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-Structure paper
| タイトル | Cryo-EM reveals a composite flavobicluster electron bifurcation site in the Bfu family member NfnABC. |
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| ジャーナル・号・ページ | Commun Biol, Vol. 8, Issue 1, Page 239, Year 2025 |
| 掲載日 | 2025年2月14日 |
著者 | Hua Li / Gerrit J Schut / Xiang Feng / Michael W W Adams / Huilin Li / ![]() |
| PubMed 要旨 | The BfuABC family is a diverse group of electron bifurcating enzymes that play key roles in anaerobic microbial metabolism. Previous studies have focused almost exclusively on the BfuABC-type ...The BfuABC family is a diverse group of electron bifurcating enzymes that play key roles in anaerobic microbial metabolism. Previous studies have focused almost exclusively on the BfuABC-type hydrogenases but the mechanism and site of electron bifurcation remain unknown. Herein we focus on the Caldicellulosiruptor saccharolyticus (Csac) NfnABC-type Bfu enzyme that catalyzes the oxidation of NADPH and simultaneous reduction of NAD and the redox protein ferredoxin (Fd). Cryo-EM structures determined with and without NAD and Fd reveal seven FeS clusters and one FAD in NfnA, one FeS cluster in NfnC, and three FeS clusters, two Zn ions, and one FMN in NfnB. The Zn ions take the place of FeS clusters previously proposed in other Bfu family members. Csac Nfn for the first time defines the minimum bifurcation site as a flavobicluster consisting of FMN, a [4Fe-4S] (B1) cluster and a [2Fe-2S] (C1) cluster. Binding of NAD to the FMN triggers a series of conformational changes, crucial to the bifurcation of two electron pairs derived from NADPH by the [B1-FMN-C1] flavobicluster into low and high potential electrons that reduce Fd and NAD, respectively. The structures lay the foundation for investigations of the proposed reaction cycle common to all Bfu enzymes. |
リンク | Commun Biol / PubMed:39953182 / PubMed Central |
| 手法 | EM (単粒子) |
| 解像度 | 2.7 - 3.3 Å |
| 構造データ | ![]() EMDB-44749: The consensus EM map of electron bifurcating Nfn-ABC holoenzyme from Caldicellulosiruptor saccharolyticus ![]() EMDB-44750: The focused refined map of the NfnBC subunits of electron bifurcating Nfn-ABC holoenzyme from Caldicellulosiruptor saccharolyticus EMDB-44751, PDB-9bov: ![]() EMDB-44752: The consensus EM map of electron bifurcating Nfn-ABC complexed with NAD from Caldicellulosiruptor saccharolyticus ![]() EMDB-44753: The focused refined map of NfnBC subunits of Csac Nfn-ABC complexed with NAD from Caldicellulosiruptor saccharolyticus EMDB-44761, PDB-9bp5: |
| 化合物 | ![]() ChemComp-FES: ![]() ChemComp-SF4: ![]() ChemComp-FAD: ![]() ChemComp-FMN: ![]() ChemComp-ZN: ![]() ChemComp-NAD: |
| 由来 |
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キーワード | OXIDOREDUCTASE / Electron bifurcating enzyme / Nfn-type BfuABC complex / FMN/B1/C1 bifurcation site |
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caldicellulosiruptor saccharolyticus (バクテリア)
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