title: Molecular characterization of the enzyme catalyzing the aryl migration reaction of isoflavonoid biosynthesis in soybean.
abstract: The first specific reaction in the biosynthesis of isoflavonoid compounds in plants is the 2-hydroxylation, coupled to aryl migration, of a flavanone. Using a functional genomics approach, we have characterized a cDNA encoding a 2-hydroxyisoflavanone synthase from soybean (Glycine max). Microsomes isolated from insect cells expressing this cytochrome P450 from a baculovirus vector convert 4', 7-dihydroxyflavanone (liquiritigenin) to 4',7-dihydroxyisoflavone (daidzein), most likely via 2,4',7-trihydroxyisoflavanone which spontaneously dehydrates to daidzein. The enzyme also converts naringenin (4',5,7-trihydroxyflavanone) to genistein, but at a lower rate. 2-Hydroxyisoflavanone synthase transcripts are strongly induced in alfalfa cell suspensions in response to elicitation.
authors.affiliation: Plant Biology Division, Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, Oklahoma, 73401, USA.
authors.forename: C L
authors.initials: CL
authors.lastname: Steele
authors.forename: M
authors.initials: M
authors.lastname: Gijzen
authors.forename: D
authors.initials: D
authors.lastname: Qutob
authors.forename: R A
authors.initials: RA
authors.lastname: Dixon
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D020224:Expressed Sequence Tags; D044950:Flavanones; D005419:Flavonoids / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D019833:Genistein / Q000378:metabolism; D006900:Hydroxylation; D007313:Insecta / Q000166:cytology / Q000235:genetics; D007529:Isoflavones / Q000378:metabolism*; D007700:Kinetics; D000455:Medicago sativa / Q000166:cytology / Q000201:enzymology / Q000235:genetics; D008861:Microsomes / Q000201:enzymology / Q000378:metabolism; D008969:Molecular Sequence Data; D010105:Oxygenases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000378:metabolism; D013025:Glycine max / Q000166:cytology / Q000201:enzymology* / Q000235:genetics
chemical_list: D044950:Flavanones; D005419:Flavonoids; D007529:Isoflavones; D011994:Recombinant Proteins; C065753:isoflavanone; C004742:daidzein; D019833:Genistein; D010105:Oxygenases; C048489:isoflavone synthase; C005273:naringenin; C083152:liquiritigenin