Structural basis of light-induced redox regulation in the Calvin–Benson cycle in cyanobacteria
| Autor: | Charles A. R. Cotton, Doryen Bubeck, Burak V. Kabasakal, Blanca Echeverria, Ciaran McFarlane, James W. Murray, Nita R. Shah |
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| Rok vydání: | 2019 |
| Předmět: |
MECHANISM
0106 biological sciences Light INTRINSICALLY DISORDERED PROTEIN carbon fixation Thermosynechococcus Calvin–Benson cycle SUPRAMOLECULAR COMPLEX Biochemistry 01 natural sciences PHOSPHORIBULOKINASE chemistry.chemical_compound Light-independent reactions Ternary complex Glyceraldehyde 3-phosphate dehydrogenase 0303 health sciences Multidisciplinary biology Phosphoribulokinase Calvin-Benson cycle CP12 Carbon fixation CHLOROPLAST food and beverages Glyceraldehyde-3-Phosphate Dehydrogenases Biological Sciences Multidisciplinary Sciences Phosphotransferases (Alcohol Group Acceptor) Science & Technology - Other Topics Oxidation-Reduction Protein Binding EXPRESSION Ribulose-Bisphosphate Carboxylase Cyanobacteria Photosynthesis Glyceraldehyde 3-Phosphate CHLAMYDOMONAS-REINHARDTII redox regulation 03 medical and health sciences Bacterial Proteins stomatognathic system GLYCERALDEHYDE-3-PHOSPHATE DEHYDROGENASE 030304 developmental biology Science & Technology photosynthesis RuBisCO chemistry RESIDUES biology.protein Glyceraldehyde 3-phosphate NADP 010606 plant biology & botany |
| Zdroj: | Proceedings of the National Academy of Sciences of the United States of America |
| ISSN: | 1091-6490 0027-8424 |
| DOI: | 10.1073/pnas.1906722116 |
| Popis: | Significance The Calvin–Benson (CB) cycle in plants, algae, and cyanobacteria fixes most of the carbon in most of the biomass on Earth. The CB cycle is regulated by the redox state, which enables it to be turned off in the dark. One part of this regulatory system is the small protein CP12, which binds to 2 essential CB-cycle enzymes in the dark, inactivating them. We have solved the structure of the complex between CP12 and the enzymes, explaining the mechanism of deactivation. Now that this is understood, this structure can be used as the starting point for modulating the redox regulation, which may have applications in improving crop productivity. Plants, algae, and cyanobacteria fix carbon dioxide to organic carbon with the Calvin–Benson (CB) cycle. Phosphoribulokinase (PRK) and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) are essential CB-cycle enzymes that control substrate availability for the carboxylation enzyme Rubisco. PRK consumes ATP to produce the Rubisco substrate ribulose bisphosphate (RuBP). GAPDH catalyzes the reduction step of the CB cycle with NADPH to produce the sugar glyceraldehyde 3-phosphate (GAP), which is used for regeneration of RuBP and is the main exit point of the cycle. GAPDH and PRK are coregulated by the redox state of a conditionally disordered protein CP12, which forms a ternary complex with both enzymes. However, the structural basis of CB-cycle regulation by CP12 is unknown. Here, we show how CP12 modulates the activity of both GAPDH and PRK. Using thermophilic cyanobacterial homologs, we solve crystal structures of GAPDH with different cofactors and CP12 bound, and the ternary GAPDH-CP12-PRK complex by electron cryo-microscopy, we reveal that formation of the N-terminal disulfide preorders CP12 prior to binding the PRK active site, which is resolved in complex with CP12. We find that CP12 binding to GAPDH influences substrate accessibility of all GAPDH active sites in the binary and ternary inhibited complexes. Our structural and biochemical data explain how CP12 integrates responses from both redox state and nicotinamide dinucleotide availability to regulate carbon fixation. |
| Databáze: | OpenAIRE |
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