Functional characterization of CmCCD1, a carotenoid cleavage dioxygenase from melon

Orange-colored melon varieties contain both β-carotene and β-ionone, while pale green and white varieties have low to undetectable levels of both compounds. A melon carotenoid cleavage dioxygenase gene has been functionally characterized by overexpression in Escherichia coli strains previously engin...

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Bibliographic Details
Published in:Phytochemistry (Oxford) 2006-08, Vol.67 (15), p.1579-1589
Main Authors: Ibdah, Mwafaq, Azulay, Yaniv, Portnoy, Vitaly, Wasserman, Boris, Bar, Einat, Meir, Ayala, Burger, Yossi, Hirschberg, Joseph, Schaffer, Arthur A., Katzir, Nurit, Tadmor, Yaakov, Lewinsohn, Efraim
Format: Article
Language:English
Subjects:
Apocarotenoids
Base Sequence
beta-carotene
beta-ionone
Biological and medical sciences
caroteinoid cleavage dioxygenase
Carotenoid cleavage dioxygenase
Carotenoids
Carotenoids - metabolism
Chromatography, High Pressure Liquid
CmCCD1
Cucumis melo
Cucumis melo L
Cucurbitaceae
Cucurbitaceae - enzymology
Dioxygenases - genetics
Dioxygenases - metabolism
DNA Primers
enzyme activity
Enzymes
Escherichia coli
Escherichia coli - genetics
Expressed Sequence Tags
fruiting
fruits (plant anatomy)
Functional expression
Fundamental and applied biological sciences. Psychology
gene expression regulation
gene overexpression
Melon
melons
Metabolism
oxygenases
pigmentation
Plant physiology and development
plant pigments
recombinant fusion proteins
Recombinant Proteins - genetics
Recombinant Proteins - metabolism
Spectrophotometry, Ultraviolet
Substrate Specificity
volatile organic compounds
Volatilization
β-Carotene
β-Ionone
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Description
Summary:Orange-colored melon varieties contain both β-carotene and β-ionone, while pale green and white varieties have low to undetectable levels of both compounds. A melon carotenoid cleavage dioxygenase gene has been functionally characterized by overexpression in Escherichia coli strains previously engineered to produce different carotenoids, releasing their corresponding apocarotenoid derivatives. Carotenoids are nutritionally important tetraterpenoid pigments that upon oxidative cleavage give rise to apocarotenoid (norisoprene) aroma volatiles. β-Carotene is the predominant pigment in orange-fleshed melon ( Cucumis melo L.) varieties, reaching levels of up to 50 μg/g FW. Pale green and white cultivars have much lower levels (0–10 μg/g FW). In parallel, β-ionone, the 9,10 cleavage product of β-carotene, is present (12–33 ng/g FW) in orange-fleshed melon varieties that accumulate β-carotene, and in much lower levels (0–5 ng/g FW) in pale green and white fleshed varieties. A search for a gene putatively responsible for the cleavage of β-carotene into β-ionone was carried out in annotated melon fruit EST databases yielding a sequence ( CmCCD1) highly similar (84%) to other plant carotenoid cleavage dioxygenase genes. To test its function, the clone was overexpressed in Escherichia coli strains previously engineered to produce different carotenoids. We show here that the CmCCD1 gene product cleaves carotenoids at positions 9,10 and 9′,10′, generating geranylacetone from phytoene; pseudoionone from lycopene; β-ionone from β-carotene, as well as α-ionone and pseudoionone from δ-carotene. CmCCD1 gene expression is upregulated upon fruit development both in orange, pale-green and white melon varieties, despite the lack of apocarotenoid volatiles in the later. Thus, the accumulation of β-ionone in melon fruit is probably limited by the availability of carotenoid substrate.
ISSN:0031-9422
1873-3700
DOI:10.1016/j.phytochem.2006.02.009