title: A novel cinnamyl alcohol dehydrogenase (CAD)-like reductase contributes to the structural diversity of monoterpenoid indole alkaloids in Rauvolfia.
abstract: Based on findings described herein, we contend that the reduction of vomilenine en route to antiarrhythmic ajmaline in planta might proceed via an alternative, novel sequence of biosynthetic steps. In the genus Rauvolfia, monoterpenoid indole alkaloids (MIAs) are formed via complex biosynthetic sequences. Despite the wealth of information about the biochemistry and molecular genetics underlying these processes, many reaction steps involving oxygenases and oxidoreductases are still elusive. Here, we describe molecular cloning and characterization of three cinnamyl alcohol dehydrogenase (CAD)-like reductases from Rauvolfia serpentina cell culture and R. tetraphylla roots. Functional analysis of the recombinant proteins, with a set of MIAs as potential substrates, led to identification of one of the enzymes as a CAD, putatively involved in lignin formation. The two remaining reductases comprise isoenzymes derived from orthologous genes of the investigated alternative Rauvolfia species. Their catalytic activity consists of specific conversion of vomilenine to 19,20-dihydrovomilenine, thus proving their exclusive involvement in MIA biosynthesis. The obtained data suggest the existence of a previously unknown bypass in the biosynthetic route to ajmaline further expanding structural diversity within the MIA family of specialized plant metabolites.
authors.affiliation: Plant Biotechnology and Metabolic Engineering, Technische Universität Darmstadt, Schnittspahnstrasse 3-5, 64287, Darmstadt, Germany.
authors.forename: Marcus
authors.initials: M
authors.lastname: Geissler
authors.affiliation: Plant Biotechnology and Metabolic Engineering, Technische Universität Darmstadt, Schnittspahnstrasse 3-5, 64287, Darmstadt, Germany.
authors.forename: Marie
authors.initials: M
authors.lastname: Burghard
authors.affiliation: Plant Biotechnology and Metabolic Engineering, Technische Universität Darmstadt, Schnittspahnstrasse 3-5, 64287, Darmstadt, Germany.
authors.forename: Jascha
authors.initials: J
authors.lastname: Volk
authors.affiliation: Plant Biotechnology and Metabolic Engineering, Technische Universität Darmstadt, Schnittspahnstrasse 3-5, 64287, Darmstadt, Germany.
authors.forename: Agata
authors.initials: A
authors.lastname: Staniek
authors.affiliation: Plant Biotechnology and Metabolic Engineering, Technische Universität Darmstadt, Schnittspahnstrasse 3-5, 64287, Darmstadt, Germany. warzecha@bio.tu-darmstadt.de.
authors.forename: Heribert
authors.initials: H
authors.lastname: Warzecha
mesh_terms: D000429:Alcohol Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D020869:Gene Expression Profiling; D026121:Indole Alkaloids / Q000378:metabolism; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000201:enzymology / Q000235:genetics; D011926:Rauwolfia / Q000201:enzymology* / Q000235:genetics; D011994:Recombinant Proteins; D046948:Secologanin Tryptamine Alkaloids / Q000737:chemistry / Q000378:metabolism*; D016415:Sequence Alignment; D013379:Substrate Specificity
chemical_list: D018076:DNA, Complementary; D026121:Indole Alkaloids; D010940:Plant Proteins; D011994:Recombinant Proteins; D046948:Secologanin Tryptamine Alkaloids; C119909:vomilenine; D010088:Oxidoreductases; D000429:Alcohol Oxidoreductases; C018656:cinnamyl alcohol dehydrogenase
keywords: Indian snakeroot; Oxidoreductase; Plant specialized metabolism; Transcriptomics; Vomilenine