Information on EC 2.7.7.69 - GDP-L-galactose phosphorylase

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The enzyme appears in viruses and cellular organisms

EC NUMBER
COMMENTARY hide
2.7.7.69
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RECOMMENDED NAME
GeneOntology No.
GDP-L-galactose phosphorylase
REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
GDP-beta-L-galactose + phosphate = beta-L-galactose 1-phosphate + GDP
show the reaction diagram
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PATHWAY
BRENDA Link
KEGG Link
MetaCyc Link
L-ascorbate biosynthesis I (L-galactose pathway)
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ascorbate metabolism
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Ascorbate and aldarate metabolism
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Metabolic pathways
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Biosynthesis of secondary metabolites
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SYSTEMATIC NAME
IUBMB Comments
GDP:alpha-L-galactose 1-phosphate guanylyltransferase
The enzyme catalyses a reaction of the Smirnoff-Wheeler pathway, the major route to ascorbate biosynthesis in plants.
ORGANISM
COMMENTARY hide
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
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UniProt
Manually annotated by BRENDA team
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Manually annotated by BRENDA team
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
malfunction
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antisense transgenic tomato plants with about 50% decrease in ascorbate (AsA) content are obtained in order to investigate the role of GGP against chilling stress. The suppression of SlGGP could decrease ascorbate levels and enhance plant sensitivity to chilling stress-induced oxidative stresses
physiological function
SUBSTRATE
PRODUCT                       
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
ADP-alpha-D-glucose + phosphate
alpha-D-glucose 1-phosphate + ADP
show the reaction diagram
alpha-D-galactose 1-phosphate + GDP
GDP-alpha-D-galactose + phosphate
show the reaction diagram
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r
alpha-D-glucose 1-phosphate + GDP
GDP-alpha-D-glucose + phosphate
show the reaction diagram
alpha-D-mannose 1-phosphate + GDP
GDP-alpha-D-mannose + phosphate
show the reaction diagram
alpha-L-galactose 1-phosphate + GDP
GDP-alpha-L-galactose + phosphate
show the reaction diagram
alpha-L-gulose 1-phosphate + GDP
GDP-alpha-L-gulose + phosphate
show the reaction diagram
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r
GDP-alpha-D-galactose + phosphate
alpha-D-galactose 1-phosphate + GDP
show the reaction diagram
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r
GDP-alpha-D-galactose + phosphate
GDP + alpha-D-galactose 1-phosphate
show the reaction diagram
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r
GDP-alpha-D-glucose + phosphate
alpha-D-glucose 1-phosphate + GDP
show the reaction diagram
GDP-alpha-D-mannose + phosphate
alpha-D-mannose 1-phosphate + GDP
show the reaction diagram
GDP-alpha-L-gulose + phosphate
alpha-L-gulose 1-phosphate + GDP
show the reaction diagram
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r
GDP-beta-L-galactose + phosphate
GDP + beta-L-galactose 1-phosphate
show the reaction diagram
UDP-alpha-D-galactose + phosphate
alpha-D-galactose 1-phosphate + UDP
show the reaction diagram
UDP-alpha-D-glucose + phosphate
alpha-D-glucose 1-phosphate + UDP
show the reaction diagram
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
GDP-beta-L-galactose + phosphate
GDP + beta-L-galactose 1-phosphate
show the reaction diagram
Q8RWE8, Q9FLP9
enzyme guanylylates a conserved active site His residue with GDP-L-galactose, forming L-galactose 1-phosphate for vitamin C synthesis, and regeneration of the enzyme with phosphate to form GDP
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r
KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
16 - 67
alpha-D-galactose 1-phosphate
10 - 29
alpha-D-glucose 1-phosphate
54
alpha-D-mannose 1-phosphate
pH 7.5, 26°C
6 - 45
alpha-L-galactose 1-phosphate
0.0044 - 0.012
GDP-alpha-D-glucose
0.52 - 1.3
GDP-alpha-D-mannose
0.0079 - 0.667
GDP-alpha-L-galactose
0.13 - 2.4
phosphate
TURNOVER NUMBER [1/s]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.023 - 6
alpha-D-galactose 1-phosphate
5.8 - 12
alpha-D-glucose 1-phosphate
0.0012
alpha-D-mannose 1-phosphate
pH 7.5, 26°C
6
alpha-L-galactose 1-phosphate
9.9 - 23
GDP-alpha-D-glucose
0.024 - 0.093
GDP-alpha-D-mannose
2.04 - 64
GDP-alpha-L-galactose
SPECIFIC ACTIVITY [µmol/min/mg]
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
14.2
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pH 7.5, 26°C, substrate GDP-alpha-D-glucose
15.1
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pH 7.5, 26°C, substrate GDP-alpha-L-galactose
SOURCE TISSUE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
SOURCE
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mRNA expression is strongly induced by exposing dark-grown seedlings to the light
Manually annotated by BRENDA team
additional information
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VTC2 gene is expressed in all deveopmental stages, and the mRNA is expressed at a higher level in green tissues than in the root. mRNA expression is strongly induced by exposing dark-grown seedlings to the light
Manually annotated by BRENDA team
LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY hide
GeneOntology No.
LITERATURE
SOURCE
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recombinant fusion protein with Yellow Fluorescent Protein
Manually annotated by BRENDA team
Cloned/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
EXPRESSION
ORGANISM
UNIPROT
LITERATURE
expression is induced by Erysiphe necator and defense signaling molecules, including salicylic acid, methyl jasmonate, and ethephon
in leaves treated by continuous darkness or light, abscisic acid or methyljasmonate, heat, or a hypoxic environment, there is some correlation between the relative levels of GGP mRNA and ascorbate concentrations. In transformed tobacco plants, activity of the GGP promoter is induced by all of these treatments
ENGINEERING
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
G224D
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less than 0.1% of wild-type activity
H238N
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less than 0.1% of wild-type activity
S290F
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less than 0.1% of wild-type activity
additional information
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construction of isoforms Vtc2/Vtc5 double mutants. Double mutants show growth arrest immediately upon germination and the cotyledons subsequently bleach. Normal growth is restored by supplementation with ascorbate or L-galactose; construction of isoforms Vtc2/Vtc5 double mutants. Double mutants show growth arrest immediately upon germination and the cotyledons subsequently bleach. Normal growth is restored by supplementation with ascorbate or L-galactose. vtc2-1 leaves contain more mannose 6-phosphate than wild-type