The mechanisms to control electron transfer reactions in the homodimeric photosynthetic reaction center based on its molecular structure

2017 Fiscal Year Final Research Report

• Project/Area Number: 15K07026
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Biophysics
• Research Institution: Osaka University
• Principal Investigator: Oh-oka Hirozo 大阪大学, 理学研究科, 准教授 (30201966)
• Research Collaborator: Itoh Shigeru ; Kurisu Genji ; Azai Chihiro
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: 光合成 / 反応中心 / ホモダイマー / ヘリオバクテリア / 光化学系 I / 電子スピン共鳴 / X線結晶構造解析

Outline of Final Research Achievements

Light-dependent charge separation in photosynthesis is driven by the reaction center (RC) membrane protein complex that is classified into four types; the green bacterial or heliobacterial, the purple bacterial, the photosystem (PS) I and II RCs. Compared to the latter three types of RCs, the molecular architecture of heliobacterial RC is still poorly understood, in part due to the lack of high-resolution structural information. Structure of the RC from Heliobacterium modesticaldum has been solved to a resolution of 3.2 angstrom. Although the X-ray structure, which was reported by Arizona group in 2017, contained no quinone molecule within its, our crystal structure has indicated that it was contained and seemed to function as a secondary acceptor A1. The ESP-EPR signals, which was derived from the charge separated state of P800+A1-, suggested that the quinone molecule had an almost similar orientation to but a little bit different location from that in PS I.

Free Research Field

生物物理