title: CYP90A1/CPD, a brassinosteroid biosynthetic cytochrome P450 of Arabidopsis, catalyzes C-3 oxidation.
abstract: Brassinosteroids (BRs) are steroidal phytohormones that regulate plant growth and development. Whereas in Arabidopsis the network-like routes of BR biosynthesis have been elucidated in considerable detail, the roles of some of the biosynthetic enzymes and their participation in the different subpathways remained to be clarified. We investigated the function of the cytochrome P450 monooxygenase CYP90A1/CPD, which earlier had been proposed to act as a BR C-23 hydroxylase. Our GC-MS and genetic analyses demonstrated that the cpd mutation arrests BR synthesis upstream of the DET2-mediated 5α reduction step and that overexpression of the C-23 hydroxylase CYP90C1 does not alleviate BR deficiency in the cpd mutant. In line with these results, we found that CYP90A1/CPD heterologously expressed in a baculovirus-insect cell system catalyzes C-3 oxidation of the early BR intermediates (22S)-22-hydroxycampesterol and (22R,23R)-22,23-dihydroxycampesterol, as well as of 6-deoxocathasterone and 6-deoxoteasterone. Enzyme kinetic data of CYP90A1/CPD and DET2, together with those of the earlier studied CYP90B1, CYP90C1, and CYP90D1, suggest that BR biosynthesis proceeds mainly via the campestanol-independent pathway.
authors: Division of Global Research Leaders, Shizuoka University, Ohya, Suruga-ku, Shizuoka 422-8529, Japan. dtonish@ipc.shizuoka.ac.jp
authors: Toshiyuki
authors: T
authors: Ohnishi
authors: Blanka
authors: B
authors: Godza
authors: Bunta
authors: B
authors: Watanabe
authors: Shozo
authors: S
authors: Fujioka
authors: Lidia
authors: L
authors: Hategan
authors: Kouhei
authors: K
authors: Ide
authors: Kiyomi
authors: K
authors: Shibata
authors: Takao
authors: T
authors: Yokota
authors: Miklos
authors: M
authors: Szekeres
authors: Masaharu
authors: M
authors: Mizutani
mesh_terms: D000818:Animals; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D060406:Brassinosteroids / Q000096:biosynthesis* / Q000737:chemistry*; D002384:Catalysis; D002460:Cell Line; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D007700:Kinetics; D009154:Mutation; D010084:Oxidation-Reduction; D018411:Spodoptera; D013250:Steroid Hydroxylases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D060406:Brassinosteroids; D003577:Cytochrome P-450 Enzyme System; C500774:cytochrome P-450 90D1, Arabidopsis; C113844:CPD protein, Arabidopsis; C113876:ROT3 protein, Arabidopsis; D013250:Steroid Hydroxylases