Information on EC 1.14.11.22 - flavone synthase

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The enzyme appears in viruses and cellular organisms

EC NUMBER
COMMENTARY hide
1.14.11.22
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RECOMMENDED NAME
GeneOntology No.
flavone synthase
REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
a flavanone + 2-oxoglutarate + O2 = a flavone + succinate + CO2 + H2O
show the reaction diagram
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PATHWAY
BRENDA Link
KEGG Link
MetaCyc Link
chrysin biosynthesis
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flavonoid biosynthesis (in equisetum)
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isoflavonoid biosynthesis II
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luteolin biosynthesis
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SYSTEMATIC NAME
IUBMB Comments
flavanone,2-oxoglutarate:oxygen oxidoreductase (dehydrating)
Requires ascorbate for full activity and Fe2+.
CAS REGISTRY NUMBER
COMMENTARY hide
138263-98-6
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ORGANISM
COMMENTARY hide
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
no activity in Glycine max
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Manually annotated by BRENDA team
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Manually annotated by BRENDA team
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UniProt
Manually annotated by BRENDA team
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
malfunction
metabolism
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
(2R)-naringenin + 2-oxoglutarate + O2
apigenin + succinate + CO2 + H2O
show the reaction diagram
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13% of the activity with (2S)-naringenin
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?
(2S)-eriodictyol + 2-oxoglutarate + O2
? + CO2 + H2O
show the reaction diagram
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?
(2S)-eriodictyol + 2-oxoglutarate + O2
luteolin + succinate + CO2 + H2O
show the reaction diagram
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ir
(2S)-naringenin + 2-oxoglutarate + O2
apigenin + succinate + CO2 + H2O
show the reaction diagram
(2S)-naringenin + 2-oxoglutarate + O2
apigenin + succinate + H2O + CO2
show the reaction diagram
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?
(2S)-pinocembrin + 2-oxoglutarate + O2
chrysin + succinate + CO2 + H2O
show the reaction diagram
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?
2-hydroxynaringenin + 2-oxoglutarate + O2
? + CO2 + H2O
show the reaction diagram
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?
cis-dihydrokaempferol + 2-oxoglutarate + O2
kaempferol + succinate + CO2 + H2O
show the reaction diagram
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?
dihydrokaempferol + 2-oxoglutarate + O2
kaempferol + succinate + CO2 + H2O
show the reaction diagram
the mutated enzymes L311F, Y240P, F146I, A120M and L311F–A120M are all able to oxidize dihydrokaempferol to kaempferol, with respective catalytic activities relative to the wild type level of 355%, 104%, 86%, 162% and 175%. L311F substitution increases the flavonol synthase activity
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?
eriodictyol + 2-oxoglutarate + O2
?
show the reaction diagram
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24% of the activity with naringenin
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?
eriodictyol + 2-oxoglutarate + O2
luteolin + succinate + CO2 + H2O
show the reaction diagram
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?
hesperetin + 2-oxoglutarate + O2
3,5-dihydroxy-2-(3-hydroxy-4-methoxyphenyl)-chromen-4-one + succinate + CO2 + H2O
show the reaction diagram
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26% of the activity with naringenin
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?
homoeriodictyol + 2-oxoglutarate + O2
5,7,4'-trihydroxy-3'-methoxyflavone + succinate + CO2 + H2O
show the reaction diagram
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97% of the activity with naringenin
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?
liquiritigenin + 2-oxoglutarate + O2
7,4'-dihydroxyflavone + succinate + CO2 + H2O
show the reaction diagram
naringenin + 2-oxoglutarate + O2
apigenin + 2-hydroxynaringenin + succinate + CO2 + H2O
show the reaction diagram
the enzyme catalyzes the conversion of naringenin to apigenin and 2-hydroxynaringenin. It is demonstrated that the enzyme is unable to catalyze the conversion of 2-hydroxynaringenin to apigenin. It is also confirmed that 2-hydroxynaringenin cannot be an intermediate product in the conversion of naringenin to apigenin, leaving the mechanism of conversion unknown
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?
naringenin + 2-oxoglutarate + O2
apigenin + succinate + CO2 + H2O
show the reaction diagram
naringenin + O2 + 2-oxoglutarate
apigenin + succinate + CO2 + H2O
show the reaction diagram
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flavone 7-O-methyltransferase (POMT-7) converts apigenin into 7-O-methyl apigenin (genkwanin), 28°C, 10 mM potassium phosphate buffer with 1% glucose, pH 6.0, 5 mM ascorbate, 10 microM FeSO4, 100 microM substrate naringenin, 15 h incubation
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?
pinocembrin + 2-oxoglutarate + O2
5-acetoxy-7-hydroxyflavone + succinate + CO2 + H2O
show the reaction diagram
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24% of the activity with naringenin
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?
pinocembrin + 2-oxoglutarate + O2
chrysin + succinate + CO2 + H2O
show the reaction diagram
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?
S-naringenin + 2-oxoglutarate + O2
apigenin + succinate + CO2 + H2O
show the reaction diagram
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purified enzyme, 3 h, 37°C, 50 microM FeSO4, 100 mg/ml catalase, 160 microM oxoglutarate, 1 mM ascorbate, 60 microM substrate (S- or R-naringenin) in 10 mM Tris/HCl buffer, pH 8.0
apigenin is converted by falvonoid 3',5'-hydroxylase to luteolin and tricetin
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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
liquiritigenin + 2-oxoglutarate + O2
7,4'-dihydroxyflavone + succinate + CO2 + H2O
show the reaction diagram
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chalcone synthase and chalcone reductase produce the flavanone precursor of 7,4'-dihydroxyflavone
nodulation induction in symbiotic Sinorhizobium meliloti by 7,4'-dihydroxyflavone (Dhf) in Medicago truncately roots
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?
naringenin + O2 + 2-oxoglutarate
apigenin + succinate + CO2 + H2O
show the reaction diagram
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flavone 7-O-methyltransferase (POMT-7) converts apigenin into 7-O-methyl apigenin (genkwanin), 28°C, 10 mM potassium phosphate buffer with 1% glucose, pH 6.0, 5 mM ascorbate, 10 microM FeSO4, 100 microM substrate naringenin, 15 h incubation
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?
S-naringenin + 2-oxoglutarate + O2
apigenin + succinate + CO2 + H2O
show the reaction diagram
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purified enzyme, 3 h, 37°C, 50 microM FeSO4, 100 mg/ml catalase, 160 microM oxoglutarate, 1 mM ascorbate, 60 microM substrate (S- or R-naringenin) in 10 mM Tris/HCl buffer, pH 8.0
apigenin is converted by falvonoid 3',5'-hydroxylase to luteolin and tricetin
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?
additional information
?
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other flavone synthase II products apigenin and luteolin are not found in roots but in seeds, 7,4'-dihydroxyflavone plays an additional role in auxin regulation
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COFACTOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
ascorbate
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required
METALS and IONS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
FeSO4
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65% reduced activity without FeSO4
Iron
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Fe2+ is required
INHIBITORS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
2,4-pyridinedicarboxylate
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potent competitive
Cu2+
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0.02 mM, complete inhibition in presence of 0.01 mM Fe2+
prunin
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competitive with respect to (2S)-naringenin
RNAi
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silencing of flavone synthase II (FNS) in hairy roots leads to 20fold less flavone synthase transcripts than in controls and reduced 7,4'-dihydroxyflavone (Dhf) levels, levels of isoflavones and other flavonoids in transgenic roots are unaffected, FNS-silencing reduces the average number of nodules on roots from about 9 (controls) to about 4, luteolin treatment of Sinorhizobium meliloti cells induce nod gene expression (nodulation inducing factor) in the symbiont, however nodulation is not restored in the roots of Medicago truncatela, Dhf treatment of Medicago truncatela root cells does restore nodulation, a transgenic symbiont overexpressing nodulation factor NodD3 can restore nodulation independently of flavonoids in the roots
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Zn2+
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0.02 mM, complete inhibition in presence of 0.01 mM Fe2+
ACTIVATING COMPOUND
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
ascorbate
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required for full activity, can not be replaced as a reductant by 2-mercaptoethanol or dithiothreitol
oxoglutarate
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no flavone synthase activity without this compound
KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.016
2-oxoglutarate
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in presence of 0.02 mM 2S-naringenin
0.008
2S-eriodictyol
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0.005
2S-naringenin
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0.0065 - 0.0199
naringenin
0.02
S-naringenin
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37°C, 50 microM FeSO4, 100 mg/ml catalase, 160 microM oxoglutarate, 1 mM ascorbate, 60 microM substrate in 10 mM Tris/HCl buffer, pH 8.0
TURNOVER NUMBER [1/s]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.002 - 0.027
naringenin
kcat/KM VALUE [1/mMs-1]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.305 - 1.372
naringenin
Ki VALUE [mM]
INHIBITOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.057
prunin
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0.0018
Pyridine 2,4-dicarboxylate
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SPECIFIC ACTIVITY [µmol/min/mg]
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
6
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optimum for the combined action of both enzymes, next optimal pH is 8.0, then pH 7.0
TEMPERATURE OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
pI VALUE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
4.9
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isoelectric focusing, pH gradient 6.6-4.0
6.42
calculated from sequence
SOURCE TISSUE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
SOURCE
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high expression rate
Manually annotated by BRENDA team
relative DvFNS expressions in petals of different cultivars using realtime RT-PCR analysis, overview
Manually annotated by BRENDA team
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high expression rate
Manually annotated by BRENDA team
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high expression rate
Manually annotated by BRENDA team
LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY hide
GeneOntology No.
LITERATURE
SOURCE
MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
48000
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gel filtration
64000
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SDS-PAGE, sum of flavone synthase and glutathione S-transferase (26000 Da)
64700
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SDS-PAGE, flavone synthase + glutathione S-transferase (26000 Da)
SUBUNITS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
dimer
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2 * 24000-25000, SDS-PAGE
Purification/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
expression of flavone synthase in Escherichia coli, purification on glutathione S-transferase (GST) affinity column
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recombinant enzyme
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Cloned/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
expressed in Escherichia coli BLR (DE3) cells
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expressed in Escherichia coli strain BL21Star
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expressed in Saccharomyces cerevisiae
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expression in Arabidopsis thaliana
expression in Escherichia coli
expression in Saccharomyces cerevisiae
expression in yeast
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gene DvFNS, real-time RT-PCR expression analysis
RT-PCR cloning of flavone synthase cDNA, subcloning in pGEX 5X-2 for expression in Escherichia coli
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the open reading frame of the flavone synthase gene PFNS-1 is cloned from Populus deltoids using RT-PCR, subcloned into Escherichia coli expression vector pGEX 5X-2, the flavone 7-O-methyltransferase into pRSF-Duet vector, both cotransformed into Escherichia coli BL21
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to produce hairy root composite plants (mixture of transgenic and non-transgenic roots) RNAi constructs including green fluorescence protein (GFP) are introduced into shoot cuttings via Agrobacterium rhizogenes-mediated transformation
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ENGINEERING
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
A120M
when the purified recombinant mutant enzyme is incubated with naringenin as substrate, the ratio of 2-hydroxynaringenin to apigenin is reduced. The mutant enzyme is able to oxidize dihydrokaempferol to kaempferol with 162% of the catalytic activity relative to wild-type enzyme
F146I
when the purified recombinant mutant enzyme is incubated with naringenin as substrate, the ratio of 2-hydroxynaringenin to apigenin is reduced. The mutant enzyme is able to oxidize dihydrokaempferol to kaempferol with 86% of the catalytic activity relative to wild-type enzyme
F146I/A120M
the enzyme activity of the double mutant is reduced to a level of about 10% of the activity of the wild type enzyme and the only product generated is apigenin
L311F
when the purified recombinant mutant enzyme is incubated with naringenin as substrate, the ratio of 2-hydroxynaringenin to apigenin is reduced. The mutant enzyme is able to oxidize dihydrokaempferol to kaempferol with 355% of the catalytic activity relative to wild-type enzyme
L311F/A120M
the double mutant catalyzes the formation of 2-hydroxynaringenin and apigenin, although the ratio of these two compounds iss lower than that generated by the wild type enzyme
L311F/F146I
the double mutant catalyzes the formation of 2-hydroxynaringenin and apigenin, although the ratio of these two compounds iss lower than that generated by the wild type enzyme
L311F/F146I/A120M
the activity of the triple mutant falls to about 5% of the wild type enzyme
L311F/F146I/Y240P
inactive mutant
L311F/F146I/Y240P/A120M
inactive mutant
L311F/Y240P
the double mutant exhibits less flavone synthase activity than either the wild type or the Y240P single mutant enzymes
Y240P
the mutant enzyme converts naringenin to apigenin without producing any 2-hydroxynaringenin. The mutant has a higher affinity (lower Km) with naringenin than the wild type enzyme, but the catalytic efficiency of the mutant is lower than that of wild type enzyme. The mutant enzyme is able to oxidize dihydrokaempferol to kaempferol with 104% of the catalytic activity relative to wild-type enzyme
Y240P/A120M
the enzyme activity of the double mutant is reduced to a level of about 10% of the activity of the wild type enzyme and the only product generated is apigenin. The mutant enzyme is able to oxidize dihydrokaempferol to kaempferol with 175% of the catalytic activity relative to wild-type enzyme
Y240P/F146I
the enzyme activity of the double mutant is reduced to a level of about 10% of the activity of the wild type enzyme and the only product generated is apigenin
additional information
APPLICATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
biotechnology
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product of the combined activity of flavone synthase and flavone 7-O-methyltransferase produces genkwanin (7-O-methyl apigenin) which exhibits antibacterial activity against Vibrio cholerae and Enterococcus faecalis, and anti-inflammatory activity, direct plant extracts result in limited amounts
synthesis
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use of enzyme for construction of a system for producing unnatural flavonoids and stilbenes in Escherichia coli by expression of the respective genes on three plasmids. Incubation of the recombinant Escherichia coli with exogenously supplied carboxylic acids leads to production of 87 different polyketides, including 36 unnatural flavonoids and stilbenes
additional information
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down-regulation by RNAi results in flavone depleted roots; down-regulation by RNAi results in significantly reduced nodulation when inoculated with Sinorhizobium meliloti