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- PDB-6rqf: 3.6 Angstrom cryo-EM structure of the dimeric cytochrome b6f comp... -
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Basic information
Entry | Database: PDB / ID: 6rqf | ||||||||||||
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Title | 3.6 Angstrom cryo-EM structure of the dimeric cytochrome b6f complex from Spinacia oleracea with natively bound thylakoid lipids and plastoquinone molecules | ||||||||||||
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![]() | PHOTOSYNTHESIS / Plastoquinol-plastocyanin oxido-reductase Cytochrome b6f Photosynthesis Electron transport | ||||||||||||
Function / homology | ![]() plastoquinol--plastocyanin reductase activity / cytochrome b6f complex / plastoquinol-plastocyanin reductase / electron transporter, transferring electrons within cytochrome b6/f complex of photosystem II activity / cytochrome complex assembly / : / : / photosynthetic electron transport chain / ubiquinol-cytochrome-c reductase activity / mitochondrial electron transport, ubiquinol to cytochrome c ...plastoquinol--plastocyanin reductase activity / cytochrome b6f complex / plastoquinol-plastocyanin reductase / electron transporter, transferring electrons within cytochrome b6/f complex of photosystem II activity / cytochrome complex assembly / : / : / photosynthetic electron transport chain / ubiquinol-cytochrome-c reductase activity / mitochondrial electron transport, ubiquinol to cytochrome c / electron transporter, transferring electrons within the cyclic electron transport pathway of photosynthesis activity / chloroplast thylakoid membrane / photosynthesis / 2 iron, 2 sulfur cluster binding / membrane => GO:0016020 / electron transfer activity / iron ion binding / heme binding / metal ion binding / plasma membrane Similarity search - Function | ||||||||||||
Biological species | ![]() | ||||||||||||
Method | ELECTRON MICROSCOPY / single particle reconstruction / cryo EM / Resolution: 3.58 Å | ||||||||||||
![]() | Malone, L.A. / Qian, P. / Mayneord, G.E. / Hitchcock, A. / Farmer, D. / Thompson, R. / Swainsbury, D.J.K. / Ranson, N. / Hunter, C.N. / Johnson, M.P. | ||||||||||||
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![]() | ![]() Title: Cryo-EM structure of the spinach cytochrome bf complex at 3.6 Å resolution. Authors: Lorna A Malone / Pu Qian / Guy E Mayneord / Andrew Hitchcock / David A Farmer / Rebecca F Thompson / David J K Swainsbury / Neil A Ranson / C Neil Hunter / Matthew P Johnson / ![]() Abstract: The cytochrome b f (cytb f ) complex has a central role in oxygenic photosynthesis, linking electron transfer between photosystems I and II and converting solar energy into a transmembrane ...The cytochrome b f (cytb f ) complex has a central role in oxygenic photosynthesis, linking electron transfer between photosystems I and II and converting solar energy into a transmembrane proton gradient for ATP synthesis. Electron transfer within cytb f occurs via the quinol (Q) cycle, which catalyses the oxidation of plastoquinol (PQH) and the reduction of both plastocyanin (PC) and plastoquinone (PQ) at two separate sites via electron bifurcation. In higher plants, cytb f also acts as a redox-sensing hub, pivotal to the regulation of light harvesting and cyclic electron transfer that protect against metabolic and environmental stresses. Here we present a 3.6 Å resolution cryo-electron microscopy (cryo-EM) structure of the dimeric cytb f complex from spinach, which reveals the structural basis for operation of the Q cycle and its redox-sensing function. The complex contains up to three natively bound PQ molecules. The first, PQ1, is located in one cytb f monomer near the PQ oxidation site (Q) adjacent to haem b and chlorophyll a. Two conformations of the chlorophyll a phytyl tail were resolved, one that prevents access to the Q site and another that permits it, supporting a gating function for the chlorophyll a involved in redox sensing. PQ2 straddles the intermonomer cavity, partially obstructing the PQ reduction site (Q) on the PQ1 side and committing the electron transfer network to turnover at the occupied Q site in the neighbouring monomer. A conformational switch involving the haem c propionate promotes two-electron, two-proton reduction at the Q site and avoids formation of the reactive intermediate semiquinone. The location of a tentatively assigned third PQ molecule is consistent with a transition between the Q and Q sites in opposite monomers during the Q cycle. The spinach cytb f structure therefore provides new insights into how the complex fulfils its catalytic and regulatory roles in photosynthesis. | ||||||||||||
History |
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Structure visualization
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Structure viewer | Molecule: ![]() ![]() |
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PDBx/mmCIF format | ![]() | 363.1 KB | Display | ![]() |
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PDB format | ![]() | 310.9 KB | Display | ![]() |
PDBx/mmJSON format | ![]() | Tree view | ![]() | |
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-Validation report
Summary document | ![]() | 2.7 MB | Display | ![]() |
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Full document | ![]() | 2.8 MB | Display | |
Data in XML | ![]() | 85.4 KB | Display | |
Data in CIF | ![]() | 115.8 KB | Display | |
Arichive directory | ![]() ![]() | HTTPS FTP |
-Related structure data
Related structure data | ![]() 4981MC M: map data used to model this data C: citing same article ( |
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Similar structure data |
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Links
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Assembly
Deposited unit | ![]()
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Components
-Protein , 3 types, 6 molecules IAKCLD
#1: Protein | Mass: 24186.504 Da / Num. of mol.: 2 / Source method: isolated from a natural source / Source: (natural) ![]() #3: Protein | Mass: 31357.020 Da / Num. of mol.: 2 / Source method: isolated from a natural source / Source: (natural) ![]() #4: Protein | Mass: 18956.480 Da / Num. of mol.: 2 / Source method: isolated from a natural source / Source: (natural) ![]() References: UniProt: P08980, plastoquinol-plastocyanin reductase |
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-Cytochrome b6-f complex subunit ... , 5 types, 10 molecules JBMENFOGPH
#2: Protein | Mass: 17456.662 Da / Num. of mol.: 2 / Source method: isolated from a natural source / Source: (natural) ![]() #5: Protein/peptide | Mass: 3452.200 Da / Num. of mol.: 2 / Source method: isolated from a natural source / Source: (natural) ![]() #6: Protein/peptide | Mass: 3774.431 Da / Num. of mol.: 2 / Source method: isolated from a natural source / Source: (natural) ![]() #7: Protein/peptide | Mass: 4171.985 Da / Num. of mol.: 2 / Source method: isolated from a natural source / Source: (natural) ![]() #8: Protein/peptide | Mass: 3170.809 Da / Num. of mol.: 2 / Source method: isolated from a natural source / Source: (natural) ![]() |
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-Non-polymers , 10 types, 29 molecules ![](data/chem/img/HEM.gif)
![](data/chem/img/HEC.gif)
![](data/chem/img/CLA.gif)
![](data/chem/img/BCR.gif)
![](data/chem/img/PL9.gif)
![](data/chem/img/6PL.gif)
![](data/chem/img/LMG.gif)
![](data/chem/img/PGV.gif)
![](data/chem/img/FES.gif)
![](data/chem/img/SQD.gif)
![](data/chem/img/HEC.gif)
![](data/chem/img/CLA.gif)
![](data/chem/img/BCR.gif)
![](data/chem/img/PL9.gif)
![](data/chem/img/6PL.gif)
![](data/chem/img/LMG.gif)
![](data/chem/img/PGV.gif)
![](data/chem/img/FES.gif)
![](data/chem/img/SQD.gif)
#9: Chemical | ChemComp-HEM / #10: Chemical | ChemComp-HEC / #11: Chemical | #12: Chemical | #13: Chemical | #14: Chemical | #15: Chemical | #16: Chemical | ChemComp-PGV / ( #17: Chemical | #18: Chemical | |
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-Details
Has ligand of interest | N |
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-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: Spinach Cytochrome b6f complex with native bound plastoquinone and thylakoid lipids Type: COMPLEX / Entity ID: #1-#8 / Source: NATURAL |
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Source (natural) | Organism: ![]() |
Buffer solution | pH: 8 |
Specimen | Embedding applied: NO / Shadowing applied: NO / Staining applied: NO / Vitrification applied: YES |
Specimen support | Grid material: COPPER / Grid mesh size: 400 divisions/in. / Grid type: Quantifoil R1.2/1.3 |
Vitrification | Instrument: LEICA EM GP / Cryogen name: ETHANE / Humidity: 90 % / Chamber temperature: 281 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: 130000 X / Nominal defocus max: 2500 nm / Nominal defocus min: 1500 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 |
Image recording | Electron dose: 1.15 e/Å2 / Detector mode: COUNTING / Film or detector model: GATAN K2 SUMMIT (4k x 4k) |
EM imaging optics | Energyfilter name: GIF Bioquantum / Energyfilter slit width: 20 eV |
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Processing
Software | Name: PHENIX / Version: (1.14_3260: phenix.real_space_refine) / Classification: refinement | ||||||||||||||||||||||||
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EM software |
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CTF correction | Type: PHASE FLIPPING AND AMPLITUDE CORRECTION | ||||||||||||||||||||||||
Particle selection | Num. of particles selected: 422660 | ||||||||||||||||||||||||
Symmetry | Point symmetry: C1 (asymmetric) | ||||||||||||||||||||||||
3D reconstruction | Resolution: 3.58 Å / Resolution method: FSC 0.143 CUT-OFF / Num. of particles: 108560 / Symmetry type: POINT |