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.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Arabidopsis / anatomy & histology
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Arabidopsis / enzymology*
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Arabidopsis / genetics
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Arabidopsis Proteins / chemistry
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Arabidopsis Proteins / genetics
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Arabidopsis Proteins / metabolism*
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Catalysis
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Cytochrome P-450 Enzyme System / chemistry
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Cytochrome P-450 Enzyme System / genetics
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Cytochrome P-450 Enzyme System / metabolism*
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Glucuronidase / analysis
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Indoles / chemistry
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Indoles / metabolism*
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Microsomes / metabolism
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Mixed Function Oxygenases / chemistry
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Mixed Function Oxygenases / genetics
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Mixed Function Oxygenases / metabolism*
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Mutation
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Phenotype
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Plant Leaves / anatomy & histology
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Plant Leaves / enzymology
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Plant Leaves / metabolism
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Plant Roots / anatomy & histology
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Plant Roots / enzymology
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Plant Roots / metabolism
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Plants, Genetically Modified / metabolism
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Recombinant Fusion Proteins / analysis
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Saccharomyces cerevisiae / genetics
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Thiazoles / chemistry
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Thiazoles / metabolism*
Substances
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Arabidopsis Proteins
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Indoles
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Recombinant Fusion Proteins
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Thiazoles
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camalexin
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dihydrocamelexic acid
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Cytochrome P-450 Enzyme System
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Mixed Function Oxygenases
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PAD3 protein, Arabidopsis
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Glucuronidase