Structural analysis of ion-bound state and transport mechanism of microbial rhodopsin by multinuclear solid-state NMR of microbial rhodopsins

2020 Fiscal Year Final Research Report

• Project/Area Number: 18H02387
• 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: Yokohama National University
• Principal Investigator: Kawamura Izuru 横浜国立大学, 大学院工学研究院, 准教授 (20452047)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 固体NMR / レチナール / 化学シフト / イオン / 多核NMR

Outline of Final Research Achievements

Membrane proteins play an important role in maintaining cell homeostasis. Among them, microbial rhodopsin is covalently bound to retinal chromophore via a protonated Schiff base, and the protein is activated by photo-isomerization. Solid-state NMR spectroscopy with multinuclear observations as well as 13C and 15N was applied to detect important interactions containing ion-bound states, contacts with water molecules, and aromatic stacking. It is found that monitoring of the alterations in NMR signals can find local structural change of microbial rhodopsin depending on pH, replacement of alkali metal ions, H/D exchange and point mutation. Furthermore, we developed a methodology such as In-situ microwave irradiation NMR method to investigate the non-thermal effects on polar group in a molecule.

Free Research Field

構造生物化学

Academic Significance and Societal Importance of the Research Achievements

膜タンパク質の反応中心における特定の水素結合や静電的な相互作用などは膜タンパク質の重要な相互作用として特徴付けられ、分子レベルでそれらの機能を理解するためのアプローチとなる。そのような相互作用に対して、構造生物化学の分野で頻繁に利用される1H, 13C, 15N核以外にも多核的な観測によって、さらに深くアプローチできることを示した。今後、微生物型ロドプシンをはじめとした多くの膜タンパク質の動的構造の解明に活用できるものと期待できる。