title: CYP71B15 (PAD3) catalyzes the final step in camalexin biosynthesis.
abstract: Camalexin represents the main phytoalexin in Arabidopsis (Arabidopsis thaliana). The camalexin-deficient phytoalexin deficient 3 (pad3) mutant has been widely used to assess the biological role of camalexin, although the exact substrate of the cytochrome P450 enzyme 71B15 encoded by PAD3 remained elusive. 2-(Indol-3-yl)-4,5-dihydro-1,3-thiazole-4-carboxylic acid (dihydrocamalexic acid) was identified as likely intermediate in camalexin biosynthesis downstream of indole-3-acetaldoxime, as it accumulated in leaves of silver nitrate-induced pad3 mutant plants and it complemented the camalexin-deficient phenotype of a cyp79b2/cyp79b3 double-knockout mutant. Recombinant CYP71B15 heterologously expressed in yeast catalyzed the conversion of dihydrocamalexic acid to camalexin with preference of the (S)-enantiomer. Arabidopsis microsomes isolated from leaves of CYP71B15-overexpressing and induced wild-type plants were capable of the same reaction but not microsomes from induced leaves of pad3 mutants. In conclusion, CYP71B15 catalyzes the final step in camalexin biosynthesis.
authors.affiliation: Lehrstuhl für Genetik, Technische Universität München, D-85350 Freising, Germany.
authors.forename: Regina
authors.initials: R
authors.lastname: Schuhegger
authors.forename: Majse
authors.initials: M
authors.lastname: Nafisi
authors.forename: Madina
authors.initials: M
authors.lastname: Mansourova
authors.forename: Bent Larsen
authors.initials: BL
authors.lastname: Petersen
authors.forename: Carl Erik
authors.initials: CE
authors.lastname: Olsen
authors.forename: Ales
authors.initials: A
authors.lastname: Svatos
authors.forename: Barbara Ann
authors.initials: BA
authors.lastname: Halkier
authors.forename: Erich
authors.initials: E
authors.lastname: Glawischnig
mesh_terms: D017360:Arabidopsis / Q000033:anatomy & histology / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002384:Catalysis; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005966:Glucuronidase / Q000032:analysis; D007211:Indoles / Q000737:chemistry / Q000378:metabolism*; D008861:Microsomes / Q000378:metabolism; D006899:Mixed Function Oxygenases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D010641:Phenotype; D018515:Plant Leaves / Q000033:anatomy & histology / Q000201:enzymology / Q000378:metabolism; D018517:Plant Roots / Q000033:anatomy & histology / Q000201:enzymology / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000032:analysis; D012441:Saccharomyces cerevisiae / Q000235:genetics; D013844:Thiazoles / Q000737:chemistry / Q000378:metabolism*; D000094162:Phytoalexins
chemical_list: D029681:Arabidopsis Proteins; D003577:Cytochrome P-450 Enzyme System; D005966:Glucuronidase; D007211:Indoles; D006899:Mixed Function Oxygenases; D011993:Recombinant Fusion Proteins; D013844:Thiazoles; C102405:camalexin; D000094162:Phytoalexins; C514755:dihydrocamelexic acid; C417307:PAD3 protein, Arabidopsis