The enzyme phosphorylates granular starch that has previously been phosphorylated by EC 2.7.9.4, alpha-glucan, water dikinase; there is no activity with unphosphorylated glucans. It transfers the beta-phosphate of ATP to the phosphoglucan, whereas the gamma-phosphate is transferred to water . In contrast to EC 2.7.9.4, which phosphorylates glucose groups in glucans on O-6, this enzyme phosphorylates glucose groups in phosphorylated starch on O-3 . The protein phosphorylates itself with the beta-phosphate of ATP, which is then transferred to the glucan .
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SYSTEMATIC NAME
IUBMB Comments
ATP:phospho-alpha-glucan, water phosphotransferase
The enzyme phosphorylates granular starch that has previously been phosphorylated by EC 2.7.9.4, alpha-glucan, water dikinase; there is no activity with unphosphorylated glucans. It transfers the beta-phosphate of ATP to the phosphoglucan, whereas the gamma-phosphate is transferred to water [1]. In contrast to EC 2.7.9.4, which phosphorylates glucose groups in glucans on O-6, this enzyme phosphorylates glucose groups in phosphorylated starch on O-3 [2]. The protein phosphorylates itself with the beta-phosphate of ATP, which is then transferred to the glucan [1].
crystalline maltodextrin (MDcryst) is used as a model substrate for glucan phosphorylating enzyme activity that mimics features of native starches, such as allomorph and crystallinity but omitted branching. Significant phosphorylation of MDcryst by PWD requires the preceding action of GWD. GWD-dependent phosphorylation alters the granule surface structure, which favors the action of PWD
dikinases use ATP as a dual phosphate donor and transfer the beta- and gamma-phosphate groups to two distinct acceptor molecules, a glucan and water. A conserved histidine residue within this domain is capable of accepting the beta-phosphate group of ATP following nucleotide binding and hydrolysis. The phosphoramidate bond is acid labile, but rather stable under alkaline conditions. The gamma-phosphate group is transferred to water
GWD phosphorylates the hydroxyl group at carbon atom 3, the gamma-phosphate group of ATP is transferred to water and the beta-phosphate group to an autocatalytical histidine residue via a phosphoramidate bond. GWD-dependent phosphorylation alters the granule surface structure, which favors the action of PWD. PWD phosphorylates also non pre-phosphorylated glucan chains
dikinases use ATP as a dual phosphate donor and transfer the beta- and gamma-phosphate groups to two distinct acceptor molecules, a glucan and water. A conserved histidine residue within this domain is capable of accepting the beta-phosphate group of ATP following nucleotide binding and hydrolysis. The phosphoramidate bond is acid labile, but rather stable under alkaline conditions. The gamma-phosphate group is transferred to water
the enzyme transfers the beta-phosphate of ATP to the phosphoglucan, whereas the gamma-phosphate is transferred to water. The protein phosphorylates itself with the beta-phosphate of ATP at a His residue of the enzyme, which is then transferred to the glucan
important enzymes of starch metabolism. Catalyzes the addition of phosphate groups to amylopectin chains at the surface of starch granules, changing its physicochemical properties
dikinases use ATP as a dual phosphate donor and transfer the beta- and gamma-phosphate groups to two distinct acceptor molecules, a glucan and water. A conserved histidine residue within this domain is capable of accepting the beta-phosphate group of ATP following nucleotide binding and hydrolysis. The phosphoramidate bond is acid labile, but rather stable under alkaline conditions. The gamma-phosphate group is transferred to water
dikinases use ATP as a dual phosphate donor and transfer the beta- and gamma-phosphate groups to two distinct acceptor molecules, a glucan and water. A conserved histidine residue within this domain is capable of accepting the beta-phosphate group of ATP following nucleotide binding and hydrolysis. The phosphoramidate bond is acid labile, but rather stable under alkaline conditions. The gamma-phosphate group is transferred to water
important enzymes of starch metabolism. Catalyzes the addition of phosphate groups to amylopectin chains at the surface of starch granules, changing its physicochemical properties
i.e. ESV1, a 50000 Da starch-binding protein. Increases action of phosphoglucan, water dikinase. ESV1 does not affect the autophosphorylation of the phosphoglucan, water dikinase
the GWD full-length protein binds to native starch granules in vivo and in vitro. Binding of GWD in vivo is dependent on the metabolic status of the cells. A significantly higher proportion of the dikinases is associated with native leaf starch granules isolated during the dark period than in the light phase of the photoperiod
the largest differences in the amino acid sequence of GWD, EC 2.7.9.4, and PWD, EC 2.7.9.5, span the non-catalytic N-terminal region. In case of PWD, the N-terminus contains a single starch-binding domain (SBD) that belongs to the well-characterized carbohydrate-binding module (CBM) family CBM20. In contrast to PWD, the identity of the N-terminal starch-binding domain of GWD is less pronounced but might be assigned to the recently identified CBM45 family
during starch metabolism, the phosphorylation of glucosyl residues of amylopectin is a repeatedly observed process. The phosphorylation is mediated by dikinases, glucan, water dikinase (GWD, EC 2.7.9.4) and phosphoglucan, water dikinase (PWD, EC 2.7.9.5). By the collaborative action of both enzymes, the initiation of a transition of alpha-glucans from highly ordered, water-insoluble state to a less order state is realized and thus the initial process of starch degradation
the starch-related dikinase utilizes ATP as dual phosphate donor transferring the terminal gamma-phosphate group to water selectively to C3 position of a glucosyl residue within amylopectin. The action of the dikinase is restricted to the granule surface and glucan chains exposed at the surface account only for a minor proportion of the entire granule. Glucan chains that are phosphorylated by the dikinase remain covalently linked to the insoluble starch particle. In Arabidopsis leaf starch, about 0.1% of the glucosyl residues are phosphorylated, respectively. PWD is mainly responsible for C3 phosphorylation. A significant PWD-mediated C3 phosphorylation requires the preceding phosphorylation by GWD in Arabidopsis thaiana wild-type starch
important enzyme of starch metabolism. Catalyzes the addition of phosphate groups to amylopectin chains at the surface of starch granules, changing its physicochemical properties
in mutant plants lacking phosphoglucan, water dikinase EC 2.7.9.5, C3-bound phosphate is reduced to levels close to detection limit. In mutant plants lacking alpha-glucan, water dikinase EC 2.7.9.4, phosphorylation at both C6- and C3-positions of glucose moieties in starch is dramatically decreased
Orzechowski, S.; Grabowska, A.; Sitnicka, D.; Siminska, J.; Felus, M.; Dudkiewicz, M.; Fudali, S.; Sobczak, M.
Analysis of the expression, subcellular and tissue localisation of phosphoglucan, water dikinase (PWD/GWD3) in Solanum tuberosum L.: A bioinformatics approach for the comparative analysis of two alpha-glucan, water dikinases (GWDs) from Solanum tuberosum L.
The analysis of the different functions of starch-phosphorylating enzymes during the development of Arabidopsis thaliana plants discloses an unexpected role for the cytosolic isoform GWD2