Activation mechanism of G protein-coupled receptors by X-ray free electron lasers

2020 Fiscal Year Final Research Report

• Project/Area Number: 18H02394
• 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: Tohoku University (2020); Institute of Physical and Chemical Research (2018-2019)
• Principal Investigator: Nango Eriko 東北大学, 多元物質科学研究所, 教授 (90376947)
• Co-Investigator(Kenkyū-buntansha): 浅田 秀基 京都大学, 医学研究科, 特定講師 (20399041)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: X線結晶構造解析

Outline of Final Research Achievements

We conducted this research to analyze dynamic structures of visual rhodopsin, which is one of G protein-coupled receptors, using X-ray free electron lasers (XFEL). So far, time-resolved crystallography using XFEL has enabled to visualize dynamic structures of several light-sensitive proteins. However, it has been challenging to measure visual rhodopsin crystals because the crystal is damaged by very weak light. It has been also challenging to obtain rhodopsin crystals diffracting with high spatial resolution. We developed a new experimental device for time-resolved serial femtosecond crystallography to transport samples discontinuously for less light contamination. We performed pump-probe type time-resolved experiments with photo-sensitive samples using the device and observed structural changes with time. In addition, various expression systems of visual rhodopsin have been examined, and crystals were obtained under several conditions.

Free Research Field

構造生物学

Academic Significance and Societal Importance of the Research Achievements

従来、活性化状態に至る途中構造など動的構造を原子分解能で得ることは困難であった。新たな放射光源であるX線自由電子レーザー（XFEL）を用いると動的構造を可視化することが可能であるが、視覚ロドプシンのような取り扱いが難しい試料の測定に適した装置や技術は達成されていなかった。本課題ではXFEL実験用装置開発に取り組み、新たな測定方法を確立した。こうした技術は他試料の動的構造決定においても貢献すると期待される。