Information on EC 2.1.1.158 - 7-methylxanthosine synthase

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

EC NUMBER
COMMENTARY hide
2.1.1.158
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RECOMMENDED NAME
GeneOntology No.
7-methylxanthosine synthase
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REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
S-adenosyl-L-methionine + xanthosine = S-adenosyl-L-homocysteine + 7-methylxanthosine
show the reaction diagram
PATHWAY
BRENDA Link
KEGG Link
MetaCyc Link
caffeine biosynthesis I
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caffeine biosynthesis II (via paraxanthine)
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theobromine biosynthesis I
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Caffeine metabolism
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Metabolic pathways
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Biosynthesis of secondary metabolites
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SYSTEMATIC NAME
IUBMB Comments
S-adenosyl-L-methionine:xanthosine N7-methyltransferase
The enzyme is specific for xanthosine, as XMP and xanthine cannot act as substrates [2,4]. The enzyme does not have N1- or N3- methylation activity [2]. This is the first methylation step in the production of caffeine.
CAS REGISTRY NUMBER
COMMENTARY hide
192827-92-2
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ORGANISM
COMMENTARY hide
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
Coffea sp.
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-
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Manually annotated by BRENDA team
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
metabolism
SUBSTRATE
PRODUCT                       
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
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
S-adenosyl-L-methionine + xanthosine
S-adenosyl-L-homocysteine + 7-methylxanthosine
show the reaction diagram
additional information
?
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COFACTOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
S-adenosyl-L-methionine
Coffea sp.
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METALS and IONS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.0737 - 0.078
Xanthosine
SPECIFIC ACTIVITY [µmol/min/mg]
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
0.32
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purified enzyme
additional information
pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
8
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assay at
8.3
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assay at
TEMPERATURE OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
20
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assay at
30
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assay at
pI VALUE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
4.7 - 5.2
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chromatofocusing
5.36
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isoelectric focusing
SOURCE TISSUE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
SOURCE
additional information
LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY hide
GeneOntology No.
LITERATURE
SOURCE
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co-localization of xanthosine methyltransferase, 7-methylxanthine methyltransferase, and 3,7-dimethylxanthine methyltransferase
Manually annotated by BRENDA team
MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
41000
gel filtration
42000
SDS-PAGE
67000
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about, gel filtration
69000
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recombinant isozyme XMT1, gel filtration
80000
about, recombinant enzyme, gel filtration
SUBUNITS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
?
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x * 37600, SDS-PAGE
Crystallization/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
purified recombinant wild-type and selenomethionine-labeled XMT, 23-28% PEG 3350, 0.2 M LiCl, 0.1 M Tris-HCl, pH 8.5-8.7, 2 mM DTT, 1 mM S-adenosyl-L-cysteine, and 1 mM xanthosine, 1-3 days, 20°C, X-ray diffraction structure determination and analysis at 2.8-3.0 A resolution
purified recombinant wild-type and selenomethionine-labeled XMT, 23-28% PEG 3350, 0.2 M LiCl, 0.1 M Tris-HCl, pH 8.5-8.7, 2 mM DTT, 2 mM S-adenosyl-L-cysteine, and 2 mM xanthosine, 1-3 days, 20°C, plate-like crystals, X-ray diffraction structure determination and analysis at 2.2 A resolution
using Linbro plates and the conventional hanging-drop technique, in the presence of the demethylated cofactor S-adenosyl-l-cysteine or xanthosine
Purification/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
native enzyme
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native enzyme 9fold from young leaves by 3 steps of ion exchange chromatography, and gel filtration
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native enzyme partially from young leaves by ammonium sulfate fractionation, gel filtration, and ultrafiltration
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recombinant His-tagged XMT1 from Escherichia coli strain BL21(DE3) to homogeneity by nickel affinity chromatography, cleavage of the His-tag with tobacco etch virus, TEV, protease, followed by gel filtration
using the His-tagged affinity chromatography
Cloned/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
DNA and amino acid sequence determination and analysis
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expression analysis
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expression in Escherichia coli
expression in Escherichia coli as His-tagged fusion protein
expression of His-tagged XMT1 in Escherichia coli strain BL21(DE3)
expression of wild-type and mutant enzymes in Escherichia coli strain BL21 (DE3), sequence comparison of caffeine synthetic enzymes from coffee
Coffea sp.
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gene CaMTL3, cDNA library construction, DNA and amino acid sequence determination and analysis, sequence comparison with other species
gene CtCS1 or CaXMT1 or CmXRS1, DNA sequence determination, phylogenetic tree, expression in Escherichia coli strain BL21(DE3)
gene XMT1, DNA and amino acid sequence determination and analysis, expression analysis
isozyme XMT1, DNA and amino acid sequence determination and analysis, phylogenetic analysis, expression of the GST-tagged enzyme in Escherichia coli Bl21(DE3)
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isozyme XMT1, functional expression in transgenic Nicotiana tabacum plant leaves
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ENGINEERING
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
A23S
Coffea sp.
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site-directed mutagenesis, the mutant exhibits no 3-N methylation activity like the wild-type, the mutant shows over 80% of wild-type 7-methylation activity
A23S/L191P/H219R
Coffea sp.
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site-directed mutagenesis, the mutant exhibits no 3-N methylation activity like the wild-type, the mutant shows over 80% of wild-type 7-methylation activity
A23S/P104Q/H219R
Coffea sp.
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site-directed mutagenesis, the mutant exhibits no 3-N methylation activity like the wild-type, the mutant shows over 80% of wild-type 7-methylation activity
A23S/P104Q/Q161H/H219R
Coffea sp.
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site-directed mutagenesis, the mutant exhibits 3-N methylation activity in contrast to the wild-type enzyme, the mutant shows 60% of wild-type 7-methylation activity
A23S/P104Q/Q161H/L191P/H219R
Coffea sp.
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site-directed mutagenesis, the mutant exhibits 3-N methylation activity in contrast to the wild-type enzyme, the mutant shows over 80% of wild-type 7-methylation activity
A23S/Q161H/H219R
Coffea sp.
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site-directed mutagenesis, the mutant exhibits 3-N methylation activity in contrast to the wild-type enzyme, the mutant shows over 80% of wild-type 7-methylation activity
A23S/Q161H/L191P/H219R
Coffea sp.
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site-directed mutagenesis, the mutant exhibits 3-N methylation activity in contrast to the wild-type enzyme, the mutant shows over 80% of wild-type 7-methylation activity
H219R
Coffea sp.
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site-directed mutagenesis, the mutant exhibits no 3-N methylation activity like the wild-type, the mutant shows over 80% of wild-type 7-methylation activity
L191P
Coffea sp.
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site-directed mutagenesis, the mutant exhibits no 3-N methylation activity like the wild-type, the mutant shows over 80% of wild-type 7-methylation activity
P104Q
Coffea sp.
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site-directed mutagenesis, the mutant exhibits no 3-N methylation activity like the wild-type, the mutant shows over 80% of wild-type 7-methylation activity
P104Q/L191P
Coffea sp.
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site-directed mutagenesis, the mutant exhibits no 3-N methylation activity like the wild-type, the mutant shows over 80% of wild-type 7-methylation activity
P104Q/Q161H
Coffea sp.
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site-directed mutagenesis, the mutant exhibits 3-N methylation activity in contrast to the wild-type enzyme, the mutant shows over 80% of wild-type 7-methylation activity
P104Q/Q161H/L191P
Coffea sp.
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site-directed mutagenesis, the mutant exhibits 3-N methylation activity in contrast to the wild-type enzyme, the mutant shows over 80% of wild-type 7-methylation activity
Q161H
Coffea sp.
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site-directed mutagenesis, the mutant exhibits 3-N methylation activity in contrast to the wild-type enzyme, the mutant shows over 80% of wild-type 7-methylation activity
Q161H/L191P
Coffea sp.
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site-directed mutagenesis, the mutant exhibits 3-N methylation activity in contrast to the wild-type enzyme, the mutant shows over 80% of wild-type 7-methylation activity
additional information
APPLICATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
agriculture
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expression of the caffeine biosynthesis enzymes in transgenic crop plants amay protect against the crop damaging larvae of pests