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Open data
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Basic information
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Title | Synechocystis PCC 6803 Phycobilisome core, complex with OCP | |||||||||
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Function / homology | ![]() light absorption / Lyases / phycobilisome / chloride ion binding / plasma membrane-derived thylakoid membrane / photoreceptor activity / photosynthesis / lyase activity Similarity search - Function | |||||||||
Biological species | ![]() ![]() ![]() ![]() | |||||||||
Method | single particle reconstruction / cryo EM / Resolution: 2.6 Å | |||||||||
![]() | Sauer PV / Sutter M / Dominguez-Martin MA / Kirst H / Kerfeld CA | |||||||||
Funding support | European Union, 1 items
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![]() | ![]() Title: Structures of a phycobilisome in light-harvesting and photoprotected states. Authors: María Agustina Domínguez-Martín / Paul V Sauer / Henning Kirst / Markus Sutter / David Bína / Basil J Greber / Eva Nogales / Tomáš Polívka / Cheryl A Kerfeld / ![]() ![]() ![]() Abstract: Phycobilisome (PBS) structures are elaborate antennae in cyanobacteria and red algae. These large protein complexes capture incident sunlight and transfer the energy through a network of embedded ...Phycobilisome (PBS) structures are elaborate antennae in cyanobacteria and red algae. These large protein complexes capture incident sunlight and transfer the energy through a network of embedded pigment molecules called bilins to the photosynthetic reaction centres. However, light harvesting must also be balanced against the risks of photodamage. A known mode of photoprotection is mediated by orange carotenoid protein (OCP), which binds to PBS when light intensities are high to mediate photoprotective, non-photochemical quenching. Here we use cryogenic electron microscopy to solve four structures of the 6.2 MDa PBS, with and without OCP bound, from the model cyanobacterium Synechocystis sp. PCC 6803. The structures contain a previously undescribed linker protein that binds to the membrane-facing side of PBS. For the unquenched PBS, the structures also reveal three different conformational states of the antenna, two previously unknown. The conformational states result from positional switching of two of the rods and may constitute a new mode of regulation of light harvesting. Only one of the three PBS conformations can bind to OCP, which suggests that not every PBS is equally susceptible to non-photochemical quenching. In the OCP-PBS complex, quenching is achieved through the binding of four 34 kDa OCPs organized as two dimers. The complex reveals the structure of the active form of OCP, in which an approximately 60 Å displacement of its regulatory carboxy terminal domain occurs. Finally, by combining our structure with spectroscopic properties, we elucidate energy transfer pathways within PBS in both the quenched and light-harvesting states. Collectively, our results provide detailed insights into the biophysical underpinnings of the control of cyanobacterial light harvesting. The data also have implications for bioengineering PBS regulation in natural and artificial light-harvesting systems. | |||||||||
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Structure visualization
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Downloads & links
-EMDB archive
Map data | ![]() | 86.9 MB | ![]() | |
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Header (meta data) | ![]() ![]() | 27 KB 27 KB | Display Display | ![]() |
Images | ![]() | 90.7 KB | ||
Masks | ![]() | 178 MB | ![]() | |
Others | ![]() ![]() | 164.5 MB 164.5 MB | ||
Archive directory | ![]() ![]() | HTTPS FTP |
-Related structure data
Related structure data | ![]() 7sc9MC ![]() 7sc7C ![]() 7sc8C ![]() 7scaC ![]() 7scbC ![]() 7sccC C: citing same article ( M: atomic model generated by this map |
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Similar structure data | Similarity search - Function & homology ![]() |
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Links
EMDB pages | ![]() ![]() |
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Related items in Molecule of the Month |
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Map
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Voxel size | X=Y=Z: 1.05 Å | ||||||||||||||||||||
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Symmetry | Space group: 1 | ||||||||||||||||||||
Details | EMDB XML:
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-Supplemental data
-Mask #1
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Sample components
+Entire : Complex of phycobilisome from Synechocystis PCC 6803 with OCP
+Supramolecule #1: Complex of phycobilisome from Synechocystis PCC 6803 with OCP
+Macromolecule #1: Allophycocyanin alpha chain
+Macromolecule #2: Allophycocyanin beta chain
+Macromolecule #3: Allophycocyanin subunit alpha-B
+Macromolecule #4: Allophycocyanin subunit beta-18
+Macromolecule #5: Phycobilisome 7.8 kDa linker polypeptide, allophycocyanin-associa...
+Macromolecule #6: Phycobiliprotein ApcE
+Macromolecule #7: Sll1873 protein
+Macromolecule #8: Phycobilisome rod-core linker polypeptide CpcG
+Macromolecule #9: Orange carotenoid-binding protein
+Macromolecule #10: PHYCOCYANOBILIN
+Macromolecule #11: beta,beta-carotene-4,4'-dione
-Experimental details
-Structure determination
Method | cryo EM |
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![]() | single particle reconstruction |
Aggregation state | particle |
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Sample preparation
Concentration | 3.8 mg/mL |
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Buffer | pH: 7.5 |
Grid | Model: Quantifoil R2/1 / Material: COPPER / Mesh: 300 / Support film - Material: GOLD / Support film - topology: HOLEY / Details: Grids were coated with streptavidin prior to use. |
Vitrification | Cryogen name: ETHANE-PROPANE / Instrument: FEI VITROBOT MARK IV / Details: Manual blotting. |
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Electron microscopy
Microscope | TFS KRIOS |
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Image recording | Film or detector model: GATAN K3 (6k x 4k) / Average electron dose: 50.0 e/Å2 |
Electron beam | Acceleration voltage: 300 kV / Electron source: ![]() |
Electron optics | Illumination mode: OTHER / Imaging mode: BRIGHT FIELD / Nominal defocus max: 1.6 µm / Nominal defocus min: 0.5 µm |
Sample stage | Cooling holder cryogen: NITROGEN |
Experimental equipment | ![]() Model: Titan Krios / Image courtesy: FEI Company |
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Image processing
-Atomic model buiding 1
Refinement | Space: REAL / Protocol: BACKBONE TRACE |
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Output model | ![]() PDB-7sc9: |