CYP98A3 from Arabidopsis thaliana Is a 3′-Hydroxylase of Phenolic Esters, a Missing Link in the Phenylpropanoid Pathway

Guillaume Schoch (1) , Simon Goepfert (1) , Marc Morant (1) , Alain Hehn (1) , Denise Meyer (1) , Pascaline Ullmann (1) , Daniele Werck-Reichhart (1)

1 IBMP - Institut de Biologie Moléculaire des Plantes

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 (+)-columbianetin 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 Km of 2.1 ± 0.4 μM for (+)-columbianetin and a kcat 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.

Domaines: Biologie moléculaire; Biochimie [q-bio.BM]; Botanique

Guillaume Schoch, Simon Goepfert, Marc Morant, Alain Hehn, Denise Meyer, et al.. CYP98A3 from Arabidopsis thaliana Is a 3′-Hydroxylase of Phenolic Esters, a Missing Link in the Phenylpropanoid Pathway. Journal of Biological Chemistry, 2001, 276 (39), pp.36566-36574. ⟨10.1074/jbc.M104047200⟩. ⟨hal-01738074⟩