Structural basis for the molecular mechanisms of photosynthetic light-harvesting, charge separation and quinone transport

2019 Fiscal Year Final Research Report

• Project/Area Number: 16H04174
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Bio-related chemistry
• Research Institution: Ibaraki University
• Principal Investigator: Otomo Seiu 茨城大学, 理工学研究科(理学野), 教授 (10213612)
• Project Period (FY): 2016-04-01 – 2020-03-31
• Keywords: 光合成 / 光捕集 / 光電変換

Outline of Final Research Achievements

Early events in photosynthesis are carried out by the antenna apparatus for light-harvesting (LH) and the reaction center (RC) for energy conversion. Since our publication of the crystal structure of a bacterial LH1-RC core complex (Nature 508, 228; 2014 and accompanying News & Views, Nature 508, 196; 2014), photosynthesis researchers are keen to resolve two fundamental questions: (i) what is the structural basis for the significantly different absorption properties of LH1-RC complexes from different photosynthetic bacteria, and (ii) how does “up-hill” energy transfer proceed in a natural photosynthetic system. Our study addresses the two questions. The results obtained from purple phototrophic bacteria provide detailed structural and spectroscopic information on the photosynthetic mechanisms of excitation energy transfer, charge separation and quinone transport, and pave the way for elucidation of the structure-function relationships in bacterial photosynthesis.

Free Research Field

生物物理化学

Academic Significance and Societal Importance of the Research Achievements

好熱性光合成細菌から単離された光合成色素タンパク質は極めて高い熱安定性を示すことから、本研究から得られた知見は光合成初期過程における励起エネルギーの伝達機構、反応中心における光誘起電荷分離機構の解明に役立つだけでなく、将来の工学的応用を見据えた人工光合成における高効率のアンテナと光電変換素子の構築に対しても根拠となる設計指針を与えるものと考えられる。また、本研究で用いたLH1-RCの性質には金属イオンが深く関与していることから、色素膜タンパク質と金属イオン間における高度な分子認識機構の解明とともに、生物の極限環境への適応戦略の解明にもつながるものとして期待できる。