Structural analysis of the complex between Fd and Fd-dependent proteins considering their redox states strictly

2023 Fiscal Year Final Research Report

• Project/Area Number: 21H02417
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 43020:Structural biochemistry-related
• Research Institution: Osaka University
• Principal Investigator: Kurisu Genji 大阪大学, 蛋白質研究所, 教授 (90294131)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 構造生物学 / 光合成 / 電子伝達 / 金属蛋白質 / レドックス代謝

Outline of Final Research Achievements

In this study, I have investigated the electron-transfer complexes formed transiently in three pairs: 1) the structure of photosystem I complex (PS1: LHC1) with Ga-substituted Fd from Green Alga was analyzed in three states, and new findings were made on the structural changes and dissociation of the new subunits from the PSI upon binding of Ga-substituted Fd. 2) For the structural analysis of cyanobacterial photosystem I (PS1) complexed with Ga-substituted Fd, we succeeded in obtaining a very high resolution of 1.97 A, as initially expected. 3) For the structural analysis of the complex of Native Fd in the reduced state and reconstituted permanently oxidized HydA1 (odt type) was not completed due to technical difficulties in obtaining the suitable crystals for X-ray analysis.

Free Research Field

構造生物化学

Academic Significance and Societal Importance of the Research Achievements

高度化してきた再構成金属タンパク質の活用をベースに，原理的に不可能と考えられてきた「酸化型」と「還元型」とで形成する活性型複合体の精密構造解析を行った。具体的には，2種類の光化学系IとFdとの構造解析を高分解能で行い，構造決定が待たれている緑藻型のFd依存性[FeFe]ヒドロゲナーゼの構造解析にも同様の方法を展開した。前者については，想定通りの結果を得て論文発表を行ったが，緑藻型[FeFe]ヒドロゲナーゼについては結晶化することができなかった。結晶化不要のCryo-EMに切り替えて活性型構造解析を展開している。本研究により，Redox状態を厳密にコントロールすることの重要性を示すことができた。