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Literature summary for 2.7.9.5 extracted from
- Starch phosphorylation: insights and perspectives (2016), Cell. Mol. Life Sci., 73, 2753-2764.
Cloned(Commentary)
| Cloned (Comment) | Organism |
|---|---|
| gene PWD, phylogenetic tree | Arabidopsis thaliana |
| gene StGWD3 | Solanum tuberosum |
Localization
| Localization | Comment | Organism | GeneOntology No. | Textmining |
|---|---|---|---|---|
| amyloplast | isozyme StGWD3 | Solanum tuberosum | 9501 | - |
| chloroplast | - |
Arabidopsis thaliana | 9507 | - |
| additional information | 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 | Arabidopsis thaliana | - |
- |
| starch granule | the enzyme acts significantly on the surface of native starch granules | Arabidopsis thaliana | - |
- |
Metals/Ions
| Metals/Ions | Comment | Organism | Structure |
|---|---|---|---|
| Mg2+ | required | Solanum tuberosum |  |
| Mg2+ | required | Arabidopsis thaliana | |
Natural Substrates/ Products (Substrates)
| Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| ATP + alpha-glucan + H2O | Solanum tuberosum | 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 | AMP + phospho-alpha-glucan + phosphate | - |
? | |
| ATP + alpha-glucan + H2O | Arabidopsis thaliana | 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 | AMP + phospho-alpha-glucan + phosphate | - |
? | |
Organism
| Organism | UniProt | Comment | Textmining |
|---|---|---|---|
| Arabidopsis thaliana | Q6ZY51 | - |
- |
| Solanum tuberosum | D2JRZ6 | gene StGWD3, a potato homologue of PWD | - |
Source Tissue
| Source Tissue | Comment | Organism | Textmining |
|---|---|---|---|
| leaf | - |
Arabidopsis thaliana | - |
Substrates and Products (Substrate)
| Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| ATP + alpha-glucan + H2O | 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 | Solanum tuberosum | AMP + phospho-alpha-glucan + phosphate | - |
? | |
| ATP + alpha-glucan + H2O | 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 | Arabidopsis thaliana | AMP + phospho-alpha-glucan + phosphate | - |
? | |
| ATP + alpha-glucan + H2O | 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 | Arabidopsis thaliana | AMP + phospho-alpha-glucan + phosphate | - |
? | |
| ATP + crystalline maltodextrin + H2O | 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 | Arabidopsis thaliana | AMP + phospho-alpha-glucosyl-maltodextrin + phosphate | - |
? | |
| additional information | no phosphorylation of the hydroxyl group at the C2 position | Arabidopsis thaliana | ? | - |
? | |
Subunits
| Subunits | Comment | Organism |
|---|---|---|
| monomer | - |
Arabidopsis thaliana |
Synonyms
| Synonyms | Comment | Organism |
|---|---|---|
| At5g26570 | locus name | Arabidopsis thaliana |
| AtPWD | - |
Arabidopsis thaliana |
| PWD | - |
Solanum tuberosum |
| PWD | - |
Arabidopsis thaliana |
| StGWD3 | - |
Solanum tuberosum |
Cofactor
| Cofactor | Comment | Organism | Structure |
|---|---|---|---|
| ATP | - |
Solanum tuberosum | |
| ATP | - |
Arabidopsis thaliana | |
General Information
| General Information | Comment | Organism |
|---|---|---|
| evolution | 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 | Arabidopsis thaliana |
| malfunction | mutants lacking the enzyme reveal a starch excess phenotype as well as growth retardation. The lack of PWD causes a reduction of G3P alone | Arabidopsis thaliana |
| metabolism | 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 | Arabidopsis thaliana |
| physiological function | 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 | Arabidopsis thaliana |
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