Abstract
Aurones are plant flavonoids that provide yellow color to the flowers of some popular ornamental plants, such as snapdragon and cosmos. In this study, we have identified an enzyme responsible for the synthesis of aurone from chalcones in the yellow snapdragon flower. The enzyme (aureusidin synthase) is a 39-kilodalton, copper-containing glycoprotein catalyzing the hydroxylation and/or oxidative cyclization of the precursor chalcones, 2',4',6',4-tetrahydroxychalcone and 2',4',6',3,4-pentahydroxychalcone. The complementary DNA encoding aureusidin synthase is expressed in the petals of aurone-containing varieties. DNA sequence analysis revealed that aureusidin synthase belongs to the plant polyphenol oxidase family, providing an unequivocal example of the function of the polyphenol oxidase homolog in plants, i.e., flower coloration.
MeSH terms
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Amino Acid Sequence
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Benzofurans / metabolism*
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Catalysis
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Catechol Oxidase / chemistry
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Catechol Oxidase / metabolism
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Cyclization
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DNA, Complementary
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Enzyme Precursors / chemistry
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Enzyme Precursors / genetics
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Enzyme Precursors / isolation & purification
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Enzyme Precursors / metabolism
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Genes, Plant
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Hydroxylation
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Magnoliopsida / enzymology*
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Magnoliopsida / genetics
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Mixed Function Oxygenases / chemistry
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Mixed Function Oxygenases / genetics
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Mixed Function Oxygenases / isolation & purification
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Mixed Function Oxygenases / metabolism
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Molecular Sequence Data
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Molecular Weight
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Pigmentation
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Plant Structures / enzymology
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Plants / enzymology
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Sequence Homology, Amino Acid
Substances
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Benzofurans
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DNA, Complementary
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Enzyme Precursors
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aureusidin
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Mixed Function Oxygenases
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aureusidin synthase
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aureusidin synthase precursor
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Catechol Oxidase