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Yorodumi- EMDB-44751: Structure of electron bifurcating Nfn-ABC complexed with NAD from... -
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Basic information
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| Title | Structure of electron bifurcating Nfn-ABC complexed with NAD from Caldicellulosiruptor saccharolyticus | |||||||||
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Keywords | Electron bifurcating enzyme / Nfn-type BfuABC complex / FMN/B1/C1 bifurcation site / OXIDOREDUCTASE | |||||||||
| Function / homology | Function and homology informationNADH dehydrogenase (quinone) / 2 iron, 2 sulfur cluster binding / 4 iron, 4 sulfur cluster binding / oxidoreductase activity / metal ion binding Similarity search - Function | |||||||||
| Biological species | ![]() Caldicellulosiruptor saccharolyticus (bacteria) | |||||||||
| Method | single particle reconstruction / cryo EM / Resolution: 3.0 Å | |||||||||
Authors | Li H | |||||||||
| Funding support | United States, 1 items
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Citation | Journal: Commun Biol / Year: 2025Title: Cryo-EM reveals a composite flavobicluster electron bifurcation site in the Bfu family member NfnABC. Authors: Hua Li / Gerrit J Schut / Xiang Feng / Michael W W Adams / Huilin Li / ![]() Abstract: 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. | |||||||||
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Structure visualization
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Downloads & links
-EMDB archive
| Map data | emd_44751.map.gz | 369.3 MB | EMDB map data format | |
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| Header (meta data) | emd-44751-v30.xml emd-44751.xml | 20.6 KB 20.6 KB | Display Display | EMDB header |
| Images | emd_44751.png | 109.5 KB | ||
| Filedesc metadata | emd-44751.cif.gz | 7.6 KB | ||
| Archive directory | http://ftp.pdbj.org/pub/emdb/structures/EMD-44751 ftp://ftp.pdbj.org/pub/emdb/structures/EMD-44751 | HTTPS FTP |
-Validation report
| Summary document | emd_44751_validation.pdf.gz | 511.9 KB | Display | EMDB validaton report |
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| Full document | emd_44751_full_validation.pdf.gz | 511.4 KB | Display | |
| Data in XML | emd_44751_validation.xml.gz | 7.4 KB | Display | |
| Data in CIF | emd_44751_validation.cif.gz | 8.6 KB | Display | |
| Arichive directory | https://ftp.pdbj.org/pub/emdb/validation_reports/EMD-44751 ftp://ftp.pdbj.org/pub/emdb/validation_reports/EMD-44751 | HTTPS FTP |
-Related structure data
| Related structure data | ![]() 9bovMC ![]() 9bp5C C: citing same article ( M: atomic model generated by this map |
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| Similar structure data | Similarity search - Function & homology F&H Search |
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Links
| EMDB pages | EMDB (EBI/PDBe) / EMDataResource |
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| Related items in Molecule of the Month |
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Map
| File | Download / File: emd_44751.map.gz / Format: CCP4 / Size: 421.9 MB / Type: IMAGE STORED AS FLOATING POINT NUMBER (4 BYTES) | ||||||||||||||||||||||||||||||||||||
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| Projections & slices | Image control
Images are generated by Spider. | ||||||||||||||||||||||||||||||||||||
| Voxel size | X=Y=Z: 0.828 Å | ||||||||||||||||||||||||||||||||||||
| Density |
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| Symmetry | Space group: 1 | ||||||||||||||||||||||||||||||||||||
| Details | EMDB XML:
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-Supplemental data
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Sample components
+Entire : Csac Nfn-ABC complex
+Supramolecule #1: Csac Nfn-ABC complex
+Macromolecule #1: Molybdopterin oxidoreductase
+Macromolecule #2: NADH dehydrogenase (Quinone)
+Macromolecule #3: NADH dehydrogenase (Ubiquinone), 24 kDa subunit
+Macromolecule #4: FE2/S2 (INORGANIC) CLUSTER
+Macromolecule #5: IRON/SULFUR CLUSTER
+Macromolecule #6: FLAVIN-ADENINE DINUCLEOTIDE
+Macromolecule #7: FLAVIN MONONUCLEOTIDE
+Macromolecule #8: ZINC ION
+Macromolecule #9: NICOTINAMIDE-ADENINE-DINUCLEOTIDE
-Experimental details
-Structure determination
| Method | cryo EM |
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Processing | single particle reconstruction |
| Aggregation state | particle |
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Sample preparation
| Buffer | pH: 7.5 Component:
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| Grid | Model: Quantifoil R2/1 / Material: COPPER / Mesh: 300 / Support film - Material: CARBON / Support film - topology: HOLEY | ||||||||||||
| Vitrification | Cryogen name: ETHANE / Chamber humidity: 100 % / Chamber temperature: 302 K / Instrument: FEI VITROBOT MARK IV |
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Electron microscopy
| Microscope | FEI TITAN KRIOS |
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| Temperature | Min: 193.0 K / Max: 193.0 K |
| Alignment procedure | Coma free - Residual tilt: 0.05 mrad |
| Image recording | Film or detector model: GATAN K3 (6k x 4k) / Digitization - Dimensions - Width: 5760 pixel / Digitization - Dimensions - Height: 4092 pixel / Number grids imaged: 1 / Number real images: 16457 / Average exposure time: 1.0 sec. / Average electron dose: 60.0 e/Å2 |
| Electron beam | Acceleration voltage: 300 kV / Electron source: FIELD EMISSION GUN |
| Electron optics | C2 aperture diameter: 70.0 µm / Illumination mode: OTHER / Imaging mode: BRIGHT FIELD / Cs: 2.7 mm / Nominal defocus max: 1.6 µm / Nominal defocus min: 1.0 µm / Nominal magnification: 105000 |
| Sample stage | Specimen holder model: FEI TITAN KRIOS AUTOGRID HOLDER / Cooling holder cryogen: NITROGEN |
| Experimental equipment | ![]() Model: Titan Krios / Image courtesy: FEI Company |
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About Yorodumi



Keywords
Caldicellulosiruptor saccharolyticus (bacteria)
Authors
United States, 1 items
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Processing
FIELD EMISSION GUN
