Updated on 2023/09/19

写真a

 
OSHIMA Atsunori
 
Organization
Cellular and Structural Physiology Institute Division Professor
Graduate School
Graduate School of Pharmaceutical Sciences
Title
Professor
Contact information
メールアドレス
External link

Degree 1

  1. 博士(理学) ( 2003.3   京都大学 ) 

Research Areas 3

  1. Life Science / Structural biochemistry

  2. Life Science / Biophysics

  3. Life Science / Molecular biology

 

Papers 34

  1. Structural insight into the activation mechanism of MrgD with heterotrimeric Gi-protein revealed by cryo-EM

    Suzuki Shota, Iida Momoko, Hiroaki Yoko, Tanaka Kotaro, Kawamoto Akihiro, Kato Takayuki, Oshima Atsunori

    COMMUNICATIONS BIOLOGY   Vol. 5 ( 1 ) page: 707   2022.7

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    Authorship:Last author, Corresponding author   Language:Japanese   Publisher:Communications Biology  

    MrgD, a member of the Mas-related G protein-coupled receptor (MRGPR) family, has high basal activity for Gi activation. It recognizes endogenous ligands, such as β-alanine, and is involved in pain and itch signaling. The lack of a high-resolution structure for MrgD hinders our understanding of whether its activation is ligand-dependent or constitutive. Here, we report two cryo-EM structures of the MrgD-Gi complex in the β-alanine-bound and apo states at 3.1 Å and 2.8 Å resolution, respectively. These structures show that β-alanine is bound to a shallow pocket at the extracellular domains. The extracellular half of the sixth transmembrane helix undergoes a significant movement and is tightly packed into the third transmembrane helix through hydrophobic residues, creating the active form. Our structures demonstrate a structural basis for the characteristic ligand recognition of MrgD. These findings provide a framework to guide drug designs targeting the MrgD receptor.

    DOI: 10.1038/s42003-022-03668-3

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  2. Structures of human pannexin-1 in nanodiscs reveal gating mediated by dynamic movement of the N terminus and phospholipids Reviewed International coauthorship

    Maki Kuzuya, Hidemi Hirano, Kenichi Hayashida, Masakatsu Watanabe, Kazumi Kobayashi, Tohru Terada, Md. Iqbal Mahmood, Florence Tama, Kazutoshi Tani, Yoshinori Fujiyoshi and Atsunori Oshima

    Science Signaling   Vol. 15 ( 720 ) page: eabg6941   2022.2

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    Authorship:Last author, Corresponding author   Language:Japanese   Publishing type:Research paper (scientific journal)  

    DOI: 10.1126/scisignal.abg6941

    Web of Science

  3. Cryo-EM structures of undocked innexin-6 hemichannels in phospholipids Reviewed

    Batuujin Burendei, Ruriko Shinozaki, Masakatsu Watanabe, Tohru Terada, Kazutoshi Tani, Yoshinori Fujiyoshi, and Atsunori Oshima

    Science Advances   Vol. 6 ( 7 ) page: eaax3157   2020.2

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    Authorship:Last author, Corresponding author   Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1126/sciadv.aax3157

  4. Atomic structure of the innexin-6 gap junction channel determined by cryo-EM Reviewed

    Oshima, A., Tani, K. and Fujiyoshi, Y.

    Nature communications   Vol. 7   page: 13681   2016.12

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    Authorship:Lead author, Corresponding author   Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1038/ncomms13681

  5. The structural basis of divalent cation block in a tetrameric prokaryotic sodium channel

    Irie Katsumasa, Oda Yoshinori, Sumikama Takashi, Oshima Atsunori, Fujiyoshi Yoshinori

    NATURE COMMUNICATIONS   Vol. 14 ( 1 ) page: 4236   2023.7

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    Language:English   Publisher:Nature Communications  

    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.

    DOI: 10.1038/s41467-023-39987-0

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  6. Recognition Mechanism of a Novel Gabapentinoid Drug, Mirogabalin, for Recombinant Human α<inf>2</inf>δ1, a Voltage-Gated Calcium Channel Subunit: Recognition mechanism of mirogabalin for α<inf>2</inf>δ1

    Kozai D., Numoto N., Nishikawa K., Kamegawa A., Kawasaki S., Hiroaki Y., Irie K., Oshima A., Hanzawa H., Shimada K., Kitano Y., Fujiyoshi Y.

    Journal of Molecular Biology   Vol. 435 ( 10 ) page: 168049   2023.5

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    Language:English   Publisher:Journal of Molecular Biology  

    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.

    DOI: 10.1016/j.jmb.2023.168049

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  7. Structure and function of H+/K+ pump mutants reveal Na+/K+ pump mechanisms

    Young Victoria C., Nakanishi Hanayo, Meyer Dylan J., Nishizawa Tomohiro, Oshima Atsunori, Artigas Pablo, Abe Kazuhiro

    NATURE COMMUNICATIONS   Vol. 13 ( 1 ) page: 5270   2022.9

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    Language:English   Publisher:Nature Communications  

    Ion-transport mechanisms evolve by changing ion-selectivity, such as switching from Na+ to H+ selectivity in secondary-active transporters or P-type-ATPases. Here we study primary-active transport via P-type ATPases using functional and structural analyses to demonstrate that four simultaneous residue substitutions transform the non-gastric H+/K+ pump, a strict H+-dependent electroneutral P-type ATPase, into a bona fide Na+-dependent electrogenic Na+/K+ pump. Conversion of a H+-dependent primary-active transporter into a Na+-dependent one provides a prototype for similar studies of ion-transport proteins. Moreover, we solve the structures of the wild-type non-gastric H+/K+ pump, a suitable drug target to treat cystic fibrosis, and of its Na+/K+ pump-mimicking mutant in two major conformations, providing insight on how Na+ binding drives a concerted mechanism leading to Na+/K+ pump phosphorylation.

    DOI: 10.1038/s41467-022-32793-0

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  8. Structural Basis for Binding of Potassium-Competitive Acid Blockers to the Gastric Proton Pump

    Tanaka Saki, Morita Mikio, Yamagishi Tatsuya, Madapally Hridya Valia, Hayashida Kenichi, Khandelia Himanshu, Gerle Christoph, Shigematsu Hideki, Oshima Atsunori, Abe Kazuhiro

    JOURNAL OF MEDICINAL CHEMISTRY   Vol. 65 ( 11 ) page: 7843 - 7853   2022.6

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    Language:Japanese   Publisher:Journal of medicinal chemistry  

    As specific inhibitors of the gastric proton pump, responsible for gastric acidification, K+-competitive acid blockers (P-CABs) have recently been utilized in the clinical treatment of gastric acid-related diseases in Asia. However, as these compounds have been developed based on phenotypic screening, their detailed binding poses are unknown. We show crystal and cryo-EM structures of the gastric proton pump in complex with four different P-CABs, tegoprazan, soraprazan, PF-03716556 and revaprazan, at resolutions reaching 2.8 Å. The structures describe molecular details of their interactions and are supported by functional analyses of mutations and molecular dynamics simulations. We reveal that revaprazan has a novel binding mode in which its tetrahydroisoquinoline moiety binds deep in the cation transport conduit. The mechanism of action of these P-CABs can now be evaluated at the molecular level, which will facilitate the rational development and improvement of currently available P-CABs to provide better treatment of acid-related gastrointestinal diseases.

    DOI: 10.1021/acs.jmedchem.2c00338

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  9. Structure and dynamics of Odinarchaeota tubulin and the implications for eukaryotic microtubule evolution Reviewed

    C. Akıl, S. Ali, L. T. Tran, J. Gaillard, W. Li, K. Hayashida, M. Hirose, T. Kato, A. Oshima, K. Fujishima, L. Blanchoin, A. Narita, R. C. Robinson

    Science Advances   Vol. 8 ( 12 ) page: eabm2225   2022.3

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1126/sciadv.abm2225

  10. Cryo-EM of the ATP11C flippase reconstituted in Nanodiscs shows a distended phospholipid bilayer inner membrane around transmembrane helix 2

    Nakanishi Hanayo, Hayashida Kenichi, Nishizawa Tomohiro, Oshima Atsunori, Abe Kazuhiro

    JOURNAL OF BIOLOGICAL CHEMISTRY   Vol. 298 ( 1 )   2022.1

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    Language:Japanese  

    DOI: 10.1016/j.jbc.2021.101498

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  11. A cryptic phosphate-binding pocket on the SPFH domain of human stomatin that regulates a novel fibril-like self-assembly

    Kataoka Koki, Suzuki Shota, Tenno Takeshi, Goda Natsuko, Hibino Emi, Oshima Atsunori, Hiroaki Hidekazu

    CURRENT RESEARCH IN STRUCTURAL BIOLOGY   Vol. 4   page: 158 - 166   2022

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    Language:Japanese   Publisher:Current Research in Structural Biology  

    Human stomatin (hSTOM) is a component of the membrane skeleton of erythrocytes that maintains the membrane's shape and stiffness through interconnecting spectrin and actin. hSTOM is a member of the protein family that possesses a single stomatin/prohibitin/flotillin/HflK (SPFH) domain at the center of the molecule. Although SPFH domain proteins are widely distributed from archaea to mammals, the detailed function of the domain remains unclear. In this study, we first determined the solution structure of the SPFH domain of hSTOM (hSTOM(SPFH)) via NMR. The solution structure of hSTOM(SPFH) is essentially identical to the already reported crystal structure of the STOM SPFH domain (mSTOM(SPFH)) of mice, except for the existence of a small hydrophilic pocket on the surface. We identified this pocket as a phosphate-binding site by comparing its NMR spectra with and without phosphate ions. Meanwhile, during the conventional process of protein NMR analysis, we eventually discovered that hSTOM(SPFH) formed a unique solid material after lyophilization. This lyophilized hSTOM(SPFH) sample was moderately slowly dissolved in a physiological buffer. Interestingly, it was resistant to dissolution against the phosphate buffer. We then found that the lyophilized hSTOM(SPFH) formed a fibril-like assembly under electron microscopy. Finally, we succeeded in reproducing this fibril-like assembly of hSTOM(SPFH) using a centrifugal ultrafiltration device, thus demonstrating that the increased protein concentration may promote self-assembly of hSTOM(SPFH) into fibril forms. Our observations may help understand the molecular function of the SPFH domain and its involvement in protein oligomerization as a component of the membrane skeleton. (245 words).

    DOI: 10.1016/j.crstbi.2022.05.002

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  12. Gastric proton pump with two occluded K+ engineered with sodium pump-mimetic mutations

    Abe Kazuhiro, Yamamoto Kenta, Irie Katsumasa, Nishizawa Tomohiro, Oshima Atsunori

    NATURE COMMUNICATIONS   Vol. 12 ( 1 )   2021.9

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  13. クライオ電子顕微鏡が加速するギャップ結合の構造研究 Invited

    大嶋篤典

    生体の科学   Vol. 71 ( 4 ) page: 315-320   2020.8

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    Authorship:Lead author   Language:Japanese  

  14. Presence of intrinsically disordered proteins can inhibit the nucleation phase of amyloid fibril formation of A beta(1-42) in amino acid sequence independent manner

    Ikeda Koki, Suzuki Shota, Shigemitsu Yoshiki, Tenno Takeshi, Goda Natsuko, Oshima Atsunori, Hiroaki Hidekazu

    SCIENTIFIC REPORTS   Vol. 10 ( 1 )   2020.7

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1038/s41598-020-69129-1

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  15. Structural insights into gap junction channels boosted by cryo-EM Invited Reviewed

    Atsunori Oshima

      Vol. 63   page: 42-48   2020.4

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    Authorship:Lead author   Language:English  

    DOI: 10.1016/j.sbi.2020.03.008

  16. Potential of cryo-EM for high-resolution structural analysis of gap junction channels Invited Reviewed

    Atsunori Oshima

    CURRENT OPINION IN STRUCTURAL BIOLOGY   Vol. 54   page: 78-85   2019.2

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    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1016/j.sbi.2019.01.005

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  17. イネキシンギャップ結合チャネルの原子分解能単粒子解析 Invited

    大嶋篤典

    顕微鏡   Vol. 52   page: 153-159   2017.12

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    Authorship:Lead author   Language:Japanese  

  18. Structure of an innexin gap junction channel and cryo-EM sample preparation Invited Reviewed

    Atsunori Oshima

    MICROSCOPY   Vol. 66 ( 6 ) page: 371-379   2017.12

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    Authorship:Lead author   Language:English  

    DOI: 10.1093/jmicro/dfx035

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  19. Hexadecameric structure of an invertebrate gap junction channel Reviewed

    Oshima, A., Matsuzawa, T., Murata, K., Tani, K. and Fujiyoshi, Y.

    J. Mol. Biol.   Vol. 428   page: 1227-1236   2016.3

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    DOI: 10.1016/j.jmb.2016.02.011.

  20. ギャップ結合チャネルの構造と多様性 Invited Reviewed

    大嶋篤典

    膜(MEMBRANE)   Vol. 41   page: 50-56   2016.3

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    Authorship:Lead author   Language:Japanese   Publishing type:Research paper (scientific journal)  

  21. GraDeR: membrane protein complex preparation for single particle cryo-EM. Reviewed

    Hauer, F., Gerle,C., Fischer, N., Oshima, A., Shinzawa-Itoh, K., Shimada, S., Yokoyama, K., Fujiyoshi, Y., Stark, H.

    Structure   Vol. 23   page: 1769-1775   2015.9

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  22. Structure and closure of connexin gap junction channels Invited Reviewed

    A. Oshima

    FEBS Letters   Vol. 588   page: 1230-1237   2014.2

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    Authorship:Lead author   Language:English  

  23. Oligomeric Structure and Functional Characterization of Caenorhabditis elegans Innexin-6 Gap Junction Protein Reviewed

    A. Oshima, T. Matsuzawa, K. Nishikawa, and Y. Fujiyoshi

    Journal of Biological Chemistry   Vol. 288   page: 10513-10521   2013.4

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  24. Asymmetric configurations and N-terminal rearrangements in connexin26 gap junction channels Reviewed

    A. Oshima, K. Tani, M. M. Toloue, Y. Hiroaki, A. Smock, S. Inukai, A. Cone, B. J. Nicholson ,G. E. Sosinsky, and Y. Fujiyoshi

    Journal of Molecular Biology     2011

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    DOI: 10.1016/j.jmb.2010.10.032

  25. Two-dimensional kinetics of inter-connexin interactions from single molecule force spectroscopy Reviewed

    F. Rico, A. Oshima, P. Hinterdorfer, Y. Fujiyoshi, and S. Scheuring

    Journal of Molecular Biology     2011

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    DOI: 10.1016/j.jmb.2011.07.013

  26. Analysis of four connexin26 mutant gap junctions and hemichannels reveals variations in hexamer stability Reviewed

    C. Ambrosi, D. Boassa, J. Pranskevich, A. Smock, A. Oshima, J. Xu, B. J. Nicholson ,G. E. Sosinsky

    Biophysical Journal     2010

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    DOI: 10.1016/j.bpj.2010.01.019

  27. 電子線結晶構造解析から導かれたギャップ結合チャネルのプラグゲーティング機構

    大嶋篤典

    顕微鏡   Vol. 44 ( 2 ) page: 87-92   2009

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  28. The M34A mutant of Connexin26 reveals active conductance states in pore-suspending membranes Reviewed

    O. Gaßmann, M. Kreir, C. Ambrosi, J. Pranskevich, A. Oshima, C. Röling, G. Sosinsky, N. Fertig, and C. Steinem

    Journal of Structural Biology     2009

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    DOI: 10.1016/j.jsb.2009.02.004

  29. Structure of the connexin 26 gap junction channel at 3.5Å resolution Reviewed

    S. Maeda, S. Nakagawa, M. Suga, E. Yamashita, A. Oshima, Y. Fujiyoshi and T. Tsukihara

    Nature     2009

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1038/nature07869

  30. Projection structure of a N-terminal deletion mutant of connexin 26 channel with decreased central pore density Reviewed

    A. Oshima, K. Tani, Y. Hiroaki, Y. Fujiyoshi, and G. E. Sosinsky

    Cell Communication and Adhesion     2008

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    DOI: 10.1080/15419060802013588

  31. Three-dimensional structure of a human connexin26 gap junction channel reveals a plug in the vestibule Reviewed

    A. Oshima, K. Tani, Y. Hiroaki, Y. Fujiyoshi, and G. E. Sosinsky

    Proceedings of the National Academy of Sciences of the United States of America     2007

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    DOI: 10.1073/pnas.0703704104

  32. Mutation of a conserved threonine in the third transmembrane helix of and connexins creates a dominant-negative closed gap junction channel Reviewed

    D. Beahm, A. Oshima, G. M. Gaietta, G. M. Hand, A. E. Smock, S. N. Zucker, M. M. Toloue, A. Chandrasekhar, B. J. Nicholson, and G. E. Sosinsky

    Journal of Biological Chemistry     2006

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    DOI: 10.1074/jbc.M506533200

  33. Roles of Met-34, Cys-64, and Arg-75 in the assembly of human connexin 26. IMPLICATION FOR KEY AMINO ACID RESIDUES FOR CHANNEL FORMATION AND FUNCTION Reviewed

    A. Oshima, T. Doi, K. Mitsuoka, S. Maeda, and Y. Fujiyoshi

    Journal of Biological Chemistry     2003

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1074/jbc.M207713200

  34. The 11Å resolution projection map of Na+/K+-ATPase calculated by application of single particle analysis to two-dimensional crystal images Reviewed

    Y. Tahara, A. Oshima, T. Hirai, K. Mitsuoka, Y. Fujiyoshi, and Y. Hayashi

    Journal of Electron Microscopy   Vol. 49 ( 4 ) page: 583-587   2000

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▼display all

MISC 1

  1. クライオ電子顕微鏡で見るギャップ結合チャネルの構造 Invited

    大嶋篤典

    細胞   Vol. 51   page: 8-11   2019

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    Authorship:Lead author   Language:Japanese  

Research Project for Joint Research, Competitive Funding, etc. 1

  1. クライオ電子顕微鏡のフィードバックに基づく膜タンパク質複合体の生産と技術支援

    2017.4 - 2022.3

    創薬等ライフサイエンス研究支援基盤事業 

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    Grant type:Competitive

KAKENHI (Grants-in-Aid for Scientific Research) 5

  1. 脂質が寄与するlarge pore channelの膜透過機構の解明

    Grant number:23H02418  2023.4 - 2027.3

    科学研究費助成事業  基盤研究(B)

    大嶋 篤典

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    Authorship:Principal investigator 

    Grant amount:\18590000 ( Direct Cost: \14300000 、 Indirect Cost:\4290000 )

  2. 脂質二重膜中におけるlarge pore channelの新しい開閉モデルの探索

    Grant number:21K19215  2021.7 - 2023.3

    科学研究費助成事業  挑戦的研究(萌芽)

    大嶋 篤典

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    Authorship:Principal investigator 

    Grant amount:\6370000 ( Direct Cost: \4900000 、 Indirect Cost:\1470000 )

  3. 高等動物細胞間結合チャネルのクライオ電子顕微鏡構造研究

    Grant number:19H03165  2019.4 - 2022.3

    科学研究費助成事業  基盤研究(B)

    大嶋 篤典

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    Authorship:Principal investigator 

    Grant amount:\17290000 ( Direct Cost: \13300000 、 Indirect Cost:\3990000 )

    本研究はコネキシンギャップ結合チャネルの高分解能構造解析をクライオ電子顕微鏡単粒子解析法で行い、コネキシンチャネルの開閉機構と生理機能の解明に迫る。ヒトのコネキシン26とコネキシン32を対象とし、可溶化状態と脂質二重膜に再構成された状態のクライオ電子顕微鏡高分解能構造解析を行い、電気生理機能解析も併用する。また試料調製法の最適化による、膜タンパク質のクライオ電子顕微鏡高分解能構造解析を加速するための技術開発を目指す。
    本研究ではギャップ結合チャネル関連タンパク質の高分解能構造解析をクライオ電子顕微鏡単粒子解析で行い、ギャップ結合チャネルを含むLarge pore channelの開閉機構と生理機能の解明を目的とした研究を行っている。
    今年度は、Cx32の野生型と神経疾患であるCMTXの原因となるCx32変異体のクライオ電顕構造解析を行った。いずれもナノディスクに再構成し、野生型はジャンクション型で、変異体はジャンクション型とヘミチャネル型の両方で原子構造を得た。野生型は複数のコンフォメーションが混じっている構造が得られた。N末端領域が不鮮明であることから、構造が動的で機能に関わる領域が不安定化していると考えられた。変異体は細胞外ドメインに構造変化がみられ、それがジャンクション形成を不安定化してヘミチャネルを生じさせることが示唆された。
    <BR>
    さらに、ヒトpannexin-1(PANX1)を哺乳動物細胞で発現、精製し、ナノディスク再構成を行った後、クライオ電子顕微鏡による高分解能構造解析を行った。野生型PANX1のapo状態(PANX1apo)、野生型PANX1に阻害剤を添加した状態(PANX1-PBN)、PANX1のC末端欠失変異体(PANX1ΔC)、PANX1のN末端欠失変異体(PANX1ΔN)を解析した。PANX1apoはN末端がチャネル通路内でファネルを形成し、通路を大きく開けている構造であるのに対し、PANX1-PBNはN末端領域が細胞質側に大きく構造変化すると同時に、脂質がチャネルの内側に存在することが確認され、チャネルの通路をブロックする密度が確認された。また、PANXΔCはPANX1apoと、PANX1ΔNはPANX1-PBNと非常に良く似た構造を取っていた。構造研究と機能解析、MDシミュレーションの共同研究を総合して、脂質がPANX1と相互作用しながらチャネル通路内へ移動する「脂質ゲーティング」が示唆された。この結果は論文にまとめて発表した。
    Cx32の構造解析が進んだことと、並行して進めていたPANX-1の構造解析を論文に発表できたため。
    Cx32の野生型は動的で複数のコンフォメーションが混ざっている可能性が考えられるため、サブユニット単位で3D variabilityの解析を行って、クラス分けを行い、コンフォメーションの分離を目指す。
    変異体と野生型の原子モデルを比較して、導入された変異が起こす構造変化を先行研究の機能解析と組み合わせて考察する。

  4. High-resolution single particle analysis of intercellular channels

    Grant number:16K07266  2016.4 - 2019.3

    Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (C)

    Oshima Atsunori

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    Authorship:Principal investigator 

    Grant amount:\4940000 ( Direct Cost: \3800000 、 Indirect Cost:\1140000 )

    We obtain the cryo-electron microscopy structures of Caenorhabditis elegans innexin-6 (INX-6) gap junction channels at atomic resolution. The INX-6 gap junction channel comprises hexadecameric subunits in an open state. The INX-6 structure is highly similar to the human connexin-26 structure, despite the lack of significant sequence similarity. We also have a hemichannel structures of INX-6 in a lipid nanodisc showing that flat double-layer densities obstruct the channel pore. Comparison of the hemichannel structures of a wild-type INX-6 in detergent and nanodisc-reconstituted N-terminal deletion mutant reveal that lipid-mediated N-terminal rearrangement and pore obstruction occur upon nanodisc reconstitution.Together with molecular dynamics simulations and electrophysiology functional assays, our results provide insight into how the large-size pore of gap junction hemichannels can be completely closed in a lipid bilayer.

  5. Studies in structural physiology of channels

    Grant number:15H05775  2015.5 - 2020.3

    FUJIYOSHI Yoshinori

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    Authorship:Coinvestigator(s) 

    Structural information of membrane proteins including channels is crucial toward gaining a better understanding of biologic functions. The information that can be gained from a protein structure strongly depends on its resolution - the higher the resolution, the more insight gained into the structure-function relationship of biologic macromolecules. We analyzed structures of proton pump, water channel AQP4, whose inhibitor could be a drug for brain edema, Na+ channel, gap junction channels and tight junction channels at high resolutions. While we could not get significant results of AChR, we analyzed structures of endothelin receptor and its complexes with the agonist and antagonists. In this project, we could get important knowledge in the research field named as structural physiology and partly elucidate how the channels work and regulate functions of the human body. We also contributed advancement of cryo-electron microscopy by developing cryo-electron microscopes.