion and/or an increase in the intracellular cAMP concentration. Net chemotaxis toward tryptone is reduced in young zygotes compared to gametes. We conclude that gamete mating leads to rapid inactivation of a gamete-specific chemosensory system.
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Affiliation(s)
- Elena G Govorunova
- Biology Department, Moscow State University, Vorobievy Gory, 119992, Moscow, Russia.
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35
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Bi A, Cui J, Ma YP, Olshevskaya E, Pu M, Dizhoor AM, Pan ZH. Ectopic expression of a microbial-type rhodopsin restores visual responses in mice with photoreceptor degeneration. Neuron 2006; 50:23-33. [PMID: 16600853 PMCID: PMC1459045 DOI: 10.1016/j.neuron.2006.02.026] [Citation(s) in RCA: 500] [Impact Index Per Article: 27.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2005] [Revised: 01/12/2006] [Accepted: 02/23/2006] [Indexed: 11/21/2022]
Abstract
The death of photoreceptor cells caused by retinal degenerative diseases often results in a complete loss of retinal responses to light. We explore the feasibility of converting inner retinal neurons to photosensitive cells as a possible strategy for imparting light sensitivity to retinas lacking rods and cones. Using delivery by an adeno-associated viral vector, here, we show that long-term expression of a microbial-type rhodopsin, channelrhodopsin-2 (ChR2), can be achieved in rodent inner retinal neurons in vivo. Furthermore, we demonstrate that expression of ChR2 in surviving inner retinal neurons of a mouse with photoreceptor degeneration can restore the ability of the retina to encode light signals and transmit the light signals to the visual cortex. Thus, expression of microbial-type channelrhodopsins, such as ChR2, in surviving inner retinal neurons is a potential strategy for the restoration of vision after rod and cone degeneration.
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Affiliation(s)
- Anding Bi
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, Michigan 48201, USA
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36
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Eberhard S, Jain M, Im CS, Pollock S, Shrager J, Lin Y, Peek AS, Grossman AR. Generation of an oligonucleotide array for analysis of gene expression in Chlamydomonas reinhardtii. Curr Genet 2005; 49:106-24. [PMID: 16333659 DOI: 10.1007/s00294-005-0041-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2005] [Revised: 10/24/2005] [Accepted: 10/25/2005] [Indexed: 01/08/2023]
Abstract
The availability of genome sequences makes it possible to develop microarrays that can be used for profiling gene expression over developmental time, as organisms respond to environmental challenges, and for comparison between wild-type and mutant strains under various conditions. The desired characteristics of microarrays (intense signals, hybridization specificity and extensive coverage of the transcriptome) were not fully met by the previous Chlamydomonas reinhardtii microarray: probes derived from cDNA sequences (approximately 300 bp) were prone to some nonspecific cross-hybridization and coverage of the transcriptome was only approximately 20%. The near completion of the C. reinhardtii nuclear genome sequence and the availability of extensive cDNA information have made it feasible to improve upon these aspects. After developing a protocol for selecting a high-quality unigene set representing all known expressed sequences, oligonucleotides were designed and a microarray with approximately 10,000 unique array elements (approximately 70 bp) covering 87% of the known transcriptome was developed. This microarray will enable researchers to generate a global view of gene expression in C. reinhardtii. Furthermore, the detailed description of the protocol for selecting a unigene set and the design of oligonucleotides may be of interest for laboratories interested in developing microarrays for organisms whose genome sequences are not yet completed (but are nearing completion).
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Affiliation(s)
- Stephan Eberhard
- Department of Plant Biology, The Carnegie Institution, 260 Panama Street, Stanford, CA, 94305, USA.
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37
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Abstract
Two rhodopsins with intrinsic ion conductance have been identified recently in Chlamydomonas reinhardtii. They were named "channelrhodopsins" ChR1 and ChR2. Both were expressed in Xenopus laevis oocytes, and their properties were studied qualitatively by two electrode voltage clamp techniques. ChR1 is specific for H+, whereas ChR2 conducts Na+, K+, Ca2+, and guanidinium. ChR2 responds to the onset of light with a peak conductance, followed by a smaller steady-state conductance. Upon a second stimulation, the peak is smaller and recovers to full size faster at high external pH. ChR1 was reported to respond with a steady-state conductance only but is demonstrated here to have a peak conductance at high light intensities too. We analyzed quantitatively the light-induced conductance of ChR1 and developed a reaction scheme that describes the photocurrent kinetics at various light conditions. ChR1 exists in two dark states, D1 and D2, that photoisomerize to the conducting states M1 and M2, respectively. Dark-adapted ChR1 is completely arrested in D1. M1 converts into D1 within milliseconds but, in addition, equilibrates with the second conducting state M2 that decays to the second dark state D2. Thus, light-adapted ChR1 represents a mixture of D1 and D2. D2 thermally reconverts to D1 in minutes, i.e., much slower than any reaction of the two photocycles.
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Affiliation(s)
- Peter Hegemann
- Experimentelle Biophysik, Fachbereich für Biologie, Humboldt-Universität zu Berlin, 10115 Berlin, Germany.
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38
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Sineshchekov OA, Govorunova EG, Jung KH, Zauner S, Maier UG, Spudich JL. Rhodopsin-mediated photoreception in cryptophyte flagellates. Biophys J 2005; 89:4310-9. [PMID: 16150961 PMCID: PMC1366995 DOI: 10.1529/biophysj.105.070920] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We show that phototaxis in cryptophytes is likely mediated by a two-rhodopsin-based photosensory mechanism similar to that recently demonstrated in the green alga Chlamydomonas reinhardtii, and for the first time, to our knowledge, report spectroscopic and charge movement properties of cryptophyte algal rhodopsins. The marine cryptophyte Guillardia theta exhibits positive phototaxis with maximum sensitivity at 450 nm and a secondary band above 500 nm. Variability of the relative sensitivities at these wavelengths and light-dependent inhibition of phototaxis in both bands by hydroxylamine suggest the involvement of two rhodopsin photoreceptors. In the related freshwater cryptophyte Cryptomonas sp. two photoreceptor currents similar to those mediated by the two sensory rhodopsins in green algae were recorded. Two cDNA sequences from G. theta and one from Cryptomonas encoding proteins homologous to type 1 opsins were identified. The photochemical reaction cycle of one Escherichia-coli-expressed rhodopsin from G. theta (GtR1) involves K-, M-, and O-like intermediates with relatively slow (approximately 80 ms) turnover time. GtR1 shows lack of light-driven proton pumping activity in E. coli cells, although carboxylated residues are at the positions of the Schiff base proton acceptor and donor as in proton pumping rhodopsins. The absorption spectrum, corresponding to the long-wavelength band of phototaxis sensitivity, makes this pigment a candidate for one of the G. theta sensory rhodopsins. A second rhodopsin from G. theta (GtR2) and the one from Cryptomonas have noncarboxylated residues at the donor position as in known sensory rhodopsins.
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Affiliation(s)
- Oleg A Sineshchekov
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Medical School, Houston, Texas 77030, USA.
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