高濃度のCO2は,TCAサイクルをオートロフィーへと後退させる
Lydia Steffens1, Eugenio Pettinato1, Thomas M Steiner2
1Institute for Molecular Microbiology and Biotechnology, University of Münster, Münster, Germany.
Nature
|April 22, 2021
まとめ
アナエロビックな微生物は,炭素固定のためのトリカルボキシル酸 (TCA) サイクルを逆転させることができる. 高い二酸化炭素 (CO2) レベルは海馬のこのサイクルを駆動し,オートロフィックな成長を可能にします.
科学分野:
- 微生物学
- 生物化学
- 地化学
背景:
- 通常,エネルギー生産に関与するトリカルボキシル酸 (TCA) 循環は,自給性炭素固定のためにいくつかの無酸素微生物で逆転することができます.
- この逆循環はフェレドキシン依存型2オキシグルタレート合成酵素のような特定の酵素を利用し,高い濃度のシトラート合成酵素を必要とします.
研究 の 目的:
- 熱愛性細菌Hippea maritimaの逆酸化TCAサイクルを駆動する条件を調査する.
- この自己栄養経路における高二酸化炭素 (CO2) 偏圧の役割を解明する.
主な方法:
- 実験分析のために,硫黄を減少させる熱愛性デルタプロテオバクテリアヒッペア・マリティマを使用した.
- 異なるCO2条件下でシトラート合成とピルベート合成を含む生化学的経路を調査した.
主要な成果:
- 高圧のCO2がHippea maritimaの逆酸化TCAサイクルを駆動するのに不可欠であることを実証した.
- アセチルコエンザイムA (アセチル-CoA) をピルバットへの還元性カルボキシル化により,ピルバット合成酵素によって触媒化することが,高CO2下において決定的であることを示した.
結論:
- 逆の酸化TCAサイクルは,Hippea maritimaの高いCO2レベルによって活発に駆動されます.
- この経路は,自己栄養的な炭素固定のための還元性TCAサイクルによりエネルギー効率の良い代替案を提供します.
- この発見は,この逆転したTCAサイクルが,初期の地球の大気中のCO2固定の重要なメカニズムであったことを示唆している.
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