Dph3は,Dph1-Dph2の [3Fe-4S] を [4Fe-4S] クラスタに変換するために,1つの鉄原子を寄付することによって,エアロビックディフタミド生物合成を可能にします

Yugang Zhang¹, Dan Su¹, Boris Dzikovski¹

¹Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States.

Journal of the American Chemical Society

|June 22, 2021

まとめ

ラジカルS-アデノシルメチオニンの酵素は機能するために鉄硫黄のクラスターを必要とします Dph3と呼ばれるタンパク質は酸素の存在下でこれらのクラスターを維持し有酸素環境で酵素の活性化を可能にします

科学分野:

生物化学
酵素学
タンパク質の構造と機能

背景:

ラジカルS-アデノシルメチオニン (ラジカル-SAM) 酵素は,様々な生物学的プロセスに不可欠です.
これらの酵素は,その触媒的活動のために [4Fe-4S] クラスターに依存しています.
[4Fe-4S]クラスターは酸素に非常に敏感で,有酸素生物の酵素機能に問題があることが知られている.

研究の目的:

ラジカル-SAM酵素,特にディフタミド生物合成酵素Dph1-Dph2が,酸素の存在下での活性を維持する方法を調査する.
Dph1-Dph2酵素複合体における鉄硫黄の役割を解明する.
エアロビック環境におけるラジカル-SAM酵素機能の保存のための潜在的なメカニズムを探求する.

主な方法:

イーストのDph1-Dph2酵素複合体を研究した
[4Fe-4S]クラスタの安定性と変換をエアロビック条件下で調査した.
Dph1-Dph2と鉄分提供タンパク質Dph3の相互作用を分析した.

主要な成果:

Dph1-Dph2の [4Fe-4S] クラスタは,酸素の存在で [3Fe-4S] クラスタに分解しやすい.
小さなタンパク質 Dph3 は [3Fe-4S] クラスタに鉄原子を寄付することが判明した.
この鉄の寄付は,分解したクラスタを機能的な [4Fe-4S] クラスタに変換し,その触媒サイクル中にDph1-Dph2の活動を回復します.

結論:

タンパク質Dph3を含む新しいメカニズムは,有酸素条件下で,ラジカル-SAM酵素における機能的な [4Fe-4S]クラスタの維持を可能にします.
この鉄の提供戦略は,酸素豊富な環境で他の急性SAM酵素の活性を維持するための一般的なメカニズムである可能性が高い.
Dph3のようなタンパク質の存在は,有酸素生物における様々な根幹-SAM酵素の機能に不可欠である可能性があります.

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