| Primary Identifier | IPR010121 | Type | Family |
| Short Name | Pyruvate_phosphate_dikinase |
| description | Pyruvate phosphate dikinase (PPDK, or pyruvate orthophosphate dikinase) is found in plants, bacteria and archaea. The amino acid sequence identity between bacterial and plant enzymes is high, and they are similar in sequence to other PEP-utilizing enzymes. PPDK catalyses the reversible conversion of ATP and pyruvate to AMP and PEP (phosphoenolpyruvate). In bacteria such as Clostridium symbiosum (Bacteroides symbiosus), PPDK uses Mg2+ and NH4+ ions as cofactors []. The enzyme has three domains: the N- and C-terminal domains each have an active site centre that catalyses a different step in the reaction, and the middle domain has a carrier histidine residue that moves between the two active centres.In plants, PPDK is localised predominantly in chloroplast stroma where it catalyses the rate-limiting step in the C4 photosynthetic pathway, namely the synthesis of PEP, which acts as the primary CO2 acceptor in C4 photosynthesis []. PPDK activity in C4 plants is strictly regulated by light, its activity decreasing in darkness. This response is regulated by phosphorylation and dephosphorylation of the enzyme using ADP; such regulation is not seen in the bacterial form of the enzyme. PPDK is also found in C3 plants, but it is not known to have a photosynthetic role []. |
