Information on EC 1.3.5.B4 - beta-carotene monoketolase

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

EC NUMBER
COMMENTARY hide
1.3.5.B4
preliminary BRENDA-supplied EC number
RECOMMENDED NAME
GeneOntology No.
beta-carotene monoketolase
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REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
beta-carotene + benzoquinone + H2O = echinenone + benzoquinol + 2 H+
show the reaction diagram
SYSTEMATIC NAME
IUBMB Comments
beta-carotene:benzoquinone 4-oxidoreductase
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ORGANISM
COMMENTARY hide
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
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UniProt
Manually annotated by BRENDA team
Haematococcus pluvialis
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Manually annotated by BRENDA team
three functional beta-carotene ketolase genes: one of the crtO and two of the crtW type
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Manually annotated by BRENDA team
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
metabolism
physiological function
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carotenoid composition and their formation under high light conditions, the contribution of the ketolase genes, crtO and two copies of crtW to ketocarotenoid synthesis and their lightdependent regulation
SUBSTRATE
PRODUCT                       
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
beta-carotene + 2 O2
canthaxanthin + 2 H2O
show the reaction diagram
beta-carotene + acceptor + H2O
echineneone + reduced acceptor
show the reaction diagram
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major product
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?
beta-carotene + benzoquinone + H2O
echinenone + benzoquinol + 2 H+
show the reaction diagram
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?
beta-carotene + NADPH + O2
echinenone + NADP+ + H2O
show the reaction diagram
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?
beta-carotene + O2
echinenone + H2O
show the reaction diagram
echineneone + acceptor + H2O
canthaxanthin + reduced acceptor
show the reaction diagram
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minor product, produced after prolonged incubation
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echinenone + benzoquinone + H2O
canthxanthin + benzoquinol + 2 H+
show the reaction diagram
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-
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?
zeaxanthin + O2
adonixanthin + H2O
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
beta-carotene + benzoquinone + H2O
echinenone + benzoquinol + 2 H+
show the reaction diagram
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?
additional information
?
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the one crtO and two crtW type beta-carotene ketolases are all functional in inserting 4-keto groups into beta-carotene as shown by functional pathway complementation in Escherichia coli. They all synthesize canthaxanthin but with different efficiencies
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COFACTOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
benzoquinone
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The addition of plastoquinoe, ubiquinone FAD, NADH, NADPH does not increase the activity.
NADPH
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other cofactors not tested
additional information
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the addition of NAPH, NADH or FAD to the crude reaction mixture does not increase the reaction rate
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INHIBITORS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
Diphenylamine
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KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.041
beta-carotene
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28C, pH 7.8
0.035
echinenone
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28C, pH 7.8
IC50 VALUE [mM]
INHIBITOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.405
Diphenylamine
Synechocystis sp.
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28C, pH 7.8
MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
61000
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SDS-PAGE
Purification/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
cobalt chelate affinity chromatograpy
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Cloned/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
expressed in Escherichia coli
genes crtO, crtW38, and crtW148, the ketolase genes crtW38 and crtW148 from Nostoc PCC 73102 are highly homologous with a similarity of 73%., functional expression and pathway complementation in Escherichia coli strain DH5alpha expressing a second plasmid generating either a beta-carotene or a zeaxanthin background
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overexpression in Arabidopsis thaliana using a double CaMV35S-bkt1 ketolase construct, individual co-expression with different Arabidopsis thaliana beta-carotene hydroxylases, i.e. AtB, CYP97A3, CYP97B3, and CYP97C1, under the control of a double CaMV35S promoter. Hydroxylase overexpression in combination with beta-carotene ketolase does not result in keto-carotenoid accumulation, but in unexpected patterns of alpha-carotene derivatives, accompanied by a reduction of alpha-carotene, instead, overview
Haematococcus pluvialis
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EXPRESSION
ORGANISM
UNIPROT
LITERATURE
downregulation of the crtO gene and the second crtW gene under high-light stress
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upregulation of gene crtW148 by high-light stress, enhancing anthaxanthin production
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