title: CYP79F1 and CYP79F2 have distinct functions in the biosynthesis of aliphatic glucosinolates in Arabidopsis.
abstract: Cytochromes P450 of the CYP79 family catalyze the conversion of amino acids to oximes in the biosynthesis of glucosinolates, a group of natural plant products known to be involved in plant defense and as a source of flavor compounds, cancer-preventing agents and bioherbicides. We report a detailed biochemical analysis of the substrate specificity and kinetics of CYP79F1 and CYP79F2, two cytochromes P450 involved in the biosynthesis of aliphatic glucosinolates in Arabidopsis thaliana. Using recombinant CYP79F1 and CYP79F2 expressed in Escherichia coli and Saccharomyces cerevisiae, respectively, we show that CYP79F1 metabolizes mono- to hexahomomethionine, resulting in both short- and long-chain aliphatic glucosinolates. In contrast, CYP79F2 exclusively metabolizes long-chain elongated penta- and hexahomomethionines. CYP79F1 and CYP79F2 are spatially and developmentally regulated, with different gene expression patterns. CYP79F2 is highly expressed in hypocotyl and roots, whereas CYP79F1 is strongly expressed in cotyledons, rosette leaves, stems, and siliques. A transposon-tagged CYP79F1 knockout mutant completely lacks short-chain aliphatic glucosinolates, but has an increased level of long-chain aliphatic glucosinolates, especially in leaves and seeds. The level of long-chain aliphatic glucosinolates in a transposon-tagged CYP79F2 knockout mutant is substantially reduced, whereas the level of short-chain aliphatic glucosinolates is not affected. Biochemical characterization of CYP79F1 and CYP79F2, and gene expression analysis, combined with glucosinolate profiling of knockout mutants demonstrate the functional role of these enzymes. This provides valuable insights into the metabolic network leading to the biosynthesis of aliphatic glucosinolates, and into metabolic engineering of altered aliphatic glucosinolate profiles to improve nutritional value and pest resistance.
authors.affiliation: Plant Biochemistry Laboratory, Department of Plant Biology, The Royal Veterinary and Agricultural University, Copenhagen, Denmark.
authors.forename: Sixue
authors.initials: S
authors.lastname: Chen
authors.forename: Erich
authors.initials: E
authors.lastname: Glawischnig
authors.forename: Kirsten
authors.initials: K
authors.lastname: Jørgensen
authors.forename: Peter
authors.initials: P
authors.lastname: Naur
authors.forename: Bodil
authors.initials: B
authors.lastname: Jørgensen
authors.forename: Carl-Erik
authors.initials: CE
authors.lastname: Olsen
authors.forename: Carsten H
authors.initials: CH
authors.lastname: Hansen
authors.forename: Hasse
authors.initials: H
authors.lastname: Rasmussen
authors.forename: John A
authors.initials: JA
authors.lastname: Pickett
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Halkier
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D003001:Cloning, Molecular; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli; D017353:Gene Deletion; D020869:Gene Expression Profiling; D005961:Glucosinolates / Q000096:biosynthesis*; D008969:Molecular Sequence Data; D010641:Phenotype; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae; D013379:Substrate Specificity
chemical_list: D005961:Glucosinolates; D012333:RNA, Messenger; D003577:Cytochrome P-450 Enzyme System