Mechanism of protein structural changes prior to photoisomerization

2020 Fiscal Year Final Research Report

• Project/Area Number: 19K15504
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 32010:Fundamental physical chemistry-related
• Research Institution: Tohoku University (2020); Osaka University (2019)
• Principal Investigator: Tahara Shinya 東北大学, 薬学研究科, 助教 (00783060)
• Project Period (FY): 2019-04-01 – 2021-03-31
• Keywords: 光受容タンパク質 / 超高速ダイナミクス / タンパク質構造変化 / ロドプシン / 紫外共鳴ラマン分光

Outline of Final Research Achievements

Rhodopsins are retinal-binding photoreceptor proteins. It has been believed that photoisomerization of the retinal chromophore drives structural changes of the protein moiety and the functions of rhodopsins. However, we recently found that protein structural changes occur prior to the photoisomerization. This study aims to elucidate molecular-level mechanism of this rapid protein structural changes. In this study, we synthesize microbial rhodopsins possessing a retinal analog which does not undergo photoisomerization and observe their protein structural changes upon photoexcitation.
We successfully synthesized Gloeobacter rhodopsin and Sensory rhodopsin II possessing the retinal analog at the high yields. Observations of their protein structural changes are the remaining step of this study and will be carried out as soon as the restriction of movement between universities due to COVID-19 is abolished.

Free Research Field

物理化学

Academic Significance and Societal Importance of the Research Achievements

光受容タンパク質は光エネルギーを利用して機能するタンパク質である。光応答タンパク質は発色団を内包する。発色団が光を吸収すると、発色団の構造変化が起こり、これによってタンパク質構造変化が駆動されると従来より考えられてきた。しかし申請者は発色団より先にタンパク質構造変化が起こることを近年示した。本研究ではこの速いタンパク質構造変化を駆動する機構を調べる。本研究で申請者は構造変化しない発色団を持つ光応答タンパク質の合成に成功し、タンパク質構造変化の測定の準備が整った。測定から得られる知見は、新規の仕組みで動く分子機械の設計指針を与える。