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- PDB-6smh: Cryo-electron microscopy structure of a RbcL-Raf1 supercomplex fr... -
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Basic information
Entry | Database: PDB / ID: 6smh | |||||||||||||||
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Title | Cryo-electron microscopy structure of a RbcL-Raf1 supercomplex from Synechococcus elongatus PCC 7942 | |||||||||||||||
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![]() | PHOTOSYNTHESIS / Rubisco / Rubisco accumulation factor1 / Raf1 / Synechococcus elongatus 7942 / Cyanobacteria | |||||||||||||||
Function / homology | ![]() ribulose bisphosphate carboxylase complex assembly / carboxysome / photorespiration / ribulose-bisphosphate carboxylase / carbon fixation / ribulose-bisphosphate carboxylase activity / reductive pentose-phosphate cycle / photosynthesis / monooxygenase activity / magnesium ion binding / cytoplasm Similarity search - Function | |||||||||||||||
Biological species | ![]() | |||||||||||||||
Method | ELECTRON MICROSCOPY / single particle reconstruction / cryo EM / Resolution: 4.3 Å | |||||||||||||||
![]() | Huang, F. / Kong, W.-W. / Sun, Y. / Chen, T. / Dykes, G.F. / Jiang, Y.L. / Liu, L.N. | |||||||||||||||
Funding support | ![]()
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![]() | ![]() Title: Rubisco accumulation factor 1 (Raf1) plays essential roles in mediating Rubisco assembly and carboxysome biogenesis. Authors: Fang Huang / Wen-Wen Kong / Yaqi Sun / Taiyu Chen / Gregory F Dykes / Yong-Liang Jiang / Lu-Ning Liu / ![]() ![]() Abstract: Carboxysomes are membrane-free organelles for carbon assimilation in cyanobacteria. The carboxysome consists of a proteinaceous shell that structurally resembles virus capsids and internal enzymes ...Carboxysomes are membrane-free organelles for carbon assimilation in cyanobacteria. The carboxysome consists of a proteinaceous shell that structurally resembles virus capsids and internal enzymes including ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco), the primary carbon-fixing enzyme in photosynthesis. The formation of carboxysomes requires hierarchical self-assembly of thousands of protein subunits, initiated from Rubisco assembly and packaging to shell encapsulation. Here we study the role of Rubisco assembly factor 1 (Raf1) in Rubisco assembly and carboxysome formation in a model cyanobacterium, PCC7942 (Syn7942). Cryo-electron microscopy reveals that Raf1 facilitates Rubisco assembly by mediating RbcL dimer formation and dimer-dimer interactions. Syn7942 cells lacking Raf1 are unable to form canonical intact carboxysomes but generate a large number of intermediate assemblies comprising Rubisco, CcaA, CcmM, and CcmN without shell encapsulation and a low abundance of carboxysome-like structures with reduced dimensions and irregular shell shapes and internal organization. As a consequence, the Raf1-depleted cells exhibit reduced Rubisco content, CO-fixing activity, and cell growth. Our results provide mechanistic insight into the chaperone-assisted Rubisco assembly and biogenesis of carboxysomes. Advanced understanding of the biogenesis and stepwise formation process of the biogeochemically important organelle may inform strategies for heterologous engineering of functional CO-fixing modules to improve photosynthesis. | |||||||||||||||
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Structure visualization
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Structure viewer | Molecule: ![]() ![]() |
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PDBx/mmCIF format | ![]() | 849.2 KB | Display | ![]() |
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PDB format | ![]() | 711.8 KB | Display | ![]() |
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-Validation report
Arichive directory | ![]() ![]() | HTTPS FTP |
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-Related structure data
Related structure data | ![]() 10235MC 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
#1: Protein | Mass: 49641.219 Da / Num. of mol.: 8 Source method: isolated from a genetically manipulated source Source: (gene. exp.) ![]() Gene: cbbL, rbcL, Synpcc7942_1426 / Production host: ![]() ![]() References: UniProt: Q31NB3, ribulose-bisphosphate carboxylase #2: Protein | Mass: 21676.561 Da / Num. of mol.: 8 Source method: isolated from a genetically manipulated source Source: (gene. exp.) ![]() Gene: Synpcc7942_0833 / Production host: ![]() ![]() |
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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: RbcL-Raf1 supercomplex of Synechococcus elongatus 7942 Type: COMPLEX / Entity ID: all / Source: RECOMBINANT |
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Source (natural) | Organism: ![]() |
Source (recombinant) | Organism: ![]() ![]() |
Buffer solution | pH: 8 |
Specimen | Embedding applied: NO / Shadowing applied: NO / Staining applied: NO / Vitrification applied: YES |
Vitrification | Cryogen name: NITROGEN |
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Electron microscopy imaging
Experimental equipment | ![]() Model: Tecnai F20 / Image courtesy: FEI Company |
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Microscopy | Model: FEI TECNAI F20 |
Electron gun | Electron source: ![]() |
Electron lens | Mode: BRIGHT FIELD |
Image recording | Electron dose: 25 e/Å2 / Detector mode: COUNTING / Film or detector model: GATAN K2 SUMMIT (4k x 4k) |
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Processing
CTF correction | Type: PHASE FLIPPING ONLY |
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3D reconstruction | Resolution: 4.3 Å / Resolution method: FSC 0.143 CUT-OFF / Num. of particles: 16022 / Symmetry type: POINT |