| Project/Area Number |
17K07304
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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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| Research Field |
Structural biochemistry
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| Research Institution | Kanazawa University |
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Principal Investigator |
SEO DAISUKE 金沢大学, 物質化学系, 助教 (10339616)
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| Project Period (FY) |
2017-04-01 – 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 2019: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
Fiscal Year 2018: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
Fiscal Year 2017: ¥2,860,000 (Direct Cost: ¥2,200,000、Indirect Cost: ¥660,000)
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| Keywords | フラボ酵素 / フェレドキシン / 酸化還元反応 / 酵素反応速度論 / フラビン / NADPH / NADH / ヒドリド転移 / 枯草菌 / 緑色硫黄細菌 / 紅色非硫黄細菌 / 光合成 / 基質阻害 / 電子伝達反応 / 酵素基質複合体 / 鉄硫黄タンパク質 / 速度論 / 構造ダイナミクス / 酵素 / 微生物 / 酵素反応 / 生物物理 |
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| Outline of Final Research Achievements |
The redox reaction catalyzed by FNR is thermodynamically reversible. But under the physiological conditions the direction is optimized toward either NAD(P)+ reduction or NAD(P)H oxidation. This research aims to reveal the regulative mechanism of the directionality of the reversible redox reaction in the context of structure-function relation based on kinetic and structure analyses approaches. Kinetic analyses of the reactions between bacterial FNRs and NADP+/H revealed that the difference in the conformation of the reduced FAD altered the rate limiting step of the NADP+ reduction reaction, indicating that the residues interacting with reduced FAD play an important roles in the regulation of the directionality. The mutation on the residues in the C-terminal region affected the stabilization of the CT complex, leading an effective hydride transfer and optimization of the redox equilibrium between FNR and NADP+/H, thus contributing to the regulation of the directionality.
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| Academic Significance and Societal Importance of the Research Achievements |
相同性は高いが生理的に要求される反応方向が異なるFNRを用いた比較研究により，これまで酸化還元平衡に基づき説明されていたFNRの触媒反応の方向性が，実際には基質結合と酸化還元状態の変化に伴う構造変化による制御を受けており，構造的にも正逆方向で異なる過程をたどることが確認された．この結果は，FAD/NAD(P)H依存型酵素の構造－機能相関に基づく反応機構の理解の礎を築くと共に，フラボ酵素の反応方向制御における還元型FADのコンホメーションの制御の重要性を新たに提示するものである．
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