| Project/Area Number |
18K06170
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 43040:Biophysics-related
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| Research Institution | Kyoto Sangyo University |
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Principal Investigator |
TSUGE Hideaki 京都産業大学, 生命科学部, 教授 (40299342)
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| Co-Investigator(Kenkyū-buntansha) |
吉田 徹 京都産業大学, 総合生命科学部, 研究員 (30724546)
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| Project Period (FY) |
2018-04-01 – 2020-03-31
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| Project Status |
Completed (Fiscal Year 2019)
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| Budget Amount *help |
¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000)
Fiscal Year 2020: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2019: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2018: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
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| Keywords | ウェルシュ菌 / 二成分毒素 / タンパク質膜透過 / ADPリボシル化 / ディフィシル菌 / クライオ電子顕微鏡 / 単粒子解析 / 超分子複合体 / イオタ毒素 / 膜結合 / アンフォールド / 膜孔 / トランスロコン / 複合体構造解析 / ADPリボシルトランスフェラーゼ / フォールディング / 膜孔形成毒素 |
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| Outline of Final Research Achievements |
The iota toxin produced by Clostridium perfringens type E is a binary toxin comprising two independent polypeptides: Ia, an ADP-ribosyltransferase, and Ib, which is involved in cell binding and translocation of Ia across the cell membrane. Here we report cryo-EM structures of the translocation channel Ib-pore and its complex with Ia. The high-resolution Ib-pore structure demonstrates a similar structural framework to that of the catalytic phi-clamp of the anthrax protective antigen pore. However, the Ia-bound Ib-pore structure shows a unique binding mode of Ia: one Ia binds to the Ib-pore, and the Ia amino-terminal domain forms multiple weak interactions with two additional Ib-pore constriction sites. Furthermore, Ib-binding induces tilting and partial unfolding of the Ia N-terminal α-helix, permitting its extension to the phi-clamp gate. This new mechanism of N-terminal unfolding is crucial for protein translocation.
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| Academic Significance and Societal Importance of the Research Achievements |
ウェルシュ菌の二成分毒素はアクチンをADPリボシル化する酵素成分のIaと、Iaを膜を介して細胞内に透過させる膜結合成分Ibからなる。Ibは中央に孔を持つIb膜孔を形成し、Iaがこの中を通過する。この二成分毒素複合体の構造を明らかにした。このことより、タンパク質膜透過の仕組みの一端を明らかにした。似た二成分毒素はディフィシル菌（ヒト感染症）や炭疽菌でもみられ、膜孔の阻害剤創薬の重要な知見となる。
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