Journal:Acta Cryst F:S2053230X19002693
From Proteopedia
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<b>Molecular Tour</b><br> | <b>Molecular Tour</b><br> | ||
| - | Phosphoribulokinase (PRK) catalyses the ATP-dependent phosphorylation of ribulose-5-phosphate to ribulose-1,5-bisphosphate. The enzyme accompanies Rubisco in autotrophic organisms and both are unique to the Calvin-Benson-Bassham (CBB) cycle of photosynthesis. Isoforms of PRK can be grouped in three classes, which occur in proteobacteria, archaea and photosynthetic organisms respectively. The crystal structure of PRK from the cyanobacterium ''Synechococcus sp.'' PCC 6301 presents a structural model for PRK from photosynthetic organisms, such as β-cyanobacteria, most green and red eukaryotic algae, and plants | + | Phosphoribulokinase (PRK) catalyses the ATP-dependent phosphorylation of ribulose-5-phosphate to ribulose-1,5-bisphosphate. The enzyme accompanies Rubisco in autotrophic organisms and both are unique to the Calvin-Benson-Bassham (CBB) cycle of photosynthesis. Isoforms of PRK can be grouped in three classes, which occur in proteobacteria, archaea and photosynthetic organisms respectively. The crystal structure of PRK from the cyanobacterium ''Synechococcus sp.'' PCC 6301 presents a structural model for PRK from photosynthetic organisms, such as β-cyanobacteria, most green and red eukaryotic algae, and plants. The enzyme is dimeric and has an alpha/beta-fold with an 18-stranded beta-sheet at its core. |
Regulation of PRK enzyme activity in response to light controls carbon fixation during photosynthesis. This occurs via reversible formation of disulfide bonds during dark inactivation and complex formation with the adaptor protein CP12 and glyceraldehyde-3-phosphate dehydrogenase, another CBB cycle enzyme. Interestingly, we find a disulphide bond between Cys40 and the P-loop residue Cys18 in our crystal structure, revealing the structural basis for redox-inactivation of PRK activity. A second disulphide bond appears to rigidify the dimer interface and may thereby contribute to regulation by the adaptor protein CP12 and glyceraldehyde-3-phosphate dehydrogenase into a supramolecular complex within which both enzymes are inhibited. | Regulation of PRK enzyme activity in response to light controls carbon fixation during photosynthesis. This occurs via reversible formation of disulfide bonds during dark inactivation and complex formation with the adaptor protein CP12 and glyceraldehyde-3-phosphate dehydrogenase, another CBB cycle enzyme. Interestingly, we find a disulphide bond between Cys40 and the P-loop residue Cys18 in our crystal structure, revealing the structural basis for redox-inactivation of PRK activity. A second disulphide bond appears to rigidify the dimer interface and may thereby contribute to regulation by the adaptor protein CP12 and glyceraldehyde-3-phosphate dehydrogenase into a supramolecular complex within which both enzymes are inhibited. | ||
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<scene name='80/809165/Cv/7'>Ribbon representation of Syn6301-PRK in the redox-blocked state</scene>. The Cys18-Cys40 disulphide bond is represented by yellow stick. Secondary structure elements are indicated. The red pointer indicates the Walker A motif (P-loop). | <scene name='80/809165/Cv/7'>Ribbon representation of Syn6301-PRK in the redox-blocked state</scene>. The Cys18-Cys40 disulphide bond is represented by yellow stick. Secondary structure elements are indicated. The red pointer indicates the Walker A motif (P-loop). | ||
| - | <scene name='80/809165/Cv/8'>Ribbon representation of MhPRK</scene> (PDB entry | + | <scene name='80/809165/Cv/8'>Ribbon representation of MhPRK</scene> (PDB entry [[5b3f]]; (Kono et al., 2017<ref>PMID:28082747</ref>)) in the apo state. The same view as in the previous scene. The red pointer indicates the Walker A motif (P-loop). |
<b>References</b><br> | <b>References</b><br> | ||
Revision as of 12:19, 26 February 2019
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