Information on EC 2.3.1.216 - 5,7-dihydroxy-2-methylchromone synthase

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The expected taxonomic range for this enzyme is: Aloe arborescens

EC NUMBER
COMMENTARY hide
2.3.1.216
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RECOMMENDED NAME
GeneOntology No.
5,7-dihydroxy-2-methylchromone synthase
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REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
5 malonyl-CoA = 5 CoA + 5,7-dihydroxy-2-methyl-4H-chromen-4-one + 5 CO2 + H2O
show the reaction diagram
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REACTION TYPE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
C-6/C-1 Claisen-type cyclization
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PATHWAY
BRENDA Link
KEGG Link
MetaCyc Link
pentaketide chromone biosynthesis
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SYSTEMATIC NAME
IUBMB Comments
malonyl-CoA:malonyl-CoA malonyltransferase (5,7-dihydroxy-2-methyl-4H-chromen-4-one-forming)
A polyketide synthase from the plant Aloe arborescens (aloe).
ORGANISM
COMMENTARY hide
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
evolution
physiological function
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the plant-specific type III polyketide synthase that produces 5,7-dihydroxy-2-methylchromone from five molecules of malonyl-CoA. The aromatic pentaketide is a biosynthetic precursor of the anti-asthmatic furochromones kehellin and visnagin
additional information
SUBSTRATE
PRODUCT                       
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
5 malonyl-CoA
5 CoA + 5,7-dihydroxy-2-methyl-4H-chromen-4-one + 5 CO2 + H2O
show the reaction diagram
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?
additional information
?
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recombinant pentaketide chromone synthasedoes not produce chalcone from 4-coumaroyl-CoA, but instead efficiently accepts malonyl-CoA as a sole substrate to carry out iterative condensations of five molecules of malonyl-CoA, producing a pentaketide, 5,7-dihydroxy-2-methylchromone. Recombinant pentaketide chromone synthaseaccepts acetyl-CoA, resulting from decarboxylation of malonyl-CoA, as a starter substrate
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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
5 malonyl-CoA
5 CoA + 5,7-dihydroxy-2-methyl-4H-chromen-4-one + 5 CO2 + H2O
show the reaction diagram
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?
MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
44000
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x * 44000, about, sequence calculation
SUBUNITS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
?
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x * 44000, about, sequence calculation
homodimer
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crystal structure analysis, molecular replacement, structure comparison, overview
Crystallization/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
crystal structure analysis, molecular replacement
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purified detagged recombinant pentaketide chromone synthase, hanging drop vapour diffusion method, mixing of 500 nl of 10 mg/ml protein in 20 mM HEPES-NaOH, pH 7.0, containing 100 mM NaCl, and 2 mM DTT, with 500 nl reservoir solution containing 100 mM Tris-HCl, pH 8.5, 14% w/v PEG 8000, and 350 mM KF, 20°C, 2 days, X-ray diffraction structure determination and analysis at 1.6 A resolution
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Purification/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
recombinant N-terminally GST-tagged pentaketide chromone synthase from Escherichia coli strain BL21(DE3) by glutathione affinity chromatography, removal of the GST-tag, anion exchange chromatography, and gel filtration to homogeneity
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Cloned/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
DNA and amino acid sequence determination and analysis, sequence comparison and phylogenetic analysis
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expression of N-terminally GST-tagged pentaketide chromone synthase in Escherichia coli strain BL21(DE3)
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ENGINEERING
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
F80A/Y82A/M207G
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site-directed mutagenesis, the total cavity volume of the F80A/Y82A/M207G triple mutant is 4fold larger than that of the wild-type pentaketide chromone synthase. The mutant not only catalyzes the iterative condensation of nine molecules of malonyl-CoA, to produce anovel nonaketide naphthopyrone, but also alters the mechanism of the cyclization to produce the angular naphthopyrone with a fused tricyclic ring system
M197G
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site-directed mutagenesis, the mutant enzyme shows altered activity compared to the wild-type enzyme producing SEK4/SEK4b like oktaketide synthase
M207G/N218A
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site-directed mutagenesis, the mutant enzyme, in contrast to the wild-type, efficiently catalyzes the successive condensation of eight molecules of malonyl-CoA to produce SEK4 and SEK4b. The pentaketide-forming pentaketide chromone synthase is thus functionally transformed into an octaketide-producing enzyme by the single amino-acid substitution, the mutant performs a C-10/C-15 aldol-type cyclization reaction, the double mutant is almost functionally identical to the single mutant M207G
M207G/N218D
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site-directed mutagenesis, the mutant enzyme, in contrast to the wild-type, efficiently catalyzes the successive condensation of eight molecules of malonyl-CoA to produce SEK4 and SEK4b. The pentaketide-forming pentaketide chromone synthase is thus functionally transformed into an octaketide-producing enzyme by the single amino-acid substitution, the mutant performs a C-10/C-15 aldol-type cyclization reaction, the double mutant is almost functionally identical to the single mutant M207G
M207G/N218E
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site-directed mutagenesis, the mutant enzyme, in contrast to the wild-type, efficiently catalyzes the successive condensation of eight molecules of malonyl-CoA to produce SEK4 and SEK4b. The pentaketide-forming pentaketide chromone synthase is thus functionally transformed into an octaketide-producing enzyme by the single amino-acid substitution, the mutant performs a C-10/C-15 aldol-type cyclization reaction, the double mutant is almost functionally identical to the single mutant M207G
M207G/N218K
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site-directed mutagenesis, the mutant enzyme, in contrast to the wild-type, efficiently catalyzes the successive condensation of eight molecules of malonyl-CoA to produce SEK4 and SEK4b. The pentaketide-forming pentaketide chromone synthase is thus functionally transformed into an octaketide-producing enzyme by the single amino-acid substitution, the mutant performs a C-10/C-15 aldol-type cyclization reaction, the double mutant is almost functionally identical to the single mutant M207G
M207G/N218Q
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site-directed mutagenesis, the mutant enzyme, in contrast to the wild-type, efficiently catalyzes the successive condensation of eight molecules of malonyl-CoA to produce SEK4 and SEK4b. The pentaketide-forming pentaketide chromone synthase is thus functionally transformed into an octaketide-producing enzyme by the single amino-acid substitution, the mutant performs a C-10/C-15 aldol-type cyclization reaction, the double mutant is almost functionally identical to the single mutant M207G
additional information
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oktaketide synthase, EC 2.3.1.-, and pentaketide chromone synthase, EC 2.3.1.216, are not functionally interconvertible by the single amino acid switch at residue 207
APPLICATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
molecular biology
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use of pentaketide chromone synthase for rational biosynthetic engineering to generate molecular diversity and pursue innovative, biologically potent compounds