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CYP79 P450 monooxygenases in gymnosperms: CYP79A118 is associated with the formation of taxiphyllin in Taxus baccata
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Cyanogenic glycosides are secondary plant compounds that are widespread in the plant kingdom. Their biosynthesis starts with the conversion of aromatic or aliphatic amino acids into their respective aldoximes, catalysed by N-hydroxylating cytochrome P450 monooxygenases (CYP) of the CYP79 family. While CYP79s are well known in
angiosperms, their occurrence in gymnosperms and other plant divisions containing cyanogenic glycoside-producing
plants has not been reported so far. We screened the transcriptomes of 72 conifer species to identify putative CYP79 genes in this plant division. From the seven resulting fulllength genes, CYP79A118 from European yew (Taxus baccata) was chosen for further characterization. Recombinant CYP79A118 produced in yeast was able to convert l-tyrosine, l-tryptophan, and l-phenylalanine into p-hydroxyphenylacetaldoxime,
indole-3-acetaldoxime, and henylacetaldoxime, respectively. However, the kinetic parameters of the enzyme and transient expression of CYP79A118 in Nicotiana benthamiana indicate that l-tyrosine is the preferred substrate in vivo. Consistent with these findings, taxiphyllin,
which is derived from l-tyrosine, was the only cyanogenic glycoside found in the different organs of T. baccata. Taxiphyllin showed highest accumulation in leaves and twigs,
moderate accumulation in roots, and only trace accumulation in seeds and the aril. Quantitative real-time PCR revealed
that CYP79A118 was expressed in plant organs rich in taxiphyllin. Our data show that CYP79s represent an ancient -
- Date created
- 2017-08-02
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- Subjects / Keywords
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- Type of Item
- Article (Published)
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- License
- Attribution 4.0 International