Information on EC 2.7.9.5 - phosphoglucan, water dikinase

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The enzyme appears in viruses and cellular organisms

EC NUMBER
COMMENTARY hide
2.7.9.5
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RECOMMENDED NAME
GeneOntology No.
phosphoglucan, water dikinase
REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
ATP + [phospho-alpha-glucan] + H2O = AMP + O-phospho-[phospho-alpha-glucan] + phosphate
show the reaction diagram
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PATHWAY
BRENDA Link
KEGG Link
MetaCyc Link
starch degradation II
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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].
CAS REGISTRY NUMBER
COMMENTARY hide
664327-94-0
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ORGANISM
COMMENTARY hide
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
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Manually annotated by BRENDA team
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
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
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
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
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
SUBSTRATE
PRODUCT                       
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
ATP + alpha-glucan + H2O
AMP + phospho-alpha-glucan + phosphate
show the reaction diagram
ATP + crystalline maltodextrin + H2O
AMP + phospho-alpha-glucosyl-maltodextrin + phosphate
show the reaction diagram
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
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ATP + phospho-maltodextrin + H2O
AMP + O-phospho-[phospho-maltodextrin] + phosphate
show the reaction diagram
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only pre-phosphorylated, crystallised (insoluble) maltodextrin
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-
?
ATP + [phospho-alpha-glucan]
AMP + O-phospho-[phospho-alpha-glucan] + phosphate
show the reaction diagram
ATP + [phospho-alpha-glucan] + H2O
AMP + O-phospho-[phospho-alpha-glucan] + phosphate
show the reaction diagram
D2JRZ6
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?
additional information
?
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NATURAL SUBSTRATES
NATURAL PRODUCTS
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
ATP + alpha-glucan + H2O
AMP + phospho-alpha-glucan + phosphate
show the reaction diagram
ATP + [phospho-alpha-glucan]
AMP + O-phospho-[phospho-alpha-glucan] + phosphate
show the reaction diagram
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the enzyme phosphorylates granular starch that has previously been phosphorylated by EC 2.7.9.4, alpha-glucan, water dikinase
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COFACTOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
METALS and IONS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
SPECIFIC ACTIVITY [µmol/min/mg]
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
0.002
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pre-phosphorylated, crystalline maltodextrin
additional information
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no activity detectable on pre-phosphorylated, soluble maltodextrin
pI VALUE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
5.8
D2JRZ6
calculated from amino acid sequence
SOURCE TISSUE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
SOURCE
D2JRZ6
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Manually annotated by BRENDA team
LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY hide
GeneOntology No.
LITERATURE
SOURCE
D2JRZ6
isozyme StGWD3
Manually annotated by BRENDA team
the enzyme acts significantly on the surface of native starch granules
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Manually annotated by BRENDA team
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
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Manually annotated by BRENDA team
MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
125000
D2JRZ6
x * 125000, SDS-PAGE
132270
D2JRZ6
x * 132270, calculated from amino acid sequence
SUBUNITS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
?
D2JRZ6
x * 125000, SDS-PAGE; x * 132270, calculated from amino acid sequence
Purification/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
ammonium sulfate precipitation, amylose resin column chromatography, and Sephadex G-25 gel filtration
D2JRZ6
Cloned/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
expressed in Escherichia coli strain JM109
D2JRZ6
gene PWD, phylogenetic tree
gene StGWD3
D2JRZ6
EXPRESSION
ORGANISM
UNIPROT
LITERATURE
the expression of isoform GWD3 during the diurnal cycle increases until 13 h of illumination, when it reaches its maximal level
D2JRZ6
the lowest level isoform GWD3 expression is 4 h after turning the light off, and it was more than 2.5times lower than the maximal expression level
D2JRZ6
ENGINEERING
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
additional information
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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