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- PDB-7q55: Single Particle Cryo-EM structure of photosynthetic A8B8 glyceral... -
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Open data
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Basic information
Entry | Database: PDB / ID: 7q55 | ||||||
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Title | Single Particle Cryo-EM structure of photosynthetic A8B8 glyceraldehyde-3-phosphate dehydrogenase hexadecamer (major conformer) from Spinacia oleracia. | ||||||
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![]() | OXIDOREDUCTASE / Photosynthesis / Calvin-Benson cycle / redox regulation | ||||||
Function / homology | ![]() glyceraldehyde-3-phosphate dehydrogenase (NADP+) (phosphorylating) / glyceraldehyde-3-phosphate dehydrogenase (NADP+) (phosphorylating) activity / reductive pentose-phosphate cycle / apoplast / glyceraldehyde-3-phosphate dehydrogenase (NAD+) (phosphorylating) activity / chloroplast / glucose metabolic process / NAD binding / NADP binding Similarity search - Function | ||||||
Biological species | ![]() | ||||||
Method | ELECTRON MICROSCOPY / single particle reconstruction / cryo EM / Resolution: 5.7 Å | ||||||
![]() | Marotta, R. / Fermani, S. / Sparla, F. / Trost, P. / Del Giudice, A. | ||||||
Funding support | ![]()
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![]() | ![]() Title: Unravelling the regulation pathway of photosynthetic AB-GAPDH. Authors: Roberto Marotta / Alessandra Del Giudice / Libero Gurrieri / Silvia Fanti / Paolo Swuec / Luciano Galantini / Giuseppe Falini / Paolo Trost / Simona Fermani / Francesca Sparla / ![]() Abstract: Oxygenic phototrophs perform carbon fixation through the Calvin-Benson cycle. Different mechanisms adjust the cycle and the light-harvesting reactions to rapid environmental changes. Photosynthetic ...Oxygenic phototrophs perform carbon fixation through the Calvin-Benson cycle. Different mechanisms adjust the cycle and the light-harvesting reactions to rapid environmental changes. Photosynthetic glyceraldehyde 3-phosphate dehydrogenase (GAPDH) is a key enzyme in the cycle. In land plants, different photosynthetic GAPDHs exist: the most abundant isoform is formed by AB heterotetramers and the least abundant by A homotetramers. Regardless of the subunit composition, GAPDH is the major consumer of photosynthetic NADPH and its activity is strictly regulated. While A-GAPDH is regulated by CP12, AB-GAPDH is autonomously regulated through the C-terminal extension (CTE) of its B subunits. Reversible inhibition of AB-GAPDH occurs via the oxidation of a cysteine pair located in the CTE and the substitution of NADP(H) with NAD(H) in the cofactor-binding site. These combined conditions lead to a change in the oligomerization state and enzyme inhibition. SEC-SAXS and single-particle cryo-EM analysis were applied to reveal the structural basis of this regulatory mechanism. Both approaches revealed that spinach (AB)-GAPDH oligomers with n = 1, 2, 4 and 5 co-exist in a dynamic system. B subunits mediate the contacts between adjacent tetramers in AB and AB oligomers. The CTE of each B subunit penetrates into the active site of a B subunit of the adjacent tetramer, which in turn moves its CTE in the opposite direction, effectively preventing the binding of the substrate 1,3-bisphosphoglycerate in the B subunits. The whole mechanism is made possible, and eventually controlled, by pyridine nucleotides. In fact, NAD(H), by removing NADP(H) from A subunits, allows the entrance of the CTE into the active site of the B subunit, hence stabilizing inhibited oligomers. | ||||||
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Structure visualization
Structure viewer | Molecule: ![]() ![]() |
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Downloads & links
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PDBx/mmCIF format | ![]() | 945.8 KB | Display | ![]() |
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PDB format | ![]() | 773.2 KB | Display | ![]() |
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-Validation report
Arichive directory | ![]() ![]() | HTTPS FTP |
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-Related structure data
Related structure data | ![]() 13826MC ![]() 7q53C ![]() 7q54C ![]() 7q56C ![]() 7q57C M: map data used to model this data C: citing same article ( |
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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
#1: Protein | Mass: 48183.789 Da / Num. of mol.: 8 / Source method: isolated from a natural source / Source: (natural) ![]() References: UniProt: P12860, glyceraldehyde-3-phosphate dehydrogenase (NADP+) (phosphorylating) #2: Protein | Mass: 43159.098 Da / Num. of mol.: 8 / Source method: isolated from a natural source / Source: (natural) ![]() References: UniProt: P19866, glyceraldehyde-3-phosphate dehydrogenase (NADP+) (phosphorylating) #3: Chemical | ChemComp-NAD / Has ligand of interest | Y | |
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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: A8B8 photosynthetic glyceraldehyde 3-phosphate dehydrogenase hetero-hexdecamer (major conformer) complexed with NAD. Type: COMPLEX / Entity ID: #1-#2 / Source: NATURAL |
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Molecular weight | Experimental value: NO |
Source (natural) | Organism: ![]() |
Buffer solution | pH: 7.4 |
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: C-flat-1.2/1.3 |
Vitrification | Instrument: FEI VITROBOT MARK IV / Cryogen name: ETHANE |
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Electron microscopy imaging
Experimental equipment | ![]() Model: Tecnai Polara / Image courtesy: FEI Company |
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Microscopy | Model: FEI POLARA 300 |
Electron gun | Electron source: ![]() |
Electron lens | Mode: BRIGHT FIELD / Nominal defocus max: 3500 nm / Nominal defocus min: 1500 nm |
Image recording | Electron dose: 42 e/Å2 / Detector mode: COUNTING / Film or detector model: GATAN K2 SUMMIT (4k x 4k) |
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Processing
Software | Name: PHENIX / Version: 1.17.1_3660: / Classification: refinement | ||||||||||||||||||||||||
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CTF correction | Type: PHASE FLIPPING AND AMPLITUDE CORRECTION | ||||||||||||||||||||||||
Symmetry | Point symmetry: C2 (2 fold cyclic) | ||||||||||||||||||||||||
3D reconstruction | Resolution: 5.7 Å / Resolution method: FSC 0.143 CUT-OFF / Num. of particles: 23611 / Symmetry type: POINT | ||||||||||||||||||||||||
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