1
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Ma J, Tang L, Tan Y, Xiao J, Wei K, Zhang X, Ma Y, Tong S, Chen J, Zhou N, Yang L, Lei Z, Li Y, Lv J, Liu J, Zhang H, Tang K, Zhang Y, Huang B. Lithium carbonate revitalizes tumor-reactive CD8 + T cells by shunting lactic acid into mitochondria. Nat Immunol 2024; 25:552-561. [PMID: 38263463 PMCID: PMC10907288 DOI: 10.1038/s41590-023-01738-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 12/18/2023] [Indexed: 01/25/2024]
Abstract
The steady flow of lactic acid (LA) from tumor cells to the extracellular space via the monocarboxylate transporter symport system suppresses antitumor T cell immunity. However, LA is a natural energy metabolite that can be oxidized in the mitochondria and could potentially stimulate T cells. Here we show that the lactate-lowering mood stabilizer lithium carbonate (LC) can inhibit LA-mediated CD8+ T cell immunosuppression. Cytoplasmic LA increased the pumping of protons into lysosomes. LC interfered with vacuolar ATPase to block lysosomal acidification and rescue lysosomal diacylglycerol-PKCθ signaling to facilitate monocarboxylate transporter 1 localization to mitochondrial membranes, thus transporting LA into the mitochondria as an energy source for CD8+ T cells. These findings indicate that targeting LA metabolism using LC could support cancer immunotherapy.
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Affiliation(s)
- Jingwei Ma
- Department of Immunology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Liang Tang
- Department of Immunology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yaoyao Tan
- Department of Biochemistry & Molecular Biology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jingxuan Xiao
- Department of Immunology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Keke Wei
- Department of Immunology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xin Zhang
- Department of Immunology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yuan Ma
- Department of Biochemistry & Molecular Biology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Shuai Tong
- Department of Immunology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jie Chen
- Department of Immunology & National Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Nannan Zhou
- Department of Immunology & National Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Li Yang
- Biotherapy Center and Cancer Center, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Zhang Lei
- Department of Oncology, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yonggang Li
- Hubei Provincial Key Laboratory for Applied Toxicology, Hubei Provincial Center for Disease Control and Prevention, Wuhan, China
| | - Jiadi Lv
- Department of Immunology & National Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Junwei Liu
- Cardiovascular Surgery, Union Hospital, Huazhong University of Science and Technology, Wuhan, China
| | - Huafeng Zhang
- Department of Pathology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Ke Tang
- Department of Biochemistry & Molecular Biology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yi Zhang
- Biotherapy Center and Cancer Center, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Bo Huang
- Department of Biochemistry & Molecular Biology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
- Department of Immunology & National Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
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2
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Bühl E, Resler T, Lam R, Asido M, Bamberg E, Schlesinger R, Bamann C, Heberle J, Wachtveitl J. Assessing the Role of R120 in the Gating of CrChR2 by Time-Resolved Spectroscopy from Femtoseconds to Seconds. J Am Chem Soc 2023; 145:21832-21840. [PMID: 37773976 DOI: 10.1021/jacs.3c05399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/01/2023]
Abstract
The light-gated ion channel channelrhodopsin-2 from Chlamydomonas reinhardtii (CrChR2) is the most frequently used optogenetic tool in neurosciences. However, the precise molecular mechanism of the channel opening and the correlation among retinal isomerization, the photocycle, and the channel activity of the protein are missing. Here, we present electrophysiological and spectroscopic investigations on the R120H variant of CrChR2. R120 is a key residue in an extended network linking the retinal chromophore to several gates of the ion channel. We show that despite the deficient channel activity, the photocycle of the variant is intact. In a comparative study for R120H and the wild type, we resolve the vibrational changes in the spectral range of the retinal and amide I bands across the time range from femtoseconds to seconds. Analysis of the amide I mode reveals a significant impairment of the ultrafast protein response after retinal excitation. We conclude that channel opening in CrChR2 is prepared immediately after retinal excitation. Additionally, chromophore isomerization is essential for both photocycle and channel activities, although both processes can occur independently.
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Affiliation(s)
- Elena Bühl
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt am Main, Max-von-Laue Strasse 7, 60438 Frankfurt, Germany
| | - Tom Resler
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Rebecca Lam
- Max Planck Institute of Biophysics, Max-von-Laue Strasse 3, 60438 Frankfurt am Main, Germany
| | - Marvin Asido
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt am Main, Max-von-Laue Strasse 7, 60438 Frankfurt, Germany
| | - Ernst Bamberg
- Max Planck Institute of Biophysics, Max-von-Laue Strasse 3, 60438 Frankfurt am Main, Germany
| | - Ramona Schlesinger
- Department of Physics, Genetic Biophysics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Christian Bamann
- Max Planck Institute of Biophysics, Max-von-Laue Strasse 3, 60438 Frankfurt am Main, Germany
| | - Joachim Heberle
- Department of Physics, Experimental Molecular Biophysics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Josef Wachtveitl
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt am Main, Max-von-Laue Strasse 7, 60438 Frankfurt, Germany
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3
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Tajima S, Kim YS, Fukuda M, Jo Y, Wang PY, Paggi JM, Inoue M, Byrne EFX, Kishi KE, Nakamura S, Ramakrishnan C, Takaramoto S, Nagata T, Konno M, Sugiura M, Katayama K, Matsui TE, Yamashita K, Kim S, Ikeda H, Kim J, Kandori H, Dror RO, Inoue K, Deisseroth K, Kato HE. Structural basis for ion selectivity in potassium-selective channelrhodopsins. Cell 2023; 186:4325-4344.e26. [PMID: 37652010 PMCID: PMC7615185 DOI: 10.1016/j.cell.2023.08.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 05/11/2023] [Accepted: 08/07/2023] [Indexed: 09/02/2023]
Abstract
KCR channelrhodopsins (K+-selective light-gated ion channels) have received attention as potential inhibitory optogenetic tools but more broadly pose a fundamental mystery regarding how their K+ selectivity is achieved. Here, we present 2.5-2.7 Å cryo-electron microscopy structures of HcKCR1 and HcKCR2 and of a structure-guided mutant with enhanced K+ selectivity. Structural, electrophysiological, computational, spectroscopic, and biochemical analyses reveal a distinctive mechanism for K+ selectivity; rather than forming the symmetrical filter of canonical K+ channels achieving both selectivity and dehydration, instead, three extracellular-vestibule residues within each monomer form a flexible asymmetric selectivity gate, while a distinct dehydration pathway extends intracellularly. Structural comparisons reveal a retinal-binding pocket that induces retinal rotation (accounting for HcKCR1/HcKCR2 spectral differences), and design of corresponding KCR variants with increased K+ selectivity (KALI-1/KALI-2) provides key advantages for optogenetic inhibition in vitro and in vivo. Thus, discovery of a mechanism for ion-channel K+ selectivity also provides a framework for next-generation optogenetics.
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Affiliation(s)
- Seiya Tajima
- Komaba Institute for Science, The University of Tokyo, Meguro, Tokyo, Japan
| | - Yoon Seok Kim
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Masahiro Fukuda
- Komaba Institute for Science, The University of Tokyo, Meguro, Tokyo, Japan
| | - YoungJu Jo
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Peter Y Wang
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Joseph M Paggi
- Department of Computer Science, Stanford University, Stanford, CA, USA
| | - Masatoshi Inoue
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Eamon F X Byrne
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Koichiro E Kishi
- Komaba Institute for Science, The University of Tokyo, Meguro, Tokyo, Japan
| | - Seiwa Nakamura
- Komaba Institute for Science, The University of Tokyo, Meguro, Tokyo, Japan
| | | | - Shunki Takaramoto
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Japan
| | - Takashi Nagata
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Japan
| | - Masae Konno
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Japan; PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan
| | - Masahiro Sugiura
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Japan
| | - Kota Katayama
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Japan
| | - Toshiki E Matsui
- Komaba Institute for Science, The University of Tokyo, Meguro, Tokyo, Japan
| | - Keitaro Yamashita
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
| | - Suhyang Kim
- Komaba Institute for Science, The University of Tokyo, Meguro, Tokyo, Japan
| | - Hisako Ikeda
- Komaba Institute for Science, The University of Tokyo, Meguro, Tokyo, Japan
| | - Jaeah Kim
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Hideki Kandori
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Japan; OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Japan
| | - Ron O Dror
- Department of Computer Science, Stanford University, Stanford, CA, USA; Institute for Computational and Mathematical Engineering, Stanford University, Stanford, CA, USA
| | - Keiichi Inoue
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Japan
| | - Karl Deisseroth
- Department of Bioengineering, Stanford University, Stanford, CA, USA; CNC Program, Stanford University, Stanford, CA, USA; Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA; Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, USA.
| | - Hideaki E Kato
- Komaba Institute for Science, The University of Tokyo, Meguro, Tokyo, Japan; Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo, Tokyo, Japan; FOREST, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan.
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4
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Burton-Smith RN, Song C, Ueno H, Murata T, Iino R, Murata K. Six states of Enterococcus hirae V-type ATPase reveals non-uniform rotor rotation during turnover. Commun Biol 2023; 6:755. [PMID: 37507515 PMCID: PMC10382590 DOI: 10.1038/s42003-023-05110-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 07/06/2023] [Indexed: 07/30/2023] Open
Abstract
The vacuolar-type ATPase from Enterococcus hirae (EhV-ATPase) is a thus-far unique adaptation of V-ATPases, as it performs Na+ transport and demonstrates an off-axis rotor assembly. Recent single molecule studies of the isolated V1 domain have indicated that there are subpauses within the three major states of the pseudo three-fold symmetric rotary enzyme. However, there was no structural evidence for these. Herein we activate the EhV-ATPase complex with ATP and identified multiple structures consisting of a total of six states of this complex by using cryo-electron microscopy. The orientations of the rotor complex during turnover, especially in the intermediates, are not as perfectly uniform as expected. The densities in the nucleotide binding pockets in the V1 domain indicate the different catalytic conditions for the six conformations. The off-axis rotor and its' interactions with the stator a-subunit during rotation suggests that this non-uniform rotor rotation is performed through the entire complex.
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Affiliation(s)
- Raymond N Burton-Smith
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, 38 Nishigonaka, Myodaiji, Okazaki, Aichi, 444-8585, Japan
- National Institute for Physiological Sciences, National Institutes of Natural Sciences, 38 Nishigonaka, Myodaiji, Okazaki, Aichi, 444-8585, Japan
| | - Chihong Song
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, 38 Nishigonaka, Myodaiji, Okazaki, Aichi, 444-8585, Japan
- National Institute for Physiological Sciences, National Institutes of Natural Sciences, 38 Nishigonaka, Myodaiji, Okazaki, Aichi, 444-8585, Japan
- Department of Physiological Sciences, School of Life Science, The Graduate University for Advanced Studies (SOKENDAI), 38 Nishigonaka, Myodaiji, Okazaki, Aichi, 444-8585, Japan
| | - Hiroshi Ueno
- Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo, 113-8656, Japan
| | - Takeshi Murata
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-Cho, Inage-Ku, Chiba, 263-8522, Japan
| | - Ryota Iino
- Institute for Molecular Science, National Institute for Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi, 444-8787, Japan
- Department of Functional Molecular Science, School of Physical Sciences, The Graduate University for Advanced Studies (SOKENDAI), 5-1 Higashiyama, Myodaiji, Okazaki, Aichi, 444-8585, Japan
| | - Kazuyoshi Murata
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, 38 Nishigonaka, Myodaiji, Okazaki, Aichi, 444-8585, Japan.
- National Institute for Physiological Sciences, National Institutes of Natural Sciences, 38 Nishigonaka, Myodaiji, Okazaki, Aichi, 444-8585, Japan.
- Department of Physiological Sciences, School of Life Science, The Graduate University for Advanced Studies (SOKENDAI), 38 Nishigonaka, Myodaiji, Okazaki, Aichi, 444-8585, Japan.
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5
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Hashimoto M, Miyagawa K, Singh M, Katayama K, Shoji M, Furutani Y, Shigeta Y, Kandori H. Specific zinc binding to heliorhodopsin. Phys Chem Chem Phys 2023; 25:3535-3543. [PMID: 36637167 DOI: 10.1039/d2cp04718g] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Heliorhodopsins (HeRs), a recently discovered family of rhodopsins, have an inverted membrane topology compared to animal and microbial rhodopsins. The slow photocycle of HeRs suggests a light-sensor function, although the actual function remains unknown. Although HeRs exhibit no specific binding of monovalent cations or anions, recent ATR-FTIR spectroscopy studies have demonstrated the binding of Zn2+ to HeR from Thermoplasmatales archaeon (TaHeR) and 48C12. Even though ion-specific FTIR spectra were observed for many divalent cations, only helical structural perturbations were observed for Zn2+-binding, suggesting a possible modification of the HeR function by Zn2+. The present study shows that Zn2+-binding lowers the thermal stability of TaHeR, and slows back proton transfer to the retinal Schiff base (M decay) during its photocycle. Zn2+-binding was similarly observed for a TaHeR opsin that lacks the retinal chromophore. We then studied the Zn2+-binding site by means of the ATR-FTIR spectroscopy of site-directed mutants. Among five and four mutants of His and Asp/Glu, respectively, only E150Q exhibited a completely different spectral feature of the α-helix (amide-I) in ATR-FTIR spectroscopy, suggesting that E150 is responsible for Zn2+-binding. Molecular dynamics (MD) simulations built a coordination structure of Zn2+-bound TaHeR, where E150 and protein bound water molecules participate in direct coordination. It was concluded that the specific binding site of Zn2+ is located at the cytoplasmic side of TaHeR, and that Zn2+-binding affects the structure and structural dynamics, possibly modifying the unknown function of TaHeR.
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Affiliation(s)
- Masanori Hashimoto
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan.
| | - Koichi Miyagawa
- Center for Computational Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan.
| | - Manish Singh
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan.
| | - Kota Katayama
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan. .,OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan.,JST-PRESTO, Kawaguchi, Saitama 332-0012, Japan
| | - Mitsuo Shoji
- Center for Computational Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan. .,JST-PRESTO, Kawaguchi, Saitama 332-0012, Japan
| | - Yuji Furutani
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan. .,OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
| | - Yasuteru Shigeta
- Center for Computational Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan.
| | - Hideki Kandori
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan. .,OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
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6
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Kimura Y, Imanishi M, Li Y, Yura Y, Ohno T, Saga Y, Madigan MT, Wang-Otomo ZY. Identification of metal-sensitive structural changes in the Ca 2+-binding photocomplex from Thermochromatium tepidum by isotope-edited vibrational spectroscopy. J Chem Phys 2022; 156:105101. [DOI: 10.1063/5.0075600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Calcium ions play a dual role in expanding the spectral diversity and structural stability of photocomplexes from several Ca2+-requiring purple sulfur phototrophic bacteria. Here, metal-sensitive structural changes in the isotopically labeled light-harvesting 1 reaction center (LH1-RC) complexes from the thermophilic purple sulfur bacterium Thermochromatium ( Tch.) tepidum were investigated by perfusion-induced attenuated total reflection (ATR) Fourier transform infrared (FTIR) spectroscopy. The ATR-FTIR difference spectra induced by exchanges between native Ca2+ and exogenous Ba2+ exhibited interconvertible structural and/or conformational changes in the metal binding sites at the LH1 C-terminal region. Most of the characteristic Ba2+/Ca2+ difference bands were detected even when only Ca ions were removed from the LH1-RC complexes, strongly indicating the pivotal roles of Ca2+ in maintaining the LH1-RC structure of Tch. tepidum. Upon 15N-, 13C- or 2H-labeling, the LH1-RC complexes exhibited characteristic 15N/14N-, 13C/12C-, or 2H/1H-isotopic shifts for the Ba2+/Ca2+ difference bands. Some of the 15N/14N or 13C/12C bands were also sensitive to further 2H-labelings. Given the band frequencies and their isotopic shifts along with the structural information of the Tch. tepidum LH1-RC complexes, metal-sensitive FTIR bands were tentatively identified to the vibrational modes of the polypeptide main chains and side chains comprising the metal binding sites. Furthermore, important new IR marker bands highly sensitive to the LH1 BChl a conformation in the Ca2+-bound states were revealed based on both ATR-FTIR and near-infrared Raman analyses. The present approach provides valuable insights concerning the dynamic equilibrium between the Ca2+- and Ba2+-bound states statically resolved by x-ray crystallography.
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Affiliation(s)
- Yukihiro Kimura
- Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan
| | - Michie Imanishi
- Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan
| | - Yong Li
- Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan
| | - Yuki Yura
- Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan
| | - Takashi Ohno
- Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan
| | - Yoshitaka Saga
- Department of Chemistry, Faculty of Science and Engineering, Kindai University, Higashi-Osaka 577-8502, Japan
| | - Michael T. Madigan
- School of Biological Sciences, Department of Microbiology, Southern Illinois University, Carbondale, Illinois 62901, USA
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7
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Katayama K, Suzuki K, Suno R, Kise R, Tsujimoto H, Iwata S, Inoue A, Kobayashi T, Kandori H. Vibrational spectroscopy analysis of ligand efficacy in human M 2 muscarinic acetylcholine receptor (M 2R). Commun Biol 2021; 4:1321. [PMID: 34815515 PMCID: PMC8635417 DOI: 10.1038/s42003-021-02836-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Accepted: 11/01/2021] [Indexed: 12/30/2022] Open
Abstract
The intrinsic efficacy of ligand binding to G protein-coupled receptors (GPCRs) reflects the ability of the ligand to differentially activate its receptor to cause a physiological effect. Here we use attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy to examine the ligand-dependent conformational changes in the human M2 muscarinic acetylcholine receptor (M2R). We show that different ligands affect conformational alteration appearing at the C=O stretch of amide-I band in M2R. Notably, ATR-FTIR signals strongly correlated with G-protein activation levels in cells. Together, we propose that amide-I band serves as an infrared probe to distinguish the ligand efficacy in M2R and paves the path to rationally design ligands with varied efficacy towards the target GPCR.
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Affiliation(s)
- Kota Katayama
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya, 466-8555, Japan.
- OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Nagoya, 466-8555, Japan.
- PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan.
| | - Kohei Suzuki
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya, 466-8555, Japan
| | - Ryoji Suno
- Department of Medical Chemistry, Kansai Medical University, Hirakata, 573-1010, Japan
| | - Ryoji Kise
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi, 980-8578, Japan
| | - Hirokazu Tsujimoto
- Department of Cell Biology and Medical Chemistry, Graduate School of Medicine, Kyoto University, Kyoto, 606-8501, Japan
| | - So Iwata
- Department of Cell Biology and Medical Chemistry, Graduate School of Medicine, Kyoto University, Kyoto, 606-8501, Japan
| | - Asuka Inoue
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi, 980-8578, Japan
| | - Takuya Kobayashi
- Department of Medical Chemistry, Kansai Medical University, Hirakata, 573-1010, Japan
- Japan Agency for Medical Research and Development, Core Research for Evolutional Science and Technology (AMED-CREST), Chiyoda-ku, Tokyo, 100-0004, Japan
| | - Hideki Kandori
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya, 466-8555, Japan.
- OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Nagoya, 466-8555, Japan.
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8
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Pham HDM, Boles GC, Armentrout PB. Sodium Binding Interactions with Aliphatic Amino Acids: A Guided Ion Beam and Computational Study. J Phys Chem A 2021; 125:6332-6347. [PMID: 34270256 DOI: 10.1021/acs.jpca.1c04374] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Metal binding affinities play a vital role in medicinal, biological, and industrial applications. In particular, metal cation-amino acid (AA) interactions contribute to protein stability such that analyzing analogous prototypical interactions is important. Here, we present a full description of the interactions of sodium cations (Na+) and six aliphatic amino acids (AA), where AA = glycine (Gly), alanine (Ala), homoalanine (hAla), valine (Val), leucine (Leu), and isoleucine (Ile). Experimentally, these interactions are evaluated using threshold collision-induced dissociation carried out in a guided ion beam tandem mass spectrometer, allowing for the determination of the kinetic-energy-dependent behavior of Na+-AA dissociation. Analysis of these dissociation cross sections, after accounting for multiple ion-molecule collisions, internal energy of reactant ions, and unimolecular decay rates, allows the determination of absolute Na+-AA bond dissociation energies (BDEs) in kJ/mol of Gly (164.0), Ala (166.9), hAla (167.9), Val (172.7), Leu (173.7), and Ile (174.6). These are favorably compared to quantum chemical calculations conducted at the B3LYP, B3P86, MP2(full), B3LYP-GD3BJ, and M06-2X levels of theory. Our combination of structural and energetic analyses provides information regarding the specific factors responsible for Na+ interactions with amino acids. Specifically, we find that the BDEs increase linearly with increasing polarizability of the amino acid.
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Affiliation(s)
- Hanh D M Pham
- Department of Chemistry, University of Utah, 315 South 1400 East, Room 2020, Salt Lake City, Utah 84112, United States
| | - Georgia C Boles
- Department of Chemistry, University of Utah, 315 South 1400 East, Room 2020, Salt Lake City, Utah 84112, United States
| | - P B Armentrout
- Department of Chemistry, University of Utah, 315 South 1400 East, Room 2020, Salt Lake City, Utah 84112, United States
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9
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Abstract
Heliorhodopsin (HeR), a recently discovered new rhodopsin family, has an inverted membrane topology compared to animal and microbial rhodopsins, and no ion-transport activity. The slow photocycle of HeRs suggests a light-sensor function, although the function remains unknown. HeRs exhibit no specific binding of monovalent cations or anions. Despite this, ATR-FTIR spectroscopy in the present study demonstrates binding of Zn2+ to HeR from Thermoplasmatales archaeon (TaHeR). The biding of Zn2+ to 0.2 mM Kd is accompanied by helical structural perturbations without altering its color. Even though ion-specific FTIR spectra were observed for many divalent cations, only helical structural perturbations were observed for Zn2+-binding. Similar results were obtained for HeR 48C12. These findings suggest a possible modification of HeR function by Zn2+.
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Affiliation(s)
- Masanori Hashimoto
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
| | - Kota Katayama
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
- OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
| | - Yuji Furutani
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
- OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
| | - Hideki Kandori
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
- OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
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10
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Kandori H. Structure/Function Study of Photoreceptive Proteins by FTIR Spectroscopy. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2020. [DOI: 10.1246/bcsj.20200109] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Hideki Kandori
- Department of Life Science and Applied Chemistry & OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Nagoya, Aichi 466-8555, Japan
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11
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Femtosecond-to-millisecond structural changes in a light-driven sodium pump. Nature 2020; 583:314-318. [DOI: 10.1038/s41586-020-2307-8] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 04/16/2020] [Indexed: 01/03/2023]
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12
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Abstract
Infrared difference spectroscopy probes vibrational changes of proteins upon their perturbation. Compared with other spectroscopic methods, it stands out by its sensitivity to the protonation state, H-bonding, and the conformation of different groups in proteins, including the peptide backbone, amino acid side chains, internal water molecules, or cofactors. In particular, the detection of protonation and H-bonding changes in a time-resolved manner, not easily obtained by other techniques, is one of the most successful applications of IR difference spectroscopy. The present review deals with the use of perturbations designed to specifically change the protein between two (or more) functionally relevant states, a strategy often referred to as reaction-induced IR difference spectroscopy. In the first half of this contribution, I review the technique of reaction-induced IR difference spectroscopy of proteins, with special emphasis given to the preparation of suitable samples and their characterization, strategies for the perturbation of proteins, and methodologies for time-resolved measurements (from nanoseconds to minutes). The second half of this contribution focuses on the spectral interpretation. It starts by reviewing how changes in H-bonding, medium polarity, and vibrational coupling affect vibrational frequencies, intensities, and bandwidths. It is followed by band assignments, a crucial aspect mostly performed with the help of isotopic labeling and site-directed mutagenesis, and complemented by integration and interpretation of the results in the context of the studied protein, an aspect increasingly supported by spectral calculations. Selected examples from the literature, predominately but not exclusively from retinal proteins, are used to illustrate the topics covered in this review.
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13
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Katayama K, Suzuki K, Suno R, Tsujimoto H, Iwata S, Kobayashi T, Kandori H. Ligand Binding-Induced Structural Changes in the M 2 Muscarinic Acetylcholine Receptor Revealed by Vibrational Spectroscopy. J Phys Chem Lett 2019; 10:7270-7276. [PMID: 31692352 DOI: 10.1021/acs.jpclett.9b02942] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
M2 muscarinic acetylcholine receptor (M2R) is a prototypical G protein-coupled receptor (GPCR) that responds to acetylcholine and mediates various cellular responses in the nervous system. Here, we used attenuated total reflection-Fourier transform infrared spectroscopy analyses on M2R reconstituted in a lipid membrane to understand the molecular mechanism behind the ligand binding-induced conformational changes. Upon agonist binding, M2R shows large spectral change of the amide-I band corresponding to backbone C═O stretch, which likely connects with the receptor activation in the lipid environment. These results pave the way to probe effects of different ligand binding on GPCRs using vibrational spectroscopy.
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Affiliation(s)
- Kota Katayama
- Department of Life Science and Applied Chemistry , Nagoya Institute of Technology , Showa-ku, Nagoya 466-8555 , Japan
- OptoBioTechnology Research Center , Nagoya Institute of Technology , Showa-ku, Nagoya 466-8555 , Japan
| | - Kohei Suzuki
- Department of Life Science and Applied Chemistry , Nagoya Institute of Technology , Showa-ku, Nagoya 466-8555 , Japan
| | - Ryoji Suno
- Department of Medical Chemistry , Kansai Medical University , Hirakata 573-1010 , Japan
| | - Hirokazu Tsujimoto
- Department of Cell Biology and Medical Chemistry, Graduate School of Medicine , Kyoto University , Kyoto 606-8501 , Japan
| | - So Iwata
- Department of Cell Biology and Medical Chemistry, Graduate School of Medicine , Kyoto University , Kyoto 606-8501 , Japan
| | - Takuya Kobayashi
- Department of Medical Chemistry , Kansai Medical University , Hirakata 573-1010 , Japan
- Japan Agency for Medical Research and Development , Core Research for Evolutional Science and Technology (AMED-CREST) , Tokyo 100-0004 , Japan
| | - Hideki Kandori
- Department of Life Science and Applied Chemistry , Nagoya Institute of Technology , Showa-ku, Nagoya 466-8555 , Japan
- OptoBioTechnology Research Center , Nagoya Institute of Technology , Showa-ku, Nagoya 466-8555 , Japan
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14
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Onoue Y, Iwaki M, Shinobu A, Nishihara Y, Iwatsuki H, Terashima H, Kitao A, Kandori H, Homma M. Essential ion binding residues for Na + flow in stator complex of the Vibrio flagellar motor. Sci Rep 2019; 9:11216. [PMID: 31375690 PMCID: PMC6677748 DOI: 10.1038/s41598-019-46038-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Accepted: 06/17/2019] [Indexed: 01/06/2023] Open
Abstract
The bacterial flagellar motor is a unique supramolecular complex which converts ion flow into rotational force. Many biological devices mainly use two types of ions, proton and sodium ion. This is probably because of the fact that life originated in seawater, which is rich in protons and sodium ions. The polar flagellar motor in Vibrio is coupled with sodium ion and the energy converting unit of the motor is composed of two membrane proteins, PomA and PomB. It has been shown that the ion binding residue essential for ion transduction is the conserved aspartic acid residue (PomB-D24) in the PomB transmembrane region. To reveal the mechanism of ion selectivity, we identified essential residues, PomA-T158 and PomA-T186, other than PomB-D24, in the Na+-driven flagellar motor. It has been shown that the side chain of threonine contacts Na+ in Na+-coupled transporters. We monitored the Na+-binding specific structural changes using ATR-FTIR spectroscopy. The signals were abolished in PomA-T158A and -T186A, as well as in PomB-D24N. Molecular dynamics simulations further confirmed the strong binding of Na+ to D24 and showed that T158A and T186A hindered the Na+ binding and transportation. The data indicate that two threonine residues (PomA-T158 and PomA-T186), together with PomB-D24, are important for Na+ conduction in the Vibrio flagellar motor. The results contribute to clarify the mechanism of ion recognition and conversion of ion flow into mechanical force.
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Affiliation(s)
- Yasuhiro Onoue
- Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8602, Japan
| | - Masayo Iwaki
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya, 466-8555, Japan
| | - Ai Shinobu
- School of Life Science and Technology, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo, 152-8550, Japan
| | - Yasutaka Nishihara
- Institute of Molecular and Cellular Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo, Tokyo, 113-0032, Japan
| | - Hiroto Iwatsuki
- Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8602, Japan
| | - Hiroyuki Terashima
- Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8602, Japan
| | - Akio Kitao
- School of Life Science and Technology, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo, 152-8550, Japan
| | - Hideki Kandori
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya, 466-8555, Japan.
| | - Michio Homma
- Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8602, Japan.
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15
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Tang D, Ren J, Lu M. Multiplexed electrochemical immunoassay for two immunoglobulin proteins based on Cd and Cu nanocrystals. Analyst 2018; 142:4794-4800. [PMID: 29159345 DOI: 10.1039/c7an01459g] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Herein, a simple and feasible electrochemical immunosensing method for simultaneous voltammetric detection of two immunoglobulin proteins, human IgG (HIgG) and rabbit IgG (RIgG), was developed using two distinguishable signal-generation tags on the same electrode. The immunosensor was prepared by immobilizing two Fab antibody fragments on a gold electrode. After this, Cu and Cd nanocrystals, as nanotags, were synthesized and functionalized with identical detection antibodies. Transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR) were employed to characterize the Cu and Cd nanocrystals. The covalently modified electrode with the Fab antibody fragments through the Au-thiolate bond (to dispel the non-specific adsorption) was investigated via scanning electron microscopy (SEM). After the sandwiched immunoreaction, the antibody-modified nanocrystals were captured on the immunosensor, which could be interrogated in pH 3.5 HCl using square-wave anodic stripping voltammetry. Experimental results also indicated that the multiplexed immunoassay enabled the simultaneous detection of HIgG and RIgG in a single run with the similar linear range from 0.01 to 10 ng mL-1, and the limits of detection (LODs) towards two analytes could be as low as 3.4 pg mL-1 (at 3σ). Acceptable assay results on precision, reproducibility, specificity, and method accuracy were also acquired. Importantly, the newly designed strategy avoided cross-talk and enzymatic introduction as compared to conventional electrochemical immunoassays, thus exhibiting a promising potential in clinical applications.
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Affiliation(s)
- Dianping Tang
- Chongqing Key Laboratory of Environmental Materials & Remediation Technologies, Chongqing University of Arts and Sciences, Chongqing 402160, PR China.
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16
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Katayama K, Furutani Y, Iwaki M, Fukuda T, Imai H, Kandori H. “In situ” observation of the role of chloride ion binding to monkey green sensitive visual pigment by ATR-FTIR spectroscopy. Phys Chem Chem Phys 2018; 20:3381-3387. [DOI: 10.1039/c7cp07277e] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
ATR-FTIR spectroscopic study elucidates the novel role of Cl−-binding in primate long-wavelength-sensitive (LWS) visual pigment.
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Affiliation(s)
- Kota Katayama
- Department of Life Science and Applied Chemistry
- Nagoya Institute of Technology
- Nagoya 466-8555
- Japan
| | - Yuji Furutani
- Department of Life and Coordination-Complex Molecular Science
- Institute for Molecular Science
- Okazaki 444-8585
- Japan
| | - Masayo Iwaki
- Department of Life Science and Applied Chemistry
- Nagoya Institute of Technology
- Nagoya 466-8555
- Japan
| | - Tetsuya Fukuda
- Department of Life Science and Applied Chemistry
- Nagoya Institute of Technology
- Nagoya 466-8555
- Japan
| | - Hiroo Imai
- Primate Research Institute
- Kyoto University
- Inuyama 484-8506
- Japan
| | - Hideki Kandori
- Department of Life Science and Applied Chemistry
- Nagoya Institute of Technology
- Nagoya 466-8555
- Japan
- OptoBio Technology Research Center
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17
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Kasuya G, Fujiwara Y, Tsukamoto H, Morinaga S, Ryu S, Touhara K, Ishitani R, Furutani Y, Hattori M, Nureki O. Structural insights into the nucleotide base specificity of P2X receptors. Sci Rep 2017; 7:45208. [PMID: 28332633 PMCID: PMC5362899 DOI: 10.1038/srep45208] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Accepted: 02/20/2017] [Indexed: 11/19/2022] Open
Abstract
P2X receptors are trimeric ATP-gated cation channels involved in diverse physiological processes, ranging from muscle contraction to nociception. Despite the recent structure determination of the ATP-bound P2X receptors, the molecular mechanism of the nucleotide base specificity has remained elusive. Here, we present the crystal structure of zebrafish P2X4 in complex with a weak affinity agonist, CTP, together with structure-based electrophysiological and spectroscopic analyses. The CTP-bound structure revealed a hydrogen bond, between the cytosine base and the side chain of the basic residue in the agonist binding site, which mediates the weak but significant affinity for CTP. The cytosine base is further recognized by two main chain atoms, as in the ATP-bound structure, but their bond lengths seem to be extended in the CTP-bound structure, also possibly contributing to the weaker affinity for CTP over ATP. This work provides the structural insights for the nucleotide base specificity of P2X receptors.
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Affiliation(s)
- Go Kasuya
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan
| | - Yuichiro Fujiwara
- Integrative Physiology, Department of Physiology, Graduate School of Medicine, Osaka University, 2-2 Yamada-oka, Suita, Osaka, 565-0871, Japan
| | - Hisao Tsukamoto
- Institute for Molecular Science, 38 Nishigo-Naka, Myodaiji, Okazaki, 444-8585, Japan
| | - Satoshi Morinaga
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.,ERATO Touhara Chemosensory Signal Project, JST, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Satoshi Ryu
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.,ERATO Touhara Chemosensory Signal Project, JST, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Kazushige Touhara
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.,ERATO Touhara Chemosensory Signal Project, JST, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Ryuichiro Ishitani
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan
| | - Yuji Furutani
- Institute for Molecular Science, 38 Nishigo-Naka, Myodaiji, Okazaki, 444-8585, Japan
| | - Motoyuki Hattori
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Physiology and Biophysics, School of Life Sciences, Fudan University, 2005 Songhu Road, Yangpu District, Shanghai, 200438, China
| | - Osamu Nureki
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan
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18
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Furutani Y, Shimizu H, Asai Y, Oiki S, Kandori H. Specific interactions between alkali metal cations and the KcsA channel studied using ATR-FTIR spectroscopy. Biophys Physicobiol 2015; 12:37-45. [PMID: 27493853 PMCID: PMC4736833 DOI: 10.2142/biophysico.12.0_37] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 08/21/2015] [Indexed: 01/20/2023] Open
Abstract
The X-ray structure of KcsA, a eubacterial potassium channel, displays a selectivity filter composed of four parallel peptide strands. The backbone carbonyl oxygen atoms of these strands solvate multiple K(+) ions. KcsA structures show different distributions of ions within the selectivity filter in solutions containing different cations. To assess the interactions of cations with the selectivity filter, we used attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy. Ion-exchange-induced ATR-FTIR difference spectra were obtained by subtracting the spectrum of KcsA soaked in K(+) solution from that obtained in Li(+), Na(+), Rb(+), and Cs(+) solutions. Large spectral changes in the amide-I and -II regions were observed upon replacing K(+) with smaller-sized cations Li(+) and Na(+) but not with larger-sized cations Rb(+) and Cs(+). These results strongly suggest that the selectivity filter carbonyls coordinating Rb(+) or Cs(+) adopt a conformation similar to those coordinating K(+) (cage configuration), but those coordinating Li(+) or Na(+) adopt a conformation (plane configuration) considerably different from those coordinating K(+). We have identified a cation-type sensitive amide-I band at 1681 cm(-1) and an insensitive amide-I band at 1659 cm(-1). The bands at 1650, 1639, and 1627 cm(-1) observed for Na(+)-coordinating carbonyls were almost identical to those observed in Li(+) solution, suggesting that KcsA forms a similar filter structure in Li(+) and Na(+) solutions. Thus, we conclude that the filter structure adopts a collapsed conformation in Li(+) solution that is similar to that in Na(+) solution but is in clear contrast to the X-ray crystal structure of KcsA with Li(+).
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Affiliation(s)
- Yuji Furutani
- Department of Life and Coordination-Complex Molecular Science, Institute for Molecular Science, Okazaki, Aichi 444-8585, Japan; Department of Frontier Materials, Nagoya Institute of Technology, Nagoya, Aichi 466-8555, Japan
| | - Hirofumi Shimizu
- Department of Molecular Physiology and Biophysics, Faculty of Medical Sciences, University of Fukui, Matsuoka, Fukui 910-1193, Japan
| | - Yusuke Asai
- Department of Frontier Materials, Nagoya Institute of Technology, Nagoya, Aichi 466-8555, Japan
| | - Shigetoshi Oiki
- Department of Molecular Physiology and Biophysics, Faculty of Medical Sciences, University of Fukui, Matsuoka, Fukui 910-1193, Japan
| | - Hideki Kandori
- Department of Frontier Materials, Nagoya Institute of Technology, Nagoya, Aichi 466-8555, Japan
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Kandori H, Furutani Y, Murata T. Infrared spectroscopic studies on the V-ATPase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1847:134-41. [PMID: 25111748 DOI: 10.1016/j.bbabio.2014.07.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Revised: 07/30/2014] [Accepted: 07/31/2014] [Indexed: 11/27/2022]
Abstract
V-ATPase is an ATP-driven rotary motor that vectorially transports ions. Together with F-ATPase, a homologous protein, several models on the ion transport have been proposed, but their molecular mechanisms are yet unknown. V-ATPase from Enterococcus hirae forms a large supramolecular protein complex (total molecular weight: ~700,000) and physiologically transports Na⁺ and Li⁺ across a hydrophobic lipid bilayer. Stabilization of these cations in the binding site has been discussed on the basis of X-ray crystal structures of a membrane-embedded domain, the K-ring (Na⁺ and Li⁺ bound forms). Sodium or lithium ion binding-induced difference FTIR spectra of the intact E. hirae V-ATPase have been measured in aqueous solution at physiological temperature. The results suggest that sodium or lithium ion binding induces the deprotonation of Glu139, a hydrogen-bonding change in the tyrosine residue and rigid α-helical structures. Identical difference FTIR spectra between the entire V-ATPase complex and K-ring strongly suggest that protein interaction with the I subunit does not cause large structural changes in the K-ring. This result supports the previously proposed Na⁺ transport mechanism by V-ATPase stating that a flip-flop movement of a carboxylate group of Glu139 without large conformational changes in the K-ring accelerates the replacement of a Na⁺ ion in the binding site. This article is part of a Special Issue entitled: Vibrational spectroscopies and bioenergetic systems.
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Affiliation(s)
- Hideki Kandori
- Department of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan; OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan.
| | - 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
| | - Takeshi Murata
- PRESTO, Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan; Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage, Chiba 263-8522, Japan
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20
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Alam J, Yamato I, Arai S, Saijo S, Mizutani K, Ishizuka-Katsura Y, Ohsawa N, Terada T, Shirouzu M, Yokoyama S, Iwata S, Kakinuma Y, Murata T. Mutant LV(476-7)AA of A-subunit of Enterococcus hirae V1-ATPase: High affinity of A3B3 complex to DF axis and low ATPase activity. SPRINGERPLUS 2014; 2:689. [PMID: 24404436 PMCID: PMC3879392 DOI: 10.1186/2193-1801-2-689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Accepted: 12/20/2013] [Indexed: 11/22/2022]
Abstract
Vacuolar ATPase (V-ATPase) of Enterococcus hirae is composed of a soluble functional domain V1 (A3B3DF) and an integral membrane domain Vo (ac), where V1 and Vo domains are connected by a central stalk, composed of D-, F-, and d-subunits; and two peripheral stalks (E- and G-subunits). We identified 120 interacting residues of A3B3 heterohexamer with D-subunit in DF heterodimer in the crystal structures of A3B3 and A3B3DF. In our previous study, we reported 10 mutants of E. hirae V1-ATPase, which showed lower binding affinities of DF with A3B3 complex leading to higher initial specific ATPase activities compared to the wild-type. In this study, we identified a mutation of A-subunit (LV476-7AA) at its C-terminal domain resulting in the A3B3 complex with higher binding affinities for wild-type or mutant DF heterodimers and lower initial ATPase activities compared to the wild-type A3B3 complex, consistent with our previous proposal of reciprocal relationship between the ATPase activity and the protein-protein binding affinity of DF axis to the A3B3 catalytic domain of E. hirae V-ATPase. These observations suggest that the binding of DF axis at the contact region of A3B3 rotary ring is relevant to its rotation activity.
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Affiliation(s)
- Jahangir Alam
- Department of Biological Science and Technology, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo, 125-8585 Japan ; Department of Genetic Engineering and Biotechnology, School of Life Sciences, Shahjalal University of Science and Technology, Sylhet, 3114 Bangladesh
| | - Ichiro Yamato
- Department of Biological Science and Technology, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo, 125-8585 Japan
| | - Satoshi Arai
- Department of Biological Science and Technology, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo, 125-8585 Japan ; Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-choInage, Chiba, 263-8522 Japan
| | - Shinya Saijo
- Department of Biological Science and Technology, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo, 125-8585 Japan ; RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo, 679-5148 Japan ; Structural Biology Research Center, Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, 305-0801 Japan
| | - Kenji Mizutani
- Department of Biological Science and Technology, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo, 125-8585 Japan ; Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-choInage, Chiba, 263-8522 Japan
| | - Yoshiko Ishizuka-Katsura
- RIKEN Systems and Structural Biology Center, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, 230-0045 Japan ; Division of Structural and Synthetic Biology, RIKEN Center for Life Science Technologies, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, 230-0045 Japan
| | - Noboru Ohsawa
- RIKEN Systems and Structural Biology Center, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, 230-0045 Japan ; Division of Structural and Synthetic Biology, RIKEN Center for Life Science Technologies, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, 230-0045 Japan
| | - Takaho Terada
- RIKEN Systems and Structural Biology Center, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, 230-0045 Japan ; RIKEN Structural Biology Laboratory, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, 230-0045 Japan
| | - Mikako Shirouzu
- RIKEN Systems and Structural Biology Center, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, 230-0045 Japan ; Division of Structural and Synthetic Biology, RIKEN Center for Life Science Technologies, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, 230-0045 Japan
| | - Shigeyuki Yokoyama
- RIKEN Systems and Structural Biology Center, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, 230-0045 Japan ; RIKEN Structural Biology Laboratory, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, 230-0045 Japan
| | - So Iwata
- RIKEN Systems and Structural Biology Center, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, 230-0045 Japan ; Division of Structural and Synthetic Biology, RIKEN Center for Life Science Technologies, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, 230-0045 Japan ; Department of Cell Biology, Faculty of Medicine, Kyoto University, Yoshidakonoe-cho, Sakyo-ku, Kyoto, 606-8501 Japan
| | - Yoshimi Kakinuma
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, 3-5-7 Tarumi, Matsuyama, Ehime, 790-8566 Japan
| | - Takeshi Murata
- Department of Chemistry, Graduate School of Science, Chiba University, 1-33 Yayoi-choInage, Chiba, 263-8522 Japan ; RIKEN Systems and Structural Biology Center, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, 230-0045 Japan ; Division of Structural and Synthetic Biology, RIKEN Center for Life Science Technologies, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, 230-0045 Japan ; JST, PRESTO, 1-33 Yayoi-cho, Inage, Chiba, 263-8522 Japan
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21
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Fukuda T, Muroda K, Kandori H. Detection of a protein-bound water vibration of halorhodopsin in aqueous solution. Biophysics (Nagoya-shi) 2013; 9:167-72. [PMID: 27493555 PMCID: PMC4629683 DOI: 10.2142/biophysics.9.167] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Accepted: 12/04/2013] [Indexed: 01/14/2023] Open
Abstract
Protein-bound water molecules play crucial roles in their structure and function, but their detection is an experimental challenge, particularly in aqueous solution at room temperature. By applying attenuated total reflection (ATR) Fourier-transform infrared (FTIR) spectroscopy to a light-driven Cl(-) pump pharaonis halorhodopsin (pHR), here we detected an O-H stretching vibration of protein-bound water molecules in the active center. The pHR(Cl(-)) minus pHR(Br(-)) ATR-FTIR spectra show random fluctuation at 3600-3000 cm(-1), frequency window of water vibration, which can be interpreted in terms of dynamical fluctuation of aqueous water at room temperature. On the other hand, we observed a reproducible spectral feature at 3617 (+)/3630 (-) cm(-1) in the pHR(Cl(-)) minus pHR(Br(-)) spectrum, which is absent in the pHR(Cl(-)) minus pHR(Cl(-)) and in the pHR(Br(-)) minus pHR(Br(-)) spectra. The water O-H stretching vibrations of pHR(Cl(-)) and pHR(Br(-)) at 3617 and 3630 cm(-1), respectively, are confirmed by light-induced difference FTIR spectra in isotope water (H2 (18)O) at 77 K. The observed water molecule presumably binds to the active center of pHR, and alter its hydrogen bond during the Cl(-) pumping photocycle.
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Affiliation(s)
- Tetsuya Fukuda
- Department of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
| | - Kosuke Muroda
- Department of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
| | - Hideki Kandori
- Department of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
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22
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Li Y, Kimura Y, Arikawa T, Wang-Otomo ZY, Ohno T. ATR–FTIR Detection of Metal-Sensitive Structural Changes in the Light-Harvesting 1 Reaction Center Complex from the Thermophilic Purple Sulfur Bacterium Thermochromatium tepidum. Biochemistry 2013; 52:9001-8. [DOI: 10.1021/bi401033y] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Yong Li
- Department
of Agrobioscience, Graduate School of Agriculture, Kobe University, Nada, Kobe 657-8501, Japan
| | - Yukihiro Kimura
- Department
of Agrobioscience, Graduate School of Agriculture, Kobe University, Nada, Kobe 657-8501, Japan
| | - Teruhisa Arikawa
- Department
of Agrobioscience, Graduate School of Agriculture, Kobe University, Nada, Kobe 657-8501, Japan
| | | | - Takashi Ohno
- Department
of Agrobioscience, Graduate School of Agriculture, Kobe University, Nada, Kobe 657-8501, Japan
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23
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Alam MJ, Arai S, Saijo S, Suzuki K, Mizutani K, Ishizuka-Katsura Y, Ohsawa N, Terada T, Shirouzu M, Yokoyama S, Iwata S, Kakinuma Y, Yamato I, Murata T. Loose binding of the DF axis with the A3B3 complex stimulates the initial activity of Enterococcus hirae V1-ATPase. PLoS One 2013; 8:e74291. [PMID: 24058539 PMCID: PMC3772951 DOI: 10.1371/journal.pone.0074291] [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] [Received: 05/17/2013] [Accepted: 07/30/2013] [Indexed: 11/17/2022] Open
Abstract
Vacuolar ATPases (V-ATPases) function as proton pumps in various cellular membrane systems. The hydrophilic V1 portion of the V-ATPase is a rotary motor, in which a central-axis DF complex rotates inside a hexagonally arranged catalytic A3B3 complex by using ATP hydrolysis energy. We have previously reported crystal structures of Enterococcushirae V-ATPase A3B3 and A3B3DF (V1) complexes; the result suggested that the DF axis induces structural changes in the A3B3 complex through extensive protein-protein interactions. In this study, we mutated 10 residues at the interface between A3B3 and DF complexes and examined the ATPase activities of the mutated V1 complexes as well as the binding affinities between the mutated A3B3 and DF complexes. Surprisingly, several V1 mutants showed higher initial ATPase activities than wild-type V1-ATPase, whereas these mutated A3B3 and DF complexes showed decreased binding affinities for each other. However, the high ATP hydrolysis activities of the mutants decreased faster over time than the activity of the wild-type V1 complex, suggesting that the mutants were unstable in the reaction because the mutant A3B3 and DF complexes bound each other more weakly. These findings suggest that strong interaction between the DF complex and A3B3 complex lowers ATPase activity, but also that the tight binding is responsible for the stable ATPase activity of the complex.
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Affiliation(s)
- Md Jahangir Alam
- Department of Biological Science and Technology, Tokyo University of Science, Chiba, Japan ; Department of Genetic Engineering and Biotechnology, School of Life Sciences, Shahjalal University of Science and Technology, Sylhet, Bangladesh
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24
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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.
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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
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25
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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]
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26
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Maréchal A, Iwaki M, Rich PR. Structural Changes in Cytochrome c Oxidase Induced by Binding of Sodium and Calcium Ions: An ATR-FTIR Study. J Am Chem Soc 2013; 135:5802-7. [DOI: 10.1021/ja4005706] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Amandine Maréchal
- Glynn Laboratory of
Bioenergetics,
Institute of Structural and Molecular Biology, University College London, Gower Street, London, WC1E 6BT, United
Kingdom
| | - Masayo Iwaki
- Glynn Laboratory of
Bioenergetics,
Institute of Structural and Molecular Biology, University College London, Gower Street, London, WC1E 6BT, United
Kingdom
| | - Peter R. Rich
- Glynn Laboratory of
Bioenergetics,
Institute of Structural and Molecular Biology, University College London, Gower Street, London, WC1E 6BT, United
Kingdom
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27
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Furutani Y, Shimizu H, Asai Y, Fukuda T, Oiki S, Kandori H. ATR-FTIR Spectroscopy Revealing the Different Vibrational Modes of the Selectivity Filter Interacting with K(+) and Na(+) in the Open and Collapsed Conformations of the KcsA Potassium Channel. J Phys Chem Lett 2012; 3:3806-3810. [PMID: 26291114 DOI: 10.1021/jz301721f] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The potassium channel is highly selective for K(+) over Na(+), and the selectivity filter binds multiple dehydrated K(+) ions upon permeation. Here, we applied attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy to extract ion-binding-induced signals of the KcsA potassium channel at neutral pH. Shifts in the peak of the amide-I signal towards lower vibrational frequencies were observed as K(+) was replaced with Na(+). These ion species-specific shifts deduced the selectivity filter as the source of the signal, which was supported by the spectra of a mutant for the selectivity filter (Y78F). The difference FTIR spectra between the solution containing various concentrations of K(+) and that containing pure Na(+) demonstrated two types of peak shifts of the amide-I vibration in response to the K(+) concentration. These signals represent the binding of K(+) ions to the different sites in the selectivity filter with different dissociation constants (KD = 9 or 18 mM).
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Affiliation(s)
- Yuji Furutani
- †Department of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
- §Division of Biomolecular Sensing, Department of Life and Coordination-Complex Molecular Science, Institute for Molecular Science, 38 Nishigo-Naka, Myodaiji, Okazaki 444-8585, Japan
| | - Hirofumi Shimizu
- ‡Department of Molecular Physiology and Biophysics, Faculty of Medical Sciences, University of Fukui, Yoshida, 910-1193 Fukui, Japan
| | - Yusuke Asai
- †Department of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
| | - Tetsuya Fukuda
- †Department of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
| | - Shigetoshi Oiki
- ‡Department of Molecular Physiology and Biophysics, Faculty of Medical Sciences, University of Fukui, Yoshida, 910-1193 Fukui, Japan
| | - Hideki Kandori
- †Department of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
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28
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Mayer F, Leone V, Langer JD, Faraldo-Gómez JD, Müller V. A c subunit with four transmembrane helices and one ion (Na+)-binding site in an archaeal ATP synthase: implications for c ring function and structure. J Biol Chem 2012; 287:39327-37. [PMID: 23007388 DOI: 10.1074/jbc.m112.411223] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The ion-driven membrane rotors of ATP synthases consist of multiple copies of subunit c, forming a closed ring. Subunit c typically comprises two transmembrane helices, and the c ring features an ion-binding site in between each pair of adjacent subunits. Here, we use experimental and computational methods to study the structure and specificity of an archaeal c subunit more akin to those of V-type ATPases, namely that from Pyrococcus furiosus. The c subunit was purified by chloroform/methanol extraction and determined to be 15.8 kDa with four predicted transmembrane helices. However, labeling with DCCD as well as Na(+)-DCCD competition experiments revealed only one binding site for DCCD and Na(+), indicating that the mature c subunit of this A(1)A(O) ATP synthase is indeed of the V-type. A structural model generated computationally revealed one Na(+)-binding site within each of the c subunits, mediated by a conserved glutamate side chain alongside other coordinating groups. An intriguing second glutamate located in-between adjacent c subunits was ruled out as a functional Na(+)-binding site. Molecular dynamics simulations indicate that the c ring of P. furiosus is highly Na(+)-specific under in vivo conditions, comparable with the Na(+)-dependent V(1)V(O) ATPase from Enterococcus hirae. Interestingly, the same holds true for the c ring from the methanogenic archaeon Methanobrevibacter ruminantium, whose c subunits also feature a V-type architecture but carry two Na(+)-binding sites instead. These findings are discussed in light of their physiological relevance and with respect to the mode of ion coupling in A(1)A(O) ATP synthases.
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Affiliation(s)
- Florian Mayer
- Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University Frankfurt/Main, 60438 Frankfurt, Germany
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