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- PDB-9bp5: Structure of electron bifurcating Nfn-ABC holoenzyme from Caldice... -
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Open data
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Basic information
Entry | Database: PDB / ID: 9bp5 | |||||||||||||||
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Title | Structure of electron bifurcating Nfn-ABC holoenzyme from Caldicellulosiruptor saccharolyticus | |||||||||||||||
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![]() | OXIDOREDUCTASE / Electron bifurcating enzyme / Nfn-type BfuABC complex / FMN/B1/C1 bifurcation site | |||||||||||||||
Function / homology | ![]() NADH dehydrogenase (quinone) / 2 iron, 2 sulfur cluster binding / 4 iron, 4 sulfur cluster binding / oxidoreductase activity / metal ion binding Similarity search - Function | |||||||||||||||
Biological species | ![]() ![]() | |||||||||||||||
Method | ELECTRON MICROSCOPY / single particle reconstruction / cryo EM / Resolution: 2.7 Å | |||||||||||||||
![]() | Li, H. / Li, H. | |||||||||||||||
Funding support | ![]()
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![]() | ![]() Title: 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. | |||||||||||||||
History |
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Structure visualization
Structure viewer | Molecule: ![]() ![]() |
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Downloads & links
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PDBx/mmCIF format | ![]() | 1.4 MB | Display | ![]() |
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PDB format | ![]() | 1.2 MB | Display | ![]() |
PDBx/mmJSON format | ![]() | Tree view | ![]() | |
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-Validation report
Arichive directory | ![]() ![]() | HTTPS FTP |
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-Related structure data
Related structure data | ![]() 44761MC ![]() 9bovC C: citing same article ( M: map data used to model this data |
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Similar structure data | Similarity search - Function & homology ![]() |
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Links
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Assembly
Deposited unit | ![]()
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Components
-Protein , 1 types, 4 molecules ADGJ
#1: Protein | Mass: 130025.906 Da / Num. of mol.: 4 Source method: isolated from a genetically manipulated source Source: (gene. exp.) ![]() ![]() Gene: Csac_0621 / Production host: ![]() |
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-NADH dehydrogenase ... , 2 types, 8 molecules BEHKCFIL
#2: Protein | Mass: 63533.527 Da / Num. of mol.: 4 Source method: isolated from a genetically manipulated source Source: (gene. exp.) ![]() ![]() Gene: Csac_0620 / Production host: ![]() #3: Protein | Mass: 19914.066 Da / Num. of mol.: 4 Source method: isolated from a genetically manipulated source Source: (gene. exp.) ![]() ![]() Gene: Csac_0619 / Production host: ![]() |
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-Non-polymers , 5 types, 60 molecules 








#4: Chemical | ChemComp-FES / #5: Chemical | ChemComp-SF4 / #6: Chemical | ChemComp-FAD / #7: Chemical | ChemComp-FMN / #8: Chemical | ChemComp-ZN / |
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-Details
Has ligand of interest | Y |
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Has protein modification | N |
-Experimental details
-Experiment
Experiment | Method: ELECTRON MICROSCOPY |
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EM experiment | Aggregation state: PARTICLE / 3D reconstruction method: single particle reconstruction |
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Sample preparation
Component | Name: Csac Nfn-ABC complex / Type: COMPLEX / Entity ID: #1-#3 / Source: NATURAL | ||||||||||||||||||||
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Molecular weight | Value: 0.76 MDa / Experimental value: YES | ||||||||||||||||||||
Source (natural) | Organism: ![]() ![]() | ||||||||||||||||||||
Buffer solution | pH: 7.5 | ||||||||||||||||||||
Buffer component |
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Specimen | Embedding applied: NO / Shadowing applied: NO / Staining applied: NO / Vitrification applied: YES | ||||||||||||||||||||
Specimen support | Grid material: COPPER / Grid mesh size: 300 divisions/in. / Grid type: Quantifoil R2/1 | ||||||||||||||||||||
Vitrification | Instrument: FEI VITROBOT MARK IV / Cryogen name: ETHANE / Humidity: 100 % / Chamber temperature: 302 K |
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Electron microscopy imaging
Experimental equipment | ![]() Model: Titan Krios / Image courtesy: FEI Company |
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Microscopy | Model: FEI TITAN KRIOS |
Electron gun | Electron source: ![]() |
Electron lens | Mode: BRIGHT FIELD / Nominal magnification: 105000 X / Nominal defocus max: 1600 nm / Nominal defocus min: 1000 nm / Cs: 2.7 mm / C2 aperture diameter: 70 µm / Alignment procedure: COMA FREE |
Specimen holder | Cryogen: NITROGEN / Specimen holder model: FEI TITAN KRIOS AUTOGRID HOLDER / Temperature (max): 193 K / Temperature (min): 193 K / Residual tilt: 0.05 mradians |
Image recording | Average exposure time: 1 sec. / Electron dose: 60 e/Å2 / Film or detector model: GATAN K3 (6k x 4k) / Num. of grids imaged: 1 / Num. of real images: 7290 |
Image scans | Width: 5760 / Height: 4092 |
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Processing
EM software | Name: PHENIX / Version: 1.21rc1_4903: / Category: model refinement | ||||||||||||||||||||||||
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CTF correction | Type: PHASE FLIPPING AND AMPLITUDE CORRECTION | ||||||||||||||||||||||||
Particle selection | Num. of particles selected: 279815 | ||||||||||||||||||||||||
Symmetry | Point symmetry: D2 (2x2 fold dihedral) | ||||||||||||||||||||||||
3D reconstruction | Resolution: 2.7 Å / Resolution method: FSC 0.143 CUT-OFF / Num. of particles: 108700 / Symmetry type: POINT | ||||||||||||||||||||||||
Refine LS restraints |
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