Friday, 29 June 2018

Pulses raised as new study reveals secrets of the plant that keeps people calm Chemical secrets of a plant used throughout history for its calming effects have been revealed in new research. These new findings came from research into Indian Snakeroot (Rauwolfia serpentina) which has been used for millennia in South and South East-Asia as a tranquilizer. Calming influence - chemistry unlocked in Indian Snakeroot (Rauwolfia serpentina) The John Innes Centre team in the lab of Professor Sarah O’Connor followed clues from the recent past to identify the genetic networks behind a critical catalyst called a sarpagan bridge enzyme. This generates an important chemical link to medicinally useful compounds in Indian snakeroot and many other plants. Lead author of the paper Dr Thu Thuy Dang of the John Innes Centre said: “We set out to find the missing enzyme that catalyses this important reaction based on a 20-year-old clue from the literature. ”Thanks to the new advancements in bioinformatic and biological chemistry approaches, we were able to identify the missing gene that encodes the enzyme among thousands of other genes from the plant." The discovery of the new oxidative enzyme that catalyzes intriguing chemistry could deliver faster routes to treatments for abnormal heart rhythms, high blood pressure and some mental disorders. The study also found that the enzyme has an adaptable mechanism that could create a suite of structurally diverse chemical products. Prof. Sarah O’Connor added: “The discovery of the sarpagan bridge enzyme, together with other scaffold generator enzymes, will provide the parts necessary for assembling and engineering of metabolic pathways in organisms such as yeast or tobacco plants for mass production of pharmaceutically important compounds. We are currently collaborating with experts in synthetic biology and yeast engineering to push this forward.” Indian snakeroot is one of the 50 fundamental herbs used in traditional Chinese medicine, where it has the name shégēn mù (Chinese: 蛇根木) or yìndù shémù (Chinese: 印度蛇木). It produces approximately 150 monoterpene indole alkaloids such as reserpine, yohimbine, and raubasine. One of the best-known alkaloids in snakeroot is ajmaline, a class Ia antiarrhythmic agent often used in diagnosis of patients suspected of having Brugada syndrome, a condition that causes disruption to the heart's normal rhythm. In other findings the study showed that the sarpagan bridge enzyme bridges two carbon atoms, a reaction particularly challenging for synthetic organic chemists, and so creates the complex three-dimensional structures found in the many class of alkaloids. The study also demonstrated for the first time that the complex alkaloid vinorine can be produced in a different organism, requiring five enzymatic steps (including the newly discovered enzyme) from the readily available intermediate strictosidine. Ultimately, this approach might be used to produce strictosidine-derived drugs such as ajmaline, which is used to treat abnormal heart rhythms, more efficiently. Dr Jakob Franke said “The discovery highlights the versatility of this group of oxidative enzymes, which makes it a very useful biocatalyst and an excellent target for engineering these alkaloid pathways. We could use this enzyme to produce drugs in a much more elegant way than any synthetic chemist could.” The full paper can be found in Nature Chemical Biology Brief Communication | Published: 25 June 2018 Sarpagan bridge enzyme has substrate-controlled cyclization and aromatization modes Thu-Thuy T. Dang, Jakob Franke, Ines Soares Teto Carqueijeiro, Chloe Langley, Vincent Courdavault & Sarah E. O’Connor Nature Chemical Biology (2018) | Download Citation Abstract Cyclization reactions that create complex polycyclic scaffolds are hallmarks of alkaloid biosynthetic pathways. We present the discovery of three homologous cytochrome P450s from three monoterpene indole alkaloid-producing plants (Rauwolfia serpentina, Gelsemium sempervirens and Catharanthus roseus) that provide entry into two distinct alkaloid classes, the sarpagans and the β-carbolines. 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Paris-Sud) for their generous gift of polyneuridine aldehyde standard. Rauwolfia serpentina seeds were a generous gift from S. Hiremath, Karnataka University, India. D.-K. Ro (University of Calgary) generously provided pESC-Leu2d. Images of R. serpentina and C. roseus were provided by T. Nguyen (Ho Chi Minh City University of Science). We thank L. Caputi (John Innes Centre) for his assistance in building the homology model of CrAS and RsSBE and L. Hill and G. Saalbach of the Molecular Analysis platform at John Innes Centre for their assistance in metabolic analysis. We are grateful to D. Grzech for her assistance in cloning mutant constructs. We thank R. Hughes and M. Franceschetti (John Innes Centre) for preparing the modified TRBO vector. Author information Author notes These authors contributed equally: Thu-Thuy T. Dang, Jakob Franke. Affiliations John Innes Centre, Department of Biological Chemistry, Norwich Research Park, Norwich, UK Thu-Thuy T. Dang, Jakob Franke, Chloe Langley & Sarah E. O’Connor Université François-Rabelais de Tours, Biomolécules et Biotechnologies Végétales, Parc de Grandmont Tours, Tours, France Ines Soares Teto Carqueijeiro & Vincent Courdavault Contributions T.-T.T.D., J.F. and S.E.O. designed the experiments and wrote the manuscript. T.-T.T.D. characterized RsSBE, GsSBE and CrAS in vitro and in vivo, and performed in planta combinatorial assay and analysis. J.F. performed all substrate purification, synthesis and product characterizations. C.L. contributed to N. benthamiana work. I.S.T.C. and V.C. performed VIGS and localization experiments. Competing interests The authors declare no competing interests. Corresponding author Correspondence to Sarah E. O’Connor. Supplementary information Supplementary Text and Figures Supplementary Figures 1–12, Supplementary Tables 1–4 Reporting Summary Rights and permissions To obtain permission to re-use content from this article visit RightsLink. About this article Publication history Received 22 September 2017 Accepted 11 April 2018 Published 25 June 2018 DOI Subjects BiosynthesisEnzymesNatural productsPlant sciences