title: Cytochrome p450 CYP79F1 from arabidopsis catalyzes the conversion of dihomomethionine and trihomomethionine to the corresponding aldoximes in the biosynthesis of aliphatic glucosinolates.
abstract: Glucosinolates are natural plant products that have received rising attention due to their role in interactions between pests and crop plants and as chemical protectors against cancer. Glucosinolates are derived from amino acids and have aldoximes as intermediates. We report that cytochrome P450 CYP79F1 catalyzes aldoxime formation in the biosynthesis of aliphatic glucosinolates in Arabidopsis thaliana. Using recombinant CYP79F1 functionally expressed in Escherichia coli, we show that both dihomomethionine and trihomomethionine are metabolized by CYP79F1 resulting in the formation of 5-methylthiopentanaldoxime and 6-methylthiohexanaldoxime, respectively. 5-methylthiopentanaldoxime is the precursor of the major glucosinolates in leaves of A. thaliana, i.e. 4-methylthiobutylglucosinolate and 4-methylsulfinylbutylglucosinolate, and a variety of other glucosinolates in Brassica sp. Transgenic A. thaliana with cosuppression of CYP79F1 have a reduced content of aliphatic glucosinolates and a highly increased level of dihomomethionine and trihomomethionine. The transgenic plants have a morphological phenotype showing loss of apical dominance and formation of multiple axillary shoots. Our data provide the first evidence that a cytochrome P450 catalyzes the N-hydroxylation of chain-elongated methionine homologues to the corresponding aldoximes in the biosynthesis of aliphatic glucosinolates.
authors.affiliation: Plant Biochemistry Laboratory, Department of Plant Biology, Department of Chemistry, and Center for Molecular Plant Physiology (PlaCe), The Royal Veterinary and Agricultural University, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Copenhagen, Denmark.
authors.forename: C H
authors.initials: CH
authors.lastname: Hansen
authors.forename: U
authors.initials: U
authors.lastname: Wittstock
authors.forename: C E
authors.initials: CE
authors.lastname: Olsen
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 / Q000378:metabolism*; D002384:Catalysis; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D004926:Escherichia coli; D005961:Glucosinolates / Q000378:metabolism*; D008715:Methionine / Q000378:metabolism*; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D005961:Glucosinolates; D010940:Plant Proteins; D011994:Recombinant Proteins; D003577:Cytochrome P-450 Enzyme System; D008715:Methionine; D006899:Mixed Function Oxygenases; C089817:cytochrome P450TYR