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A New Metabolic Map: Does Non-enzymatic Carbon Metabolism Exist Within Cells

Research Project

Project/Area Number 20K21294
Research Category

Grant-in-Aid for Challenging Research (Exploratory)

Allocation TypeMulti-year Fund
Review Section Medium-sized Section 38:Agricultural chemistry and related fields
Research InstitutionMeiji University

Principal Investigator

Osanai Takashi  明治大学, 農学部, 専任准教授 (60512316)

Project Period (FY) 2020-07-30 – 2023-03-31
Project Status Completed (Fiscal Year 2022)
Budget Amount *help
¥3,380,000 (Direct Cost: ¥2,600,000、Indirect Cost: ¥780,000)
Fiscal Year 2021: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2020: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Keywordsクエン酸回路 / シアノバクテリア / TCA回路 / 生化学 / 酵素 / 代謝 / オキサロ酢酸 / 代謝再構成 / 代謝酵素 / アセチルCoA / 合成生物学
Outline of Research at the Start

本研究では、細胞内の代謝に非酵素的な反応が存在することを明らかにする。細胞内の代謝は、酵素によって常温常圧においても反応が進む。中心代謝では酵素の多くが同定され、酵素反応を基盤とする代謝地図が完成した。しかし、申請者が代謝工学を進める過程で、酵素反応だけでは説明がつかない結果が得られてきた。
そこで申請者は、細胞内で非酵素的な反応が起こっているとの仮説に至り、本研究において検証する。中心となる代謝は、シアノバクテリアのピルビン酸代謝とクエン酸回路である。この代謝の中に非酵素的な反応があると仮定し、その存在を明らかにする。特にオキサロ酢酸に着目し、非酵素的な反応を含む新しい代謝地図を作成する。

Outline of Final Research Achievements

In vitro metabolic reconstruction studies have suggested that the citric acid cycle in cyanobacteria undergoes directional changes primarily influenced by pH (Ito et al., 2021, Plant J). This discovery implies that the citric acid cycle in cyanobacteria operates differently from typical organisms. Biochemical analyses revealed that the oxidation reaction activity of malate dehydrogenase is extremely weak. Further investigation of enzymes involved in malate metabolism showed that malic enzyme, which converts malate to pyruvate, exhibits significantly higher activity than malate dehydrogenase (Katayama et al., 2022, mBio). These results clearly indicate that the citric acid cycle in cyanobacteria is a specialized pathway (Katayama et al., 2022, mBio).
These findings highlight the unique characteristics and individuality of organisms, even in their typical primary metabolism within microalgae.

Academic Significance and Societal Importance of the Research Achievements

シネコシスティスのクエン酸回路を中心に、複数の酵素を用いたin vitroの代謝再構成の実験が有効であることを示した。また、リンゴ酸デヒドロゲナーゼの生化学解析結果をもとに、シネコシスティスのクエン酸回路の特殊性を明らかにして、新しい代謝経路を発見した。この経路は、シネコシスティスのみならず、シアノバクテリア一般の経路であることも生化学的に示しており、代謝における高い保存性のある成果を得ることができた。また、真核微細藻類であるシアニディオシゾンメローラなどの酵素特性と比較すると、同じ微細藻類でも性質が異なることがわかった。このように、光合成生物の炭素代謝において、新しい視点を得ることができた。

Report

(4 results)
  • 2022 Annual Research Report   Final Research Report ( PDF )
  • 2021 Research-status Report
  • 2020 Research-status Report
  • Research Products

    (10 results)

All 2022 2021 2020

All Journal Article (8 results) (of which Peer Reviewed: 8 results,  Open Access: 5 results) Presentation (2 results) (of which Int'l Joint Research: 1 results,  Invited: 2 results)

  • [Journal Article] Malic Enzyme, not Malate Dehydrogenase, Mainly Oxidizes Malate That Originates from the Tricarboxylic Acid Cycle in Cyanobacteria.2022

    • Author(s)
      Katayama N, Iwazumi K, Suzuki H, Osanai T, Ito S.
    • Journal Title

      mBio

      Volume: 13 Issue: 6

    • DOI

      10.1128/mbio.02187-22

    • Related Report
      2022 Annual Research Report
    • Peer Reviewed / Open Access
  • [Journal Article] Biochemical Properties of β-Amylase from Red Algae and Improvement of Its Thermostability through Immobilization2022

    • Author(s)
      Murakami Miyabi、Osanai Takashi
    • Journal Title

      ACS Omega

      Volume: 7 Issue: 41 Pages: 36195-36205

    • DOI

      10.1021/acsomega.2c03315

    • Related Report
      2022 Annual Research Report
    • Peer Reviewed / Open Access
  • [Journal Article] Biochemical elucidation of citrate accumulation in Synechocystis sp. PCC 6803 via kinetic analysis of aconitase2021

    • Author(s)
      Nishii Maki、Ito Shoki、Katayama Noriaki、Osanai Takashi
    • Journal Title

      Scientific Reports

      Volume: 11 Issue: 1 Pages: 17131-17131

    • DOI

      10.1038/s41598-021-96432-2

    • Related Report
      2021 Research-status Report
    • Peer Reviewed / Open Access
  • [Journal Article] Efficient extraction and preservation of thermotolerant phycocyanins from red alga Cyanidioschyzon merolae2021

    • Author(s)
      Yoshida Chihiro、Murakami Miyabi、Niwa Anna、Takeya Masahiro、Osanai Takashi
    • Journal Title

      Journal of Bioscience and Bioengineering

      Volume: 131 Issue: 2 Pages: 161-167

    • DOI

      10.1016/j.jbiosc.2020.09.021

    • NAID

      40022484428

    • Related Report
      2020 Research-status Report
    • Peer Reviewed
  • [Journal Article] Four-carbon dicarboxylic acid production through the reductive branch of the open cyanobacterial tricarboxylic acid cycle in Synechocystis sp. PCC 68032021

    • Author(s)
      Iijima Hiroko、Watanabe Atsuko、Sukigara Haruna、Iwazumi Kaori、Shirai Tomokazu、Kondo Akihiko、Osanai Takashi
    • Journal Title

      Metabolic Engineering

      Volume: 65 Pages: 88-98

    • DOI

      10.1016/j.ymben.2021.03.007

    • Related Report
      2020 Research-status Report
    • Peer Reviewed
  • [Journal Article] Fumarase From Cyanidioschyzon merolae Stably Shows High Catalytic Activity for Fumarate Hydration Under High Temperature Conditions2020

    • Author(s)
      Ito Shoki、Iwazumi Kaori、Sukigara Haruna、Osanai Takashi
    • Journal Title

      Frontiers in Microbiology

      Volume: 11 Pages: 2190-2190

    • DOI

      10.3389/fmicb.2020.560894

    • Related Report
      2020 Research-status Report
    • Peer Reviewed / Open Access
  • [Journal Article] Effect of pH on metabolite excretion and cell morphology of Euglena gracilis under dark, anaerobic conditions2020

    • Author(s)
      Yoshioka Kazumasa、Suzuki Kengo、Osanai Takashi
    • Journal Title

      Algal Research

      Volume: 51 Pages: 102084-102084

    • DOI

      10.1016/j.algal.2020.102084

    • Related Report
      2020 Research-status Report
    • Peer Reviewed
  • [Journal Article] Reconstitution of oxaloacetate metabolism in the tricarboxylic acid cycle in Synechocystis sp. PCC 6803: discovery of important factors that directly affect the conversion of oxaloacetate2020

    • Author(s)
      Ito Shoki、Hakamada Takumi、Ogino Tatsumi、Osanai Takashi
    • Journal Title

      The Plant Journal

      Volume: 105 Issue: 6 Pages: 1449-1458

    • DOI

      10.1111/tpj.15120

    • Related Report
      2020 Research-status Report
    • Peer Reviewed / Open Access
  • [Presentation] 微細藻類の基礎研究をベースにしたスモールベンチャーの創業2022

    • Author(s)
      小山内崇
    • Organizer
      植物科学シンポジウム
    • Related Report
      2022 Annual Research Report
    • Invited
  • [Presentation] Organic acid excretion from cyanobacteria during fermentation2020

    • Author(s)
      Takashi Osanai
    • Organizer
      International on-line Workshop Programme “Genetic modification tools in cyanobacteria and microalgae”
    • Related Report
      2020 Research-status Report
    • Int'l Joint Research / Invited

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Published: 2020-08-03   Modified: 2024-01-30  

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