Functional evolution of pyrenoids in chlorarachniophytes

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K06285
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 45020:Evolutionary biology-related
• Research Institution: University of Tsukuba
• Principal Investigator: Hirakawa Yoshihisa 筑波大学, 生命環境系, 助教 (40647319)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 藻類 / 光合成 / 葉緑体 / 二酸化炭素 / ピレノイド / 収斂進化

Outline of Final Research Achievements

Approximately one-third of the global carbon assimilation is estimated to occur within pyrenoids, which are widely present in eukaryotic algae. Pyrenoids are involved in CO2-concentrating mechanisms (CCMs) supplying CO2 to the carbon-fixing enzyme Rubisco. Although Rubisco is the predominant component of pyrenoids, other pyrenoid-associated proteins remain to be elucidated in most algae. To understand the diversity and evolution of pyrenoid-based CCMs among algae, we here investigated the pyrenoid proteome of a marine chlorarachniophyte alga. Our localization experiments demonstrated the specific targeting of eight proteins to pyrenoids. These included a putative Rubisco-binding linker, carbonic anhydrase, membrane transporter, and uncharacterized GTPase proteins. Notably, most of these proteins were unique to this algal lineage. This study provides insights into the convergent evolution of CO2-concentrating organelles at the molecular level.

Free Research Field

藻類進化学

Academic Significance and Societal Importance of the Research Achievements

海で固定化された二酸化炭素の一部は長期的に蓄積される「ブルーカーボン」と呼ばれ、大気中の二酸化炭素の削減に貢献するものとして注目されている。本研究では、海産の微細藻類が効率的に二酸化炭素を固定化するメカニズムの一端を明らかにした。これは、藻類に普遍的に存在するピレノイドの進化の謎に迫るだけでなく、ブルーカーボンの潜在的な可能性の理解に繋がる内容である。