Analysis of Assembly Intermediates of Photosynthetic Pigment Proteins by RNA-Probe-Based Exhaustive Single-Molecule Spectroscopy

2022 Fiscal Year Final Research Report

• Project/Area Number: 21K19200
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 43:Biology at molecular to cellular levels, and related fields
• Research Institution: Tohoku University
• Principal Investigator: Shibata Yutaka 東北大学, 理学研究科, 准教授 (20300832)
• Project Period (FY): 2021-07-09 – 2023-03-31
• Keywords: 単一分子分光 / RNAプローブ / 光化学系修復

Outline of Final Research Achievements

Photosystem II (PSII) has been known to be repeatedly damaged and repaired in photosynthesis organisms. Here I proposed and tried a method to detect the assembly intermediates of PSII using designed RNA probes. A model organism Chlamydomonas was used. Since D1 subunit at the center of the PSII complex is the target of the repair process, I designed an RNA probe which is complementary to the mRNA sequence of D1 subunit and contains Alexa555 at its both ends as the fluorophore. Chlamydomonas cells were incubated under high light and then under mild light to activate the repair process. Thylakoid membranes were isolated from the cells treated as above and the RNA probe was hybridized with the thylakoids. I detected the fluorescence signal of Alexa555 from the hybridized thylakoid membranes, confirming the validity of the method proposed in the present project.

Free Research Field

光生物物理学

Academic Significance and Societal Importance of the Research Achievements

光合成タンパク質のAssembly過程の解明は、光合成研究において未だ解明されていない難問の一つである。水から電子を引き抜く過程は、分子に大きな酸化力の実現を要求し、同時に大量の酸素分子を発生させる。高い酸化力が内在することや、反応性の高い酸素分子が大量発生することは、どちらもタンパク質の損傷の原因となる。こうした困難な状況をやり繰りするため、生物は壊れないタンパク質を進化させるのではなく、壊れても迅速に修復が可能となるシステムを進化させた。人工の新規タンパク質を設計し合成することが可能となりつつある現代において、光合成系の修復機構解明は人工光合成を実現させる上でも示唆に富むものとなる。