title: Functional genomic analysis of alkaloid biosynthesis in Hyoscyamus niger reveals a cytochrome P450 involved in littorine rearrangement.
abstract: Tropane alkaloids are valuable pharmaceutical drugs derived from solanaceous plants such as Hyoscyamus niger (black henbane). The biosynthesis of these molecules, including the nature of the enigmatic rearrangement of (R)-littorine to (S)-hyoscyamine, is not completely understood. To test the hypothesis that a cytochrome P450 enzyme is involved in this rearrangement, we used virus-induced gene silencing to silence a cytochrome P450, CYP80F1, identified from H. niger roots by EST sequencing. Silencing CYP80F1 resulted in reduced hyoscyamine levels and the accumulation of littorine. Hyoscyamine was observed in CYP80F1-expressing tobacco hairy roots supplied with (R)-littorine. Expression in yeast confirmed that CYP80F1 catalyzes the oxidation of (R)-littorine with rearrangement to form hyoscyamine aldehyde, a putative precursor to hyoscyamine, and without rearrangement to form 3'-hydroxylittorine. Our data strongly support the involvement of CYP80F1 in the rearrangement of littorine to hyoscyamine.
authors.affiliation: Plant Biotechnology Institute, 110 Gymnasium Place, Saskatoon, Saskatchewan S7N OW9, Canada.
authors.forename: Rong
authors.initials: R
authors.lastname: Li
authors.forename: Darwin W
authors.initials: DW
authors.lastname: Reed
authors.forename: Enwu
authors.initials: E
authors.lastname: Liu
authors.forename: Jacek
authors.initials: J
authors.lastname: Nowak
authors.forename: Lawrence E
authors.initials: LE
authors.lastname: Pelcher
authors.forename: Jonathan E
authors.initials: JE
authors.lastname: Page
authors.forename: Patrick S
authors.initials: PS
authors.lastname: Covello
mesh_terms: D000470:Alkaloids / Q000096:biosynthesis*; D001286:Atropine Derivatives / Q000378:metabolism*; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism*; D018076:DNA, Complementary; D020224:Expressed Sequence Tags; D020868:Gene Silencing; D018745:Genome, Plant; D032304:Hyoscyamus / Q000235:genetics*; D008969:Molecular Sequence Data; D034622:RNA Interference; D012441:Saccharomyces cerevisiae / Q000235:genetics
chemical_list: D000470:Alkaloids; D001286:Atropine Derivatives; D018076:DNA, Complementary; C063158:littorine; D003577:Cytochrome P-450 Enzyme System