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Suzuki S, Tanaka K, Nishikawa K, Suzuki H, Oshima A, Fujiyoshi Y. Structural basis of hydroxycarboxylic acid receptor signaling mechanisms through ligand binding. Nat Commun 2023; 14:5899. [PMID: 37736747 PMCID: PMC10516952 DOI: 10.1038/s41467-023-41650-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 09/12/2023] [Indexed: 09/23/2023] Open
Abstract
Hydroxycarboxylic acid receptors (HCA) are expressed in various tissues and immune cells. HCA2 and its agonist are thus important targets for treating inflammatory and metabolic disorders. Only limited information is available, however, on the active-state binding of HCAs with agonists. Here, we present cryo-EM structures of human HCA2-Gi and HCA3-Gi signaling complexes binding with multiple compounds bound. Agonists were revealed to form a salt bridge with arginine, which is conserved in the HCA family, to activate these receptors. Extracellular regions of the receptors form a lid-like structure that covers the ligand-binding pocket. Although transmembrane (TM) 6 in HCAs undergoes dynamic conformational changes, ligands do not directly interact with amino acids in TM6, suggesting that indirect signaling induces a slight shift in TM6 to activate Gi proteins. Structural analyses of agonist-bound HCA2 and HCA3 together with mutagenesis and molecular dynamics simulation provide molecular insights into HCA ligand recognition and activation mechanisms.
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Affiliation(s)
- Shota Suzuki
- TMDU Advanced Research Institute, Tokyo Medical and Dental University Bunkyo-ku, Tokyo, Japan
| | - Kotaro Tanaka
- Cellular and Structural Physiology Institute (CeSPI), Nagoya University, Nagoya, Japan
- Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, Japan
| | - Kouki Nishikawa
- Joint Research Course for Advanced Biomolecular Characterization, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | - Hiroshi Suzuki
- TMDU Advanced Research Institute, Tokyo Medical and Dental University Bunkyo-ku, Tokyo, Japan
| | - Atsunori Oshima
- Cellular and Structural Physiology Institute (CeSPI), Nagoya University, Nagoya, Japan
- Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, Japan
- Institute for Glyco-core Research (iGCORE), Nagoya University, Nagoya, Japan
- Center for One Medicine Innovative Translational Research, Gifu University Institute for Advanced Study, Gifu City, Japan
| | - Yoshinori Fujiyoshi
- TMDU Advanced Research Institute, Tokyo Medical and Dental University Bunkyo-ku, Tokyo, Japan.
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2
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Kamegawa A, Suzuki S, Suzuki H, Nishikawa K, Numoto N, Fujiyoshi Y. Structural analysis of the water channel AQP2 by single-particle cryo-EM. J Struct Biol 2023; 215:107984. [PMID: 37315821 DOI: 10.1016/j.jsb.2023.107984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 05/19/2023] [Accepted: 06/10/2023] [Indexed: 06/16/2023]
Abstract
Water channels, which are small membrane proteins almost entirely buried in lipid membranes, are challenging research targets for single-particle cryo-electron microscopy (cryo-EM), a powerful technique routinely used to determine the structures of membrane proteins. Because the single-particle method enables structural analysis of a whole protein with flexible parts that interfere with crystallization, we have focused our efforts on analyzing water channel structures. Here, utilizing this system, we analyzed the structure of full-length aquaporin-2 (AQP2), a primary regulator of vasopressin-dependent reabsorption of water at the renal collecting ducts. The 2.9 Å resolution map revealed a cytoplasmic extension of the cryo-EM density that was presumed to be the highly flexible C-terminus at which the localization of AQP2 is regulated in the renal collecting duct cells. We also observed a continuous density along the common water pathway inside the channel pore and lipid-like molecules at the membrane interface. Observations of these constructions in the AQP2 structure analyzed without any fiducial markers (e.g., a rigidly bound antibody) indicate that single-particle cryo-EM will be useful for investigating water channels in native states as well as in complexes with chemical compounds.
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Affiliation(s)
- Akiko Kamegawa
- Cellular and Structural Physiology Laboratory (CeSPL), Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
| | - Shota Suzuki
- Cellular and Structural Physiology Laboratory (CeSPL), Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
| | - Hiroshi Suzuki
- Cellular and Structural Physiology Laboratory (CeSPL), Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
| | - Kouki Nishikawa
- Joint Research Course for Advanced Biomolecular Characterization, Faculty of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan
| | - Nobutaka Numoto
- Medical Research Institute, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8501, Japan
| | - Yoshinori Fujiyoshi
- Cellular and Structural Physiology Laboratory (CeSPL), Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
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Imai S, Suzuki H, Fujiyoshi Y, Shimada I. Dynamically regulated two-site interaction of viral RNA to capture host translation initiation factor. Nat Commun 2023; 14:4977. [PMID: 37640715 PMCID: PMC10462655 DOI: 10.1038/s41467-023-40582-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 07/27/2023] [Indexed: 08/31/2023] Open
Abstract
Many RNA viruses employ internal ribosome entry sites (IRESs) in their genomic RNA to commandeer the host's translational machinery for replication. The IRES from encephalomyocarditis virus (EMCV) interacts with eukaryotic translation initiation factor 4 G (eIF4G), recruiting the ribosomal subunit for translation. Here, we analyze the three-dimensional structure of the complex composed of EMCV IRES, the HEAT1 domain fragment of eIF4G, and eIF4A, by cryo-electron microscopy. Two distinct eIF4G-interacting domains on the IRES are identified, and complex formation changes the angle therebetween. Further, we explore the dynamics of these domains by using solution NMR spectroscopy, revealing conformational equilibria in the microsecond to millisecond timescale. In the lowly-populated conformations, the base-pairing register of one domain is shifted with the structural transition of the three-way junction, as in the complex structure. Our study provides insights into the viral RNA's sophisticated strategy for optimal docking to hijack the host protein.
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Affiliation(s)
- Shunsuke Imai
- RIKEN Center for Biosystems Dynamics Research, Tsurumi-ku, Yokohama, 230-0045, Japan.
| | - Hiroshi Suzuki
- Cellular and Structural Physiology Laboratory (CeSPL), Tokyo Medical and Dental University, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Yoshinori Fujiyoshi
- Cellular and Structural Physiology Laboratory (CeSPL), Tokyo Medical and Dental University, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Ichio Shimada
- RIKEN Center for Biosystems Dynamics Research, Tsurumi-ku, Yokohama, 230-0045, Japan.
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, 739-8528, Japan.
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Irie K, Oda Y, Sumikama T, Oshima A, Fujiyoshi Y. The structural basis of divalent cation block in a tetrameric prokaryotic sodium channel. Nat Commun 2023; 14:4236. [PMID: 37454189 PMCID: PMC10349818 DOI: 10.1038/s41467-023-39987-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 07/06/2023] [Indexed: 07/18/2023] Open
Abstract
Divalent cation block is observed in various tetrameric ion channels. For blocking, a divalent cation is thought to bind in the ion pathway of the channel, but such block has not yet been directly observed. So, the behaviour of these blocking divalent cations remains still uncertain. Here, we elucidated the mechanism of the divalent cation block by reproducing the blocking effect into NavAb, a well-studied tetrameric sodium channel. Our crystal structures of NavAb mutants show that the mutations increasing the hydrophilicity of the inner vestibule of the pore domain enable a divalent cation to stack on the ion pathway. Furthermore, non-equilibrium molecular dynamics simulation showed that the stacking calcium ion repel sodium ion at the bottom of the selectivity filter. These results suggest the primary process of the divalent cation block mechanism in tetrameric cation channels.
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Affiliation(s)
- Katsumasa Irie
- Department of Biophysical Chemistry, School of Pharmaceutical Sciences, Wakayama Medical University, 25-1, Shichibancho, Wakayama, 640-8156, Japan.
- Cellular and Structural Physiology Institute (CeSPI), Nagoya University, Furo-cho, Chikusa, Nagoya, 464-8601, Japan.
| | - Yoshinori Oda
- Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Furo-cho, Chikusa, Nagoya, 464-8601, Japan
| | - Takashi Sumikama
- PRESTO, JST, Kawaguchi, 332-0012, Japan
- Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kanazawa, 920-1192, Japan
| | - Atsunori Oshima
- Cellular and Structural Physiology Institute (CeSPI), Nagoya University, Furo-cho, Chikusa, Nagoya, 464-8601, Japan
- Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Furo-cho, Chikusa, Nagoya, 464-8601, Japan
- Institute for Glyco-core Research (iGCORE), Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan
- Center for One Medicine Innovative Translational Research, Gifu University Institute for Advanced Study, Gifu, 501-11193, Japan
| | - Yoshinori Fujiyoshi
- Cellular and Structural Physiology Laboratory (CeSPL), Advanced Research Institute, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo, Tokyo, 113-8510, Japan
- CeSPIA Inc., 2-1-1, Otemachi, Chiyoda, Tokyo, 100-0004, Japan
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Kozai D, Numoto N, Nishikawa K, Kamegawa A, Kawasaki S, Hiroaki Y, Irie K, Oshima A, Hanzawa H, Shimada K, Kitano Y, Fujiyoshi Y. Recognition mechanism of a novel gabapentinoid drug, mirogabalin, for recombinant human α 2δ1, a voltage-gated calcium channel subunit. J Mol Biol 2023; 435:168049. [PMID: 36933823 DOI: 10.1016/j.jmb.2023.168049] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Revised: 02/22/2023] [Accepted: 03/12/2023] [Indexed: 03/17/2023]
Abstract
Mirogabalin is a novel gabapentinoid drug with a hydrophobic bicyclo substituent on the γ-aminobutyric acid moiety that targets the voltage-gated calcium channel subunit α2δ1. Here, to reveal the mirogabalin recognition mechanisms of α2δ1, we present structures of recombinant human α2δ1 with and without mirogabalin analyzed by cryo-electron microscopy. These structures show the binding of mirogabalin to the previously reported gabapentinoid binding site, which is the extracellular dCache_1 domain containing a conserved amino acid binding motif. A slight conformational change occurs around the residues positioned close to the hydrophobic group of mirogabalin. Mutagenesis binding assays identified that residues in the hydrophobic interaction region, in addition to several amino acid binding motif residues around the amino and carboxyl groups of mirogabalin, are critical for mirogabalin binding. The A215L mutation introduced to decrease the hydrophobic pocket volume predictably suppressed mirogabalin binding and promoted the binding of another ligand, L-Leu, with a smaller hydrophobic substituent than mirogabalin. Alterations of residues in the hydrophobic interaction region of α2δ1 to those of the α2δ2, α2δ3, and α2δ4 isoforms, of which α2δ3 and α2δ4 are gabapentin-insensitive, suppressed the binding of mirogabalin. These results support the importance of hydrophobic interactions in α2δ1 ligand recognition.
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Affiliation(s)
- Daisuke Kozai
- Cellular and Structural Physiology Institute (CeSPI), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan; Japan Biological Informatics Consortium, 2-4-32 Aomi, Koto-ku, Tokyo 135-0063, Japan; Advanced Research Institute, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8501, Japan.
| | - Nobutaka Numoto
- Medical Research Institute, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8501, Japan.
| | - Kouki Nishikawa
- CeSPIA Inc., 2-1-1 Otemachi, Chiyoda-ku, Tokyo 100-0004, Japan; Joint Research Course for Advanced Biomolecular Characterization, Faculty of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan.
| | - Akiko Kamegawa
- Advanced Research Institute, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8501, Japan; CeSPIA Inc., 2-1-1 Otemachi, Chiyoda-ku, Tokyo 100-0004, Japan.
| | - Shohei Kawasaki
- Daiichi Sankyo RD Novare Co., Ltd., 1-16-13 Kitakasai, Edogawa-ku, Tokyo 134-8630, Japan.
| | - Yoko Hiroaki
- Cellular and Structural Physiology Institute (CeSPI), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan; Japan Biological Informatics Consortium, 2-4-32 Aomi, Koto-ku, Tokyo 135-0063, Japan.
| | - Katsumasa Irie
- Cellular and Structural Physiology Institute (CeSPI), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan; Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.
| | - Atsunori Oshima
- Cellular and Structural Physiology Institute (CeSPI), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan; Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan; Institute for Glyco-core Research (iGCORE), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.
| | - Hiroyuki Hanzawa
- Daiichi Sankyo RD Novare Co., Ltd., 1-16-13 Kitakasai, Edogawa-ku, Tokyo 134-8630, Japan.
| | - Kousei Shimada
- Daiichi Sankyo Co., Ltd., 1-2-58 Hiromachi, Shinagawa-ku, Tokyo 140-8710, Japan.
| | - Yutaka Kitano
- Daiichi Sankyo Co., Ltd., 1-2-58 Hiromachi, Shinagawa-ku, Tokyo 140-8710, Japan.
| | - Yoshinori Fujiyoshi
- Advanced Research Institute, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8501, Japan; CeSPIA Inc., 2-1-1 Otemachi, Chiyoda-ku, Tokyo 100-0004, Japan.
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Fujiyoshi MRA, Fujiyoshi Y, Gimpaya N, Bechara R, Jeyalingam T, Calo NC, Forbes N, Khan R, Atalla M, Toshimori A, Shimamura Y, Tanabe M, Mosko J, Inoue H, Grover S. A114 UNIFIED MAGNIFYING ENDOSCOPIC CLASSIFICATION (UMEC) FOR GASTROINTESTINAL LESIONS: A NORTH AMERICAN EDUCATION STUDY. J Can Assoc Gastroenterol 2023. [PMCID: PMC9991233 DOI: 10.1093/jcag/gwac036.114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 03/09/2023] Open
Abstract
Abstract
Background
Magnification endoscopy and magnification narrow-band imaging are image enhanced endoscopy technologies that may allow for the diagnosis of advanced neoplasia in the GI tract on the basis of imaging characteristics. Recently, the Unified Magnifying Endoscopic Classification (UMEC) has been developed, which unified the criteria for the esophagus, stomach, and colon. UMEC divides optical diagnosis into one of the three categories: non-neoplastic, intramucosal neoplasia, and deep submucosal invasive cancer.
Purpose
The objective of this study is to educate North American endoscopists on the use of the UMEC schema, and to ascertain performance of the UMEC framework among North American endoscopists.
Method
Using UMEC, five North American endoscopists (>1000 procedures) without prior training in magnifying endoscopy independently diagnosed previously collected endoscopic image set of the esophagus, stomach, and colon. The endoscopists were trained on the use of UMEC via an eleven-minute training video with exemplars of each element of UMEC from esophagus, stomach, and colon. All endoscopists were blinded to white-light and non-magnifying NBI findings as well as histopathological diagnosis. The diagnostic performance of UMEC was assessed while using the gold standard histopathology as a reference.
Result(s)
A total of 299 gastrointestinal lesions (77 esophagus, 92 stomach, and 130 colon) were assessed using UMEC. For esophageal squamous cell carcinoma, the sensitivity, specificity, and accuracy for all 5 endoscopists ranged from 65.2% (95% CI: 50.9–77.9) to 87.0% (95% CI: 75.3–94.6), 77.4% (95% CI: 60.9–89.6) to 96.8% (95% CI: 86.8–99.8), and 75.3% to 87.0%, respectively. For gastric adenocarcinoma, the sensitivity, specificity, and accuracy for all 5 endoscopists ranged from 94.9% (95% CI: 85.0–99.1) to 100%, 52.9% (95% CI: 39.4–66.2) to 92.2% (95% CI: 82.7–97.5), and 73.3% to 93.3%, respectively. For colorectal adenocarcinoma, the sensitivity, specificity, and accuracy for all 5 endoscopists ranged from 76.2% (95% CI: 62.0–87.3) to 83.3% (95% CI: 70.3–92.5), 89.7% (95% CI: 82.1–94.9) to 97.7% (95% CI: 93.1–99.6), and 86.8% to 90.7%, respectively.
Image
Conclusion(s)
UMEC is a simple and practical classification that can be used to introduce and educate endoscopists to magnification narrow-band imaging and optical diagnosis.
Please acknowledge all funding agencies by checking the applicable boxes below
CAG
Disclosure of Interest
M. R. A. Fujiyoshi Grant / Research support from: 2022 CAG/AbbVie Education Research Grant, Y. Fujiyoshi: None Declared, N. Gimpaya: None Declared, R. Bechara: None Declared, T. Jeyalingam: None Declared, N. Calo: None Declared, N. Forbes: None Declared, R. Khan: None Declared, M. Atalla: None Declared, A. Toshimori: None Declared, Y. Shimamura: None Declared, M. Tanabe: None Declared, J. Mosko: None Declared, H. Inoue: None Declared, S. Grover: None Declared
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Affiliation(s)
- M R A Fujiyoshi
- Division of Gastroenterology, St. Michael's Hospital, University of Toronto , Toronto , Canada
- Digestive Diseases Center, Showa University Koto Toyosu Hospital , Tokyo , Japan
| | - Y Fujiyoshi
- Division of Gastroenterology, St. Michael's Hospital, University of Toronto , Toronto , Canada
- Digestive Diseases Center, Showa University Koto Toyosu Hospital , Tokyo , Japan
| | - N Gimpaya
- Division of Gastroenterology, St. Michael's Hospital, University of Toronto , Toronto , Canada
| | - R Bechara
- Division of Gastroenterology, Kingston General and Hotel Dieu Hospital, Queen's University , Kingston
| | - T Jeyalingam
- Division of Gastroenterology, University Health Network, University of Toronto , Toronto
| | - N C Calo
- Division of Gastroenterology, University of Ottawa , Ottawa
| | - N Forbes
- Division of Gastroenterology, University of Calgary , Calgary , Canada
| | - R Khan
- Division of Gastroenterology, St. Michael's Hospital, University of Toronto , Toronto , Canada
| | - M Atalla
- Division of Gastroenterology, St. Michael's Hospital, University of Toronto , Toronto , Canada
| | - A Toshimori
- Digestive Diseases Center, Showa University Koto Toyosu Hospital , Tokyo , Japan
| | - Y Shimamura
- Digestive Diseases Center, Showa University Koto Toyosu Hospital , Tokyo , Japan
| | - M Tanabe
- Digestive Diseases Center, Showa University Koto Toyosu Hospital , Tokyo , Japan
| | - J Mosko
- Division of Gastroenterology, St. Michael's Hospital, University of Toronto , Toronto , Canada
| | - H Inoue
- Digestive Diseases Center, Showa University Koto Toyosu Hospital , Tokyo , Japan
| | - S Grover
- Division of Gastroenterology, St. Michael's Hospital, University of Toronto , Toronto , Canada
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Zhao AY, Gimpaya N, Lisondra J, Fujiyoshi R, Fujiyoshi Y, Khan R, Tham D, Scaffidi MA, Bansal R, Walsh C, Grover SC. A119 DEVELOPMENT AND EVALUATION OF LOW-COST GEL POLYPS FOR POLYPECTOMY SKILLS TRAINING IN NOVICE ENDOSCOPISTS. J Can Assoc Gastroenterol 2023. [PMCID: PMC9991154 DOI: 10.1093/jcag/gwac036.119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 03/09/2023] Open
Abstract
Background Polypectomy is an essential skill for endoscopists to acquire. As polyps are encountered ad hoc during colonoscopies, exposure to polypectomy in clinical training may vary. There is a need to deliver a curriculum that standardizes exposure to polypectomy while remaining cost-effective for endoscopy programs worldwide. Purpose To develop low-cost simulated polyps that can be incorporated into endoscopic training programs, and to evaluate their perceived realism and useability for polypectomy training. Method We designed 3D molds based on the Paris classification, a validated rubric for polyp morphology. The polyps are depicted in Figure 1. Using low-cost materials, we created gel-based polyps compatible with physical colonic simulators. Current versions of the polyps were finalized based on visual realism and durability. Expert (performed >1000 procedures) and novice (<25 procedures) endoscopists were invited to perform simulated polypectomies and evaluate the realism of the polyps. Using a 7-point Likert scale (“strongly disagree” to “strongly agree”), we administered a survey adapted from the Direct Observed Polypectomy Skills (DOPyS) checklist to evaluate the polyps on practicality of design and useability for training. Additionally, the simulator’s resemblance to human polypectomy was assessed through a scale with 1 indicating “low resemblance” and 7 indicating “high resemblance”. The ease of identifying morphology was also evaluated, with 1 indicating “difficult” and 7 indicating “easy”. Result(s) The survey was completed by 11 expert endoscopists and 10 novices. The median score submitted by experts on the polyps’ useability in training the technique for mobilization of the polyp was 7 (IQR 6-7). Experts rated the simulator’s practicality in teaching cold snare or electrocautery techniques with a median score of 6 (IQR 6-7). Lastly, the ability of the simulator to develop skills in identifying and treating the residual polyp was assessed by expert endoscopists, giving it a median score of 6 (IQR 6-7). The simulators were tested on similarity to human polypectomy, with the median score of expert groups being 5 (IQR 5-6), and novice groups being 6 (IQR 6-6). Both groups were asked to rate if morphology could be identified using the simulator; the median score of expert groups being 6 (IQR 6-7), and 6.5 for novice endoscopists (IQR 5-7). Image ![]()
Conclusion(s) The development of simulated polyps with differing morphologies using low-cost and common materials with high realism is feasible. These polyps may potentially be integrated into different endoscopic training programs. Please acknowledge all funding agencies by checking the applicable boxes below None Disclosure of Interest A. Zhao: None Declared, N. Gimpaya: None Declared, J. Lisondra: None Declared, R. Fujiyoshi: None Declared, Y. Fujiyoshi: None Declared, R. Khan Grant / Research support from: Rishad Khan has received research grants from AbbVie (2018) and Ferring Pharmaceuticals (2019) and research funding from Pendopharm (2019). , D. Tham: None Declared, M. Scaffidi: None Declared, R. Bansal: None Declared, C. Walsh: None Declared, S. Grover Shareholder of: Samir C. Grover has equity in Volo Healthcare., Grant / Research support from: Samir C. Grover has received research grants and personal fees from AbbVie and Ferring Pharmaceuticals, personal fees from Takeda, education grants from Janssen.
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Affiliation(s)
- A Y Zhao
- Division of Gastroenterology, St. Michael's Hospital
| | - N Gimpaya
- Division of Gastroenterology, St. Michael's Hospital
| | - J Lisondra
- Division of Gastroenterology, St. Michael's Hospital
| | - R Fujiyoshi
- Division of Gastroenterology, St. Michael's Hospital
| | - Y Fujiyoshi
- Division of Gastroenterology, St. Michael's Hospital
| | - R Khan
- Division of Gastroenterology, St. Michael's Hospital,Department of Medicine, University of Toronto
| | - D Tham
- Division of Gastroenterology, St. Michael's Hospital
| | - M A Scaffidi
- Division of Gastroenterology, St. Michael's Hospital
| | - R Bansal
- Division of Gastroenterology, St. Michael's Hospital
| | - C Walsh
- Division of Gastroenterology, Hepatology, and Nutrition and the Research and Learning Institutes, The Hospital for Sick Children,Department of Pediatrics, University of Toronto Faculty of medicine,The Wilson Centre, University of Toronto, Toronto, Canada
| | - S C Grover
- Division of Gastroenterology, St. Michael's Hospital,Department of Medicine, University of Toronto
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Naydenova K, Kamegawa A, Peet MJ, Henderson R, Fujiyoshi Y, Russo CJ. On the reduction in the effects of radiation damage to two-dimensional crystals of organic and biological molecules at liquid-helium temperature. Ultramicroscopy 2022; 237:113512. [PMID: 35367901 PMCID: PMC9355890 DOI: 10.1016/j.ultramic.2022.113512] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 02/24/2022] [Accepted: 03/06/2022] [Indexed: 11/17/2022]
Abstract
We have studied the fading of electron diffraction spots from two-dimensional (2D) crystals of paraffin (C44H90), purple membrane (bacteriorhodopsin) and aquaporin 4 (AQP4) at stage temperatures between 4K and 100K. We observed that the diffraction spots at resolutions between 3 Å and 20 Å fade more slowly at liquid-helium temperatures compared to liquid-nitrogen temperatures, by a factor of between 1.2 and 1.8, depending on the specimens. If the reduction in the effective rate of radiation damage for 2D crystals at liquid-helium temperature (as measured by spot fading) can be shown to extend to macromolecular assemblies embedded in amorphous ice, this would suggest that valuable improvements to electron cryomicroscopy (cryoEM) of biological specimens could be made by reducing the temperature of the specimens under irradiation below what is obtainable using standard liquid-nitrogen cryostats.
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Affiliation(s)
- Katerina Naydenova
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Akiko Kamegawa
- Cellular and Structural Physiology Laboratory (CeSPL), Tokyo Medical and Dental University, Yushima, Bunkyo-ku, Tokyo, Japan
| | - Mathew J Peet
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Richard Henderson
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Yoshinori Fujiyoshi
- Cellular and Structural Physiology Laboratory (CeSPL), Tokyo Medical and Dental University, Yushima, Bunkyo-ku, Tokyo, Japan
| | - Christopher J Russo
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK.
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9
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Tanimura Y, Hiroaki Y, Mori M, Fujiyoshi Y. Cell-based flow cytometry assay for simultaneous detection of multiple autoantibodies in a single serum sample. Anal Biochem 2022; 650:114721. [DOI: 10.1016/j.ab.2022.114721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2021] [Revised: 04/06/2022] [Accepted: 05/04/2022] [Indexed: 11/17/2022]
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10
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Kuzuya M, Hirano H, Hayashida K, Watanabe M, Kobayashi K, Terada T, Mahmood MI, Tama F, Tani K, Fujiyoshi Y, Oshima A. Structures of human pannexin-1 in nanodiscs reveal gating mediated by dynamic movement of the N terminus and phospholipids. Sci Signal 2022; 15:eabg6941. [PMID: 35133866 DOI: 10.1126/scisignal.abg6941] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Pannexin (PANX) family proteins form large-pore channels that mediate purinergic signaling. We analyzed the cryo-EM structures of human PANX1 in lipid nanodiscs to elucidate the gating mechanism and its regulation by the amino terminus in phospholipids. The wild-type channel has an amino-terminal funnel in the pore, but in the presence of the inhibitor probenecid, a cytoplasmically oriented amino terminus and phospholipids obstruct the pore. Functional analysis using whole-cell patch-clamp and oocyte voltage clamp showed that PANX1 lacking the amino terminus did not open and had a dominant negative effect on channel activity, thus confirming that the amino-terminal domain played an essential role in channel opening. These observations suggest that dynamic conformational changes in the amino terminus of human PANX1 are associated with lipid movement in and out of the pore. Moreover, the data provide insight into the gating mechanism of PANX1 and, more broadly, other large-pore channels.
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Affiliation(s)
- Maki Kuzuya
- Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Hidemi Hirano
- Cellular and Structural Physiology Institute (CeSPI), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Kenichi Hayashida
- Cellular and Structural Physiology Institute (CeSPI), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Masakatsu Watanabe
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
| | | | - Tohru Terada
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyō-ku, Tokyo 113-8657, Japan
| | - Md Iqbal Mahmood
- Department of Physics, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Florence Tama
- Department of Physics, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.,Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.,RIKEN Center for Computational Science, Kobe, Hyogo 650-0047, Japan
| | - Kazutoshi Tani
- Graduate School of Medicine, Mie University, 2-174 Edobashi Tsu, Mie 514-8507, Japan
| | - Yoshinori Fujiyoshi
- Advanced Research Institute, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyō-ku, Tokyo 113-8510, Japan.,CeSPIA Inc., Otemachi, Chiyoda, Tokyo 100-0004, Japan
| | - Atsunori Oshima
- Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.,Cellular and Structural Physiology Institute (CeSPI), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.,Institute for Glyco-core Research (iGCORE), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
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11
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Oda Y, Takahashi C, Harada S, Nakamura S, Sun D, Kiso K, Urata Y, Miyachi H, Fujiyoshi Y, Honigmann A, Uchida S, Ishihama Y, Toyoshima F. Discovery of anti-inflammatory physiological peptides that promote tissue repair by reinforcing epithelial barrier formation. Sci Adv 2021; 7:eabj6895. [PMID: 34788088 PMCID: PMC8597994 DOI: 10.1126/sciadv.abj6895] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 09/28/2021] [Indexed: 05/10/2023]
Abstract
Epithelial barriers that prevent dehydration and pathogen invasion are established by tight junctions (TJs), and their disruption leads to various inflammatory diseases and tissue destruction. However, a therapeutic strategy to overcome TJ disruption in diseases has not been established because of the lack of clinically applicable TJ-inducing molecules. Here, we found TJ-inducing peptides (JIPs) in mice and humans that corresponded to 35 to 42 residue peptides of the C terminus of alpha 1-antitrypsin (A1AT), an acute-phase anti-inflammatory protein. JIPs were inserted into the plasma membrane of epithelial cells, which promoted TJ formation by directly activating the heterotrimeric G protein G13. In a mouse intestinal epithelial injury model established by dextran sodium sulfate, mouse or human JIP administration restored TJ integrity and strongly prevented colitis. Our study has revealed TJ-inducing anti-inflammatory physiological peptides that play a critical role in tissue repair and proposes a previously unidentified therapeutic strategy for TJ-disrupted diseases.
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Affiliation(s)
- Yukako Oda
- Department of Biosystems Science, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto 606-8507, Japan
| | - Chisato Takahashi
- Department of Molecular and Cellular BioAnalysis, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
- Laboratory of Analytical Chemistry, Faculty of Pharmaceutical Sciences, Doshisha Women’s College of Liberal Arts, Kyoto 610-0395, Japan
| | - Shota Harada
- Laboratory of Human Interface, Graduate School of Systems Life Sciences, Kyushu University, Fukuoka 819-0395, Japan
| | - Shun Nakamura
- Cellular and Structural Physiology Laboratory, Advanced Research Institute, Tokyo Medical and Dental University, Tokyo 113-8510, Japan
- CeSPIA Inc., Tokyo 100-0004, Japan
| | - Daxiao Sun
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01309, Germany
| | - Kazumi Kiso
- Department of Biosystems Science, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto 606-8507, Japan
| | - Yuko Urata
- Department of Biosystems Science, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto 606-8507, Japan
| | - Hitoshi Miyachi
- Reproductive Engineering Team, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto 606-8507, Japan
| | - Yoshinori Fujiyoshi
- Cellular and Structural Physiology Laboratory, Advanced Research Institute, Tokyo Medical and Dental University, Tokyo 113-8510, Japan
- CeSPIA Inc., Tokyo 100-0004, Japan
| | - Alf Honigmann
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01309, Germany
| | - Seiichi Uchida
- Laboratory of Human Interface, Graduate School of Systems Life Sciences, Kyushu University, Fukuoka 819-0395, Japan
| | - Yasushi Ishihama
- Department of Molecular and Cellular BioAnalysis, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
| | - Fumiko Toyoshima
- Department of Biosystems Science, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto 606-8507, Japan
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12
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Nakanishi H, Irie K, Segawa K, Hasegawa K, Fujiyoshi Y, Nagata S, Abe K. Crystal structure of a human plasma membrane phospholipid flippase. J Biol Chem 2020; 295:10180-10194. [PMID: 32493773 DOI: 10.1074/jbc.ra120.014144] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 05/29/2020] [Indexed: 12/27/2022] Open
Abstract
ATP11C, a member of the P4-ATPase flippase, translocates phosphatidylserine from the outer to the inner plasma membrane leaflet, and maintains the asymmetric distribution of phosphatidylserine in the living cell. We present the crystal structures of a human plasma membrane flippase, ATP11C-CDC50A complex, in a stabilized E2P conformation. The structure revealed a deep longitudinal crevice along transmembrane helices continuing from the cell surface to the phospholipid occlusion site in the middle of the membrane. We observed that the extension of the crevice on the exoplasmic side is open, and the complex is therefore in an outward-open E2P state, similar to a recently reported cryo-EM structure of yeast flippase Drs2p-Cdc50p complex. We noted extra densities, most likely bound phosphatidylserines, in the crevice and in its extension to the extracellular side. One was close to the phosphatidylserine occlusion site as previously reported for the human ATP8A1-CDC50A complex, and the other in a cavity at the surface of the exoplasmic leaflet of the bilayer. Substitutions in either of the binding sites or along the path between them impaired specific ATPase and transport activities. These results provide evidence that the observed crevice is the conduit along that phosphatidylserine traverses from the outer leaflet to its occlusion site in the membrane and suggest that the exoplasmic cavity is important for phospholipid recognition. They also yield insights into how phosphatidylserine is incorporated from the outer leaflet of the plasma membrane into the transmembrane.
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Affiliation(s)
- Hanayo Nakanishi
- Cellular and Structural Physiology Institute, Nagoya University, Nagoya, Japan
| | - Katsumasa Irie
- Cellular and Structural Physiology Institute, Nagoya University, Nagoya, Japan.,Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, Japan
| | - Katsumori Segawa
- WPI Immunology Frontier Research Center, Osaka University, Osaka, Japan
| | - Kazuya Hasegawa
- Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo, Japan
| | - Yoshinori Fujiyoshi
- TMDU Advanced Research Institute, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, Japan.,CeSPIA Inc, 2-1-1, Otemachi, Chiyoda, Tokyo, Japan
| | - Shigekazu Nagata
- WPI Immunology Frontier Research Center, Osaka University, Osaka, Japan
| | - Kazuhiro Abe
- Cellular and Structural Physiology Institute, Nagoya University, Nagoya, Japan .,Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, Japan
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13
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Yokoyama Y, Terada T, Shimizu K, Nishikawa K, Kozai D, Shimada A, Mizoguchi A, Fujiyoshi Y, Tani K. Development of a deep learning-based method to identify "good" regions of a cryo-electron microscopy grid. Biophys Rev 2020; 12:349-354. [PMID: 32162215 DOI: 10.1007/s12551-020-00669-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Accepted: 02/26/2020] [Indexed: 02/05/2023] Open
Abstract
Recent advances in cryo-electron microscopy (cryo-EM) have enabled protein structure determination at atomic resolutions. Cryo-EM specimens are prepared by rapidly freezing a protein solution on a metal grid coated with a holey carbon film; this results in the formation of an ice film on each hole. The thickness of the ice film is a critical factor for high-resolution structure determination; ice that is too thick degrades the contrast of the protein image while ice that is too thin excludes the protein from the hole or denatures the protein. Therefore, trained researchers need to manually select "good" regions with appropriate ice thicknesses for imaging. To reduce the time spent on such tasks, we developed a deep learning program consisting of a "detector" and a "classifier" to identify good regions from low-magnification EM images. In our method, the holes in a low-magnification EM image are detected via a detector, and the ice image on each hole is classified as either good or bad via a classifier. The detector detected more than 95% of the holes regardless of the type of samples. The classifier was trained for different types of samples because the appropriate ice thickness varies between sample types. The accuracies of the classifiers were 93.8% for a soluble protein sample (β-galactosidase) and 95.3% for a membrane protein sample (bovine heart cytochrome c oxidase). In addition, we found that a training data set containing ~ 2100 hole images from 300 low-magnification EM images was sufficient to obtain good accuracy, such as higher than 90%. We expect that the throughput of the cryo-EM data collection step will be greatly improved by using our method.
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Affiliation(s)
- Yuichi Yokoyama
- Graduate School of Interdisciplinary Information Studies, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Tohru Terada
- Interfaculty Initiative in Information Studies, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan. .,Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
| | - Kentaro Shimizu
- Interfaculty Initiative in Information Studies, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.,Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Kouki Nishikawa
- TMDU Advanced Research Institute, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan.,CeSPIA Inc., 2-1-1, Otemachi, Chiyoda-ku, Tokyo, 100-0004, Japan
| | - Daisuke Kozai
- Cellular and Structural Physiology Institute, Nagoya University, Chikusa-ku, Nagoya, 464-8601, Japan
| | - Atsuhiro Shimada
- Department of Applied Life Science, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan
| | - Akira Mizoguchi
- Graduate School of Medicine, Mie University, 2-174 Edobashi, Tsu, Mie, 514-8507, Japan
| | - Yoshinori Fujiyoshi
- TMDU Advanced Research Institute, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan.,CeSPIA Inc., 2-1-1, Otemachi, Chiyoda-ku, Tokyo, 100-0004, Japan
| | - Kazutoshi Tani
- Graduate School of Medicine, Mie University, 2-174 Edobashi, Tsu, Mie, 514-8507, Japan
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14
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Shimomura T, Yonekawa Y, Nagura H, Tateyama M, Fujiyoshi Y, Irie K. A native prokaryotic voltage-dependent calcium channel with a novel selectivity filter sequence. eLife 2020; 9:52828. [PMID: 32093827 PMCID: PMC7041947 DOI: 10.7554/elife.52828] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 01/07/2020] [Indexed: 12/20/2022] Open
Abstract
Voltage-dependent Ca2+ channels (Cavs) are indispensable for coupling action potentials with Ca2+ signaling in living organisms. The structure of Cavs is similar to that of voltage-dependent Na+ channels (Navs). It is known that prokaryotic Navs can obtain Ca2+ selectivity by negative charge mutations of the selectivity filter, but native prokaryotic Cavs had not yet been identified. We report the first identification of a native prokaryotic Cav, CavMr, whose selectivity filter contains a smaller number of negatively charged residues than that of artificial prokaryotic Cavs. A relative mutant whose selectivity filter was replaced with that of CavMr exhibits high Ca2+ selectivity. Mutational analyses revealed that the glycine residue of the CavMr selectivity filter is a determinant for Ca2+ selectivity. This glycine residue is well conserved among subdomains I and III of eukaryotic Cavs. These findings provide new insight into the Ca2+ selectivity mechanism that is conserved from prokaryotes to eukaryotes. Electrical signals in the brain and muscles allow animals – including humans – to think, make memories and move around. Cells generate these signals by enabling charged particles known as ions to pass through the physical barrier that surrounds all cells, the cell membrane, at certain times and in certain locations. The ions pass through pores made by various channel proteins, which generally have so-called “selectivity filters” that only allow particular types of ions to fit through. For example, the selectivity filters of a family of channels in mammals known as the Cavs only allow calcium ions to pass through. Another family of ion channels in mammals are similar in structure to the Cavs but their selectivity filters only allow sodium ions to pass through instead of calcium ions. Ion channels are found in all living cells including in bacteria. It is thought that the Cavs and sodium-selective channels may have both evolved from Cav-like channels in an ancient lifeform that was the common ancestor of modern bacteria and animals. Previous studies in bacteria found that modifying the selectivity filters of some sodium-selective channels known as BacNavs allowed calcium ions to pass through the mutant channels instead of sodium ions. However, no Cav channels had been identified in bacteria so far, representing a missing link in the evolutionary history of ion channels. Shimomura et al. have now found a Cav-like channel in a bacterium known as Meiothermus ruber. Like all proteins, ion channels are made from amino acids and comparing the selectivity filter of the M. ruber Cav with those of mammalian Cavs and the calcium-selective BacNav mutants from previous studies revealed one amino acid that plays a particularly important role. This amino acid is a glycine that helps select which ions may pass through the pore and is also present in the selectivity filters of many Cavs in mammals. Together these findings suggest that the Cav channel from M. ruber is similar to the mammal Cav channels and may more closely resemble the Cav-like channels thought to have existed in the common ancestor of bacteria and animals. Since other channel proteins from bacteria are useful genetic tools for studies in human and other animal cells, the Cav channel from M. ruber has the potential to be used to stimulate calcium signaling in experiments.
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Affiliation(s)
- Takushi Shimomura
- Cellular and Structural Physiology Institute (CeSPI), Nagoya University, Nagoya, Japan.,Division of Biophysics and Neurobiology, National Institute for Physiological Sciences, Okazaki, Japan
| | - Yoshiki Yonekawa
- Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, Japan
| | - Hitoshi Nagura
- Cellular and Structural Physiology Institute (CeSPI), Nagoya University, Nagoya, Japan
| | - Michihiro Tateyama
- Division of Biophysics and Neurobiology, National Institute for Physiological Sciences, Okazaki, Japan
| | - Yoshinori Fujiyoshi
- Cellular and Structural Physiology Institute (CeSPI), Nagoya University, Nagoya, Japan.,CeSPIA Inc, Tokyo, Japan
| | - Katsumasa Irie
- Cellular and Structural Physiology Institute (CeSPI), Nagoya University, Nagoya, Japan.,Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, Japan
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15
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Burendei B, Shinozaki R, Watanabe M, Terada T, Tani K, Fujiyoshi Y, Oshima A. Cryo-EM structures of undocked innexin-6 hemichannels in phospholipids. Sci Adv 2020; 6:eaax3157. [PMID: 32095518 PMCID: PMC7015682 DOI: 10.1126/sciadv.aax3157] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Accepted: 12/02/2019] [Indexed: 06/01/2023]
Abstract
Gap junctions form intercellular conduits with a large pore size whose closed and open states regulate communication between adjacent cells. The structural basis of the mechanism by which gap junctions close, however, remains uncertain. Here, we show the cryo-electron microscopy structures of Caenorhabditis elegans innexin-6 (INX-6) gap junction proteins in an undocked hemichannel form. In the nanodisc-reconstituted structure of the wild-type INX-6 hemichannel, flat double-layer densities obstruct the channel pore. Comparison of the hemichannel structures of a wild-type INX-6 in detergent and nanodisc-reconstituted amino-terminal deletion mutant reveals that lipid-mediated amino-terminal rearrangement and pore obstruction occur upon nanodisc reconstitution. Together with molecular dynamics simulations and electrophysiology functional assays, our results provide insight into the closure of the INX-6 hemichannel in a lipid bilayer before docking of two hemichannels.
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Affiliation(s)
- Batuujin Burendei
- Division of Biological Science, School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Ruriko Shinozaki
- Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Masakatsu Watanabe
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Tohru Terada
- Interfaculty Initiative in Information Studies, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Kazutoshi Tani
- Cellular and Structural Physiology Institute (CeSPI), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Yoshinori Fujiyoshi
- Cellular and Structural Physiology Institute (CeSPI), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
- CeSPIA Inc., Ōtemachi, Chiyoda, Tokyo 100-0004, Japan
| | - Atsunori Oshima
- Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
- Cellular and Structural Physiology Institute (CeSPI), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
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16
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Yamamoto K, Dubey V, Irie K, Nakanishi H, Khandelia H, Fujiyoshi Y, Abe K. A single K +-binding site in the crystal structure of the gastric proton pump. eLife 2019; 8:47701. [PMID: 31436534 PMCID: PMC6706254 DOI: 10.7554/elife.47701] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 08/05/2019] [Indexed: 11/13/2022] Open
Abstract
The gastric proton pump (H+,K+-ATPase), a P-type ATPase responsible for gastric acidification, mediates electro-neutral exchange of H+ and K+ coupled with ATP hydrolysis, but with an as yet undetermined transport stoichiometry. Here we show crystal structures at a resolution of 2.5 Å of the pump in the E2-P transition state, in which the counter-transporting cation is occluded. We found a single K+ bound to the cation-binding site of the H+,K+-ATPase, indicating an exchange of 1H+/1K+ per hydrolysis of one ATP molecule. This fulfills the energy requirement for the generation of a six pH unit gradient across the membrane. The structural basis of K+ recognition is resolved and supported by molecular dynamics simulations, establishing how the H+,K+-ATPase overcomes the energetic challenge to generate an H+ gradient of more than a million-fold-one of the highest cation gradients known in mammalian tissue-across the membrane.
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Affiliation(s)
- Kenta Yamamoto
- Cellular and Structural Physiology Institute, Nagoya University, Nagoya, Japan.,Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, Japan
| | - Vikas Dubey
- Department of Physics, Chemistry and Pharmacy, PHYLIFE, University of Southern Denmark, Odense, Denmark
| | - Katsumasa Irie
- Cellular and Structural Physiology Institute, Nagoya University, Nagoya, Japan.,Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, Japan
| | - Hanayo Nakanishi
- Cellular and Structural Physiology Institute, Nagoya University, Nagoya, Japan.,Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, Japan
| | - Himanshu Khandelia
- Department of Physics, Chemistry and Pharmacy, PHYLIFE, University of Southern Denmark, Odense, Denmark
| | - Yoshinori Fujiyoshi
- Cellular and Structural Physiology Institute, Nagoya University, Nagoya, Japan.,CeSPIA Inc, Tokyo, Japan
| | - Kazuhiro Abe
- Cellular and Structural Physiology Institute, Nagoya University, Nagoya, Japan.,Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, Japan
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17
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Nakamura S, Irie K, Tanaka H, Nishikawa K, Suzuki H, Saitoh Y, Tamura A, Tsukita S, Fujiyoshi Y. Morphologic determinant of tight junctions revealed by claudin-3 structures. Nat Commun 2019; 10:816. [PMID: 30778075 PMCID: PMC6379431 DOI: 10.1038/s41467-019-08760-7] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Accepted: 01/28/2019] [Indexed: 01/07/2023] Open
Abstract
Tight junction is a cell adhesion apparatus functioning as barrier and/or channel in the paracellular spaces of epithelia. Claudin is the major component of tight junction and polymerizes to form tight junction strands with various morphologies that may correlate with their functions. Here we present the crystal structure of mammalian claudin-3 at 3.6 Å resolution. The third transmembrane helix of claudin-3 is clearly bent compared with that of other subtypes. Structural analysis of additional two mutants with a single mutation representing other subtypes in the third helix indicates that this helix takes a bent or straight structure depending on the residue. The presence or absence of the helix bending changes the positions of residues related to claudin-claudin interactions and affects the morphology and adhesiveness of the tight junction strands. These results evoke a model for tight junction strand formation with different morphologies – straight or curvy strands – observed in native epithelia. The main components of tight junctions (TJ) are claudins that polymerize and form meshwork architectures called TJ strands. Here the authors present the 3.6 Å crystal structure of murine claudin-3 and show that residue P134 causes a bending of the third transmembrane helix which affects the morphology and adhesiveness of the TJ strands.
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Affiliation(s)
- Shun Nakamura
- Cellular and Structural Physiology Institute, Nagoya University, Furo-cho, Chikusa, Nagoya, 464-8601, Japan.,Graduate School of Pharmaceutical Sciences, Nagoya University, Furo-cho, Chikusa, Nagoya, 464-8601, Japan
| | - Katsumasa Irie
- Cellular and Structural Physiology Institute, Nagoya University, Furo-cho, Chikusa, Nagoya, 464-8601, Japan.,Graduate School of Pharmaceutical Sciences, Nagoya University, Furo-cho, Chikusa, Nagoya, 464-8601, Japan
| | - Hiroo Tanaka
- Laboratory of Biological Science, Graduate School of Frontier Biosciences and Graduate School of Medicine, Osaka University, Suita, Osaka, 565-0871, Japan
| | - Kouki Nishikawa
- Cellular and Structural Physiology Institute, Nagoya University, Furo-cho, Chikusa, Nagoya, 464-8601, Japan
| | - Hiroshi Suzuki
- Cellular and Structural Physiology Institute, Nagoya University, Furo-cho, Chikusa, Nagoya, 464-8601, Japan.,Laboratory of Molecular Electron Microscopy, The Rockefeller University, New York, 10065, USA
| | - Yasunori Saitoh
- Cellular and Structural Physiology Institute, Nagoya University, Furo-cho, Chikusa, Nagoya, 464-8601, Japan.,Research Institute for Interdisciplinary Science, Okayama University, Tsushima Naka 3-1-1, Kita, Okayama, 700-8530, Japan
| | - Atsushi Tamura
- Laboratory of Biological Science, Graduate School of Frontier Biosciences and Graduate School of Medicine, Osaka University, Suita, Osaka, 565-0871, Japan
| | - Sachiko Tsukita
- Laboratory of Biological Science, Graduate School of Frontier Biosciences and Graduate School of Medicine, Osaka University, Suita, Osaka, 565-0871, Japan
| | - Yoshinori Fujiyoshi
- Cellular and Structural Physiology Institute, Nagoya University, Furo-cho, Chikusa, Nagoya, 464-8601, Japan. .,CeSPIA Inc., 2-1-1 Otemachi, Chiyoda, Tokyo, 100-0004, Japan.
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18
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Yamaguchi H, Kamegawa A, Nakata K, Kashiwagi T, Mizukoshi T, Fujiyoshi Y, Tani K. Structural insights into thermostabilization of leucine dehydrogenase from its atomic structure by cryo-electron microscopy. J Struct Biol 2018; 205:11-21. [PMID: 30543982 DOI: 10.1016/j.jsb.2018.12.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 11/02/2018] [Accepted: 12/05/2018] [Indexed: 02/07/2023]
Abstract
Leucine dehydrogenase (LDH, EC 1.4.1.9) is a NAD+-dependent oxidoreductase that catalyzes the deamination of branched-chain l-amino acids (BCAAs). LDH of Geobacillus stearothermophilus (GstLDH) is a highly thermostable enzyme that has been applied for the quantification or production of BCAAs. Here the cryo-electron microscopy (cryo-EM) structures of apo and NAD+-bound LDH are reported at 3.0 and 3.2 Å resolution, respectively. On comparing the structures, the two overall structures are almost identical, but it was observed that the partial conformational change was triggered by the interaction between Ser147 and the nicotinamide moiety of NAD+. NAD+ binding also enhanced the strength of oligomerization interfaces formed by the core domains. Such additional interdomain interaction is in good agreement with our experimental results showing that the residual activity of NAD+-bound form was approximately three times higher than that of the apo form after incubation at 80 °C. In addition, sequence comparison of three structurally known LDHs indicated a set of candidates for site-directed mutagenesis to improve thermostability. Subsequent mutation analysis actually revealed that non-conserved residues, including Ala94, Tyr127, and the C-terminal region, are crucial for oligomeric thermostability.
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Affiliation(s)
- Hiroki Yamaguchi
- Institute for Innovation, Ajinomoto Co., Inc., 1-1 Suzuki-cho, Kawasaki 210-8681, Japan
| | - Akiko Kamegawa
- Cellular and Structural Physiology Institute, Nagoya University, Chikusa, Nagoya 464-8601, Japan; CeSPIA Inc., 2-1-1, Otemachi, Chiyoda, Tokyo 100-0004, Japan
| | - Kunio Nakata
- Institute for Innovation, Ajinomoto Co., Inc., 1-1 Suzuki-cho, Kawasaki 210-8681, Japan
| | - Tatsuki Kashiwagi
- Institute for Innovation, Ajinomoto Co., Inc., 1-1 Suzuki-cho, Kawasaki 210-8681, Japan
| | - Toshimi Mizukoshi
- Institute for Innovation, Ajinomoto Co., Inc., 1-1 Suzuki-cho, Kawasaki 210-8681, Japan.
| | - Yoshinori Fujiyoshi
- Cellular and Structural Physiology Institute, Nagoya University, Chikusa, Nagoya 464-8601, Japan; CeSPIA Inc., 2-1-1, Otemachi, Chiyoda, Tokyo 100-0004, Japan; Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Corporation, Tokyo, Japan.
| | - Kazutoshi Tani
- Cellular and Structural Physiology Institute, Nagoya University, Chikusa, Nagoya 464-8601, Japan.
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19
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Nakamura S, Fujiyoshi Y, Irie K. Enhancement of the thermostability of mouse claudin-3 on complex formation with the carboxyl-terminal region of Clostridium perfringens enterotoxin improves crystal quality. Acta Crystallogr F Struct Biol Commun 2018; 74:150-155. [PMID: 29497018 DOI: 10.1107/s2053230x18002005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 01/02/2018] [Indexed: 11/10/2022]
Abstract
Tight junctions regulate substance permeation through intercellular spaces as a physical barrier or a paracellular pathway, and play an important role in maintaining the internal environment. Claudins, which are tetraspan-transmembrane proteins, are pivotal components of tight junctions. In mammals 27 claudin subtypes have been identified, each of which interacts with specific subtypes. Although the crystal structures of several subtypes have been determined, the molecular mechanisms underlying subtype specificity remain unclear. Here, mouse claudin-3 (mCldn3) was crystallized in complex with the C-terminal region of Clostridium perfringens enterotoxin (C-CPE) for the structural analysis of an additional claudin subtype. mCldn3 alone was difficult to crystallize, but complex formation with C-CPE enhanced the thermostability of mCldn3 and facilitated its crystallization. The introduction of an S313A mutation into C-CPE further improved its thermostability, and the resolution limits of the diffraction data sets improved from 8 Å for the wild-type complex to 4.7 Å for the S313A mutant complex.
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Affiliation(s)
- Shun Nakamura
- Department of Basic Medical Science, Graduate School of Pharmaceutical Science, Nagoya University, Chikusa, Nagoya 464-8601, Japan
| | - Yoshinori Fujiyoshi
- Cellular and Structural Physiology Institute, Nagoya University, Chikusa, Nagoya 464-8601, Japan
| | - Katsumasa Irie
- Department of Basic Medical Science, Graduate School of Pharmaceutical Science, Nagoya University, Chikusa, Nagoya 464-8601, Japan
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20
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Irie K, Haga Y, Shimomura T, Fujiyoshi Y. Optimized expression and purification of NavAb provide the structural insight into the voltage dependence. FEBS Lett 2018; 592:274-283. [PMID: 29274127 DOI: 10.1002/1873-3468.12955] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 12/11/2017] [Accepted: 12/15/2017] [Indexed: 01/05/2023]
Abstract
Voltage-gated sodium channels are crucial for electro-signalling in living systems. Analysis of the molecular mechanism requires both fine electrophysiological evaluation and high-resolution channel structures. Here, we optimized a dual expression system of NavAb, which is a well-established standard of prokaryotic voltage-gated sodium channels, for E. coli and insect cells using a single plasmid vector to analyse high-resolution protein structures and measure large ionic currents. Using this expression system, we evaluated the voltage dependence and determined the crystal structures of NavAb wild-type and two mutants, E32Q and N49K, whose voltage dependence were positively shifted and essential interactions were lost in voltage sensor domain. The structural and functional comparison elucidated the molecular mechanisms of the voltage dependence of prokaryotic voltage-gated sodium channels.
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Affiliation(s)
- Katsumasa Irie
- Cellular and Structural Physiology Institute (CeSPI), Nagoya University, Japan.,Graduate School of Pharmaceutical Sciences, Nagoya University, Japan
| | - Yukari Haga
- Graduate School of Pharmaceutical Sciences, Nagoya University, Japan
| | - Takushi Shimomura
- Cellular and Structural Physiology Institute (CeSPI), Nagoya University, Japan
| | - Yoshinori Fujiyoshi
- Cellular and Structural Physiology Institute (CeSPI), Nagoya University, Japan.,CeSPIA Inc., Tokyo, Japan
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21
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Abe K, Shimokawa J, Naito M, Munson K, Vagin O, Sachs G, Suzuki H, Tani K, Fujiyoshi Y. The cryo-EM structure of gastric H +,K +-ATPase with bound BYK99, a high-affinity member of K +-competitive, imidazo[1,2-a]pyridine inhibitors. Sci Rep 2017; 7:6632. [PMID: 28747707 PMCID: PMC5529566 DOI: 10.1038/s41598-017-06698-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Accepted: 06/21/2017] [Indexed: 12/13/2022] Open
Abstract
The gastric proton pump H+,K+-ATPase acidifies the gastric lumen, and thus its inhibitors, including the imidazo[1,2-a]pyridine class of K+-competitive acid blockers (P-CABs), have potential application as acid-suppressing drugs. We determined the electron crystallographic structure of H+,K+-ATPase at 6.5 Å resolution in the E2P state with bound BYK99, a potent P-CAB with a restricted ring structure. The BYK99 bound structure has an almost identical profile to that of a previously determined structure with bound SCH28080, the original P-CAB prototype, but is significantly different from the previously reported P-CAB-free form, illustrating a common conformational change is required for P-CAB binding. The shared conformational changes include a distinct movement of transmembrane helix 2 (M2), from its position in the previously reported P-CAB-free form, to a location proximal to the P-CAB binding site in the present BYK99-bound structure. Site-specific mutagenesis within M2 revealed that D137 and N138, which face the P-CAB binding site in our model, significantly affect the inhibition constant (Ki) of P-CABs. We also found that A335 is likely to be near the bridging nitrogen at the restricted ring structure of the BYK99 inhibitor. These provide clues to elucidate the binding site parameters and mechanism of P-CAB inhibition of gastric acid secretion.
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Affiliation(s)
- Kazuhiro Abe
- Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, 464-8601, Japan. .,Cellular and Structural Physiology Institute, Nagoya University, Nagoya, 464-8601, Japan. .,Core Research for Evolutional Science and Technology, Japan Science and Technology Corporation, Chiyoda, Tokyo, 100-0004, Japan.
| | - Jun Shimokawa
- Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, 464-8601, Japan
| | - Mao Naito
- Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya, 464-8601, Japan.,Cellular and Structural Physiology Institute, Nagoya University, Nagoya, 464-8601, Japan
| | | | | | | | - Hiroshi Suzuki
- Laboratory of Molecular Electron Microscopy, Rockefeller University, New York, 10065, USA
| | - Kazutoshi Tani
- Cellular and Structural Physiology Institute, Nagoya University, Nagoya, 464-8601, Japan
| | - Yoshinori Fujiyoshi
- Cellular and Structural Physiology Institute, Nagoya University, Nagoya, 464-8601, Japan.,Core Research for Evolutional Science and Technology, Japan Science and Technology Corporation, Chiyoda, Tokyo, 100-0004, Japan.,CeSPIA Inc., 2-1-1, Otemachi, Chiyoda, Tokyo, 100-0004, Japan
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22
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Suzuki H, Tani K, Fujiyoshi Y. Crystal structures of claudins: insights into their intermolecular interactions. Ann N Y Acad Sci 2017; 1397:25-34. [PMID: 28605828 DOI: 10.1111/nyas.13371] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 04/06/2017] [Accepted: 04/10/2017] [Indexed: 12/14/2022]
Abstract
Claudins are four-transmembrane proteins that constitute the backbone of tight junction strands via self-polymerization in the apicolateral membranes of epithelial cells. Together with their cell-cell adhesion function, claudin proteins form the paracellular barrier and/or channels through epithelial cell sheets whose permeability is primarily dependent on the claudin subtype. Recently determined crystal structures of several claudins revealed the unique claudin fold of four transmembrane helices in a left-handed helical bundle with an extracellular β-sheet domain. Here, we focus on the structural basis of the intermolecular interactions between claudin molecules and between the Clostridium perfringens enterotoxin and its receptor claudins.
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Affiliation(s)
- Hiroshi Suzuki
- Cellular and Structural Physiology Institute (CeSPI), Nagoya University, Chikusa, Nagoya, Japan
| | - Kazutoshi Tani
- Cellular and Structural Physiology Institute (CeSPI), Nagoya University, Chikusa, Nagoya, Japan
| | - Yoshinori Fujiyoshi
- Cellular and Structural Physiology Institute (CeSPI), Nagoya University, Chikusa, Nagoya, Japan.,Department of Basic Medical Science, Graduate School of Pharmaceutical Science, Nagoya University, Chikusa, Nagoya, Japan
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23
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Oshima A, Tani K, Fujiyoshi Y. Atomic structure of the innexin-6 gap junction channel determined by cryo-EM. Nat Commun 2016; 7:13681. [PMID: 27905396 PMCID: PMC5146279 DOI: 10.1038/ncomms13681] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 10/24/2016] [Indexed: 01/01/2023] Open
Abstract
Innexins, a large protein family comprising invertebrate gap junction channels, play an essential role in nervous system development and electrical synapse formation. Here we report the cryo-electron microscopy structures of Caenorhabditis elegans innexin-6 (INX-6) gap junction channels at atomic resolution. We find that the arrangements of the transmembrane helices and extracellular loops of the INX-6 monomeric structure are highly similar to those of connexin-26 (Cx26), despite the lack of significant sequence similarity. The INX-6 gap junction channel comprises hexadecameric subunits but reveals the N-terminal pore funnel, consistent with Cx26. The helix-rich cytoplasmic loop and C-terminus are intercalated one-by-one through an octameric hemichannel, forming a dome-like entrance that interacts with N-terminal loops in the pore. These observations suggest that the INX-6 cytoplasmic domains are cooperatively associated with the N-terminal funnel conformation, and an essential linkage of the N-terminal with channel activity is presumably preserved across gap junction families.
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Affiliation(s)
- Atsunori Oshima
- Cellular and Structural Physiology Institute (CeSPI), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.,Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Kazutoshi Tani
- Cellular and Structural Physiology Institute (CeSPI), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Yoshinori Fujiyoshi
- Cellular and Structural Physiology Institute (CeSPI), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.,Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
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24
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Shihoya W, Nishizawa T, Okuta A, Tani K, Dohmae N, Fujiyoshi Y, Nureki O, Doi T. Activation mechanism of endothelin ET B receptor by endothelin-1. Nature 2016; 537:363-368. [PMID: 27595334 DOI: 10.1038/nature19319] [Citation(s) in RCA: 109] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 07/20/2016] [Indexed: 12/14/2022]
Abstract
Endothelin, a 21-amino-acid peptide, participates in various physiological processes, such as regulation of vascular tone, humoral homeostasis, neural crest cell development and neurotransmission. Endothelin and its G-protein-coupled receptor are involved in the development of various diseases, such as pulmonary arterial hypertension, and thus are important therapeutic targets. Here we report crystal structures of human endothelin type B receptor in the ligand-free form and in complex with the endogenous agonist endothelin-1. The structures and mutation analysis reveal the mechanism for the isopeptide selectivity between endothelin-1 and -3. Transmembrane helices 1, 2, 6 and 7 move and envelop the entire endothelin peptide, in a virtually irreversible manner. The agonist-induced conformational changes are propagated to the receptor core and the cytoplasmic G-protein coupling interface, and probably induce conformational flexibility in TM6. A comparison with the M2 muscarinic receptor suggests a shared mechanism for signal transduction in class A G-protein-coupled receptors.
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Affiliation(s)
- Wataru Shihoya
- Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Chikusa, Nagoya 464-8601, Japan.,Cellular and Structural Physiology Institute, Nagoya University, Chikusa, Nagoya 464-8601, Japan.,Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Bunkyo, Tokyo 113-0032, Japan
| | - Tomohiro Nishizawa
- Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Bunkyo, Tokyo 113-0032, Japan.,Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Akiko Okuta
- Cellular and Structural Physiology Institute, Nagoya University, Chikusa, Nagoya 464-8601, Japan
| | - Kazutoshi Tani
- Cellular and Structural Physiology Institute, Nagoya University, Chikusa, Nagoya 464-8601, Japan
| | - Naoshi Dohmae
- Biomolecular Characterization Unit, RIKEN Center for Sustainable Resource Science, Wako, Saitama 351-0198, Japan
| | - Yoshinori Fujiyoshi
- Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Chikusa, Nagoya 464-8601, Japan.,Cellular and Structural Physiology Institute, Nagoya University, Chikusa, Nagoya 464-8601, Japan
| | - Osamu Nureki
- Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Bunkyo, Tokyo 113-0032, Japan
| | - Tomoko Doi
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
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25
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Abe K, Fujiyoshi Y. Cryo-electron microscopy for structure analyses of membrane proteins in the lipid bilayer. Curr Opin Struct Biol 2016; 39:71-78. [DOI: 10.1016/j.sbi.2016.06.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Revised: 05/20/2016] [Accepted: 06/01/2016] [Indexed: 12/12/2022]
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26
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Shimomura T, Irie K, Fujiyoshi Y. Molecular determinants of prokaryotic voltage-gated sodium channels for recognition of local anesthetics. FEBS J 2016; 283:2881-95. [DOI: 10.1111/febs.13776] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2016] [Revised: 05/22/2016] [Accepted: 06/06/2016] [Indexed: 11/28/2022]
Affiliation(s)
- Takushi Shimomura
- Cellular and Structural Physiology Institute (CeSPI); Nagoya University; Japan
| | - Katsumasa Irie
- Cellular and Structural Physiology Institute (CeSPI); Nagoya University; Japan
- Graduate School of Pharmaceutical Science; Nagoya University; Japan
| | - Yoshinori Fujiyoshi
- Cellular and Structural Physiology Institute (CeSPI); Nagoya University; Japan
- Graduate School of Pharmaceutical Science; Nagoya University; Japan
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27
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Okuta A, Tani K, Nishimura S, Fujiyoshi Y, Doi T. Thermostabilization of the Human Endothelin Type B Receptor. J Mol Biol 2016; 428:2265-2274. [PMID: 27038509 DOI: 10.1016/j.jmb.2016.03.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Revised: 03/19/2016] [Accepted: 03/22/2016] [Indexed: 01/25/2023]
Abstract
The peptide hormone endothelin, produced by the vascular endothelium, is involved in several physiological functions, including maintenance of vascular tone and humoral homeostasis. Endothelin transmits signals through the endothelin receptor, a G-protein-coupled receptor. Structural studies of the endothelin type B receptor (ETBR) have been unsuccessful due to its structural flexibility and instability in detergent-solubilized solution. To overcome these problems, we explored thermostabilization of human ETBR by establishing an ETBR expression system in Escherichia coli, followed by systematic alanine scanning mutagenesis. Among 297 point mutations, 11 thermostabilizing residues were selected and further mutated to other amino acids. The thermostability indices of these residues, represented by the ratios of endothelin-1 (ET-1) binding activities with or without heat treatment at 27°C for 30min in a ligand-free form, were compared. The ligand affinity and apparent melting temperature (Tm) of the five most thermostable mutants, R124Y, D154A, K270A, S342A, and I381A, were then examined. The apparent Tm of three single mutants, R124Y, D154A, and K270A, was approximately 7°C higher than that of the wild type. The apparent Tm value of a combination of the five residues, named the Y5 ETBR mutant, was 17°C higher than that of the wild type. The Y5 ETBR mutant exhibited an affinity for ET-1 and activated Gq similar to the wild type. Further investigation of the pharmacological properties affected by combinatorial mutations of ET-1, ET-3, TxET-1, and K8794 suggested that Y5 ETBR is highly suitable for representing a ligand-free form of ETBR and is potentially applicable for studying an ET-1-bound form.
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Affiliation(s)
- Akiko Okuta
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan; Cellular and Structural Physiology Institute, Nagoya University, Chikusa, Nagoya 464-8601, Japan
| | - Kazutoshi Tani
- Cellular and Structural Physiology Institute, Nagoya University, Chikusa, Nagoya 464-8601, Japan
| | - Shoko Nishimura
- Cellular and Structural Physiology Institute, Nagoya University, Chikusa, Nagoya 464-8601, Japan
| | - Yoshinori Fujiyoshi
- Cellular and Structural Physiology Institute, Nagoya University, Chikusa, Nagoya 464-8601, Japan; Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Chikusa, Nagoya 464-8601, Japan
| | - Tomoko Doi
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
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28
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Oshima A, Matsuzawa T, Murata K, Tani K, Fujiyoshi Y. Hexadecameric structure of an invertebrate gap junction channel. J Mol Biol 2016; 428:1227-1236. [DOI: 10.1016/j.jmb.2016.02.011] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Revised: 02/05/2016] [Accepted: 02/08/2016] [Indexed: 12/12/2022]
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29
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Oshima A, Matsuzawa T, Murata K, Tani K, Fujiyoshi Y. Three-Dimensional Structure of Innexin GAP Junction Channels Studied by Electron Crystallography. Biophys J 2016. [DOI: 10.1016/j.bpj.2015.11.1901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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30
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Nagura H, Doi T, Fujiyoshi Y. Characterization of physiological phenotypes of dentate gyrus synapses of PDZ1/2 domain-deficient PSD-95-knockin mice. Eur J Neurosci 2015; 43:618-25. [PMID: 26684546 DOI: 10.1111/ejn.13155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 12/11/2015] [Accepted: 12/14/2015] [Indexed: 11/27/2022]
Abstract
The hippocampal formation is involved in several important brain functions of animals, such as memory formation and pattern separation, and the synapses in the dentate gyrus (DG) play critical roles as the first step in the hippocampal circuit. Previous studies have reported that mice with genetic modifications of the PDZ1/2 domains of postsynaptic density (PSD)-95 exhibit altered synaptic properties in the DG and impaired hippocampus-dependent behaviors. Based on the involvement of the DG in the regulation of behaviors, these data suggest that the abnormal behavior of these knockin (KI) mice is due partly to altered DG function. Precise understanding of the phenotypes of these mutant mice requires characterization of the synaptic properties of the DG, and here we provide detailed studies of DG synapses. We have demonstrated global changes in the PSD membrane-associated guanylate kinase expression pattern in the DG of mutant mice, and DG synapses in these mice exhibited increased long-term potentiation under a wide range of stimulus intensities, although the N-methyl-d-aspartic acid receptor dependence of the long-term potentiation was unchanged. Furthermore, our data also indicate increased silent synapses in the DG of the KI mice. These findings suggest that abnormal protein expression and physiological properties disrupt the function of DG neurons in these KI mice.
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Affiliation(s)
- Hitoshi Nagura
- Cellular and Structural Physiology Institute, Nagoya University, Nagoya, 464-8601, Japan
| | - Tomoko Doi
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto, Japan
| | - Yoshinori Fujiyoshi
- Cellular and Structural Physiology Institute, Nagoya University, Nagoya, 464-8601, Japan.,Department of Basic Medical Science, Graduate School of Pharmaceutical Science, Nagoya University, Nagoya, Japan
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31
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Kamegawa A, Hiroaki Y, Tani K, Fujiyoshi Y. Two-dimensional crystal structure of aquaporin-4 bound to the inhibitor acetazolamide. Microscopy (Oxf) 2015; 65:177-84. [PMID: 26908838 PMCID: PMC4817316 DOI: 10.1093/jmicro/dfv368] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Accepted: 11/06/2015] [Indexed: 12/23/2022] Open
Abstract
Acetazolamide (AZA) reduces the water permeability of aquaporin-4, the predominant water channel in the brain. We determined the structure of aquaporin-4 in the presence of AZA using electron crystallography. Most of the features of the 5-Å density map were consistent with those of the previously determined atomic model. The map showed a protruding density from near the extracellular pore entrance, which most likely represents the bound AZA. Molecular docking simulations supported the location of the protrusion as the likely AZA-binding site. These findings suggest that AZA reduces water conduction by obstructing the pathway at the extracellular entrance without inducing a large conformational change in the protein.
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Affiliation(s)
- Akiko Kamegawa
- Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Yoko Hiroaki
- Cellular and Structural Physiology Institute, Nagoya University, Nagoya 464-8601, Japan
| | - Kazutoshi Tani
- Cellular and Structural Physiology Institute, Nagoya University, Nagoya 464-8601, Japan
| | - Yoshinori Fujiyoshi
- Graduate School of Pharmaceutical Sciences, Nagoya University, Nagoya 464-8601, Japan Cellular and Structural Physiology Institute, Nagoya University, Nagoya 464-8601, Japan
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32
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Fujiyoshi Y. P1Structure-Guided Drug Development based on Cryo-Electron Microscopy. Microscopy (Oxf) 2015. [DOI: 10.1093/jmicro/dfv062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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33
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Minatohara K, Murata Y, Fujiyoshi Y, Doi T. An intracellular domain with a novel sequence regulates cell surface expression and synaptic clustering of leucine-rich repeat transmembrane proteins in hippocampal neurons. J Neurochem 2015; 134:618-28. [DOI: 10.1111/jnc.13159] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2014] [Revised: 04/23/2015] [Accepted: 05/05/2015] [Indexed: 11/29/2022]
Affiliation(s)
- Keiichiro Minatohara
- Department of Biophysics; Graduate School of Science; Kyoto University; Kyoto Japan
| | - Yasunobu Murata
- Department of Biophysics; Graduate School of Science; Kyoto University; Kyoto Japan
| | - Yoshinori Fujiyoshi
- Department of Basic Medicinal Sciences; Graduate School of Pharmaceutical Sciences; Nagoya University; Nagoya Japan
- Cellular and Structural Physiology Institute; Nagoya University; Nagoya Japan
| | - Tomoko Doi
- Department of Biophysics; Graduate School of Science; Kyoto University; Kyoto Japan
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Jiko C, Davies KM, Shinzawa-Itoh K, Tani K, Maeda S, Mills DJ, Tsukihara T, Fujiyoshi Y, Kühlbrandt W, Gerle C. Bovine F1Fo ATP synthase monomers bend the lipid bilayer in 2D membrane crystals. eLife 2015; 4:e06119. [PMID: 25815585 PMCID: PMC4413875 DOI: 10.7554/elife.06119] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 03/26/2015] [Indexed: 01/06/2023] Open
Abstract
We have used a combination of electron cryo-tomography, subtomogram averaging, and electron crystallographic image processing to analyse the structure of intact bovine F1Fo ATP synthase in 2D membrane crystals. ATPase assays and mass spectrometry analysis of the 2D crystals confirmed that the enzyme complex was complete and active. The structure of the matrix-exposed region was determined at 24 Å resolution by subtomogram averaging and repositioned into the tomographic volume to reveal the crystal packing. F1Fo ATP synthase complexes are inclined by 16° relative to the crystal plane, resulting in a zigzag topology of the membrane and indicating that monomeric bovine heart F1Fo ATP synthase by itself is sufficient to deform lipid bilayers. This local membrane curvature is likely to be instrumental in the formation of ATP synthase dimers and dimer rows, and thus for the shaping of mitochondrial cristae. DOI:http://dx.doi.org/10.7554/eLife.06119.001 Cells use a molecule called adenosine triphosphate (or ATP for short) to power many processes that are vital for life. Animals, plants, and fungi primarily make their ATP in a specialised compartment called the mitochondrion, which is found inside their cells. The mitochondrion is often referred to as the powerhouse of cells as it captures and stores the energy that animals gain from eating food in the molecule ATP. Other enzymes in the cell break apart ATP to release the stored energy, which they use to power various cellular processes. The interior architecture of the mitochondrion includes a highly folded inner membrane where electrical energy is transformed into chemical energy. The tight folding of the inner membrane is thought to make this process more efficient. An enzyme named ATP synthase performs the final steps of the energy transformation process by producing ATP (ATP synthase literally means ‘ATP maker’). This enzyme sits in pairs along the edges of the inner membrane folds. This raises the question: does the ATP synthase cause the membrane to fold or does this enzyme just ‘prefer’ these folded edges (which are instead caused by something else inside the mitochondrion)? To investigate this question, Jiko, Davies et al. extracted ATP synthase from the mitochondria of cow hearts and mixed them with modified fat molecules to form a ‘2D membrane crystal’: a membrane containing an ordered pattern of enzymes. An electron microscope was used to generate a three-dimensional volume of the 2D membrane crystal via a process similar to a MRI or CAT scan that one might have in hospital. In the three-dimensional volume of the membrane crystal, Jiko, Davies et al. discovered that instead of being flat as expected, the membrane of the 2D membrane crystal was rippled and that this ripple was caused by the membrane-embedded part of the ATP synthase. The geometry of the ripple exactly matched half of the bend at the edge of the membrane folds in the mitochondrion. Therefore, Jiko, Davies et al. concluded that a pair of ATP synthases, as found in mitochondria, was responsible for defining the tight folds of the inner mitochondrial membrane. DOI:http://dx.doi.org/10.7554/eLife.06119.002
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Affiliation(s)
- Chimari Jiko
- Institute for Protein Research, Osaka University, Osaka, Japan
| | - Karen M Davies
- Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt am Main, Germany
| | - Kyoko Shinzawa-Itoh
- Picobiology Institute, Department of Life Science, Graduate School of Life Science, University of Hyogo, Kamigori, Japan
| | - Kazutoshi Tani
- Cellular and Structural Physiology Institute, Nagoya University, Nagoya, Japan
| | - Shintaro Maeda
- Picobiology Institute, Department of Life Science, Graduate School of Life Science, University of Hyogo, Kamigori, Japan
| | - Deryck J Mills
- Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt am Main, Germany
| | - Tomitake Tsukihara
- Picobiology Institute, Department of Life Science, Graduate School of Life Science, University of Hyogo, Kamigori, Japan
| | - Yoshinori Fujiyoshi
- Cellular and Structural Physiology Institute, Nagoya University, Nagoya, Japan
| | - Werner Kühlbrandt
- Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt am Main, Germany
| | - Christoph Gerle
- Picobiology Institute, Department of Life Science, Graduate School of Life Science, University of Hyogo, Kamigori, Japan
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Saitoh Y, Suzuki H, Tani K, Nishikawa K, Irie K, Ogura Y, Tamura A, Tsukita S, Fujiyoshi Y. Tight junctions. Structural insight into tight junction disassembly by Clostridium perfringens enterotoxin. Science 2015; 347:775-8. [PMID: 25678664 DOI: 10.1126/science.1261833] [Citation(s) in RCA: 147] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The C-terminal region of Clostridium perfringens enterotoxin (C-CPE) can bind to specific claudins, resulting in the disintegration of tight junctions (TJs) and an increase in the paracellular permeability across epithelial cell sheets. Here we present the structure of mammalian claudin-19 in complex with C-CPE at 3.7 Å resolution. The structure shows that C-CPE forms extensive hydrophobic and hydrophilic interactions with the two extracellular segments of claudin-19. The claudin-19/C-CPE complex shows no density of a short extracellular helix that is critical for claudins to assemble into TJ strands. The helix displacement may thus underlie C-CPE-mediated disassembly of TJs.
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Affiliation(s)
- Yasunori Saitoh
- Cellular and Structural Physiology Institute, Nagoya University, Chikusa, Nagoya 464-8601, Japan. Department of Basic Medical Science, Graduate School of Pharmaceutical Science, Nagoya University, Chikusa, Nagoya 464-8601, Japan
| | - Hiroshi Suzuki
- Cellular and Structural Physiology Institute, Nagoya University, Chikusa, Nagoya 464-8601, Japan
| | - Kazutoshi Tani
- Cellular and Structural Physiology Institute, Nagoya University, Chikusa, Nagoya 464-8601, Japan
| | - Kouki Nishikawa
- Cellular and Structural Physiology Institute, Nagoya University, Chikusa, Nagoya 464-8601, Japan
| | - Katsumasa Irie
- Cellular and Structural Physiology Institute, Nagoya University, Chikusa, Nagoya 464-8601, Japan. Department of Basic Medical Science, Graduate School of Pharmaceutical Science, Nagoya University, Chikusa, Nagoya 464-8601, Japan
| | - Yuki Ogura
- Laboratory of Biological Science, Graduate School of Frontier Biosciences and Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
| | - Atsushi Tamura
- Laboratory of Biological Science, Graduate School of Frontier Biosciences and Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
| | - Sachiko Tsukita
- Laboratory of Biological Science, Graduate School of Frontier Biosciences and Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan
| | - Yoshinori Fujiyoshi
- Cellular and Structural Physiology Institute, Nagoya University, Chikusa, Nagoya 464-8601, Japan. Department of Basic Medical Science, Graduate School of Pharmaceutical Science, Nagoya University, Chikusa, Nagoya 464-8601, Japan.
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Suzuki H, Tani K, Tamura A, Tsukita S, Fujiyoshi Y. Model for the Architecture of Claudin-Based Paracellular Ion Channels through Tight Junctions. J Mol Biol 2015; 427:291-7. [DOI: 10.1016/j.jmb.2014.10.020] [Citation(s) in RCA: 133] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Revised: 10/24/2014] [Accepted: 10/29/2014] [Indexed: 12/13/2022]
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Abe K, Tani K, Fujiyoshi Y. Systematic comparison of molecular conformations of H+,K+-ATPase reveals an important contribution of the A-M2 linker for the luminal gating. J Biol Chem 2014; 289:30590-30601. [PMID: 25231997 PMCID: PMC4215238 DOI: 10.1074/jbc.m114.584623] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Gastric H+,K+-ATPase, an ATP-driven proton pump responsible for gastric acidification, is a molecular target for anti-ulcer drugs. Here we show its cryo-electron microscopy (EM) structure in an E2P analog state, bound to magnesium fluoride (MgF), and its K+-competitive antagonist SCH28080, determined at 7 Å resolution by electron crystallography of two-dimensional crystals. Systematic comparison with other E2P-related cryo-EM structures revealed that the molecular conformation in the (SCH)E2·MgF state is remarkably distinguishable. Although the azimuthal position of the A domain of the (SCH)E2·MgF state is similar to that in the E2·AlF (aluminum fluoride) state, in which the transmembrane luminal gate is closed, the arrangement of transmembrane helices in the (SCH)E2·MgF state shows a luminal-open conformation imposed on by bound SCH28080 at its luminal cavity, based on observations of the structure in the SCH28080-bound E2·BeF (beryllium fluoride) state. The molecular conformation of the (SCH)E2·MgF state thus represents a mixed overall structure in which its cytoplasmic and luminal half appear to be independently modulated by a phosphate analog and an antagonist bound to the respective parts of the enzyme. Comparison of the molecular conformations revealed that the linker region connecting the A domain and the transmembrane helix 2 (A-M2 linker) mediates the regulation of luminal gating. The mechanistic rationale underlying luminal gating observed in H+,K+-ATPase is consistent with that observed in sarcoplasmic reticulum Ca2+-ATPase and other P-type ATPases and is most likely conserved for the P-type ATPase family in general.
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Affiliation(s)
- Kazuhiro Abe
- Cellular and Structural Physiology Institute and Nagoya University, Nagoya 464-8601, Japan; Graduate School of Pharmaceutical Science, Nagoya University, Nagoya 464-8601, Japan.
| | - Kazutoshi Tani
- Cellular and Structural Physiology Institute and Nagoya University, Nagoya 464-8601, Japan
| | - Yoshinori Fujiyoshi
- Cellular and Structural Physiology Institute and Nagoya University, Nagoya 464-8601, Japan; Graduate School of Pharmaceutical Science, Nagoya University, Nagoya 464-8601, Japan
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Bando Y, Irie K, Shimomura T, Umeshima H, Kushida Y, Kengaku M, Fujiyoshi Y, Hirano T, Tagawa Y. Control of Spontaneous Ca2+ Transients Is Critical for Neuronal Maturation in the Developing Neocortex. Cereb Cortex 2014; 26:106-117. [PMID: 25112282 DOI: 10.1093/cercor/bhu180] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Neural activity plays roles in the later stages of development of cortical excitatory neurons, including dendritic and axonal arborization, remodeling, and synaptogenesis. However, its role in earlier stages, such as migration and dendritogenesis, is less clear. Here we investigated roles of neural activity in the maturation of cortical neurons, using calcium imaging and expression of prokaryotic voltage-gated sodium channel, NaChBac. Calcium imaging experiments showed that postmigratory neurons in layer II/III exhibited more frequent spontaneous calcium transients than migrating neurons. To test whether such an increase of neural activity may promote neuronal maturation, we elevated the activity of migrating neurons by NaChBac expression. Elevation of neural activity impeded migration, and induced premature branching of the leading process before neurons arrived at layer II/III. Many NaChBac-expressing neurons in deep cortical layers were not attached to radial glial fibers, suggesting that these neurons had stopped migration. Morphological and immunohistochemical analyses suggested that branched leading processes of NaChBac-expressing neurons differentiated into dendrites. Our results suggest that developmental control of spontaneous calcium transients is critical for maturation of cortical excitatory neurons in vivo: keeping cellular excitability low is important for migration, and increasing spontaneous neural activity may stop migration and promote dendrite formation.
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Affiliation(s)
- Yuki Bando
- Department of Biophysics, Kyoto University Graduate School of Science, Kyoto 606-8502, Japan.,CREST, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan
| | - Katsumasa Irie
- Department of Biophysics, Kyoto University Graduate School of Science, Kyoto 606-8502, Japan.,Cellular and Structural Physiology Institute, Nagoya University, Nagoya, Aichi 464-8601, Japan
| | - Takushi Shimomura
- Department of Biophysics, Kyoto University Graduate School of Science, Kyoto 606-8502, Japan.,Cellular and Structural Physiology Institute, Nagoya University, Nagoya, Aichi 464-8601, Japan
| | - Hiroki Umeshima
- Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto 606-8501, Japan
| | - Yuki Kushida
- Department of Biophysics, Kyoto University Graduate School of Science, Kyoto 606-8502, Japan
| | - Mineko Kengaku
- Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto 606-8501, Japan
| | - Yoshinori Fujiyoshi
- Department of Biophysics, Kyoto University Graduate School of Science, Kyoto 606-8502, Japan.,Cellular and Structural Physiology Institute, Nagoya University, Nagoya, Aichi 464-8601, Japan
| | - Tomoo Hirano
- Department of Biophysics, Kyoto University Graduate School of Science, Kyoto 606-8502, Japan
| | - Yoshiaki Tagawa
- Department of Biophysics, Kyoto University Graduate School of Science, Kyoto 606-8502, Japan.,CREST, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan
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Oshima A, Matsuzawa T, Murata K, Nishikawa K, Fujiyoshi Y. Electron microscopy and functional analysis of recombinant innexin gap junctions. Acta Crystallogr A Found Adv 2014. [DOI: 10.1107/s2053273314091487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Innexin is a molecular component of invertebrate gap junctions, which have an important role in neural and muscular electrical activity in invertebrates. Although the structure of vertebrate connexin26 was revealed by X-ray crystallography [1], the structure of innexin channels remains poorly understood. To study the structure of innexin gap junction channels, we expressed and purified Caenorhabditis elegans innexin-6 (INX-6) gap junction channels, and characterized their molecular dimensions and channel permeability using electron microscopy (EM) and a fluorescent dye transfer assay, respectively [2]. Negative-staining and thin-section EM of isolated INX-6 gap junction plaques revealed a loosely packed hexagonal lattice. We performed single particle analysis of purified INX-6 channels with negative-staining and cryo EM. Based on the negative-stain EM images, the class average of the junction form had a longitudinal height of 220 Å, a channel diameter of 110 Å in the absence of detergent micelles, and an extracellular gap space of 60 Å, whereas the class average of the hemichannels had diameters of up to 140 Å in the presence of detergent micelles. Cryo EM images revealed rotational peaks that could be related to the INX-6 subunits. Structural analysis of the reconstituted INX-6 channels with single particle analysis and electron tomography suggested that the oligomeric number of the INX-6 channel was distinct from that of the dodecameric connexin channel. Dye transfer experiments indicated that the INX-6-GFP-His channels were permeable to 3-kDa and 10-kDa dextran-conjugated tracers. These findings indicate that INX-6 channels have a characteristic oligomer component that differs from that in connexin gap junction channels.
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Suzuki H, Nishizawa T, Tani K, Yamazaki Y, Tamura A, Ishitani R, Dohmae N, Tsukita S, Nureki O, Fujiyoshi Y. Crystal Structure of a Claudin Provides Insight into the Architecture of Tight Junctions. Science 2014; 344:304-7. [DOI: 10.1126/science.1248571] [Citation(s) in RCA: 261] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Morito D, Nishikawa K, Hoseki J, Kitamura A, Kotani Y, Kiso K, Kinjo M, Fujiyoshi Y, Nagata K. Moyamoya disease-associated protein mysterin/RNF213 is a novel AAA+ ATPase, which dynamically changes its oligomeric state. Sci Rep 2014; 4:4442. [PMID: 24658080 PMCID: PMC3963067 DOI: 10.1038/srep04442] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Accepted: 03/06/2014] [Indexed: 12/05/2022] Open
Abstract
Moyamoya disease is an idiopathic human cerebrovascular disorder that is characterized by progressive stenosis and abnormal collateral vessels. We recently identified mysterin/RNF213 as its first susceptibility gene, which encodes a 591-kDa protein containing enzymatically active P-loop ATPase and ubiquitin ligase domains and is involved in proper vascular development in zebrafish. Here we demonstrate that mysterin further contains two tandem AAA+ ATPase modules and forms huge ring-shaped oligomeric complex. AAA+ ATPases are known to generally mediate various biophysical and mechanical processes with the characteristic ring-shaped structure. Fluorescence correlation spectroscopy and biochemical evaluation suggested that mysterin dynamically changes its oligomeric forms through ATP/ADP binding and hydrolysis cycles. Thus, the moyamoya disease-associated gene product is a unique protein that functions as ubiquitin ligase and AAA+ ATPase, which possibly contributes to vascular development through mechanical processes in the cell.
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Affiliation(s)
- Daisuke Morito
- Laboratory of Molecular and Cellular Biology, Faculty of Life Sciences, Kyoto Sangyo University, Kyoto 603-8555, Japan
| | - Kouki Nishikawa
- Cellular and Structural Physiology Institute, Nagoya University, Nagoya, 464-8601, Japan
| | - Jun Hoseki
- 1] Research Unit for Physiological Chemistry, The Center for the Promotion of Interdisciplinary Education and Research, Kyoto University, Kyoto, 606-8502, Japan [2] Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, 606-8502, Japan
| | - Akira Kitamura
- Laboratory of Molecular Cell Dynamics, Faculty of Advanced Life Science, Hokkaido University, Sapporo, 001-0021, Japan
| | - Yuri Kotani
- Laboratory of Molecular and Cellular Biology, Faculty of Life Sciences, Kyoto Sangyo University, Kyoto 603-8555, Japan
| | - Kazumi Kiso
- Laboratory of Molecular and Cellular Biology, Faculty of Life Sciences, Kyoto Sangyo University, Kyoto 603-8555, Japan
| | - Masataka Kinjo
- Laboratory of Molecular Cell Dynamics, Faculty of Advanced Life Science, Hokkaido University, Sapporo, 001-0021, Japan
| | - Yoshinori Fujiyoshi
- Cellular and Structural Physiology Institute, Nagoya University, Nagoya, 464-8601, Japan
| | - Kazuhiro Nagata
- Laboratory of Molecular and Cellular Biology, Faculty of Life Sciences, Kyoto Sangyo University, Kyoto 603-8555, Japan
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Ge Y, Takino H, Sato F, Yamada S, Masaki A, Fujiyoshi Y, Hattori H, Morita A, Kuo TT, Inagaki H. Distinctive immunoglobulinVHgene features of cutaneous marginal zone lymphomas in Asian cases. Br J Dermatol 2014; 170:735-7. [DOI: 10.1111/bjd.12614] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Y. Ge
- Department of Anatomic Pathology and Molecular Diagnostics; Nagoya City University Graduate School of Medical Sciences; 1 Kawasumi Mizuho-cho Mizuho-ku, Nagoya 467-8601 Japan
| | - H. Takino
- Department of Anatomic Pathology and Molecular Diagnostics; Nagoya City University Graduate School of Medical Sciences; 1 Kawasumi Mizuho-cho Mizuho-ku, Nagoya 467-8601 Japan
| | - F. Sato
- Department of Anatomic Pathology and Molecular Diagnostics; Nagoya City University Graduate School of Medical Sciences; 1 Kawasumi Mizuho-cho Mizuho-ku, Nagoya 467-8601 Japan
| | - S. Yamada
- Department of Anatomic Pathology and Molecular Diagnostics; Nagoya City University Graduate School of Medical Sciences; 1 Kawasumi Mizuho-cho Mizuho-ku, Nagoya 467-8601 Japan
| | - A. Masaki
- Department of Anatomic Pathology and Molecular Diagnostics; Nagoya City University Graduate School of Medical Sciences; 1 Kawasumi Mizuho-cho Mizuho-ku, Nagoya 467-8601 Japan
| | - Y. Fujiyoshi
- Department of Anatomic Pathology and Molecular Diagnostics; Nagoya City University Graduate School of Medical Sciences; 1 Kawasumi Mizuho-cho Mizuho-ku, Nagoya 467-8601 Japan
| | - H. Hattori
- Department of Anatomic Pathology and Molecular Diagnostics; Nagoya City University Graduate School of Medical Sciences; 1 Kawasumi Mizuho-cho Mizuho-ku, Nagoya 467-8601 Japan
| | - A. Morita
- Department of Geriatric and Environmental Dermatology; Nagoya City University Graduate School of Medical Sciences; Nagoya Japan
| | - T-T. Kuo
- Department of Pathology; Chang Gung Memorial Hospital; Taoyuan Taiwan
| | - H. Inagaki
- Department of Anatomic Pathology and Molecular Diagnostics; Nagoya City University Graduate School of Medical Sciences; 1 Kawasumi Mizuho-cho Mizuho-ku, Nagoya 467-8601 Japan
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Suzuki H, Ito Y, Yamazaki Y, Mineta K, Uji M, Abe K, Tani K, Fujiyoshi Y, Tsukita S. The four-transmembrane protein IP39 of Euglena forms strands by a trimeric unit repeat. Nat Commun 2013; 4:1766. [PMID: 23612307 PMCID: PMC3644091 DOI: 10.1038/ncomms2731] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Accepted: 03/12/2013] [Indexed: 11/09/2022] Open
Abstract
Euglenoid flagellates have striped surface structures comprising pellicles, which allow the cell shape to vary from rigid to flexible during the characteristic movement of the flagellates. In Euglena gracilis, the pellicular strip membranes are covered with paracrystalline arrays of a major integral membrane protein, IP39, a putative four-membrane-spanning protein with the conserved sequence motif of the PMP-22/EMP/MP20/Claudin superfamily. Here we report the three-dimensional structure of Euglena IP39 determined by electron crystallography. Two-dimensional crystals of IP39 appear to form a striated pattern of antiparallel double-rows in which trimeric IP39 units are longitudinally polymerised, resulting in continuously extending zigzag-shaped lines. Structural analysis revealed an asymmetric molecular arrangement in the trimer, and suggested that at least four different interactions between neighbouring protomers are involved. A combination of such multiple interactions would be important for linear strand formation of membrane proteins in a lipid bilayer.
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Affiliation(s)
- Hiroshi Suzuki
- Cellular and Structural Physiology Institute, Nagoya University, Nagoya 464-8601, Japan
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Tani K, Fujiyoshi Y. Water channel structures analysed by electron crystallography. Biochim Biophys Acta Gen Subj 2013; 1840:1605-13. [PMID: 24120524 DOI: 10.1016/j.bbagen.2013.10.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Revised: 09/30/2013] [Accepted: 10/03/2013] [Indexed: 11/17/2022]
Abstract
BACKGROUND The mechanisms underlying water transport through aquaporin (AQP) have been debated for two decades. The water permeation phenomenon of AQP seems inexplicable because the Grotthuss mechanism does not allow for simultaneous fast water permeability and inhibition of proton transfer through the hydrogen bonds of water molecules. SCOPE OF REVIEW The AQP1 structure determined by electron crystallography provided the first insights into the proton exclusion mechanism despite fast water permeation. Although several studies have provided clues about the mechanism based on the AQP structure, each proposed mechanism remains incomplete. The present review is focused on AQP function and structure solved by electron crystallography in an attempt to fill the gaps between the findings in the absence and presence of lipids. MAJOR CONCLUSIONS Many AQP structures can be superimposed regardless of the determination method. The AQP fold is preserved even under conditions lacking lipids, but the water arrangement in the channel pore differs. The differences might be explained by dipole moments formed by the two short helices in the lipid bilayer. In addition, structure analyses of double-layered two-dimensional crystals of AQP suggest an array formation and cell adhesive function. GENERAL SIGNIFICANCE Electron crystallography findings not only have contributed to resolve some of the water permeation mechanisms, but have also elucidated the multiple functions of AQPs in the membrane. The roles of AQPs in the brain remain obscure, but their multiple activities might be important in the regulation of brain and other biological functions. This article is part of a Special Issue entitled Aquaporins.
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Affiliation(s)
- Kazutoshi Tani
- Cellular and Structural Physiology Institute, Nagoya University, Furo-cho, Chikusa, Nagoya, Japan
| | - Yoshinori Fujiyoshi
- Cellular and Structural Physiology Institute, Nagoya University, Furo-cho, Chikusa, Nagoya, Japan.
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Abstract
Electron crystallography is an important method for determining the structure of membrane proteins. In this paper, we show the impact of a carbon sandwich preparation on the preservation of crystalline sample quality, using characteristic examples of two-dimensional (2D) crystals from gastric H(+),K(+)-ATPase and their analyzed images. Compared with the ordinary single carbon support film preparation, the carbon sandwich preparation dramatically enhanced the resolution of images from flat sheet 2D crystals. As water evaporation is restricted in the carbon-sandwiched specimen, the improvement could be due to the strong protective effect of the retained water against drastic changes in the environment surrounding the specimen, such as dehydration and increased salt concentrations. This protective effect by the carbon sandwich technique helped to maintain the inherent and therefore best crystal conditions for analysis. Together with its strong compensation effect for the image shift due to beam-induced specimen charging, the carbon sandwich technique is a powerful method for preserving crystals of membrane proteins with larger hydrophilic regions, such as H(+),K(+)-ATPase, and thus constitutes an efficient and high-quality method for collecting data for the structural analysis of these types of membrane proteins by electron crystallography.
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Affiliation(s)
- Fan Yang
- Faculty of Science, Department of Biophysics, Kyoto University, Oiwake, Kitashirakawa, Sakyo-ku, Kyoto 606-0852, Japan
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Abstract
In biological science, there are still many interesting and fundamental yet difficult questions, such as those in neuroscience, remaining to be answered. Structural and functional studies of membrane proteins, which are key molecules of signal transduction in neural and other cells, are essential for understanding the molecular mechanisms of many fundamental biological processes. Technological and instrumental advancements of electron microscopy have facilitated comprehension of structural studies of biological components, such as membrane proteins. While X-ray crystallography has been the main method of structure analysis of proteins including membrane proteins, electron crystallography is now an established technique to analyze structures of membrane proteins in the lipid bilayer, which is close to their natural biological environment. By utilizing cryo-electron microscopes with helium-cooled specimen stages, structures of membrane proteins were analyzed at a resolution better than 3 Å. Such high-resolution structural analysis of membrane proteins by electron crystallography opens up the new research field of structural physiology. Considering the fact that the structures of integral membrane proteins in their native membrane environment without artifacts from crystal contacts are critical in understanding their physiological functions, electron crystallography will continue to be an important technology for structural analysis. In this chapter, I will present several examples to highlight important advantages and to suggest future directions of this technique.
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Affiliation(s)
- Yoshinori Fujiyoshi
- Department of Basic Biology, Cellular and Structural Physiology Institute, Nagoya University, Furo-cho, Chikusa, Nagoya, Japan
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Tani K, Arthur CP, Tamakoshi M, Yokoyama K, Mitsuoka K, Fujiyoshi Y, Gerle C. Visualization of two distinct states of disassembly in the bacterial V-ATPase from Thermus thermophilus. Microscopy (Oxf) 2013; 62:467-74. [PMID: 23572213 DOI: 10.1093/jmicro/dft020] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
V-ATPases are multisubunit, membrane-bound, energy-converting, cellular machines whose assembly and disassembly is innately connected to their activity in vivo. In vitro V-ATPases show a propensity for disassembly that greatly complicates their functional, and, in particular, structural characterization. Direct structural evidence for early stages of their disassembly has not been reported yet. We analyzed the structure of the V-ATPase from Thermus thermophilus in a single negatively stained two-dimensional (2-D) crystal both by electron tomography and by electron crystallography. Our analysis demonstrated that for 2-D crystals of fragile macromolecular complexes, which are too heterogenous or too few for the merging of image data from many crystals, single-crystal 3-D reconstructions by electron tomography and electron crystallography are expedient tools of analysis. The asymmetric unit in the 2-D crystal lattice contains two different V-ATPase complexes that appear to be in an early stage of disassembly and with either one or both peripheral stalks not being visualized, suggesting the involvement of the peripheral stalks in early stages of disassembly.
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Affiliation(s)
- Kazutoshi Tani
- Cellular and Structural Physiology Institute, Nagoya University, Nagoya 464-8601, Japan
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Oshima A, Matsuzawa T, Nishikawa K, Fujiyoshi Y. Oligomeric structure and functional characterization of Caenorhabditis elegans Innexin-6 gap junction protein. J Biol Chem 2013; 288:10513-21. [PMID: 23460640 DOI: 10.1074/jbc.m112.428383] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Innexin is the molecular component of invertebrate gap junctions. Here we successfully expressed and purified Caenorhabditis elegans innexin-6 (INX-6) gap junction channels and characterized the molecular dimensions and channel permeability using electron microscopy (EM) and microinjection of fluorescent dye tracers, respectively. Negative staining and thin-section EM of isolated INX-6 gap junction membranes revealed a loosely packed hexagonal lattice and a greater cross-sectional width than that of connexin26 and connexin43 (Cx43)-GFP. In gel filtration analysis, the elution profile of purified INX-6 channels in dodecyl maltoside solution exhibited a peak at ∼400 kDa that was shifted to ∼800 kDa in octyl glucose neopentyl glycol. We also obtained the class averages of purified INX-6 channels from these peak fractions by single particle analysis. The class average from the ∼800-kDa fraction showed features of the junction form with a longitudinal height of 220 Å, a channel diameter of 110 Å in the absence of detergent micelles, and an extracellular gap space of 60 Å, whereas the class averages from the ∼400-kDa fraction showed diameters of up to 140 Å in the presence of detergent micelles. These findings indicate that the purified INX-6 channels are predominantly hemichannels in dodecyl maltoside and docked junction channels in octyl glucose neopentyl glycol. Dye transfer experiments revealed that the INX-6-GFP-His channels are permeable to 3- and 10-kDa tracers, whereas no significant amounts of these tracers passed through the Cx43-GFP channels. Based on these findings, INX-6 channels have a larger overall structure and greater permeability than connexin channels.
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Affiliation(s)
- Atsunori Oshima
- Cellular and Structural Physiology Institute (CeSPI), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.
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Goda M, Fujiyoshi Y, Sugimoto M, Fujii R. Novel dichromatic chromatophores in the integument of the mandarin fish Synchiropus splendidus. Biol Bull 2013; 224:14-17. [PMID: 23493504 DOI: 10.1086/bblv224n1p14] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Affiliation(s)
- Makoto Goda
- Cellular and Structural Physiology Institute (CeSPI), Nagoya University, Furo-cho, Chikusa, Nagoya 464-8601, Japan.
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