title: Identification of a Noroxomaritidine Reductase with Amaryllidaceae Alkaloid Biosynthesis Related Activities.
abstract: Amaryllidaceae alkaloids are a large group of plant natural products with over 300 documented structures and diverse biological activities. Several groups of Amaryllidaceae alkaloids including the hemanthamine- and crinine-type alkaloids show promise as anticancer agents. Two reduction reactions are required for the production of these compounds: the reduction of norcraugsodine to norbelladine and the reduction of noroxomaritidine to normaritidine, with the enantiomer of noroxomaritidine dictating whether the derivatives will be the crinine-type or hemanthamine-type. It is also possible for the carbon-carbon double bond of noroxomaritidine to be reduced, forming the precursor for maritinamine or elwesine depending on the enantiomer reduced to an oxomaritinamine product. In this study, a short chain alcohol dehydrogenase/reductase that co-expresses with the previously discovered norbelladine 4'-O-methyltransferase from Narcissus sp. and Galanthus spp. was cloned and expressed in Escherichia coli Biochemical analyses and x-ray crystallography indicates that this protein functions as a noroxomaritidine reductase that forms oxomaritinamine from noroxomaritidine through a carbon-carbon double bond reduction. The enzyme also reduces norcraugsodine to norbelladine with a 400-fold lower specific activity. These studies identify a missing step in the biosynthesis of this pharmacologically important class of plant natural products.
authors.affiliation: From the Donald Danforth Plant Science Center, St. Louis, Missouri 63132 and the Department of Biology, Washington University in St. Louis, St. Louis, Missouri 63130.
authors.forename: Matthew B
authors.initials: MB
authors.lastname: Kilgore
authors.affiliation: the Department of Biology, Washington University in St. Louis, St. Louis, Missouri 63130.
authors.forename: Cynthia K
authors.initials: CK
authors.lastname: Holland
authors.affiliation: the Department of Biology, Washington University in St. Louis, St. Louis, Missouri 63130.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Jez
authors.affiliation: From the Donald Danforth Plant Science Center, St. Louis, Missouri 63132 and tmkutchan@danforthcenter.org.
authors.forename: Toni M
authors.initials: TM
authors.lastname: Kutchan
mesh_terms: D047151:Amaryllidaceae Alkaloids / Q000737:chemistry* / Q000378:metabolism; D027801:Galanthus / Q000201:enzymology* / Q000235:genetics; D031427:Narcissus / Q000201:enzymology* / Q000235:genetics; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D047151:Amaryllidaceae Alkaloids; D010940:Plant Proteins; D011994:Recombinant Proteins; D010088:Oxidoreductases
keywords: Amaryllidaceae alkaloids; crystal structure; enzyme structure; norbelladine; noroxomaritidine reductase; reductase; secondary metabolism; transcriptomics