1
|
Shionoya T, Mizuno M, Kandori H, Mizutani Y. Contact-Mediated Retinal-Opsin Coupling Enables Proton Pumping in Gloeobacter Rhodopsin. J Phys Chem B 2022; 126:7857-7869. [PMID: 36173382 DOI: 10.1021/acs.jpcb.2c04208] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
When a chromophore embedded in a photoreceptive protein undergoes a reaction upon photoexcitation, the photoreaction triggers structural changes in the protein moiety that are necessary for the function of the protein. It is thus essential to elucidate the coupling between the chromophore and protein moiety to understand the functional mechanism for photoreceptive proteins, but the mechanism by which this coupling occurs remains poorly understood. Here, we show that nonbonded atomic contacts play an essential role in driving functionally important structural changes following photoisomerization of the chromophore in Gloeobacter rhodopsin (GR). Time-resolved ultraviolet resonance Raman spectroscopy revealed that the substitution of Trp222, which contacts with methyl groups of the retinal chromophore, with a Phe residue reduced the extent of structural change. The proton-pumping activity of the GR mutant was as small as 9% of that of the wild type. Time-resolved visible absorption and resonance Raman spectra showed that the photocycle of the mutant proceeded to the L intermediate following the all-trans to 13-cis photoisomerization step but did not result in the deprotonation of the chromophore. The present results demonstrate that the atomic contacts between the chromophore and the Trp222 side chain induce the structural changes necessary for proton transfer. The requirement for dense atomic packing in a protein structure for the efficient propagation of structural changes through a coupling mechanism is discussed.
Collapse
Affiliation(s)
- Tomomi Shionoya
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Misao Mizuno
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Hideki Kandori
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya, Aichi 466-8555, Japan
| | - Yasuhisa Mizutani
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| |
Collapse
|
2
|
Feroz H, Ferlez B, Oh H, Mohammadiarani H, Ren T, Baker CS, Gajewski JP, Lugar DJ, Gaudana SB, Butler P, Hühn J, Lamping M, Parak WJ, Blatt MR, Kerfeld CA, Smirnoff N, Vashisth H, Golbeck JH, Kumar M. Liposome-based measurement of light-driven chloride transport kinetics of halorhodopsin. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183637. [PMID: 33930372 DOI: 10.1016/j.bbamem.2021.183637] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 04/14/2021] [Accepted: 04/22/2021] [Indexed: 11/30/2022]
Abstract
We report a simple and direct fluorimetric vesicle-based method for measuring the transport rate of the light-driven ions pumps as specifically applied to the chloride pump, halorhodopsin, from Natronomonas pharaonis (pHR). Previous measurements were cell-based and methods to determine average single channel permeability challenging. We used a water-in-oil emulsion method for directional pHR reconstitution into two different types of vesicles: lipid vesicles and asymmetric lipid-block copolymer vesicles. We then used stopped-flow experiments combined with fluorescence correlation spectroscopy to determine per protein Cl- transport rates. We obtained a Cl- transport rate of 442 (±17.7) Cl-/protein/s in egg phosphatidyl choline (PC) lipid vesicles and 413 (±26) Cl-/protein/s in hybrid block copolymer/lipid (BCP/PC) vesicles with polybutadine-polyethylene oxide (PB12PEO8) on the outer leaflet and PC in the inner leaflet at a photon flux of 1450 photons/protein/s. Normalizing to a per photon basis, this corresponds to 0.30 (±0.07) Cl-/photon and 0.28 (±0.04) Cl-/photon for pure PC and BCP/PC hybrid vesicles respectively, both of which are in agreement with recently reported turnover of ~500 Cl-/protein/s from flash photolysis experiments and with voltage-clamp measurements of 0.35 (±0.16) Cl-/photon in pHR-expressing oocytes as well as with a pHR quantum efficiency of ~30%.
Collapse
Affiliation(s)
- Hasin Feroz
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, USA
| | - Bryan Ferlez
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA
| | - Hyeonji Oh
- Department of Chemical Engineering, The University of Texas at Austin, Austin, TX, USA
| | | | - Tingwei Ren
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, USA
| | - Carol S Baker
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA
| | - John P Gajewski
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA
| | - Daniel J Lugar
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA
| | - Sandeep B Gaudana
- MSU-DOE Plant Research Laboratory and Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA
| | - Peter Butler
- Department of Biomedical Engineering, The Pennsylvania State University, University Park, PA, USA
| | - Jonas Hühn
- Department of Physics and Chemistry, Philipps University of Marburg, Marburg, Germany
| | - Matthias Lamping
- Department of Physics and Chemistry, Philipps University of Marburg, Marburg, Germany
| | - Wolfgang J Parak
- Center of Hybrid Nanostructures (CHyN), Universität Hamburg, Hamburg, Germany
| | - Michael R Blatt
- Laboratory of Plant Physiology and Biophysics, Institute of Molecular Cell and Systems Biology, Bower Building, University of Glasgow, Glasgow G12 8QQ, UK
| | - Cheryl A Kerfeld
- MSU-DOE Plant Research Laboratory and Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA; Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA, USA; Environmental Genomics and Systems Biology and Molecular Biophysics and Integrated Bioimaging Divisions, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | | | - Harish Vashisth
- Department of Chemical Engineering, The University of New Hampshire, Durham, NH, USA
| | - John H Golbeck
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA; Department of Chemistry, The Pennsylvania State University, University Park, PA, USA
| | - Manish Kumar
- Department of Civil, Architectural and Environmental Engineering, The University of Texas at Austin, Austin, TX, USA.
| |
Collapse
|
3
|
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.
Collapse
|
4
|
Yamamoto A, Tsukamoto T, Suzuki K, Hashimoto E, Kobashigawa Y, Shibasaki K, Uchida T, Inagaki F, Demura M, Ishimori K. Spectroscopic Characterization of Halorhodopsin Reconstituted into Nanodisks Using Native Lipids. Biophys J 2020; 118:2853-2865. [PMID: 32396848 DOI: 10.1016/j.bpj.2020.04.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Revised: 04/06/2020] [Accepted: 04/22/2020] [Indexed: 10/24/2022] Open
Abstract
We successfully reconstituted single Natronomonas pharaonis halorhodopsin (NpHR) trimers into a nanodisk (ND) using the native archaeal lipid (NL) and an artificial lipid having a zwitterionic headgroup, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC). Incorporation of single trimeric NpHR into NDs was confirmed by sodium dodecyl sulfate polyacrylamide gel electrophoresis, size-exclusion chromatography, and visible circular dichroism spectroscopy. The Cl- binding affinity of NpHR in NDs using NL (NL-ND NpHR) or POPC (POPC-ND NpHR) was examined by absorption spectroscopy, showing that the Cl--releasing affinities (Kd,N↔O) of these ND-reconstituted NpHRs are more than 10 times higher than that obtained from native NpHR membrane fragments (MFs) harvested from a NpHR-overexpressing archaeal strain (MF NpHR). The photoreaction kinetics of these ND-reconstituted NpHRs revealed that the Cl- uptake was faster than that of MF NpHR. These differences in the Cl--releasing and uptake properties of ND-reconstituted NpHRs and MF NpHR may arise from suppression of protein conformational changes associated with Cl- release from the trimeric NpHR caused by ND reconstitution, conformational perturbation in the trimeric state, and loss of the trimer-trimer interactions. On the other hand, POPC-ND NpHR demonstrated accelerated Cl- uptake compared to NL-ND NpHR, suggesting that the negative charge on the archaeal membrane surface regulates the photocycle of NpHR. Although NL-ND NpHR and MF NpHR are embedded in the same lipid, the lower Cl--binding affinity at the initial state (Kd,initial) and faster recovering from the NpHR' state to the original state of the photoreaction cycle were observed for NL-ND NpHR, probably because of insufficient interactions with a chromophore in the native membrane, bacterioruberin in reconstituted NDs. Our results indicate that specific interactions of NpHR with surrounding lipids and bacterioruberin, structural flexibility of the membrane, and interactions between trimeric NpHRs may be necessary for efficient Cl- pumping.
Collapse
Affiliation(s)
- Ayumi Yamamoto
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, Japan
| | - Takashi Tsukamoto
- Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan; Global Station for Soft Matter, Global Institution for Collaborative Research and Education, Hokkaido University, Sapporo, Japan
| | - Kenshiro Suzuki
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, Japan
| | - Eri Hashimoto
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, Japan
| | | | - Kousuke Shibasaki
- Graduate School of Life Science, Hokkaido University, Sapporo, Japan
| | - Takeshi Uchida
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, Japan; Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, Japan
| | - Fuyuhiko Inagaki
- Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan
| | - Makoto Demura
- Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan; Global Station for Soft Matter, Global Institution for Collaborative Research and Education, Hokkaido University, Sapporo, Japan.
| | - Koichiro Ishimori
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, Japan; Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, Japan.
| |
Collapse
|
5
|
Feroz H, Ferlez B, Lefoulon C, Ren T, Baker CS, Gajewski JP, Lugar DJ, Gaudana SB, Butler PJ, Hühn J, Lamping M, Parak WJ, Hibberd JM, Kerfeld CA, Smirnoff N, Blatt MR, Golbeck JH, Kumar M. Light-Driven Chloride Transport Kinetics of Halorhodopsin. Biophys J 2019; 115:353-360. [PMID: 30021110 DOI: 10.1016/j.bpj.2018.06.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 05/19/2018] [Accepted: 06/05/2018] [Indexed: 01/25/2023] Open
Abstract
Despite growing interest in light-driven ion pumps for use in optogenetics, current estimates of their transport rates span two orders of magnitude due to challenges in measuring slow transport processes and determining protein concentration and/or orientation in membranes in vitro. In this study, we report, to our knowledge, the first direct quantitative measurement of light-driven Cl- transport rates of the anion pump halorohodopsin from Natronomonas pharaonis (NpHR). We used light-interfaced voltage clamp measurements on NpHR-expressing oocytes to obtain a transport rate of 219 (± 98) Cl-/protein/s for a photon flux of 630 photons/protein/s. The measurement is consistent with the literature-reported quantum efficiency of ∼30% for NpHR, i.e., 0.3 isomerizations per photon absorbed. To reconcile our measurements with an earlier-reported 20 ms rate-limiting step, or 35 turnovers/protein/s, we conducted, to our knowledge, novel consecutive single-turnover flash experiments that demonstrate that under continuous illumination, NpHR bypasses this step in the photocycle.
Collapse
Affiliation(s)
- Hasin Feroz
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania
| | - Bryan Ferlez
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania
| | - Cecile Lefoulon
- Laboratory of Plant Physiology and Biophysics, Institute of Molecular Cell and Systems Biology, University of Glasgow, Glasgow, United Kingdom
| | - Tingwei Ren
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania
| | - Carol S Baker
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania
| | - John P Gajewski
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania
| | - Daniel J Lugar
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania
| | - Sandeep B Gaudana
- MSU-DOE Plant Research Laboratory and Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan
| | - Peter J Butler
- Department of Biomedical Engineering, The Pennsylvania State University, University Park, Pennsylvania
| | - Jonas Hühn
- Department of Physics and Chemistry, Philipps University of Marburg, Marburg, Germany
| | - Matthias Lamping
- Department of Physics and Chemistry, Philipps University of Marburg, Marburg, Germany
| | - Wolfgang J Parak
- Department of Physics and Chemistry, Philipps University of Marburg, Marburg, Germany
| | - Julian M Hibberd
- Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom
| | - Cheryl A Kerfeld
- MSU-DOE Plant Research Laboratory and Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan; Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, California; Environmental Genomics and Systems Biology, Lawrence Berkeley National Laboratory, Berkeley, California
| | | | - Michael R Blatt
- Laboratory of Plant Physiology and Biophysics, Institute of Molecular Cell and Systems Biology, University of Glasgow, Glasgow, United Kingdom
| | - John H Golbeck
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania; Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania
| | - Manish Kumar
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania.
| |
Collapse
|
6
|
Mizuno M, Shimoo Y, Kandori H, Mizutani Y. Effect of a bound anion on the structure and dynamics of halorhodopsin from Natronomonas pharaonis. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2019; 6:054703. [PMID: 31673569 PMCID: PMC6811361 DOI: 10.1063/1.5125621] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/24/2019] [Accepted: 10/09/2019] [Indexed: 06/10/2023]
Abstract
Active ion transport across membranes is vital to maintaining the electrochemical gradients of ions in cells and is mediated by transmembrane proteins. Halorhodopsin (HR) functions as a light-driven inward pump for chloride ions. The protein contains all-trans-retinal bound to a specific lysine residue through a protonated Schiff base. Interaction between the bound chloride ion and the protonated Schiff base is crucial for ion transport because chloride ion movement is driven by the flipping of the protonated Schiff base upon photoisomerization. However, it remains unknown how this interaction evolves in the HR photocycle. Here, we addressed the effect of the bound anion on the structure and dynamics of HR from Natronomonas pharaonis in the early stage of the photocycle. Comparison of the chloride-bound, formate-bound, and anion-depleted forms provided insights into the interaction between the bound anion and the chromophore/protein moiety. In the unphotolyzed state, the bound anion affects the π-conjugation of the polyene chain and the hydrogen bond of the protonated Schiff base of the retinal chromophore. Picosecond time scale measurements showed that the band intensities of the W16 and W18 modes of the tryptophan residues decreased instantaneously upon photoexcitation of the formate-bound form. In contrast, these intensity decreases were delayed for the chloride-bound and anion-depleted forms. These observations suggest the stronger interactions of the bound formate ion with the retinal chromophore and the chromophore pocket. On the nanosecond to microsecond timescales, we found that the interaction between the protonated Schiff base and the bound ion is broken upon formation of the K intermediate and is recovered following translocation of the bound anion toward the protonated Schiff base in the L intermediate. Our results demonstrate that the hydrogen-bonding ability of the bound anion plays an essential role in the ion transport of light-driven anion pumps.
Collapse
Affiliation(s)
- Misao Mizuno
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Yumi Shimoo
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Hideki Kandori
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya, Aichi 466-8555, Japan
| | - Yasuhisa Mizutani
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| |
Collapse
|
7
|
Hasemi T, Kikukawa T, Watanabe Y, Aizawa T, Miyauchi S, Kamo N, Demura M. Photochemical study of a cyanobacterial chloride-ion pumping rhodopsin. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2018; 1860:136-146. [PMID: 30529327 DOI: 10.1016/j.bbabio.2018.12.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 11/30/2018] [Accepted: 12/04/2018] [Indexed: 10/27/2022]
Abstract
Mastigocladopsis repens halorhodopsin (MrHR) is a Cl--pumping rhodopsin that belongs to a distinct cluster far from other Cl- pumps. We investigated its pumping function by analyzing its photocycle and the effect of amino acid replacements. MrHR can bind I- similar to Cl- but cannot transport it. I--bound MrHR undergoes a photocycle but lacks the intermediates after L, suggesting that, in the Cl--pumping photocycle, Cl- moves to the cytoplasmic (CP) channel during L decay. A photocycle similar to that of the I--bound form was also observed for a mutant of the Asp200 residue, which is superconserved and assumed to be deprotonated in most microbial rhodopsins. This residue is probably close to the Cl--binding site and the protonated Schiff base, in which a chromophore retinal binds to a specific Lys residue. However, the D200N mutation affected neither the Cl--binding affinity nor the absorption spectrum, but completely eliminated the Cl--pumping function. Thus, the Asp200 residue probably protonates in the dark state but deprotonates during the photocycle. Indeed, a H+ release was detected for photolyzed MrHR by using an indium‑tin oxide electrode, which acts as a good time-resolved pH sensor. This H+ release disappeared in the I--bound form of the wild-type and Cl--bound form of the D200N mutant. Thus, Asp200 residue probably deprotonates during L decay and then drives the Cl- movement to the CP channel.
Collapse
Affiliation(s)
- Takatoshi Hasemi
- Faculty of Advanced Life Science, Hokkaido University, Sapporo 060-0810, 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 060-0810, Japan.
| | - Yumi Watanabe
- Faculty of Advanced Life Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Tomoyasu Aizawa
- 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 060-0810, Japan
| | - Seiji Miyauchi
- Graduate School of Pharmaceutical Sciences, Toho University, Chiba 274-8510, Japan
| | - Naoki Kamo
- Faculty of Advanced Life Science, Hokkaido University, Sapporo 060-0810, 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 060-0810, Japan
| |
Collapse
|
8
|
Engelhard C, Chizhov I, Siebert F, Engelhard M. Microbial Halorhodopsins: Light-Driven Chloride Pumps. Chem Rev 2018; 118:10629-10645. [DOI: 10.1021/acs.chemrev.7b00715] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
| | - Igor Chizhov
- Institute for Biophysical Chemistry, Hannover Medical School, OE8830 Carl-Neuberg-Straße 1, 30625 Hannover, Germany
| | - Friedrich Siebert
- Institut für Molekulare Medizin und Zellforschung, Sektion Biophysik, Albert-Ludwigs-Universität Freiburg, Hermann-Herderstr. 9, 79104 Freiburg, Germany
| | - Martin Engelhard
- Max Planck Institute for Molecular Physiology, Otto Hahn Str. 11, 44227 Dortmund, Germany
| |
Collapse
|
9
|
Mizuno M, Nakajima A, Kandori H, Mizutani Y. Structural Evolution of a Retinal Chromophore in the Photocycle of Halorhodopsin from Natronobacterium pharaonis. J Phys Chem A 2018; 122:2411-2423. [DOI: 10.1021/acs.jpca.7b12332] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Misao Mizuno
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan, and
| | - Ayumi Nakajima
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan, and
| | - Hideki Kandori
- Department of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya, Aichi 466-8555, Japan
| | - Yasuhisa Mizutani
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan, and
| |
Collapse
|
10
|
Honda N, Tsukamoto T, Sudo Y. Comparative evaluation of the stability of seven-transmembrane microbial rhodopsins to various physicochemical stimuli. Chem Phys Lett 2017. [DOI: 10.1016/j.cplett.2017.05.055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
|
11
|
Niho A, Yoshizawa S, Tsukamoto T, Kurihara M, Tahara S, Nakajima Y, Mizuno M, Kuramochi H, Tahara T, Mizutani Y, Sudo Y. Demonstration of a Light-Driven SO42– Transporter and Its Spectroscopic Characteristics. J Am Chem Soc 2017; 139:4376-4389. [DOI: 10.1021/jacs.6b12139] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Akiko Niho
- Faculty
of Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan
| | - Susumu Yoshizawa
- Atmosphere
and Ocean Research Institute, The University of Tokyo, Chiba 277-8564, Japan
| | - Takashi Tsukamoto
- Faculty
of Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan
- Graduate
School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan
| | - Marie Kurihara
- Graduate
School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan
| | - Shinya Tahara
- Molecular
Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako 351-0198, Japan
| | - Yu Nakajima
- Atmosphere
and Ocean Research Institute, The University of Tokyo, Chiba 277-8564, Japan
| | - Misao Mizuno
- Department
of Chemistry, Graduate School of Science, Osaka University, 1-1
Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Hikaru Kuramochi
- Molecular
Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako 351-0198, Japan
- Ultrafast
Spectroscopy Research Team, RIKEN Center for Advanced Photonics (RAP), 2-1 Hirosawa, Wako 351-0198, Japan
| | - Tahei Tahara
- Molecular
Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako 351-0198, Japan
- Ultrafast
Spectroscopy Research Team, RIKEN Center for Advanced Photonics (RAP), 2-1 Hirosawa, Wako 351-0198, Japan
| | - Yasuhisa Mizutani
- Department
of Chemistry, Graduate School of Science, Osaka University, 1-1
Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Yuki Sudo
- Faculty
of Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan
- Graduate
School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan
| |
Collapse
|
12
|
Chan SK, Kawaguchi H, Kubo H, Murakami M, Ihara K, Maki K, Kouyama T. Crystal Structure of the 11-cis Isomer of Pharaonis Halorhodopsin: Structural Constraints on Interconversions among Different Isomeric States. Biochemistry 2016; 55:4092-104. [DOI: 10.1021/acs.biochem.6b00277] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Siu Kit Chan
- Department
of Physics, Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan
| | - Haruki Kawaguchi
- Department
of Physics, Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan
| | - Hiroki Kubo
- Department
of Physics, Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan
| | - Midori Murakami
- Department
of Physics, Graduate School of Science, Nagoya University, 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, Nagoya 464-8602, Japan
| | - Tsutomu Kouyama
- Department
of Physics, Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan
- RIKEN Harima Branch, 1-1-1, Kouto, Sayo, Hyogo, Japan
| |
Collapse
|
13
|
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.
Collapse
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
| |
Collapse
|
14
|
Kikukawa T, Kusakabe C, Kokubo A, Tsukamoto T, Kamiya M, Aizawa T, Ihara K, Kamo N, Demura M. Probing the Cl − -pumping photocycle of pharaonis halorhodopsin: Examinations with bacterioruberin, an intrinsic dye, and membrane potential-induced modulation of the photocycle. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1847:748-58. [DOI: 10.1016/j.bbabio.2015.05.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2015] [Revised: 05/01/2015] [Accepted: 05/04/2015] [Indexed: 10/23/2022]
|
15
|
Relationship between the reconstituted vesicle size and the transmembrane protein-to-lipid ratio. Colloids Surf A Physicochem Eng Asp 2014. [DOI: 10.1016/j.colsurfa.2014.02.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
|
16
|
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.
Collapse
Affiliation(s)
- Kousuke Shibasaki
- Faculty of Advanced Life Science, Hokkaido University , Sapporo 060-0810, Japan
| | | | | | | | | | | | | | | |
Collapse
|
17
|
Furutani Y, Kimura T, Okamoto K. Development of a rapid Buffer-exchange system for time-resolved ATR-FTIR spectroscopy with the step-scan mode. Biophysics (Nagoya-shi) 2013; 9:123-9. [PMID: 27493550 PMCID: PMC4629687 DOI: 10.2142/biophysics.9.123] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Accepted: 07/16/2013] [Indexed: 12/31/2022] Open
Abstract
Attenuated total reflectance (ATR)-FTIR spectroscopy has been widely used to probe protein structural changes under various stimuli, such as light absorption, voltage change, and ligand binding, in aqueous conditions. Time-resolved measurements require a trigger, which can be controlled electronically; therefore, light and voltage changes are suitable. Here we developed a novel, rapid buffer-exchange system for time-resolved ATR-FTIR spectroscopy to monitor the ligand- or ion-binding re-action of a protein. By using the step-scan mode (time resolution; 2.5 ms), we confirmed the completion of the buffer-exchange reaction within ∼25 ms; the process was monitored by the infrared absorption change of a nitrate band at 1,350 cm(-1). We also demonstrated the anion-binding reaction of a membrane protein, Natronomonas pharaonis halorhodopsin (pHR), which binds a chloride ion in the initial anion-binding site near the retinal chromophore. The formation of chloride- or nitrate-bound pHR was confirmed by an increase of the retinal absorption band at 1,528 cm(-1). It also should be noted that low sample consumption (∼1 µg of protein) makes this new method a powerful technique to understand ligand-protein and ion-protein interactions, particularly for membrane proteins.
Collapse
Affiliation(s)
- Yuji Furutani
- Department of Life and Coordination-Complex Molecular Science, Institute for Molecular Science, 38 Nishigo-Naka, Myodaiji, Okazaki 444-8585, Japan; Department of Structural Molecular Science, The Graduate University for Advanced Studies (SOKENDAI), 38 Nishigo-Naka, Myodaiji, Okazaki 444-8585, Japan
| | - Tetsunari Kimura
- Department of Life and Coordination-Complex Molecular Science, Institute for Molecular Science, 38 Nishigo-Naka, Myodaiji, Okazaki 444-8585, Japan; Department of Structural Molecular Science, The Graduate University for Advanced Studies (SOKENDAI), 38 Nishigo-Naka, Myodaiji, Okazaki 444-8585, Japan
| | - Kido Okamoto
- UNISOKU Co., Ltd., 2-4-3 Kasugano, Hirakata, Osaka 573-0131, Japan
| |
Collapse
|
18
|
Distortion of the amide-I and -II bands of an α-helical membrane protein, pharaonis halorhodopsin, depends on thickness of gold films utilized for surface-enhanced infrared absorption spectroscopy. Chem Phys 2013. [DOI: 10.1016/j.chemphys.2012.11.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
|
19
|
Ser(262) determines the chloride-dependent colour tuning of a new halorhodopsin from Haloquadratum walsbyi. Biosci Rep 2013; 32:501-9. [PMID: 22716305 PMCID: PMC3475450 DOI: 10.1042/bsr20120054] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Light is an important environmental signal for all organisms on earth because it is essential for physiological signalling and the regulation of most biological systems. Halophiles found in salt-saturated ponds encode various archaeal rhodopsins and thereby harvest various wavelengths of light either for ion transportation or as sensory mediators. HR (halorhodopsin), one of the microbial rhodopsins, senses yellow light and transports chloride or other halides into the cytoplasm to maintain the osmotic balance during cell growth, and it exists almost ubiquitously in all known halobacteria. To date, only two HRs, isolated from HsHR (Halobacterium salinarum HR) and NpHR (Natronomonas pharaonis HR), have been characterized. In the present study, two new HRs, HmHR (Haloarcula marismortui HR) and HwHR (Haloquadratum walsbyi HR), were functionally overexpressed in Escherichia coli, and the maximum absorbance (λmax) of the purified proteins, the light-driven chloride uptake and the chloride-binding affinity were measured. The results showed them to have similar properties to two HRs reported previously. However, the λmax of HwHR is extremely consistent in a wide range of salt/chloride concentrations, which had not been observed previously. A structural-based sequence alignment identified a single serine residue at 262 in HwHR, which is typically a conserved alanine in all other known HRs. A Ser262 to alanine replacement in HwHR eliminated the chloride-independent colour tuning, whereas an Ala246 to serine mutagenesis in HsHR transformed it to have chloride-independent colour tuning similar to that of HwHR. Thus Ser262 is a key residue for the mechanism of chloride-dependent colour tuning in HwHR.
Collapse
|
20
|
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]
|
21
|
Salt bridge in the conserved His-Asp cluster inGloeobacterrhodopsin contributes to trimer formation. FEBS Lett 2013; 587:322-7. [DOI: 10.1016/j.febslet.2012.12.022] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2012] [Revised: 12/12/2012] [Accepted: 12/13/2012] [Indexed: 12/18/2022]
|
22
|
Furutani Y, Fujiwara K, Kimura T, Kikukawa T, Demura M, Kandori H. Dynamics of Dangling Bonds of Water Molecules in pharaonis Halorhodopsin during Chloride Ion Transportation. J Phys Chem Lett 2012; 3:2964-2969. [PMID: 26292234 DOI: 10.1021/jz301287n] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Ion transportation via the chloride ion pump protein pharaonis halorhodopsin (pHR) occurs through the sequential formation of several intermediates during a photocyclic reaction. Although the structural details of each intermediate state have been studied, the role of water molecules in the translocation of chloride ions inside of the protein at physiological temperatures remains unclear. To analyze the structural dynamics of water inside of the protein, we performed time-resolved Fourier transform infrared (FTIR) spectroscopy under H2O or H2(18)O hydration and successfully assigned water O-H stretching bands. We found that a dangling water band at 3626 cm(-1) in pHR disappears in the L1 and L2 states. On the other hand, relatively intense positive bands at 3605 and 3608 cm(-1) emerged upon the formation of the X(N) and O states, respectively, suggesting that the chloride transportation is accompanied by dynamic rearrangement of the hydrogen-bonding network of the internal water molecules in pHR.
Collapse
Affiliation(s)
- Yuji Furutani
- †Department of Life and Coordination-Complex Molecular Science, Institute for Molecular Science, 38 Nishigo-Naka, Myodaiji, Okazaki 444-8585, Japan
- ‡Department of Structural Molecular Science, The Graduate University for Advanced Studies (SOKENDAI), 38 Nishigo-Naka, Myodaiji, Okazaki 444-8585, Japan
| | - Kuniyo Fujiwara
- †Department of Life and Coordination-Complex Molecular Science, Institute for Molecular Science, 38 Nishigo-Naka, Myodaiji, Okazaki 444-8585, Japan
- ‡Department of Structural Molecular Science, The Graduate University for Advanced Studies (SOKENDAI), 38 Nishigo-Naka, Myodaiji, Okazaki 444-8585, Japan
| | - Tetsunari Kimura
- †Department of Life and Coordination-Complex Molecular Science, Institute for Molecular Science, 38 Nishigo-Naka, Myodaiji, Okazaki 444-8585, Japan
- ‡Department of Structural Molecular Science, The Graduate University for Advanced Studies (SOKENDAI), 38 Nishigo-Naka, Myodaiji, Okazaki 444-8585, Japan
| | - Takashi Kikukawa
- ¶Faculty of Advanced Life Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Makoto Demura
- ¶Faculty of Advanced Life Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Hideki Kandori
- #Department of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
| |
Collapse
|
23
|
Homotrimer formation and dissociation of pharaonis halorhodopsin in detergent system. Biophys J 2012; 102:2906-15. [PMID: 22735541 DOI: 10.1016/j.bpj.2012.05.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2011] [Revised: 05/06/2012] [Accepted: 05/08/2012] [Indexed: 12/13/2022] Open
Abstract
Halorhodopsin from NpHR is a light-driven Cl(-) pump that forms a trimeric NpHR-bacterioruberin complex in the native membrane. In the case of NpHR expressed in Escherichia coli cell, NpHR forms a robust homotrimer in a detergent DDM solution. To identify the important residue for the homotrimer formation, we carried out mutation experiments on the aromatic amino acids expected to be located at the molecular interface. The results revealed that Phe(150) was essential to form and stabilize the NpHR trimer in the DDM solution. Further analyses for examining the structural significance of Phe(150) showed the dissociation of the trimer in F150A (dimer) and F150W (monomer) mutants. Only the F150Y mutant exhibited dissociation into monomers in an ionic strength-dependent manner. These results indicated that spatial positions and interactions between F150-aromatic side chains were crucial to homotrimer stabilization. This finding was supported by QM calculations. In a functional respect, differences in the reaction property in the ground and photoexcited states were revealed. The analysis of photointermediates revealed a decrease in the accumulation of O, which is important for Cl(-) release, and the acceleration of the decay rate in L1 and L2, which are involved in Cl(-) transfer inside the molecule, in the trimer-dissociated mutants. Interestingly, the affinity of them to Cl(-) in the photoexcited state increased rather than the trimer, whereas that in the ground state was almost the same without relation to the oligomeric state. It was also observed that the efficient recovery of the photocycle to the ground state was inhibited in the mutants. In addition, a branched pathway that was not included in Cl(-) transportation was predicted. These results suggest that the trimer assembly may contribute to the regulation of the dynamics in the excited state of NpHR.
Collapse
|
24
|
Muroda K, Nakashima K, Shibata M, Demura M, Kandori H. Protein-bound water as the determinant of asymmetric functional conversion between light-driven proton and chloride pumps. Biochemistry 2012; 51:4677-84. [PMID: 22583333 DOI: 10.1021/bi300485r] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Bacteriorhodopsin (BR) and halorhodopsin (HR) are light-driven outward proton and inward chloride pumps, respectively. They have similar protein architecture, being composed of seven-transmembrane helices that bind an all-trans-retinal. BR can be converted into a chloride pump by a single amino acid replacement at position 85, suggesting that BR and HR share a common transport mechanism, and the ionic specificity is determined by the amino acid at that position. However, HR cannot be converted into a proton pump by the corresponding reverse mutation. Here we mutated 6 and 10 amino acids of HR into BR-like, whereas such multiple HR mutants never pump protons. Light-induced Fourier transform infrared spectroscopy revealed that hydrogen bonds of the retinal Schiff base and water are both strong for BR and both weak for HR. Multiple HR mutants exhibit strong hydrogen bonds of the Schiff base, but the hydrogen bond of water is still weak. We concluded that the cause of nonfunctional conversion of HR is the lack of strongly hydrogen-bonded water, the functional determinant of the proton pump.
Collapse
Affiliation(s)
- Kosuke Muroda
- Department of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya, Japan
| | | | | | | | | |
Collapse
|
25
|
Sasaki T, Razak NWA, Kato N, Mukai Y. Characteristics of halorhodopsin-bacterioruberin complex from Natronomonas pharaonis membrane in the solubilized system. Biochemistry 2012; 51:2785-94. [PMID: 22369627 DOI: 10.1021/bi201876p] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Halorhodopsin is a retinal protein with a seven-transmembrane helix and acts as an inward light-driven Cl(-) pump. In this study, structural state of the solubilized halorhodopsin (NpHR) from the biomembrane of mutant strain KM-1 of Natronomonas pharaonis in nonionic detergent was investigated. A gel filtration chromatography monitored absorbances at 280 and 504 nm corresponding to the protein and a lipid soluble pigment of bacterioruberin (BR), respectively, has clearly detected an oligomer formation of the NpHRs and a complex formation between the NpHR and BR in the solubilized system. A molar ratio of NpHR:BR in the solubilized complex was close to 1:1. Further SDS-PAGE analysis of the solubilized NpHR cross-linked by 1% glutaraldehyde has revealed that the NpHR forms homotrimer in detergent system. Although this trimeric structure was stable in the presence of NaCl, it was dissociated to the monomer by the heat treatment at 45 °C in the desalted condition. The same tendency has been reported in the case of trimeric NpHR expressed heterologously on the E. coli membrane, leading to a conclusion that the change of strength of the trimeric association dependent on the ion binding is a universal feature of the NpHR. Interestingly, the trimer dissociation on the NpHR was accompanied by the complete dissociation of the BR molecule from the protein, indicated that the cavity formed by the NpHR protomers in the trimeric conformation is important for tight binding of the BR. Because the binding affinity for Cl(-) and the resistance to hydroxylamine under light illumination showed only minor differences between the NpHR in the solubilized state and that on the biomembrane, the influences of solubilization to the tertiary structure and function of the protein are thought to be minor. This NpHR-BR complex in the solubilized system has a potential to be a good model system to investigate the intermolecular interaction between the membrane protein and lipid.
Collapse
Affiliation(s)
- Takanori Sasaki
- School of Science and Technology, Meiji University, Tama-ku, Kawasaki-shi, Kanagawa 214-8571, Japan.
| | | | | | | |
Collapse
|
26
|
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.
Collapse
Affiliation(s)
- Yasutaka Yamashita
- Faculty of Advanced Life Science, Hokkaido University, Sapporo 060-0810, Japan
| | | | | | | | | | | | | | | | | |
Collapse
|
27
|
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
| |
Collapse
|
28
|
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.
Collapse
Affiliation(s)
- Keiichi Inoue
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | | | | | | | | |
Collapse
|
29
|
|
30
|
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]
|
31
|
Sasaki T, Kubo M, Kikukawa T, Kamiya M, Aizawa T, Kawano K, Kamo N, Demura M. Halorhodopsin fromNatronomonas pharaonisForms a Trimer Even in the Presence of a Detergent, Dodecyl-β-d-maltoside. Photochem Photobiol 2009; 85:130-6. [DOI: 10.1111/j.1751-1097.2008.00406.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
32
|
Maeda H, Terasaki M, Haketa Y, Mihashi Y, Kusunose Y. BF(2) complexes of alpha-alkyl-substituted dipyrrolyldiketones as acyclic anion receptors. Org Biomol Chem 2007; 6:433-6. [PMID: 18219407 DOI: 10.1039/b718317h] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
alpha-Alkyl-substituted dipyrrolyldiketones have exhibited anion binding behaviours with pyrrole rotations, whose rates depend on the alkyl chain lengths.
Collapse
Affiliation(s)
- Hiromitsu Maeda
- Department of Bioscience and Biotechnology, Ritsumeikan University, Kusatsu, 525-8577, Japan.
| | | | | | | | | |
Collapse
|
33
|
Affiliation(s)
- Hiromitsu Maeda
- Department of Bioscience and Biotechnology, Faculty of Science and Engineering, Ritsumeikan University, Kusatsu 525‐8577, Japan, Fax: +81‐77‐561‐2659
- Department of Materials Molecular Science, Institute for Molecular Science (IMS), Okazaki, 444‐8787, Japan
| |
Collapse
|
34
|
Klare JP, Chizhov I, Engelhard M. Microbial rhodopsins: scaffolds for ion pumps, channels, and sensors. Results Probl Cell Differ 2007; 45:73-122. [PMID: 17898961 DOI: 10.1007/400_2007_041] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Microbial rhodopsins have been intensively researched for the last three decades. Since the discovery of bacteriorhodopsin, the scope of microbial rhodopsins has been considerably extended, not only in view of the large number of family members, but also their functional properties as pumps, sensors, and channels. In this review, we give a short overview of old and newly discovered microbial rhodopsins, the mechanism of signal transfer and ion transfer, and we discuss structural and mechanistic aspects of phototaxis.
Collapse
Affiliation(s)
- Johann P Klare
- Fachbereich Physik, University Osnabrück, Barbarastrasse 7, 49069, Osnabrück, Germany
| | | | | |
Collapse
|
35
|
Mevorat-Kaplan K, Brumfeld V, Engelhard M, Sheves M. The protonated Schiff base of halorhodopsin from Natronobacterium pharaonis is hydrolyzed at elevated temperatures. Photochem Photobiol 2007; 82:1414-21. [PMID: 16602834 DOI: 10.1562/2005-12-16-ra-756] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Halorhodopsin from Natronobacterium pharaonis (pHR) is a light-driven chloride pump in which photoisomerzation of a retinal chromophore triggers a photocycle which leads to a chloride anion transport across the plasma membrane. Similarly to other retinal proteins the protonated Schiff base (PSB), which covalently links the retinal to the protein, does not experience hydrolysis reaction at room temperature even though several water molecules are located in the protonated Schiff base (PSB) vicinity. In the present studies we have revealed that in contrast to other studied archaeal rhodopsins, temperature increase to about 70 degrees C hydrolyses the PSB linkage of pHR. The rate of the reaction is affected by Cl-concentration and reveals an anion binding site (in addition to the Cl- in the SB vicinity) with a binding constant of 100mM (measured at 70 degrees C). We suggest that this binding site is located on the extracellular side and its possible role in the Cl-pumping mechanism is discussed. The rate of the hydrolysis reaction is affected by the nature of the anion bound to pHR. Substitution of the Cl- anion by Br-, I- and SCN- exhibits similar behavior to that of CI- in the region of 100mM but higher concentrations are needed for N3-, HCOO- and NO2-to achieve similar behavior. Steady state pigment illumination accelerates the reaction and reduces the energy of activation and the frequency factor. Adjusting the sample temperature to 25 degrees C following the hydrolysis reaction led to about 80% pigment recovery. However, the newly reformed pigment is different from the mother pigment and has different characteristics. It is concluded that the apo-membrane adopts a modified conformation and/or aggregated state which rebinds the retinal to give a new conformation of the pHR pigment.
Collapse
Affiliation(s)
- Keren Mevorat-Kaplan
- Department of Organic Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel
| | | | | | | |
Collapse
|
36
|
Hasegawa C, Kikukawa T, Miyauchi S, Seki A, Sudo Y, Kubo M, Demura M, Kamo N. Interaction of the Halobacterial Transducer to a Halorhodopsin Mutant Engineered so as to Bind the Transducer: Cl− Circulation Within the Extracellular Channel†. Photochem Photobiol 2007; 83:293-302. [PMID: 16978043 DOI: 10.1562/2006-06-09-ra-916] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
An alkali-halophilic archaeum, Natronomonas pharaonis, contains two rhodopsins that are halorhodopsin (phR), a light-driven inward Cl- pump and phoborhodopsin (ppR), the receptor of negative phototaxis functioning by forming a signaling complex with a transducer, pHtrII (Sudo Y. et al., J. Mol. Biol. 357 [2006] 1274). Previously, we reported that the phR double mutant, P240T/F250Y(phR), can bind with pHtrII. This mutant itself can transport Cl-, while the net transport was stopped upon formation of the complex. The flash-photolysis data were analyzed by a scheme in which phR --> 4 P1 --> P2 --> 4 P3 --> P4 --> phR. The P3 of the wild-type and the double mutant contained two components, X- and O-intermediates. After the complex formation, however, the P3 of the double mutant lacked the X-intermediate. These observations imply that the X-intermediate (probably the N-intermediate) is the state having Cl- in the cytoplasmic binding site and that the complex undergoes an extracellular Cl- circulation because of the inhibition of formation of the X-intermediate.
Collapse
Affiliation(s)
- Chisa Hasegawa
- Laboratory of Biophysical Chemistry, Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan
| | | | | | | | | | | | | | | |
Collapse
|
37
|
Seki A, Miyauchi S, Hayashi S, Kikukawa T, Kubo M, Demura M, Ganapathy V, Kamo N. Heterologous expression of Pharaonis halorhodopsin in Xenopus laevis oocytes and electrophysiological characterization of its light-driven Cl- pump activity. Biophys J 2007; 92:2559-69. [PMID: 17208978 PMCID: PMC1864822 DOI: 10.1529/biophysj.106.093153] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Natronomonas pharaonis halorhodopsin (pHR) is an archaeal rhodopsin functioning as an inward-directed, light-driven Cl- pump. To characterize the electrophysiological features of the Cl- pump activity of pHR, we expressed pHR in Xenopus laevis oocytes and analyzed its photoinduced Cl- pump activity using the two-electrode voltage-clamp technique. Photoinduced outward currents were observed only in the presence of Cl-, Br-, I-, NO3-, and SCN-, but not in control oocytes, indicating that photoinduced anion currents were mediated by pHR. The relationship between photoinduced Cl- current via pHR and the light intensity was linear, demonstrating that transport of Cl- is driven by a single-photon reaction and that the steady-state current is proportional to the excited pHR molecule. The current-voltage relationship for pHR-mediated photoinduced currents was also linear between -150 mV and +50 mV. The slope of the line describing the current-voltage relationship increased as the number of the excited pHR molecules was increased by the light intensity. The reversal potential (VR) for Cl- as the substrate for the anion pump activity of pHR was about -400 mV. The value for VR was independent of light intensity, meaning that the VR reflects the intrinsic value of the excited pHR molecule. The value of VR changed significantly for the R123K mutant of pHR. We also show that the Cl- pump activity of pHR can generate a substantial negative membrane potential, indicating that pHR is a very potent Cl- pump. We have also analyzed the kinetics of voltage-dependent Cl- pump activity as well as that of the photocycle. Based on these data, a kinetic model for voltage-dependent Cl- transport via pHR is presented.
Collapse
Affiliation(s)
- Akiteru Seki
- Graduate School of Pharmaceutical Sciences, Laboratory of Biomolecular Systems, Creative Research Initiative Sosei, and Department of Biomolecular Science, Faculty of Advanced Life Sciences, Hokkaido University, Sapporo, Japan
| | | | | | | | | | | | | | | |
Collapse
|
38
|
Mevorat-Kaplan K, Brumfeld V, Engelhard M, Sheves M. The Protonated Schiff Base of Halorhodopsin from Natronobacterium pharaonis is Hydrolyzed at Elevated Temperatures. Photochem Photobiol 2006. [DOI: 10.1111/j.1751-1097.2006.tb09793.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
39
|
Sudo Y, Yamabi M, Kato S, Hasegawa C, Iwamoto M, Shimono K, Kamo N. Importance of specific hydrogen bonds of archaeal rhodopsins for the binding to the transducer protein. J Mol Biol 2006; 357:1274-82. [PMID: 16483604 DOI: 10.1016/j.jmb.2006.01.061] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2005] [Revised: 01/09/2006] [Accepted: 01/13/2006] [Indexed: 11/18/2022]
Abstract
Four rhodopsins, bacteriorhodopsin (bR), halorhodopsin (hR), sensory rhodopsin (sR) and phoborhodopsin (pR) exist in archaeal membranes. bR and hR work as a light-driven ion pump. sR and pR work as a photo-sensor of phototaxis, and form signaling complexes in membranes with their respective cognate transducer proteins HtrI (with sR) and HtrII (with pR), through which light signals are transmitted to the cytoplasm. What is the determining factor(s) of the specific binding to form the complex? Binding of the wild-type or mutated rhodopsins with HtrII was measured by isothermal titration calorimetric analysis (ITC). bR and hR could not bind with HtrII. On the other hand, sR could bind to HtrII, although the dissociation constant (K(D)) was about 100 times larger than that of pR. An X-ray crystallographic structure of the pR/HtrII complex revealed formation of two specific hydrogen bonds whose pairs are Tyr199(pR)/Asn74(HtrII) and Thr189(pR)/Glu43(HtrII)/Ser62(HtrII). To investigate the importance of these hydrogen bonds, the K(D) value for the binding of various mutants of bR, hR, sR and pR with HtrII was estimated by ITC. The K(D) value of T189V(pR)/Y199F(pR), double mutant/HtrII complex, was about 100-fold larger than that of the wild-type pR, whose K(D) value was 0.16 microM. On the other hand, bR and hR double mutants, P200T(bR)/V210Y(bR) and P240T(hR)/F250Y(hR), were able to bind with HtrII. The K(D) value of these complexes was estimated to be 60.1(+/-10.7) microM for bR and to be 29.1(+/-6.1) microM for hR, while the wild-type bR and hR did not bind with HtrII. We concluded that these two specific hydrogen bonds play important roles in the binding between the rhodopsins and transducer protein.
Collapse
Affiliation(s)
- Yuki Sudo
- Laboratory of Biophysical Chemistry, Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan.
| | | | | | | | | | | | | |
Collapse
|
40
|
Hasegawa K, Kimura Y, Ono TA. Oxidation of the Mn cluster induces structural changes of NO3- functionally bound to the Cl- site in the oxygen-evolving complex of photosystem II. Biophys J 2004; 86:1042-50. [PMID: 14747339 PMCID: PMC1303897 DOI: 10.1016/s0006-3495(04)74179-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Cl(-) is an indispensable cofactor for photosynthetic O(2) evolution and is functionally replaced by NO(3)(-). Structural changes of an isotopically labeled NO(3)(-) ion, induced by the oxidation of the Mn cluster (S(1)-to-S(2)), were detected by FTIR spectroscopy. NO(3)(-)-substituted photosystem II core particles showed (14)N(16)O(3)(-)/(15)N(16)O(3)(-) and (14)N(16)O(3)(-)/(14)N(18)O(3)(-) isotopic bands in the S(2)/S(1) spectra with markedly high signal/noise ratio. These bands appeared only in the region from 1415 to 1284 cm(-1), indicating that the bands do not arise from a metal-bound NO(3)(-) but from an ionic NO(3)(-). The intensity of the bands exhibited a quantitatively proportional relationship with the O(2) activity. These results demonstrate that the NO(3)(-) functionally bound to the Cl(-) site couples to the Mn cluster structurally, but is not associated with the cluster as a direct ligand. Comparison of the bands for two isotopes ((15)N and (18)O) and their simulations enable us to assign each band to the S(1) and S(2) states. The results indicate that the NO(3)(-) ion bound to the Cl(-) site is highly asymmetric in S(1) but rather symmetric in S(2). Since NO(3)(-) functionally replaces Cl(-), most of the conclusions drawn from this study will be also applicable to Cl(-).
Collapse
Affiliation(s)
- Koji Hasegawa
- Laboratory for Photo-Biology (I), RIKEN Photodynamics Research Center, The Institute of Physical and Chemical Research, 519-1399 Aoba, Aramaki, Aoba, Sendai 980-0845, Japan.
| | | | | |
Collapse
|
41
|
|
42
|
Sato M, Kikukawa T, Araiso T, Okita H, Shimono K, Kamo N, Demura M, Nitta K. Ser-130 of Natronobacterium pharaonis halorhodopsin is important for the chloride binding. Biophys Chem 2003; 104:209-16. [PMID: 12834839 DOI: 10.1016/s0301-4622(02)00368-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Pharaonis halorhodopsin (phR) is an inward light-driven chloride ion pump from Natronobacterium pharaonis. In order to clarify the role of Ser-130(phR) residue which corresponds to Ser-115(shR) for salinarum hR on the anion-binding affinity, the wild-type and Ser-130 mutants substituted with Thr, Cys and Ala were expressed in E. coli cells and solubilized with 0.1% n-dodecyl beta-D-maltopyranoside The absorption maximum (lambda(max)) of the S130T mutant indicated a blue shift from that of the wild type in the absence and presence of chloride. For S130A, a large red shift (12 nm) in the absence of chloride was observed. The wild-type and all mutants showed the blue-shift of lambda(max) upon Cl(-) addition, from which the dissociation constants of Cl(-) were determined. The dissociation constants were 5, 89, 153 and 159 mM for the wild-type, S130A, S130T and S130C, respectively, at pH 7.0 and 25 degrees C. Circular dichroic spectra of the wild-type and the Ser-130 mutants exhibited an oligomerization. The present study revealed that the Ser-130 of N. pharaonis halorhodopsin is important for the chloride binding.
Collapse
Affiliation(s)
- Maki Sato
- Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan
| | | | | | | | | | | | | | | |
Collapse
|
43
|
Metzler DE, Metzler CM, Sauke DJ. Light and Life. Biochemistry 2001. [DOI: 10.1016/b978-012492543-4/50026-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|