大気中の水素からバクテリアのエネルギーを抽出するための構造的基礎

Rhys Grinter¹, Ashleigh Kropp², Hari Venugopal³

¹Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia. rhys.grinter@monash.edu.

Nature

|March 8, 2023

まとめ

空気細菌は,大気中の水素 (H₂) をエネルギー源として使用します. 研究者は,酸素の存在下でもH₂を効率的に酸化する酵素であるMycobacterium smegmatis hydrogenase Hucの構造とメカニズムを発見した.

科学分野:

生物化学
微生物学
環境科学

背景:

様々な有酸素細菌は,大気中の水素 (H₂) をエネルギーとして利用し,大気組成と土壌の生物多様性に影響を与えます.
大気中のH₂酸化を司る酵素は[NiFe]ヒドロゲネーゼスーパーファミリーに属しているが,そのメカニズムは,特に酸素感受性および電子移転に関して不明である.

研究の目的:

Mycobacterium smegmatis hydrogenase Hucの構造を決定し,そのメカニズムを調査する.
酸素の存在下でHucが低濃度H2の酸化を触媒化し,電子を呼吸連鎖に転送する方法を解明する.

主な方法:

クリオ電子顕微鏡を用いて,Hucの構造を決定した.
酵素の触媒機構と酸素不敏感性を調べるために生化学的測定を行った.

主要な成果:

Hucの冷凍-EM構造は,膜に関連した茎を持つオクタメリック複合体を明らかにしました.
Hucは大気中のH2を効率的に酸化し,メナキノン還元と結合し,狭い水性ガスチャネルのために酸素に無感性である.
Huc内の3つの [3Fe-4S]クラスターは,エネルギー的に実現可能なH₂酸化のためにその性質を調節する.

結論:

この発見は,重要な生地化学的プロセスである大気中のH2酸化のメカニズム的基礎を提供します.
Hucは,長距離キノンの輸送を伴う新しいエネルギー結合方式を使用しています.
この研究は,環境空気のH₂酸化のための新しい触媒を開発するための道を開きます.

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