Information on EC 2.7.7.74 - 1L-myo-inositol 1-phosphate cytidylyltransferase

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The expected taxonomic range for this enzyme is: Bacteria, Archaea

EC NUMBER
COMMENTARY hide
2.7.7.74
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RECOMMENDED NAME
GeneOntology No.
1L-myo-inositol 1-phosphate cytidylyltransferase
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REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
CTP + 1L-myo-inositol 1-phosphate = diphosphate + CDP-1L-myo-inositol
show the reaction diagram
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PATHWAY
BRENDA Link
KEGG Link
MetaCyc Link
di-myo-inositol phosphate biosynthesis
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myo-inositol biosynthesis
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Inositol phosphate metabolism
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SYSTEMATIC NAME
IUBMB Comments
CTP:1L-myo-inositol 1-phosphate cytidylyltransferase
In many organisms this activity is catalysed by a bifunctional enzyme. The cytidylyltransferase domain of the bifunctional EC 2.7.7.74/EC 2.7.8.34 (CTP:inositol-1-phosphate cytidylyltransferase/CDP-inositol:inositol-1-phosphate transferase) is absolutely specific for CTP and 1L-myo-inositol 1-phosphate. The enzyme is involved in biosynthesis of bis(1L-myo-inositol) 1,3'-phosphate, a widespread organic solute in microorganisms adapted to hot environments.
ORGANISM
COMMENTARY hide
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
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UniProt
Manually annotated by BRENDA team
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UniProt
Manually annotated by BRENDA team
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UniProt
Manually annotated by BRENDA team
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
malfunction
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deleting the gene encoding the key enzyme in di-myo-inositol phosphate synthesis, CTP:inositol-1-phosphate cytidylyltransferase/CDP-inositol:inositol-1-phosphate transferase, abolishes di-myo-inositol phosphate synthesis. Mutants deficient in di-myo-inositol phosphate use aspartate to cope with heat stress
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
CDP-glycerol + 1L-myo-inositol 1-phosphate
CMP + 1-(1X-glyceryl) myo-inosityl phosphate 3-phosphate
show the reaction diagram
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-
-
?
CTP + 1D-myo-inositol 3-phosphate
diphosphate + CDP-L-myo-inositol
show the reaction diagram
CTP + 1L-myo-inositol 1-phosphate
diphosphate + CDP-1L-myo-inositol
show the reaction diagram
CTP + inositol 1-phosphate
diphosphate + CDP-inositol
show the reaction diagram
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?
additional information
?
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enzyme is highly specific for CTP and inositol-1-phosphate. No substrates: ATP, GTP, UTP, myo-inositol, glycerol, DL-glycerol-phosphate, alpha-glucose-1-phosphate, beta-glucose-1-phosphate, glucose-6-phosphate, fructose-6-phosphate, fructose-1-phosphate and galactose-1-phosphate
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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
CTP + 1D-myo-inositol 3-phosphate
diphosphate + CDP-L-myo-inositol
show the reaction diagram
O29976
the enzyme is involved in the synthesis of di-myo-inositol phosphate. Archaeoglobus fulgidus accumulates di-myo-inositol phosphate and diglycerol phosphate in response to heat and osmotic stresses, respectively, and the level of glycero-phospho-myo-inositol increases primarily when the two stresses are combined
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?
CTP + 1L-myo-inositol 1-phosphate
diphosphate + CDP-1L-myo-inositol
show the reaction diagram
METALS and IONS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
Co2+
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20 mM, 11% of the activity with Mg2+
additional information
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no activity with Ni2+
ACTIVATING COMPOUND
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate
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i.e. CHAPS, or Triton X-100, absolutely required
Triton X-100
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or CHAPS, absolutely required
additional information
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presence of detergent is absolutely required
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KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.87
1D-myo-inositol 3-phosphate
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pH and temperature not specified in the publication
0.87
1L-myo-inositol 1-phosphate
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90C, pH 7.0, cytoplasmic CTP:inositol-1-phosphate cytidylyltransferase domain of the bifunctional enzyme (EC 2.7.7.74/EC 2.7.8.34)
0.58 - 1.8
CTP
2.6
Inositol 1-phosphate
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75C, pH 8.0
SPECIFIC ACTIVITY [µmol/min/mg]
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
59.8
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75C, pH 8.0
62.9
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90C, pH 7.0, cytoplasmic CTP:inositol-1-phosphate cytidylyltransferase domain of the bifunctional enzyme (EC 2.7.7.74/EC 2.7.8.34)
pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
pH RANGE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
5.5 - 8.5
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pH 5.5: about 30% of maximal activity, pH 8.5: about 65% of maximal activity
6.5 - 7.5
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maximal activity
TEMPERATURE OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
TEMPERATURE RANGE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
45
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no activity below
60 - 100
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activity of the enzyme is undetectable at temperatures below 60C, and maximal activity is reached between 90 and 95C, at 100C about 25% of maximal activity
75
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about one third of the activity at 95C
90 - 95
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maximal activity
LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY hide
GeneOntology No.
LITERATURE
SOURCE
PDB
SCOP
CATH
ORGANISM
UNIPROT
Archaeoglobus fulgidus (strain ATCC 49558 / VC-16 / DSM 4304 / JCM 9628 / NBRC 100126)
Pseudomonas aeruginosa (strain ATCC 15692 / DSM 22644 / CIP 104116 / JCM 14847 / LMG 12228 / 1C / PRS 101 / PAO1)
Pseudomonas aeruginosa (strain ATCC 15692 / DSM 22644 / CIP 104116 / JCM 14847 / LMG 12228 / 1C / PRS 101 / PAO1)
Pseudomonas aeruginosa (strain ATCC 15692 / DSM 22644 / CIP 104116 / JCM 14847 / LMG 12228 / 1C / PRS 101 / PAO1)
Pseudomonas aeruginosa (strain ATCC 15692 / DSM 22644 / CIP 104116 / JCM 14847 / LMG 12228 / 1C / PRS 101 / PAO1)
Pseudomonas aeruginosa (strain ATCC 15692 / DSM 22644 / CIP 104116 / JCM 14847 / LMG 12228 / 1C / PRS 101 / PAO1)
Pseudomonas aeruginosa (strain ATCC 15692 / DSM 22644 / CIP 104116 / JCM 14847 / LMG 12228 / 1C / PRS 101 / PAO1)
Pseudomonas aeruginosa (strain ATCC 15692 / DSM 22644 / CIP 104116 / JCM 14847 / LMG 12228 / 1C / PRS 101 / PAO1)
Pseudomonas aeruginosa (strain ATCC 15692 / DSM 22644 / CIP 104116 / JCM 14847 / LMG 12228 / 1C / PRS 101 / PAO1)
Pseudomonas aeruginosa (strain ATCC 15692 / DSM 22644 / CIP 104116 / JCM 14847 / LMG 12228 / 1C / PRS 101 / PAO1)
Pseudomonas aeruginosa (strain ATCC 15692 / DSM 22644 / CIP 104116 / JCM 14847 / LMG 12228 / 1C / PRS 101 / PAO1)
Pseudomonas aeruginosa (strain ATCC 15692 / DSM 22644 / CIP 104116 / JCM 14847 / LMG 12228 / 1C / PRS 101 / PAO1)
SUBUNITS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
Crystallization/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
crystal structure of the enzyme in the apo form is solved to a 1.9 A resolution. The structure of IPCT is composed of a central seven-stranded mixed beta-sheet, of which six beta-strands are parallel, surrounded by six alpha-helices, a fold reminiscent of the dinucleotide-binding Rossmann fold; hanging-drop vapor diffusion method at 20C, X-ray structure of the cytoplasmic CTP:inositol-1-phosphate cytidylyltransferase domain of the bifunctional enzyme (EC 2.7.7.74/EC 2.7.8.34). The structure of the enzyme in the apo form was solved to a 1.9 A resolution. The structure of CTP:inositol-1-phosphate cytidylyltransferase is composed of a central seven-stranded mixed beta-sheet, of which six beta-strands are parallel, surrounded by six alpha-helices, a fold reminiscent of the dinucleotide-binding Rossmann fold
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crystallization of the CTP:inositol-1-phosphate cytidylyltransferase domain in the apo form. The crystals diffracted to 2.4 A resolution using a synchrotron source and belong to the orthorhombic space group P2(1)2(1)2, with unit-cell parameters a = 154.7, b = 83.9, c = 127.7 A
structure shows a conserved motif of sugar nucleotide transferases (COG1213) with a structurally reinforced C-terminal Cys bonded to the core of the protein. During catalysis, the conserved Asp107 serves as an electrostatic anchor to which the metal ion (most likely Mg2+) binds. Upon binding, the triphosphate group of the nucleotide interacts with a metal ion as well as the phosphate of the inositol. The O atom of the inositol phosphate group that is polarized by this interaction attacks the triphosphate and causes its cleavage to release the diphosphate group. Lys24 stabilizes the developing negative charge in the transition state and Arg14 serves as a release agent
TEMPERATURE STABILITY
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
75
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half-life 5 h
85
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10 min, 80% residual activity
90
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10 min, 12% residual activity
Purification/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
purification CTP:inositol-1-phosphate cytidylyltransferase domain
the cytoplasmic domain of the bifunctional enzyme (EC 2.7.7.74/EC 2.7.8.34) is produced in Escherichia coli; using metal affinity chromatography and gel filtration
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Cloned/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
cytoplasmic domain of IPCT is expressed in Escherichia coli as a His-tagged fusion protein; the cytoplasmic domain of the bifunctional enzyme (EC 2.7.7.74/EC 2.7.8.34) is produced in Escherichia coli
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expression in Escherichia coli
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the CTP:inositol-1-phosphate cytidylyltransferase domain of the bifunctional CTP:inositol-1-phosphate cytidylyltransferase/CDP-inositol:inositol-1-phosphate transferase (EC 2.7.7.74/EC 2.7.8.34) is cloned and expressed in Escherichia coli