Characterization and Functional Identification of a Novel Plant 4,5-Extradiol Dioxygenase Involved in Betalain Pigment Biosynthesis in Portulaca grandiflora

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Etat: Public
Version: Final published version
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ID Serval
serval:BIB_14E51F606B66
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Institution
Titre
Characterization and Functional Identification of a Novel Plant 4,5-Extradiol Dioxygenase Involved in Betalain Pigment Biosynthesis in Portulaca grandiflora
Périodique
Plant Physiology
Auteur⸱e⸱s
Christinet Laurent, Burdet Frédéric X., Zaiko Maïa, Hinz Ursula, Zrÿd Jean-Pierre
Statut éditorial
Publié
Date de publication
2004
Peer-reviewed
Oui
Volume
134
Numéro
1
Pages
265-274
Langue
anglais
Résumé
Betalains are pigments that replace anthocyanins in the majority of families of the plant order Caryophyllales. Betalamic acid is the common chromophore of betalains. The key enzyme of the betalain biosynthetic pathway is an extradiol dioxygenase that opens the cyclic ring of dihydroxy-phenylalanine (DOPA) between carbons 4 and 5, thus producing an unstable seco-DOPA that rearranges nonenzymatically to betalamic acid. A gene for a 4,5-DOPA-dioxygenase has already been isolated from the fungus Amanita muscaria, but no homolog was ever found in plants. To identify the plant gene, we constructed subtractive libraries between different colored phenotypes of isogenic lines of Portulaca grandiflora (Portulacaceae) and between different stages of flower bud formation. Using in silico analysis of differentially expressed cDNAs, we identified a candidate showing strong homology at the level of translated protein with the LigB domain present in several bacterial extradiol 4,5-dioxygenases. The gene was expressed only in colored flower petals. The function of this gene in the betalain biosynthetic pathway was confirmed by biolistic genetic complementation in white petals of P. grandiflora genotypes lacking the gene for color formation. This gene named DODA is the first characterized member of a novel family of plant dioxygenases phylogenetically distinct from Amanita sp. DOPA-dioxygenase. Homologs of DODA are present not only in betalain-producing plants but also, albeit with some changes near the catalytic site, in other angiosperms and in the bryophyte Physcomitrella patens. These homologs are part of a novel conserved plant gene family probably involved in aromatic compound metabolism.
Mots-clé
betalains DOPA dioxygenase
Pubmed
Création de la notice
12/07/2009 16:21
Dernière modification de la notice
21/11/2022 8:30
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