
低電位フェレドキシンにおいて、[4Fe-4S]クラスター近傍のアスパラギン酸残基の側鎖のプロトン化状態が、還元状態の安定性に影響を与え、酸化還元電位を制御する重要な役割を果たしている。


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Ferredoxin is a small iron-sulfur protein and acts as an electron carrier. Low-potential ferredoxins harbor [4Fe-4S] cluster(s), which play(s) a crucial role as the redox center. Low-potential ferredoxins are able to cover a wide range of redox potentials (−700 to −200 mV); however, the mechanisms underlying the factors which control the redox potential are still enigmatic. Here, we determined the neutron structure of ferredoxin from Bacillus thermoproteolyticus , and experimentally revealed the exact hydrogen-bonding network involving the [4Fe-4S] cluster. The density functional theory calculations based on the hydrogen-bonding network revealed that protonation states of the sidechain of Asp64 close to the [4Fe-4S] cluster critically affected the stability of the reduced state in the cluster. These findings provide the first identification of the intrinsic control factor of redox potential for the [4Fe-4S] cluster in low-potential ferredoxins.

### Competing Interest Statement

The authors have declared no competing interest.

Protonation/deprotonation-driven switch for the redox stability of low-potential [4Fe-4S] ferredoxin

低電位フェレドキシンにおける酸化還元安定性のプロトン化-脱プロトン化駆動スイッチ


低電位フェレドキシンにおける酸化還元安定性のプロトン化/脱プロトン化駆動スイッチ
