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Article Dans Une Revue Journal of Biological Chemistry Année : 2009

Isolation and Functional Characterization of CYP71AJ4 Encoding for the First P450 Monooxygenase of Angular Furanocoumarin Biosynthesis

Résumé

The biosynthesis of linear and angular furanocoumarins is still poorly understood at the molecular level, with only psoralen synthase (CYP71AJ1) identified from Ammi majus. Using cDNA probes inferred from CYP71AJ1, three orthologs were isolated from Apium graveolens (CYP71AJ2) and Pastinaca sativa (CYP71AJ3 and-4) and functionally expressed in yeast cells. CYP71AJ2 and CYP71AJ3 displayed psoralen synthase activity, whereas CYP71AJ4 only catalyzed the conversion of ()-colum-bianetin to angelicin and negligible amounts of a hydroxylated columbianetin by-product. CYP71AJ4 thus constitutes the first fully characterized P450 monooxygenase specific for the angular furanocoumarin pathway. The angelicin synthase exhibited an apparent K m of 2.1 0.4 M for ()-columbianetin and a k cat of 112 14 min 1. Moreover, the use of 3-deuterated ()-columbianetin as substrate led to an almost complete " metabolic switch, " resulting in the synthesis of anti-3-hydroxy-3-deuterated()-columbianetin. This confirms that angelicin synthase attacks columbianetin by syn-elimination of hydrogen from C-3. Sequence comparison between psoralen synthase (CYP71AJ3) and angelicin synthase (CYP71AJ4) showed 70% identity, whereas the identity dropped to 40% in those regions thought to provide the substrate recognition sites. Accordingly, CYP71AJ3 and CYP71AJ4 might be derived from a common ancestor of unknown functionality by gene duplication and subsequent molecular evolution. Furanocoumarins are natural plant metabolites characterized by a furane moiety fused to benzopyran-2-one. The position of the furane substitution distinguishes two large groups of compounds, the linear (psoralens) and the angular furanocou-marins (angelicin and derivatives) (Fig.
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hal-01738063 , version 1 (20-03-2018)

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Romain Larbat, Alain Hehn, Joachim Hans, Sarah Schneider, Hélène Jugdé, et al.. Isolation and Functional Characterization of CYP71AJ4 Encoding for the First P450 Monooxygenase of Angular Furanocoumarin Biosynthesis. Journal of Biological Chemistry, 2009, 284 (8), pp.4776-4785. ⟨10.1074/jbc.M807351200⟩. ⟨hal-01738063⟩
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