title: CYP83b1 is the oxime-metabolizing enzyme in the glucosinolate pathway in Arabidopsis.
abstract: CYP83B1 from Arabidopsis thaliana has been identified as the oxime-metabolizing enzyme in the biosynthetic pathway of glucosinolates. Biosynthetically active microsomes isolated from Sinapis alba converted p-hydroxyphenylacetaldoxime and cysteine into S-alkylated p-hydroxyphenylacetothiohydroximate, S-(p-hydroxyphenylacetohydroximoyl)-l-cysteine, the next proposed intermediate in the glucosinolate pathway. The production was shown to be dependent on a cytochrome P450 monooxygenase. We searched the genome of A. thaliana for homologues of CYP71E1 (P450ox), the only known oxime-metabolizing enzyme in the biosynthetic pathway of the evolutionarily related cyanogenic glucosides. By a combined use of bioinformatics, published expression data, and knock-out phenotypes, we identified the cytochrome P450 CYP83B1 as the oxime-metabolizing enzyme in the glucosinolate pathway as evidenced by characterization of the recombinant protein expressed in Escherichia coli. The data are consistent with the hypothesis that the oxime-metabolizing enzyme in the cyanogenic pathway (P450ox) was mutated into a "P450mox" that converted oximes into toxic compounds that the plant detoxified into glucosinolates.
authors.affiliation: Plant Biochemistry Laboratory, The Royal Veterinary and Agricultural University, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark.
authors.forename: C H
authors.initials: CH
authors.lastname: Hansen
authors.forename: L
authors.initials: L
authors.lastname: Du
authors.forename: P
authors.initials: P
authors.lastname: Naur
authors.forename: C E
authors.initials: CE
authors.lastname: Olsen
authors.forename: K B
authors.initials: KB
authors.lastname: Axelsen
authors.forename: A J
authors.initials: AJ
authors.lastname: Hick
authors.forename: J A
authors.initials: JA
authors.lastname: Pickett
authors.forename: B A
authors.initials: BA
authors.lastname: Halkier
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins; D003545:Cysteine / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D004926:Escherichia coli; D018745:Genome, Plant; D005960:Glucosides / Q000378:metabolism; D005961:Glucosinolates / Q000378:metabolism*; D008861:Microsomes / Q000201:enzymology; D009149:Mustard Plant / Q000201:enzymology; D010091:Oximes / Q000378:metabolism*; D010105:Oxygenases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D010641:Phenotype; D010802:Phylogeny; D010946:Plants, Medicinal
chemical_list: D029681:Arabidopsis Proteins; D005960:Glucosides; D005961:Glucosinolates; D010091:Oximes; C010519:thiohydroximic acid ester; D003577:Cytochrome P-450 Enzyme System; D010105:Oxygenases; C431937:CYP83B1 protein, Arabidopsis; C110889:cytochrome P-450 CYP71E1 (sorghum); D003545:Cysteine