1
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Matsunami-Nakamura R, Tamogami J, Takeguchi M, Ishikawa J, Kikukawa T, Kamo N, Nara T. Key determinants for signaling in the sensory rhodopsin II/transducer complex are different between Halobacterium salinarum and Natronomonas pharaonis. FEBS Lett 2023; 597:2334-2344. [PMID: 37532685 DOI: 10.1002/1873-3468.14711] [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] [Received: 07/03/2023] [Revised: 07/19/2023] [Accepted: 07/20/2023] [Indexed: 08/04/2023]
Abstract
The cell membrane of Halobacterium salinarum contains a retinal-binding photoreceptor, sensory rhodopsin II (HsSRII), coupled with its cognate transducer (HsHtrII), allowing repellent phototaxis behavior for shorter wavelength light. Previous studies on SRII from Natronomonas pharaonis (NpSRII) pointed out the importance of the hydrogen bonding interaction between Thr204NpSRII and Tyr174NpSRII in signal transfer from SRII to HtrII. Here, we investigated the effect on phototactic function by replacing residues in HsSRII corresponding to Thr204NpSRII and Tyr174NpSRII . Whereas replacement of either residue altered the photocycle kinetics, introduction of any mutations at Ser201HsSRII and Tyr171HsSRII did not eliminate negative phototaxis function. These observations imply the possibility of the presence of an unidentified molecular mechanism for photophobic signal transduction differing from NpSRII-NpHtrII.
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Affiliation(s)
| | - Jun Tamogami
- College of Pharmaceutical Sciences, Matsuyama University, Japan
| | - Miki Takeguchi
- College of Pharmaceutical Sciences, Matsuyama University, Japan
| | - Junya Ishikawa
- College of Pharmaceutical Sciences, Matsuyama University, Japan
| | - Takashi Kikukawa
- Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan
| | - Naoki Kamo
- College of Pharmaceutical Sciences, Matsuyama University, Japan
- Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan
| | - Toshifumi Nara
- College of Pharmaceutical Sciences, Matsuyama University, Japan
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2
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Kikukawa T. Unique Cl - pump rhodopsin with close similarity to H + pump rhodopsin. Biophys Physicobiol 2021; 18:317-326. [PMID: 35087698 PMCID: PMC8756000 DOI: 10.2142/biophysico.bppb-v18.038] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 12/20/2021] [Indexed: 12/01/2022] Open
Abstract
Microbial rhodopsin is a ubiquitous membrane protein in unicellular microorganisms. Similar to animal rhodopsin, this protein consists of seven transmembrane helices and the chromophore retinal. However, unlike animal rhodopsin, microbial rhodopsin acts as not only a photosignal receptor but also a light-activated ion transporter and light-switchable enzyme. In this article, the third Cl- pump microbial rhodopsin will be introduced. The physiological importance of Cl- pumps has not been clarified. Despite this, their mechanisms, especially that of the first Cl- pump halorhodopsin (HR), have been studied to characterize them as model proteins for membrane anion transporters. The third Cl- pump defines a phylogenetic cluster distinct from other microbial rhodopsins. However, this Cl- pump conserves characteristic residues for not only the Cl- pump HR but also the H+ pump bacteriorhodopsin (BR). Reflecting close similarity to BR, the third Cl- pump begins to pump H+ outwardly after single amino acid replacement. This mutation activates several residues that have no roles in the original Cl- pump function but act as important H+ relay residues in the H+ pump mutant. Thus, the third Cl- pump might be the model protein for functional differentiation because this rhodopsin seems to be the Cl- pump occurring immediately after functional differentiation from the BR-type H+ pump.
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Affiliation(s)
- Takashi Kikukawa
- Faculty of Advanced Life Science, Hokkaido University, Sapporo, Hokkaido 060–0810, Japan
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3
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Inoue K. Diversity, Mechanism, and Optogenetic Application of Light-Driven Ion Pump Rhodopsins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1293:89-126. [PMID: 33398809 DOI: 10.1007/978-981-15-8763-4_6] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Ion-transporting microbial rhodopsins are widely used as major molecular tools in optogenetics. They are categorized into light-gated ion channels and light-driven ion pumps. While the former passively transport various types of cations and anions in a light-dependent manner, light-driven ion pumps actively transport specific ions, such as H+, Na+, Cl-, against electrophysiological potential by using light energy. Since the ion transport by these pumps induces hyperpolarization of membrane potential and inhibit neural firing, light-driven ion-pumping rhodopsins are mostly applied as inhibitory optogenetics tools. Recent progress in genome and metagenome sequencing identified more than several thousands of ion-pumping rhodopsins from a wide variety of microbes, and functional characterization studies has been revealing many new types of light-driven ion pumps one after another. Since light-gated channels were reviewed in other chapters in this book, here the rapid progress in functional characterization, molecular mechanism study, and optogenetic application of ion-pumping rhodopsins were reviewed.
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Affiliation(s)
- Keiichi Inoue
- The Institute for Solid State Physics, The University of Tokyo, Chiba, Japan.
- PRESTO, Japan Science and Technology Agency, Saitama, Japan.
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4
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Functional Mechanism of Cl --Pump Rhodopsin and Its Conversion into H + Pump. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1293:55-71. [PMID: 33398807 DOI: 10.1007/978-981-15-8763-4_4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Cl--pump rhodopsin is the second discovered microbial rhodopsin. Although its physiological role has not been fully clarified, its functional mechanism has been studied as a model for anion transporters. After the success of neural activation by channel rhodopsin, the first Cl--pump halorhodopsin (HR) had become widely used as a neural silencer. The emergence of artificial and natural anion channel rhodopsins lowered the importance of HRs. However, the longer absorption maxima of approximately 585-600 nm for HRs are still advantageous for applications in mammalian brains and collaborations with neural activators possessing shorter absorption maxima. In this chapter, the variation and functional mechanisms of Cl- pumps are summarized. After the discovery of HR, Cl--pump rhodopsins were confined to only extremely halophilic haloarchaea. However, after 2014, two Cl--pump groups were newly discovered in marine and terrestrial bacteria. These Cl- pumps are phylogenetically distinct from HRs and have unique characteristics. In particular, the most recently identified Cl- pump has close similarity with the H+ pump bacteriorhodopsin and was converted into the H+ pump by a single amino acid replacement.
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5
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Haque S, Kikukawa T, Tamaoki N. Photoisomerization of azobenzene units drives the photochemical reaction cycles of proteorhodopsin and bacteriorhodopsin analogues. Org Biomol Chem 2020; 18:6312-6327. [PMID: 32748909 DOI: 10.1039/d0ob01486a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this study we substituted the retinal units in proteorhodopsin (PR) and bacteriorhodopsin (BR) with azo chromophores to investigate the mechanism of photoinduced proton pumping in rhodopsins and potentially develop new artificial molecular pumps. We used an indium tin oxide electrode to investigate the photoinduced proton transfer of the azo analogues of PR and BR. We also employed flash photolysis to determine the characteristic photocycles, comprising multiple transient intermediates, of the azo chromophore-bound PR and BR. Moreover, our studies of the photoinduced proton pumping functions of azo-proteoopsin and azo-bacterioopsin complexes revealed that they did not pump protons upon illumination, even though they underwent photoinduced proton transfer and the characteristic photocycle. Mutational analysis suggested that the proton pumping malfunction of the azo analogues of PR and BR resulted from the absence of proton transfer reactions through cytoplasmic channels, even though these reactions were evoked in extracellular channels. Based on our experimental findings, we propose herein a putative model of the proton transfer reaction mechanism for the azo analogues of PR and BR.
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Affiliation(s)
- Shariful Haque
- Research Institute for Electronic Science, Hokkaido University, Kita 20, Nishi 10, Kita-ku, Sapporo, Japan. and Graduate School of Life Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, Japan
| | - Takashi Kikukawa
- Faculty of Advanced Life Science, Hokkaido University, Sapporo, 060-0810, Japan and Global Station for Soft Matter, Global Institution for Collaborative Research and Education, Hokkaido University, Sapporo, 001-0021, Japan
| | - Nobuyuki Tamaoki
- Research Institute for Electronic Science, Hokkaido University, Kita 20, Nishi 10, Kita-ku, Sapporo, Japan. and Graduate School of Life Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, Japan
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6
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Kouyama T, Ihara K, Maki K, Chan SK. Three-Step Isomerization of the Retinal Chromophore during the Anion Pumping Cycle of Halorhodopsin. Biochemistry 2018; 57:6013-6026. [PMID: 30211543 DOI: 10.1021/acs.biochem.8b00631] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The anion pumping cycle of halorhodopsin from Natronomonas pharaonis ( pHR) is initiated when the all- trans/15- anti isomer of retinal is photoisomerized into the 13- cis/15- anti configuration. A recent crystallographic study suggested that a reaction state with 13- cis/15- syn retinal occurred during the anion release process, i.e., after the N state with the 13- cis/15- anti retinal and before the O state with all- trans/15- anti retinal. In this study, we investigated the retinal isomeric composition in a long-living reaction state at various bromide ion concentrations. It was found that the 13- cis isomer (csHR'), in which the absorption spectrum was blue-shifted by ∼8 nm compared with that of the trans isomer (taHR), accumulated significantly when a cold suspension of pHR-rich claret membranes in 4 M NaBr was illuminated with continuous light. Analysis of flash-induced absorption changes suggested that the branching of the trans photocycle into the 13- cis isomer (csHR') occurs during the decay of an O-like state (O') with 13- cis/15- syn retinal; i.e., O' can decay to either csHR' or O with all- trans/15- anti retinal. The efficiency of the branching reaction was found to be dependent on the bromide ion concentration. At a very high bromide ion concentration, the anion pumping cycle is described by the scheme taHR -( hν) → K → L1a ↔ L1b ↔ N ↔ N' ↔ O' ↔ csHR' ↔ taHR. At a low bromide ion concentration, on the other hand, O' decays into taHR via O.
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Affiliation(s)
- Tsutomu Kouyama
- Department of Physics, Graduate School of Science , Nagoya University , Furo-cho, Chikusa-ku, Nagoya 464-8602 , Japan
| | - Kunio Ihara
- Center for Gene Research , Nagoya University , Nagoya 464-8602 , Japan
| | - Kosuke Maki
- Department of Physics, Graduate School of Science , Nagoya University , Furo-cho, Chikusa-ku, Nagoya 464-8602 , Japan
| | - Siu Kit Chan
- Department of Physics, Graduate School of Science , Nagoya University , Furo-cho, Chikusa-ku, Nagoya 464-8602 , Japan
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7
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Sakajiri Y, Sugano E, Watanabe Y, Sakajiri T, Tabata K, Kikuchi T, Tomita H. Natronomonas pharaonis halorhodopsin Ser81 plays a role in maintaining chloride ions near the Schiff base. Biochem Biophys Res Commun 2018; 503:2326-2332. [PMID: 29964009 DOI: 10.1016/j.bbrc.2018.06.156] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 06/27/2018] [Indexed: 02/02/2023]
Abstract
Optogenetic technologies have often been used as tools for neuronal activation or silencing by light. Natronomonas pharaonis halorhodopsin (NpHR) is a light-driven chloride ion pump. Upon light absorption, a chloride ion passes through the cell membrane, which is accompanied by the temporary binding of a chloride ion with Thr126 at binding site-1 (BS1) near the protonated Schiff base in NpHR. However, the mechanism of stabilization of the binding state between a chloride ion and BS1 has not been investigated. Therefore, to identify a key component of the chloride ion transport pathway as well as to acquire dynamic information about the chloride ion-BS1 binding state, we performed a rough analysis of the chloride ion pathway shape followed by molecular dynamics (MD) simulations for both wild-type and mutant NpHR structures. The MD simulations showed that the hydrogen bond between Thr126 and the chloride ion was retained in the wild-type protein, while the chloride ion could not be retained at and tended to leave BS1 in the S81A mutant. We found that the direction of the Thr126 side chain was fixed by a hydroxyl group of Ser81 through a hydrogen bond and that Thr126 bound to a chloride ion in the wild-type protein, while this interaction was lost in the S81A mutant, resulting in rotation of the Thr126 side chain and reduction in the interaction between Thr126 and a chloride ion. To confirm the role of S81, patch clamp recordings were performed using cells expressing NpHR S81A mutant protein. Considered together with the results that the NpHR S81A-expressing cells did not undergo hyperpolarization under light stimulation, our results indicate that Ser81 plays a key role in chloride migration. Our findings might be relevant to ongoing clinical trials using optogenetic gene therapy in blind patients.
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Affiliation(s)
- Yuko Sakajiri
- The United Graduate School of Agricultural Sciences, Iwate University, 3-18-8 Ueda, Morioka, Iwate, 020-8550, Japan.
| | - Eriko Sugano
- The United Graduate School of Agricultural Sciences, Iwate University, 3-18-8 Ueda, Morioka, Iwate, 020-8550, Japan; Laboratory of Visual Neuroscience, Graduate Course in Biological Sciences, Iwate University, 4-3-5 Ueda, Morioka, Iwate, 020-8551, Japan.
| | - Yoshito Watanabe
- Laboratory of Visual Neuroscience, Graduate Course in Biological Sciences, Iwate University, 4-3-5 Ueda, Morioka, Iwate, 020-8551, Japan.
| | - Tetsuya Sakajiri
- Department of Applied Life Sciences, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka, 599-8531, Japan.
| | - Kitako Tabata
- Laboratory of Visual Neuroscience, Graduate Course in Biological Sciences, Iwate University, 4-3-5 Ueda, Morioka, Iwate, 020-8551, Japan.
| | - Takeshi Kikuchi
- Department of Bioinformatics, College of Life Sciences, Ritsumeikan University, 1-1-1 Noji-higashi, Kusatsu Shiga, 525-8577, Japan.
| | - Hiroshi Tomita
- The United Graduate School of Agricultural Sciences, Iwate University, 3-18-8 Ueda, Morioka, Iwate, 020-8550, Japan; Laboratory of Visual Neuroscience, Graduate Course in Biological Sciences, Iwate University, 4-3-5 Ueda, Morioka, Iwate, 020-8551, Japan; Clinical Research, Innovation and Education Center, Tohoku University Hospital, 1-1 Seiryo, Aoba, Sendai, Miyagi, 980-8574, Japan.
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8
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Tamogami J, Kikukawa T, Ohkawa K, Ohsawa N, Nara T, Demura M, Miyauchi S, Kimura-Someya T, Shirouzu M, Yokoyama S, Shimono K, Kamo N. Interhelical interactions between D92 and C218 in the cytoplasmic domain regulate proton uptake upon N-decay in the proton transport of Acetabularia rhodopsin II. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2018; 183:35-45. [PMID: 29684719 DOI: 10.1016/j.jphotobiol.2018.04.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 04/07/2018] [Accepted: 04/07/2018] [Indexed: 01/01/2023]
Abstract
Acetabularia rhodopsin II (ARII or Ace2), an outward light-driven algal proton pump found in the giant unicellular marine alga Acetabularia acetabulum, has a unique property in the cytoplasmic (CP) side of its channel. The X-ray crystal structure of ARII in a dark state suggested the formation of an interhelical hydrogen bond between C218ARII and D92ARII, an internal proton donor to the Schiff base (Wada et al., 2011). In this report, we investigated the photocycles of two mutants at position C218ARII: C218AARII which disrupts the interaction with D92ARII, and C218SARII which potentially forms a stronger hydrogen bond. Both mutants exhibited slower photocycles compared to the wild-type pump. Together with several kinetic changes of the photoproducts in the first half of the photocycle, these replacements led to specific retardation of the N-to-O transition in the second half of the photocycle. In addition, measurements of the flash-induced proton uptake and release using a pH-sensitive indium-tin oxide electrode revealed a concomitant delay in the proton uptake. These observations strongly suggest the importance of a native weak hydrogen bond between C218ARII and D92ARII for proper proton translocation in the CP channel during N-decay. A putative role for the D92ARII-C218ARII interhelical hydrogen bond in the function of ARII is discussed.
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Affiliation(s)
- Jun Tamogami
- College of Pharmaceutical Sciences, Matsuyama University, Matsuyama, Ehime 790-8578, Japan.
| | - Takashi Kikukawa
- Faculty of Advanced Life Science, Hokkaido University, Sapporo 060-0810, Japan; Global Station for Soft Matter, Global Institution for Collaborative Research and Education, Hokkaido University, Sapporo 001-0021, Japan
| | - Keisuke Ohkawa
- College of Pharmaceutical Sciences, Matsuyama University, Matsuyama, Ehime 790-8578, Japan
| | - Noboru Ohsawa
- RIKEN Systems and Structural Biology Center, Yokohama 230-0045, Japan; RIKEN Center for Life Science Technologies, Yokohama 230-0045, Japan
| | - Toshifumi Nara
- College of Pharmaceutical Sciences, Matsuyama University, Matsuyama, Ehime 790-8578, Japan
| | - Makoto Demura
- Faculty of Advanced Life Science, Hokkaido University, Sapporo 060-0810, Japan; Global Station for Soft Matter, Global Institution for Collaborative Research and Education, Hokkaido University, Sapporo 001-0021, Japan
| | - Seiji Miyauchi
- College of Pharmaceutical Sciences, Matsuyama University, Matsuyama, Ehime 790-8578, Japan; Graduate School of Pharmaceutical Sciences, Toho University, Funabashi, Chiba 274-8510, Japan
| | - Tomomi Kimura-Someya
- RIKEN Systems and Structural Biology Center, Yokohama 230-0045, Japan; RIKEN Center for Life Science Technologies, Yokohama 230-0045, Japan
| | - Mikako Shirouzu
- RIKEN Systems and Structural Biology Center, Yokohama 230-0045, Japan; RIKEN Center for Life Science Technologies, Yokohama 230-0045, Japan
| | - Shigeyuki Yokoyama
- RIKEN Systems and Structural Biology Center, Yokohama 230-0045, Japan; RIKEN Structural Biology Laboratory, Yokohama 230-0045, Japan
| | - Kazumi Shimono
- College of Pharmaceutical Sciences, Matsuyama University, Matsuyama, Ehime 790-8578, Japan; Graduate School of Pharmaceutical Sciences, Toho University, Funabashi, Chiba 274-8510, Japan
| | - Naoki Kamo
- College of Pharmaceutical Sciences, Matsuyama University, Matsuyama, Ehime 790-8578, Japan; Faculty of Advanced Life Science, Hokkaido University, Sapporo 060-0810, Japan
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9
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Harris A, Saita M, Resler T, Hughes-Visentin A, Maia R, Pranga-Sellnau F, Bondar AN, Heberle J, Brown LS. Molecular details of the unique mechanism of chloride transport by a cyanobacterial rhodopsin. Phys Chem Chem Phys 2018; 20:3184-3199. [PMID: 29057415 DOI: 10.1039/c7cp06068h] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Microbial rhodopsins are well known as versatile and ubiquitous light-driven ion transporters and photosensors. While the proton transport mechanism has been studied in great detail, much less is known about various modes of anion transport. Until recently, only two main groups of light-driven anion pumps were known, archaeal halorhodopsins (HRs) and bacterial chloride pumps (known as ClRs or NTQs). Last year, another group of cyanobacterial anion pumps with a very distinct primary structure was reported. Here, we studied the chloride-transporting photocycle of a representative of this new group, Mastigocladopsis repens rhodopsin (MastR), using time-resolved spectroscopy in the infrared and visible ranges and site-directed mutagenesis. We found that, in accordance with its unique amino acid sequence containing many polar residues in the transmembrane region of the protein, its photocycle features a number of unusual molecular events not known for other anion-pumping rhodopsins. It appears that light-driven chloride ion transfers by MastR are coupled with translocation of protons and water molecules as well as perturbation of several polar sidechains. Of particular interest is transient deprotonation of Asp-85, homologous to the cytoplasmic proton donor of light-driven proton pumps (such as Asp-96 of bacteriorhodopsin), which may serve as a regulatory mechanism.
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Affiliation(s)
- Andrew Harris
- Department of Physics and Biophysics Interdepartmental Group, University of Guelph, 50 Stone Road East, Guelph, Ontario N1G 2W1, Canada.
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10
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Chen XR, Huang YC, Yi HP, Yang CS. A Unique Light-Driven Proton Transportation Signal in Halorhodopsin from Natronomonas pharaonis. Biophys J 2017; 111:2600-2607. [PMID: 28002736 DOI: 10.1016/j.bpj.2016.11.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Revised: 11/03/2016] [Accepted: 11/07/2016] [Indexed: 11/26/2022] Open
Abstract
Halorhodopsin (HR) is a seven-transmembrane retinylidene protein from haloarchaea that is commonly known to function as a light-driven inward chloride pump. However, previous studies have indicated that despite the general characteristics that most HRs share, HRs from distinct species differ in many aspects. We present indium-tin-oxide-based photocurrent measurements that reveal a light-induced signal generated by proton release that is observed solely in NpHR via purified protein-based assays, demonstrating that indeed HRs are not all identical. We conducted mutagenesis studies on several conserved residues that are considered critical for chloride stability among HRs. Intriguingly, the photocurrent signals were eliminated after specific point mutations. We propose an NpHR light-driven, cytoplasmic-side proton circulation model to explain the unique light-induced photocurrent recorded in NpHR. Notably, the photocurrent and various photocycle intermediates were recorded simultaneously. This approach provides a high-resolution method for further investigations of the proton-assisted chloride translocation mechanism.
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Affiliation(s)
- Xiao-Ru Chen
- Department of Biochemical Science and Technology, National Taiwan University, Taipei, Taiwan
| | - Yuan-Chi Huang
- Department of Biochemical Science and Technology, National Taiwan University, Taipei, Taiwan
| | - Hsiu-Ping Yi
- Department of Biochemical Science and Technology, National Taiwan University, Taipei, Taiwan
| | - Chii-Shen Yang
- Department of Biochemical Science and Technology, National Taiwan University, Taipei, Taiwan.
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11
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Tsukamoto T, Yoshizawa S, Kikukawa T, Demura M, Sudo Y. Implications for the Light-Driven Chloride Ion Transport Mechanism of Nonlabens marinus Rhodopsin 3 by Its Photochemical Characteristics. J Phys Chem B 2017; 121:2027-2038. [PMID: 28194973 DOI: 10.1021/acs.jpcb.6b11101] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Several new retinal-based photoreceptor proteins that act as light-driven electrogenic halide ion pumps have recently been discovered. Some of them, called "NTQ" rhodopsins, contain a conserved Asn-Thr-Gln motif in the third or C-helix. In this study, we investigated the photochemical characteristics of an NTQ rhodopsin, Nonlabens marinus rhodopsin 3 (NM-R3), which was discovered in the N. marinus S1-08T strain, using static and time-resolved spectroscopic techniques. We demonstrate that NM-R3 binds a Cl- in the vicinity of the retinal chromophore accompanied by a spectral blueshift from 568 nm in the absence of Cl- to 534 nm in the presence of Cl-. From the Cl- concentration dependence, we estimated the affinity (dissociation constant, Kd) for Cl- in the original state as 24 mM, which is ca. 10 times weaker than that of archaeal halorhodopsins but ca. 3 times stronger than that of a marine bacterial Cl- pumping rhodopsin (C1R). NM-R3 showed no dark-light adaptation of the retinal chromophore and predominantly possessed an all-trans-retinal, which is responsible for the light-driven Cl- pump function. Flash-photolysis experiments suggest that NM-R3 passes through five or six photochemically distinct intermediates (K, L(N), O1, O2, and NM-R3'). From these results, we assume that the Cl- is released and taken up during the L(N)-O1 transition from a transiently formed cytoplasmic (CP) binding site and the O2-NM-R3' or the NM-R3'-original NM-R3 transitions from the extracellular (EC) side, respectively. We propose a mechanism for the Cl- transport by NM-R3 based on our results and its recently reported crystal structure.
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Affiliation(s)
- Takashi Tsukamoto
- Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University , 700-8530 Okayama, Japan
| | - Susumu Yoshizawa
- Atmosphere and Ocean Research Institute, The University of Tokyo , Chiba 277-8564, Japan
| | | | | | - Yuki Sudo
- Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University , 700-8530 Okayama, Japan
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12
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Kouyama T, Kawaguchi H, Nakanishi T, Kubo H, Murakami M. Crystal structures of the L1, L2, N, and O states of pharaonis halorhodopsin. Biophys J 2016; 108:2680-90. [PMID: 26039169 PMCID: PMC4457492 DOI: 10.1016/j.bpj.2015.04.027] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Revised: 04/17/2015] [Accepted: 04/20/2015] [Indexed: 01/15/2023] Open
Abstract
Halorhodopsin from Natronomonas pharaonis (pHR) functions as a light-driven halide ion pump. In the presence of halide ions, the photochemical reaction of pHR is described by the scheme: K→ L1 → L2 → N → O → pHR′ → pHR. Here, we report light-induced structural changes of the pHR-bromide complex observed in the C2 crystal. In the L1-to-L2 transition, the bromide ion that initially exists in the extracellular vicinity of retinal moves across the retinal Schiff base. Upon the formation of the N state with a bromide ion bound to the cytoplasmic vicinity of the retinal Schiff base, the cytoplasmic half of helix F moves outward to create a water channel in the cytoplasmic interhelical space, whereas the extracellular half of helix C moves inward. During the transition from N to an N-like reaction state with retinal assuming the 13-cis/15-syn configuration, the translocated bromide ion is released into the cytoplasmic medium. Subsequently, helix F relaxes into its original conformation, generating the O state. Anion uptake from the extracellular side occurs when helix C relaxes into its original conformation. These structural data provide insight into the structural basis of unidirectional anion transport.
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Affiliation(s)
- Tsutomu Kouyama
- Department of Physics, Graduate School of Science, Nagoya University, Nagoya, Japan; RIKEN Harima Branch, 1-1-1, Kouto, Sayo, Hyogo, Japan.
| | - Haruki Kawaguchi
- Department of Physics, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Taichi Nakanishi
- Department of Physics, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Hiroki Kubo
- Department of Physics, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Midori Murakami
- Department of Physics, Graduate School of Science, Nagoya University, Nagoya, Japan
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Tamogami J, Sato K, Kurokawa S, Yamada T, Nara T, Demura M, Miyauchi S, Kikukawa T, Muneyuki E, Kamo N. Formation of M-Like Intermediates in Proteorhodopsin in Alkali Solutions (pH ≥ ∼8.5) Where the Proton Release Occurs First in Contrast to the Sequence at Lower pH. Biochemistry 2016; 55:1036-48. [DOI: 10.1021/acs.biochem.5b01196] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jun Tamogami
- College
of Pharmaceutical Sciences, Matsuyama University, Matsuyama, Ehime 790-8578, Japan
- Faculty
of Advanced Life Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Keitaro Sato
- Department
of Physics, Faculty of Science and Engineering, Chuo University, Tokyo 112-8551, Japan
| | - Sukuna Kurokawa
- Department
of Physics, Faculty of Science and Engineering, Chuo University, Tokyo 112-8551, Japan
| | - Takumi Yamada
- Department
of Physics, Faculty of Science and Engineering, Chuo University, Tokyo 112-8551, Japan
| | - Toshifumi Nara
- College
of Pharmaceutical Sciences, Matsuyama University, Matsuyama, Ehime 790-8578, Japan
| | - Makoto Demura
- Faculty
of Advanced Life Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Seiji Miyauchi
- Faculty
of Advanced Life Science, Hokkaido University, Sapporo 060-0810, Japan
- Faculty
of Pharmaceutical Sciences, Toho University, Funabashi 274-8510, Japan
| | - Takashi Kikukawa
- Faculty
of Advanced Life Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Eiro Muneyuki
- Department
of Physics, Faculty of Science and Engineering, Chuo University, Tokyo 112-8551, Japan
| | - Naoki Kamo
- College
of Pharmaceutical Sciences, Matsuyama University, Matsuyama, Ehime 790-8578, Japan
- Faculty
of Advanced Life Science, Hokkaido University, Sapporo 060-0810, Japan
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Hasemi T, Kikukawa T, Kamo N, Demura M. Characterization of a Cyanobacterial Chloride-pumping Rhodopsin and Its Conversion into a Proton Pump. J Biol Chem 2015; 291:355-62. [PMID: 26578511 DOI: 10.1074/jbc.m115.688614] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Indexed: 11/06/2022] Open
Abstract
Light-driven ion-pumping rhodopsins are widely distributed in microorganisms and are now classified into the categories of outward H(+) and Na(+) pumps and an inward Cl(-) pump. These different types share a common protein architecture and utilize the photoisomerization of the same chromophore, retinal, to evoke photoreactions. Despite these similarities, successful pump-to-pump conversion had been confined to only the H(+) pump bacteriorhodopsin, which was converted to a Cl(-) pump in 1995 by a single amino acid replacement. In this study we report the first success of the reverse conversion from a Cl(-) pump to a H(+) pump. A novel microbial rhodopsin (MrHR) from the cyanobacterium Mastigocladopsis repens functions as a Cl(-) pump and belongs to a cluster that is far distant from the known Cl(-) pumps. With a single amino acid replacement, MrHR is converted to a H(+) pump in which dissociable residues function almost completely in the H(+) relay reactions. MrHR most likely evolved from a H(+) pump, but it has not yet been highly optimized into a mature Cl(-) pump.
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Affiliation(s)
- Takatoshi Hasemi
- From the Faculty of Advanced Life Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Takashi Kikukawa
- From the Faculty of Advanced Life Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Naoki Kamo
- From the Faculty of Advanced Life Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Makoto Demura
- From the Faculty of Advanced Life Science, Hokkaido University, Sapporo 060-0810, Japan
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15
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Shibasaki K, Shigemura H, Kikukawa T, Kamiya M, Aizawa T, Kawano K, Kamo N, Demura M. Role of Thr218 in the light-driven anion pump halorhodopsin from Natronomonas pharaonis. Biochemistry 2013; 52:9257-68. [PMID: 24298916 DOI: 10.1021/bi401295e] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Halorhodopsin (HR) is an inward-directed light-driven halogen ion pump, and NpHR is a HR from Natronomonas pharaonis. Unphotolyzed NpHR binds halogen ion in the vicinity of the Schiff base, which links retinal to Lys256. This halogen ion is transported during the photocycle. We made various mutants of Thr218, which is located one half-turn up from the Schiff base to the cytoplasm (CP) channel, and analyzed the photocycle using a sequential irreversible model. Four photochemically defined intermediates (P(i), i = 1-4) were adequate to describe the photocycle. The third component, P₃, was a quasi-equilibrium complex between the N and O intermediates, where a N ↔ O + Cl⁻ equilibrium was attained. The K(d,N↔O) values of this equilibrium for various mutants were determined, and the value of Thr (wild type) was the highest. The partial molar volume differences between N and O, ΔV(N→O), were estimated from the pressure dependence of K(d,N↔O). A comparison between K(d,N↔O) and ΔV(N→O) led to the conclusion that water entry by the F-helix opening at O may occur, which may increase K(d,N↔O). For some mutants, however, large ΔV(N→O) values were found, whereas the K(d,N↔O) values were small. This suggests that the special coordination of a water molecule with the OH group of Thr is necessary for the increase in K(d,N↔O). Mutants with a small K(d,N↔O) showed low pumping activities in the presence of inside negative membrane potential, while the mutant activities were not different in the absence of membrane potential. The effect of the mutation on the pumping activities is discussed.
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Affiliation(s)
- Kousuke Shibasaki
- Faculty of Advanced Life Science, Hokkaido University , Sapporo 060-0810, Japan
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16
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Thermodynamic parameters of anion binding to halorhodopsin from Natronomonas pharaonis by isothermal titration calorimetry. Biophys Chem 2013; 172:61-7. [DOI: 10.1016/j.bpc.2013.01.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Revised: 01/10/2013] [Accepted: 01/14/2013] [Indexed: 11/21/2022]
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17
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Tamogami J, Kikukawa T, Nara T, Shimono K, Demura M, Kamo N. Photoinduced proton release in proteorhodopsin at low pH: the possibility of a decrease in the pK(a) of Asp227. Biochemistry 2012; 51:9290-301. [PMID: 23095117 DOI: 10.1021/bi300940p] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Proteorhodopsin (PR) is one of the microbial rhodopsins that are found in marine eubacteria and likely functions as an outward light-driven proton pump. Previously, we [Tamogami, J., et al. (2009) Photochem. Photobiol.85, 578-589] reported the occurrence of a photoinduced proton transfer in PR between pH 5 and 10 using a transparent ITO (indium-tin oxide) or SnO(2) electrode that works as a time-resolving pH electrode. In the study presented here, the proton transfer at low pH (<4) was investigated. Under these conditions, Asp97, the primary counterion to the protonated Schiff base, is protonated. We observed a first proton release that was followed by an uptake; during this process, however, the M intermediate did not form. Through the use of experiments with several PR mutants, we found that Asp227 played an essential role in proton release. This residue corresponds to the Asp212 residue of bacteriorhodopsin, the so-called secondary Schiff base counterion. We estimated the pK(a) of this residue in both the dark and the proton-releasing photoproduct to be ~3.0 and ~2.3, respectively. The pK(a) value of Asp227 in the dark was also estimated spectroscopically and was approximately equal to that determined with the ITO experiments, which may imply the possibility of the release of a proton from Asp227. In the absence of Cl(-), we observed the proton release in D227N and found that Asp97, the primary counterion, played a key role. It is inferred that the negative charge is required to stabilize the photoproducts through the deprotonation of Asp227 (first choice), the binding of Cl(-) (second choice), or the deprotonation of Asp97. The photoinduced proton release (possibly by the decrease in the pK(a) of the secondary counterion) in acidic media was also observed in other microbial rhodopsins with the exception of the Anabaena sensory rhodopsin, which lacks the dissociable residue at the position of Asp212 of BR or Asp227 of PR and halorhodopsin. The implication of this pK(a) decrease is discussed.
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Affiliation(s)
- Jun Tamogami
- College of Pharmaceutical Sciences, Matsuyama University, Matsuyama, Ehime 790-8578, Japan.
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18
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Bell SG, Yang W, Tan ABH, Zhou R, Johnson EOD, Zhang A, Zhou W, Rao Z, Wong LL. The crystal structures of 4-methoxybenzoate bound CYP199A2 and CYP199A4: structural changes on substrate binding and the identification of an anion binding site. Dalton Trans 2012; 41:8703-14. [PMID: 22695988 DOI: 10.1039/c2dt30783a] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The crystal structures of the 4-methoxybenzoate bound forms of cytochrome P450 enzymes CYP199A2 and CYP199A4 from the Rhodopseudomonas palustris strains CGA009 and HaA2 have been solved. The structures of these two enzymes, which share 86% sequence identity, are very similar though some differences are found on the proximal surface. In these structures the enzymes have a closed conformation, in contrast to the substrate-free form of CYP199A2 where an obvious substrate access channel is observed. The switch from an open to a closed conformation arises from pronounced residue side-chain movements and alterations of ion pair and hydrogen bonding interactions at the entrance of the access channel. A chloride ion bound just inside the protein surface caps the entrance to the active site and protects the substrate and the heme from the external solvent. In both structures the substrate is held in place via hydrophobic and hydrogen bond interactions. The methoxy group is located over the heme iron, accounting for the high activity and selectivity of these enzymes for oxidative demethylation of the substrate. Mutagenesis studies on CYP199A4 highlight the involvement of hydrophobic (Phe185) and hydrophilic (Arg92, Ser95 and Arg243) amino acid residues in the binding of para-substituted benzoates by these enzymes.
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Affiliation(s)
- Stephen G Bell
- Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford, OX1 3QR, UK.
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19
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Tamogami J, Kikukawa T, Ikeda Y, Demura M, Nara T, Kamo N. Photo-induced bleaching of sensory rhodopsin II (phoborhodopsin) from Halobacterium salinarum by hydroxylamine: identification of the responsible intermediates. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2012; 106:87-94. [PMID: 22104601 DOI: 10.1016/j.jphotobiol.2011.10.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Revised: 10/18/2011] [Accepted: 10/21/2011] [Indexed: 05/31/2023]
Abstract
Sensory rhodopsin II from Halobacterium salinarum (HsSRII) is a retinal protein in which retinal binds to a specific lysine residue through a Schiff base. Here, we investigated the photobleaching of HsSRII in the presence of hydroxylamine. For identification of intermediate(s) attacked by hydroxylamine, we employed the flash-induced bleaching method. In order to change the concentration of intermediates, such as M- and O-intermediates, experiments were performed under varying flashlight intensities and concentrations of azide that accelerated only the M-decay. We found the proportional relationship between the bleaching rate and area under the concentration-time curve of M, indicating a preferential attack of hydroxylamine on M. Since hydroxylamine is a water-soluble reagent, we hypothesize that for M, hydrophilicity or water-accessibility increases specifically in the moiety of Schiff base. Thus, hydroxylamine bleaching rates may be an indication of conformational changes near the Schiff base. We also considered the possibility that azide may induce a small conformational change around the Schiff base. We compared the hydroxylamine susceptibility between HsSRII and NpSRII (SRII from Natronomonas pharaonis) and found that the M of HsSRII is about three times more susceptible than that of the stable NpSRII. In addition, long illumination to HsSRII easily produced M-like photoproduct, P370. We thus infer that the instability of HsSRII under illumination may be related to this increase of hydrophilicity at M and P370.
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Affiliation(s)
- Jun Tamogami
- College of Pharmaceutical Sciences, Matsuyama University, Matsuyama, Ehime, Japan
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20
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Yamashita Y, Kikukawa T, Tsukamoto T, Kamiya M, Aizawa T, Kawano K, Miyauchi S, Kamo N, Demura M. Expression of salinarum halorhodopsin in Escherichia coli cells: solubilization in the presence of retinal yields the natural state. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:2905-12. [PMID: 21925140 DOI: 10.1016/j.bbamem.2011.08.035] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Revised: 08/27/2011] [Accepted: 08/30/2011] [Indexed: 11/29/2022]
Abstract
Salinarum halorhodopsin (HsHR), a light-driven chloride ion pump of haloarchaeon Halobacterium salinarum, was heterologously expressed in Escherichia coli. The expressed HsHR had no color in the E. coli membrane, but turned purple after solubilization in the presence of all-trans retinal. This colored HsHR was purified by Ni-chelate chromatography in a yield of 3-4 mg per liter culture. The purified HsHR showed a distinct chloride pumping activity by incorporation into the liposomes, and showed even in the detergent-solubilized state, its typical behaviors in both the unphotolyzed and photolyzed states. Upon solubilization, HsHR expressed in the E. coli membrane attains the proper folding and a trimeric assembly comparable to those in the native membranes.
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Affiliation(s)
- Yasutaka Yamashita
- Faculty of Advanced Life Science, Hokkaido University, Sapporo 060-0810, Japan
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21
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Boyden ES. A history of optogenetics: the development of tools for controlling brain circuits with light. F1000 BIOLOGY REPORTS 2011; 3:11. [PMID: 21876722 PMCID: PMC3155186 DOI: 10.3410/b3-11] [Citation(s) in RCA: 124] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Understanding how different kinds of neuron in the brain work together to implement sensations, feelings, thoughts, and movements, and how deficits in specific kinds of neuron result in brain diseases, has long been a priority in basic and clinical neuroscience. “Optogenetic” tools are genetically encoded molecules that, when targeted to specific neurons in the brain, enable their activity to be driven or silenced by light. These molecules are microbial opsins, seven-transmembrane proteins adapted from organisms found throughout the world, which react to light by transporting ions across the lipid membranes of cells in which they are genetically expressed. These tools are enabling the causal assessment of the roles that different sets of neurons play within neural circuits, and are accordingly being used to reveal how different sets of neurons contribute to the emergent computational and behavioral functions of the brain. These tools are also being explored as components of prototype neural control prosthetics capable of correcting neural circuit computations that have gone awry in brain disorders. This review gives an account of the birth of optogenetics and discusses the technology and its applications.
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Affiliation(s)
- Edward S Boyden
- Media Lab, McGovern Institute, Department of Brain and Cognitive Sciences and Department of Biological Engineering MIT, 77 Massachusetts Avenue, Cambridge, MA 02139 USA
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22
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Boyden ES. A history of optogenetics: the development of tools for controlling brain circuits with light. F1000 BIOLOGY REPORTS 2011; 3:11. [PMID: 21876722 DOI: 10.3410/b] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Understanding how different kinds of neuron in the brain work together to implement sensations, feelings, thoughts, and movements, and how deficits in specific kinds of neuron result in brain diseases, has long been a priority in basic and clinical neuroscience. "Optogenetic" tools are genetically encoded molecules that, when targeted to specific neurons in the brain, enable their activity to be driven or silenced by light. These molecules are microbial opsins, seven-transmembrane proteins adapted from organisms found throughout the world, which react to light by transporting ions across the lipid membranes of cells in which they are genetically expressed. These tools are enabling the causal assessment of the roles that different sets of neurons play within neural circuits, and are accordingly being used to reveal how different sets of neurons contribute to the emergent computational and behavioral functions of the brain. These tools are also being explored as components of prototype neural control prosthetics capable of correcting neural circuit computations that have gone awry in brain disorders. This review gives an account of the birth of optogenetics and discusses the technology and its applications.
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Affiliation(s)
- Edward S Boyden
- Media Lab, McGovern Institute, Department of Brain and Cognitive Sciences and Department of Biological Engineering MIT, 77 Massachusetts Avenue, Cambridge, MA 02139 USA
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23
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Chow BY, Chuong AS, Klapoetke NC, Boyden ES. Synthetic physiology strategies for adapting tools from nature for genetically targeted control of fast biological processes. Methods Enzymol 2011; 497:425-43. [PMID: 21601097 DOI: 10.1016/b978-0-12-385075-1.00018-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The life and operation of cells involve many physiological processes that take place over fast timescales of milliseconds to minutes. Genetically encoded technologies for driving or suppressing specific fast physiological processes in intact cells, perhaps embedded within intact tissues in living organisms, are critical for the ability to understand how these physiological processes contribute to emergent cellular and organismal functions and behaviors. Such "synthetic physiology" tools are often incredibly complex molecular machines, in part because they must operate at high speeds, without causing side effects. We here explore how synthetic physiology molecules can be identified and deployed in cells, and how the physiology of these molecules in cellular contexts can be assessed and optimized. For concreteness, we discuss these methods in the context of the "optogenetic" light-gated ion channels and pumps that we have developed over the past few years as synthetic physiology tools and widely disseminated for use in neuroscience for probing the role of specific brain cell types in neural computations, behaviors, and pathologies. We anticipate that some of the insights revealed here may be of general value for the field of synthetic physiology, as they raise issues that will be of importance for the development and use of high-performance, high-speed, side-effect free physiological control tools in heterologous expression systems.
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Affiliation(s)
- Brian Y Chow
- Synthetic Neurobiology Group, The Media Laboratory and McGovern Institute, Departments of Biological Engineering and Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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Tamogami J, Kikukawa T, Ikeda Y, Takemura A, Demura M, Kamo N. The photochemical reaction cycle and photoinduced proton transfer of sensory rhodopsin II (Phoborhodopsin) from Halobacterium salinarum. Biophys J 2010; 98:1353-63. [PMID: 20371336 DOI: 10.1016/j.bpj.2009.12.4288] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Revised: 12/08/2009] [Accepted: 12/09/2009] [Indexed: 10/19/2022] Open
Abstract
Sensory rhodopsin II (HsSRII, also called phoborhodopsin) is a negative phototaxis receptor of Halobacterium salinarum, a bacterium that avoids blue-green light. In this study, we expressed the protein in Escherichia coli cells, and reconstituted the purified protein with phosphatidylcholine. The reconstituted HsSRII was stable. We examined the photocycle by flash-photolysis spectroscopy in the time range of milliseconds to seconds, and measured proton uptake/release using a transparent indium-tin oxide electrode. The pKa of the counterion of the Schiff base, Asp(73), was 3.0. Below pH 3, the depleted band was observed on flash illumination, but the positive band in the difference spectra was not found. Above pH 3, the basic photocycle was HsSRII (490) --> M (350) --> O (520) --> Y (490) --> HsSRII, where the numbers in parentheses are the maximum wavelengths. The decay rate of O-intermediate and Y-intermediate were pH-independent, whereas the M-intermediate decay was pH-dependent. For 3 < pH < 4.5, the M-decay was one phase, and the rate decreased with an increase in pH. For 4.5 < pH < 6.5, the decay was one phase with pH-independent rates, and azide markedly accelerated the M-decay. These findings suggest the existence of a protonated amino acid residue (X-H) that may serve as a proton relay to reprotonate the Schiff base. Above pH 6.5, the M-decay showed two phases. The fast M-decay was pH-independent and originated from the molecule having a protonated X-H, and the slow M-decay originated from the molecule having a deprotonated X, in which the proton came directly from the outside. The analysis yielded a value of 7.5 for the pKa of X-H. The proton uptake and release occurred during M-decay and O-decay, respectively.
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Affiliation(s)
- Jun Tamogami
- Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan; Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan
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25
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Sasaki T, Aizawa T, Kamiya M, Kikukawa T, Kawano K, Kamo N, Demura M. Effect of Chloride Binding on the Thermal Trimer−Monomer Conversion of Halorhodopsin in the Solubilized System. Biochemistry 2009; 48:12089-95. [DOI: 10.1021/bi901380c] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Takanori Sasaki
- Faculty of Life Science, Hokkaido University, Sapporo 060-0810, Japan
- School of Science and Technology, Meiji University, Tama-ku, Kawasaki-shi, Kanagawa 214-8571, Japan
| | - Tomoyasu Aizawa
- Faculty of Life Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Masakatsu Kamiya
- Faculty of Life Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Takashi Kikukawa
- Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Keiichi Kawano
- Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Naoki Kamo
- College of Pharmaceutical Sciences, Matsuyama University, Bunkyo-cho, Matsuyama 790-8578, Japan
| | - Makoto Demura
- Faculty of Life Science, Hokkaido University, Sapporo 060-0810, Japan
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26
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Inoue K, Kubo M, Demura M, Kamo N, Terazima M. Reaction dynamics of halorhodopsin studied by time-resolved diffusion. Biophys J 2009; 96:3724-34. [PMID: 19413978 DOI: 10.1016/j.bpj.2008.12.3932] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2008] [Revised: 12/24/2008] [Accepted: 12/31/2008] [Indexed: 11/26/2022] Open
Abstract
Reaction dynamics of a chloride ion pump protein, halorhodopsin (HR), from Natronomonas pharaonis (N. pharaonis) (NpHR) was studied by the pulsed-laser-induced transient grating (TG) method. A detailed investigation of the TG signal revealed that there is a spectrally silent diffusion process besides the absorption-observable reaction dynamics. We interpreted these dynamics in terms of release, diffusion, and uptake of the Cl(-) ion. From a quantitative global analysis of the signals at various grating wavenumbers, it was concluded that the release of the Cl(-) ion is associated with the L2 --> (L2 (or N) <==> O) process, and uptake of Cl(-) occurs with the (L2 (or N) <==> O) -->NpHR' process. The diffusion coefficient of NpHR solubilized in a detergent did not change during the cyclic reaction. This result contrasts the behavior of many photosensor proteins and implies that the change in the H-bond network from intra- to intermolecular is not significant for the activity of this protein pump.
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Affiliation(s)
- Keiichi Inoue
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
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27
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Suzuki D, Furutani Y, Inoue K, Kikukawa T, Sakai M, Fujii M, Kandori H, Homma M, Sudo Y. Effects of chloride ion binding on the photochemical properties of salinibacter sensory rhodopsin I. J Mol Biol 2009; 392:48-62. [PMID: 19560470 DOI: 10.1016/j.jmb.2009.06.050] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2009] [Revised: 05/31/2009] [Accepted: 06/18/2009] [Indexed: 10/20/2022]
Abstract
Microbial organisms utilize light not only as energy sources but also as signals by which rhodopsins (containing retinal as a chromophore) work as photoreceptors. Sensory rhodopsin I (SRI) is a dual photoreceptor that regulates both negative and positive phototaxis in microbial organisms, such as the archaeon Halobacterium salinarum and the eubacterium Salinibacter ruber. These organisms live in highly halophilic environments, suggesting the possibility of the effects of salts on the function of SRI. However, such effects remain unclear because SRI proteins from H. salinarum (HsSRI) are unstable in dilute salt solutions. Recently, we characterized a new SRI protein (SrSRI) that is stable even in the absence of salts, thus allowing us to investigate the effects of salts on the photochemical properties of SRI. In this study, we report that the absorption maximum of SrSRI is shifted from 542 to 556 nm in a Cl(-)-dependent manner with a K(m) of 307+/-56 mM, showing that Cl(-)-binding sites exist in SRI. The bathochromic shift was caused not only by NaCl but also by other salts (NaI, NaBr, and NaNO(3)), implying that I(-), Br(-), and NO(3)(-) can also bind to SrSRI. In addition, the photochemical properties during the photocycle are also affected by chloride ion binding. Mutagenesis studies strongly suggested that a conserved residue, His131, is involved in the Cl(-)-binding site. In light of these results, we discuss the effects of the Cl(-) binding to SRI and the roles of Cl(-) binding in its function.
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28
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Song Y, Gunner M. Using Multiconformation Continuum Electrostatics to Compare Chloride Binding Motifs in α-Amylase, Human Serum Albumin, and Omp32. J Mol Biol 2009; 387:840-56. [DOI: 10.1016/j.jmb.2009.01.038] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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29
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Tamogami J, Kikukawa T, Miyauchi S, Muneyuki E, Kamo N. A Tin Oxide Transparent Electrode Provides the Means for Rapid Time-resolved pH Measurements: Application to Photoinduced Proton Transfer of Bacteriorhodopsin and Proteorhodopsin. Photochem Photobiol 2009; 85:578-89. [DOI: 10.1111/j.1751-1097.2008.00520.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Kubo M, Kikukawa T, Miyauchi S, Seki A, Kamiya M, Aizawa T, Kawano K, Kamo N, Demura M. Role of Arg123 in Light-driven Anion Pump Mechanisms ofpharaonisHalorhodopsin. Photochem Photobiol 2009; 85:547-55. [DOI: 10.1111/j.1751-1097.2009.00538.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Gruia AD, Bondar AN, Smith JC, Fischer S. Mechanism of a molecular valve in the halorhodopsin chloride pump. Structure 2005; 13:617-27. [PMID: 15837200 DOI: 10.1016/j.str.2005.01.021] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2004] [Revised: 12/23/2004] [Accepted: 01/08/2005] [Indexed: 11/30/2022]
Abstract
Halorhodopsin is a light-driven chloride anion pump in which the trans-->cis photoisomerization of a retinal chromophore triggers a photocycle resulting in the translocation of chloride across the plasma membrane. The mechanism of chloride transfer past the cis retinal is determined here by computing multiple pathways for this process. The calculations reveal two conditions of the valve mechanism. First, a lumen absent in the ground state structure is transiently opened by chloride passage. Second, this activated opening, which is achieved by flexible deformation of the surrounding protein, is shown to significantly raise the chloride translocation barrier between photocycles, thus preventing chloride backflow. Unlike macroscopic valve designs, the protein allows differential ion flows in the pumping and resting states that are tuned to match the physiological timescales of the cell, thus creating a "kinetic" valve.
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Affiliation(s)
- Andreea D Gruia
- Computational Biochemistry, IWR, Heidelberg University, Im Neuenheimer Feld 368, D-69210 Heidelberg, Germany
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