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Literature summary for 2.7.9.4 extracted from
- Starch phosphorylation: insights and perspectives (2016), Cell. Mol. Life Sci., 73, 2753-2764.
Cloned(Commentary)
| Cloned (Comment) | Organism |
|---|---|
| gene GWD1, the gene is located on chromosome 1, phylogenetic tree | Arabidopsis thaliana |
| gene GWD2 | Arabidopsis thaliana |
Protein Variants
| Protein Variants | Comment | Organism |
|---|---|---|
| additional information | generation of antisense transgenic lines which reveal more but smaller tubers | Solanum tuberosum |
Localization
| Localization | Comment | Organism | GeneOntology No. | Textmining |
|---|---|---|---|---|
| amyloplast | - |
Solanum tuberosum | 9501 | - |
| chloroplast | - |
Solanum tuberosum | 9507 | - |
| chloroplast | - |
Arabidopsis thaliana | 9507 | - |
| chloroplast envelope | the expression of AtGWD2 is in a relatively late stage of plant development | Arabidopsis thaliana | 9941 | - |
| 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 | nonamylolytic, starch granule-associated protein in potato. Phosphorylated glucans are more abundant at the granule surface of potato leaf starch during the beginning of starch mobilization | Solanum tuberosum | - |
- |
| 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 | 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 | AMP + phospho-alpha-glucan + phosphate | - |
? | |
| 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 | 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 followingnucleotide binding and hydrolysis | AMP + phospho-alpha-glucan + phosphate | - |
? | |
Organism
| Organism | UniProt | Comment | Textmining |
|---|---|---|---|
| Arabidopsis thaliana | Q9SAC6 | - |
- |
| Arabidopsis thaliana | Q9STV0 | - |
- |
| Solanum tuberosum | Q9AWA5 | - |
- |
Source Tissue
| Source Tissue | Comment | Organism | Textmining |
|---|---|---|---|
| leaf | - |
Solanum tuberosum | - |
| leaf | - |
Arabidopsis thaliana | - |
| tuber | - |
Solanum tuberosum | - |
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 | Arabidopsis thaliana | 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 | 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 followingnucleotide binding and hydrolysis | Arabidopsis thaliana | AMP + phospho-alpha-glucan + phosphate | - |
? | |
| ATP + alpha-glucan + H2O | GWD phosphorylates the hydroxyl group at carbon atom 6, the gamma-phosphate group of ATP is transferred to water and the beta-phosphate group to an autocatalytical histidine residue via a phosphoramidate bond | Arabidopsis thaliana | AMP + phospho-alpha-glucan + phosphate | - |
? | |
| ATP + alpha-glucan + H2O | GWD phosphorylates the hydroxyl group at carbon atoms 6 and 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. The phosphoramidate bond is acid labile, but rather stable under alkaline conditions. The gamma-phosphate group is transferred to water. GWD-dependent incorporation of starch phosphate monoesters is higher after removing these surface-exposed glucans by amylolytic enzymes | Arabidopsis thaliana | AMP + phospho-alpha-glucan + phosphate | - |
? | |
| ATP + alpha-glucan + H2O | the starch-binding R1 protein from potato catalyzes the glucan phosphorylation in a dikinase reaction type. 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 | Solanum tuberosum | 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. MDcryst has a higher degree of crystallinity and, therefore, recombinant GWD phosphorylates MDcryst with much higher rates than any other native starches tested so far. The incorporation of phosphate esters results in the release of phosphorylated (single, double, and triple phosphorylated glucan chains) as well as neutral maltodextrins from the water-insoluble MDcryst, indicating that the action of GWD disrupts the ordered arrangement of maltodextrins at the particle surface | Arabidopsis thaliana | AMP + phospho-alpha-glucosyl-maltodextrin + phosphate | - |
? | |
| additional information | no phosphorylation of the hydroxyl group at the C2 position | Solanum tuberosum | ? | - |
? | |
| 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 |
|---|---|---|
| alpha-glucan water dikinase 1 | - |
Solanum tuberosum |
| alpha-glucan water dikinase 1 | - |
Arabidopsis thaliana |
| alpha-glucan water dikinase 2 | - |
Arabidopsis thaliana |
| At4g24450 | locus name | Arabidopsis thaliana |
| GWD | - |
Solanum tuberosum |
| GWD | - |
Arabidopsis thaliana |
| GWD1 | - |
Solanum tuberosum |
| GWD1 | - |
Arabidopsis thaliana |
| GWD2 | - |
Arabidopsis thaliana |
| R1 | - |
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 | AtGWD2 knockout mutants do not accumulate high amounts of starch nor have a visible growth phenotype compared to wild-type plants | Arabidopsis thaliana |
| malfunction | melting enthalpy and crystallinity of purified starches are higher if GWD-mediated starch phosphorylation is suppressed. R1 reduction results in a starch excess phenotype in leaves, e.g., the accumulation of high amounts of starch at the end of a normal dark phase because of the decreased rates of leaf starch degradation. In addition, the lowered expression of R1 in these plants is accompanied by a reduction in cold-induced sweeting in tubers. Transgenic potato plants with reduced StGWD expression, show impeded starch degradation and an overall reduction in starch phosphate content. In transgenic potato lines with reduced expression of StGWD, small alteration in storage starch metabolism is reported | Solanum tuberosum |
| malfunction | mutants lacking the enzyme reveal a starch excess phenotype as well as growth retardation. The lack of GWD causes a reduction of G6P and G3P. The lack of GWD in mature Arabidopsis thaliana plants as observed in the null mutant sex1-8 results in a fivefold increased leaf starch content compared to wild-type plants. Although the internal structure of sex1-8 starch granules is similar to wild-type, the length as well as the abundance of glucan chains exposed on the granule surface differs in the mutant. The lack of GWD in mature sex1-8 plants results in a shift of the chain length distribution towards shorter glucan chains at the granule surface, the abundance of glucan chains at the granule surface is increased in the mutant compared to wild-type. Similar to the Arabidopsis GWD null mutant, the altered surface properties are also present in two partially complemented sex1-8 mutants which have compared to WT an approx. 79% and 93% lowered GWD protein level, respectively. Reduced expression of GWD impair the elongation of existing glucan chains catalyzed by starch synthase 1 (AtSS1), one of the dominate starch synthesizing activity in Arabidopsis. Impaired starch degradation caused by GWD deficiency may lead to lowered export of sugars to heterotrophic tissue and an overall reduction of biomass | Arabidopsis thaliana |
| metabolism | during starch metabolism, the phosphorylation of glucosyl residues of amylopectin is a repeatedly observed process. The phosphorylation is mediated by dikinases, the glucan, water dikinase (GWD, EC 2.7.9.4) and the 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 C6 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. GWD is responsible for C3 and C6 phosphorylation. A significant PWD-mediated C3 phosphorylation requires the preceding phosphorylation by GWD in Arabidopsis thaliana wild-type starch. GWD preferentially acts on crystalline surfaces and GWD-mediated phosphorylation enables a phase transition at the granule surface from a solid to a more soluble state enabling a significant amylolysis | Arabidopsis thaliana |
| physiological function | the starch-related dikinase utilizes ATP as dual phosphate donor transferring the terminal gamma-phosphate group to water selectively to C6 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 and potato tuber starch about 0.1 and 1% of the glucosyl residues are phosphorylated, respectively. A direct access of AtGWD2 to leaf starch granules in vivo and an overall impact on transitory starch metabolism is excluded | Arabidopsis thaliana |
| physiological function | the starch-related dikinase utilizes ATP as dual phosphate donor transferring the terminal gamma-phosphate group to water selectively to C6 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 potato tuber starch, about 1% of the glucosyl residues are phosphorylated, respectively | Solanum tuberosum |
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