The enzymes from the plants Zea mays (maize) and Arabidopsis thaliana are bifunctional and catalyse both the phosphorylation and dephosphorylation of EC 2.7.9.1 (pyruvate, phosphate dikinase). cf. EC 2.7.4.27, [pyruvate, phosphate dikinase]-phosphate phosphotransferase [2-5]. The enzyme is specific for a reaction intermediate form of EC 2.7.9.1, and phosphorylates a threonine located adjacent to the catalytic histidine. The phosphorylation only takes place if the histidine is already phosphorylated [3-5].
Regulation of C4 photosynthesis: purification and properties of the protein catalyzing ADP-mediated inactivation and Pi-mediated activation of pyruvate,Pi dikinase.
Chastain CJ, Botschner M, Harrington GE, Thompson BJ, Mills SE, Sarath G, Chollet R
Title
Further analysis of maize C(4) pyruvate,orthophosphate dikinase phosphorylation by its bifunctional regulatory protein using selective substitutions of the regulatory Thr-456 and catalytic His-458 residues.