Publications

• Missing enzymes in the biosynthesis of the anticancer drug vinblastine in Madagascar periwinkle.

  Caputi L., Franke J., Farrow S.C., Chung K., Payne R.M.E., Nguyen T.-D., Dang T.-T.T., Soares Teto Carqueijeiro I., Koudounas K., Duge de Bernonville T., Ameyaw B., Jones D.M., Vieira I.J.C., Courdavault V., O'Connor S.E.

  Vinblastine, a potent anticancer drug, is produced by <i>Catharanthus roseus</i> (Madagascar periwinkle) in small quantities, and heterologous reconstitution of vinblastine biosynthesis could provide an additional source of this drug. However, the chemistry underlying vinblastine synthesis makes i ... >> More

  Vinblastine, a potent anticancer drug, is produced by <i>Catharanthus roseus</i> (Madagascar periwinkle) in small quantities, and heterologous reconstitution of vinblastine biosynthesis could provide an additional source of this drug. However, the chemistry underlying vinblastine synthesis makes identification of the biosynthetic genes challenging. Here we identify the two missing enzymes necessary for vinblastine biosynthesis in this plant: an oxidase and a reductase that isomerize stemmadenine acetate into dihydroprecondylocarpine acetate, which is then deacetoxylated and cyclized to either catharanthine or tabersonine via two hydrolases characterized herein. The pathways show how plants create chemical diversity and also enable development of heterologous platforms for generation of stemmadenine-derived bioactive compounds. << Less

  Science 360:1235-1239(2018) [PubMed] [EuropePMC]

  This publication is cited by 7 other entries.

• Structural basis of cycloaddition in biosynthesis of iboga and aspidosperma alkaloids.

  Caputi L., Franke J., Bussey K., Farrow S.C., Vieira I.J.C., Stevenson C.E.M., Lawson D.M., O'Connor S.E.

  Cycloaddition reactions generate chemical complexity in a single step. Here we report the crystal structures of three homologous plant-derived cyclases involved in the biosynthesis of iboga and aspidosperma alkaloids. These enzymes act on the same substrate, named angryline, to generate three dist ... >> More

  Cycloaddition reactions generate chemical complexity in a single step. Here we report the crystal structures of three homologous plant-derived cyclases involved in the biosynthesis of iboga and aspidosperma alkaloids. These enzymes act on the same substrate, named angryline, to generate three distinct scaffolds. Mutational analysis reveals how these highly similar enzymes control regio- and stereo-selectivity. << Less

  Nat. Chem. Biol. 16:383-386(2020) [PubMed] [EuropePMC]

  This publication is cited by 5 other entries.

• Evolution and diversification of carboxylesterase-like [4+2] cyclases in aspidosperma and iboga alkaloid biosynthesis.

  DeMars M.D. II, O'Connor S.E.

  Monoterpene indole alkaloids (MIAs) are a large and diverse class of plant natural products, and their biosynthetic construction has been a subject of intensive study for many years. The enzymatic basis for the production of aspidosperma and iboga alkaloids, which are produced exclusively by membe ... >> More

  Monoterpene indole alkaloids (MIAs) are a large and diverse class of plant natural products, and their biosynthetic construction has been a subject of intensive study for many years. The enzymatic basis for the production of aspidosperma and iboga alkaloids, which are produced exclusively by members of the Apocynaceae plant family, has recently been discovered. Three carboxylesterase (CXE)-like enzymes from <i>Catharanthus roseus</i> and <i>Tabernanthe iboga</i> catalyze regio- and enantiodivergent [4+2] cycloaddition reactions to generate the aspidosperma (tabersonine synthase, TS) and iboga (coronaridine synthase, CorS; catharanthine synthase, CS) scaffolds from a common biosynthetic intermediate. Here, we use a combined phylogenetic and biochemical approach to investigate the evolution and functional diversification of these cyclase enzymes. Through ancestral sequence reconstruction, we provide evidence for initial evolution of TS from an ancestral CXE followed by emergence of CorS in two separate lineages, leading in turn to CS exclusively in the <i>Catharanthus</i> genus. This progression from aspidosperma to iboga alkaloid biosynthesis is consistent with the chemotaxonomic distribution of these MIAs. We subsequently generate and test a panel of chimeras based on the ancestral cyclases to probe the molecular basis for differential cyclization activity. Finally, we show through partial heterologous reconstitution of tabersonine biosynthesis using non-pathway enzymes how aspidosperma alkaloids could have first appeared as "underground metabolites" via recruitment of promiscuous enzymes from common protein families. Our results provide insight into the evolution of biosynthetic enzymes and how new secondary metabolic pathways can emerge through small but important sequence changes following co-option of preexisting enzymatic functions. << Less

  Proc. Natl. Acad. Sci. U.S.A. 121:e2318586121-e2318586121(2024) [PubMed] [EuropePMC]

  This publication is cited by 5 other entries.