Monoterpene indole alkaloids comprise a diverse family of over 2000 plant-produced natural products. This pathway provides an outstanding example of how nature creates chemical diversity from a ...single precursor, in this case from the intermediate strictosidine. The enzymes that elicit these seemingly disparate products from strictosidine have hitherto been elusive. Here we show that the concerted action of two enzymes commonly involved in natural product metabolism-an alcohol dehydrogenase and a cytochrome P450-produces unexpected rearrangements in strictosidine when assayed simultaneously. The tetrahydro-β-carboline of strictosidine aglycone is converted into akuammicine, a Strychnos alkaloid, an elusive biosynthetic transformation that has been investigated for decades. Importantly, akuammicine arises from deformylation of preakuammicine, which is the central biosynthetic precursor for the anti-cancer agents vinblastine and vincristine, as well as other biologically active compounds. This discovery of how these enzymes can function in combination opens a gateway into a rich family of natural products.The biosynthetic pathway of preakuammicine, a monoterpene precursor of the anti-cancer agent vinblastine, has remained largely unexplored. Here, the authors provide transcriptomic and biochemical data to identify two enzymes that, in tandem, convert strictosidine to akuammicine, the stable shunt product of preakuammicine.
Plants produce an enormous array of biologically active metabolites, often with stereochemical variations on the same molecular scaffold. These changes in stereochemistry dramatically impact ...biological activity. Notably, the stereoisomers of the heteroyohimbine alkaloids show diverse pharmacological activities. We reported a medium chain dehydrogenase/reductase (MDR) from Catharanthus roseus that catalyses formation of a heteroyohimbine isomer. Here we report the discovery of additional heteroyohimbine synthases (HYSs), one of which produces a mixture of diastereomers. The crystal structures for three HYSs have been solved, providing insight into the mechanism of reactivity and stereoselectivity, with mutation of one loop transforming product specificity. Localization and gene silencing experiments provide a basis for understanding the function of these enzymes in vivo. This work sets the stage to explore how MDRs evolved to generate structural and biological diversity in specialized plant metabolism and opens the possibility for metabolic engineering of new compounds based on this scaffold.
The metabolism of monoterpene indole alkaloids (MIAs) is an outstanding example of how plants shape chemical diversity from a single precursor. Here we report the discovery of novel enzymes from the
...Alstonia scholaris
tree, a cytochrome P450, an NADPH dependent oxidoreductase and a BAHD acyltransferase that together synthesize the indole alkaloid akuammiline with a unique methanoquinolizidine cage structure. The two paralogous cytochrome P450 enzymes rhazimal synthase (AsRHS) and geissoschizine oxidase (AsGO) catalyse the cyclization of the common precursor geissoschizine and they direct the MIA metabolism towards to the two structurally distinct and medicinally important MIA classes of
akuammilan
and
strychnos
alkaloids, respectively. To understand the pathway divergence, we investigated the catalytic mechanism of the two P450 enzymes by homology modelling and reciprocal mutations. Upon conducting mutant enzyme assays, we identified a single amino acid residue that mediates the space in active sites, switches the enzymatic reaction outcome and impacts the cyclization regioselectivity. Our results represent a significant advance in MIA metabolism, paving the way for discovery of downstream genes in
akuammilan
alkaloid biosynthesis and facilitating future synthetic biology applications. We anticipate that our work presents, for the first time, insights at the molecular level for plant P450 catalytic activity with a significant key role in the diversification of alkaloid metabolism, and provides the basis for designing new drugs.
Discovery of a cytochrome P450 which synthesizes the plant-derived alkaloid scaffold of methanoquinolizidine is reported. Additionally, an ADH reductase and a BAHD acyltransferase were discovered to complete the biosynthesis of alkaloid akummiline.
Plants sequester intermediates of metabolic pathways into different cellular compartments, but the mechanisms by which these molecules are transported remain poorly understood. Monoterpene indole ...alkaloids, a class of specialized metabolites that includes the anticancer agent vincristine, antimalarial quinine and neurotoxin strychnine, are synthesized in several different cellular locations. However, the transporters that control the movement of these biosynthetic intermediates within cellular compartments have not been discovered. Here we present the discovery of a tonoplast localized nitrate/peptide family (NPF) transporter from Catharanthus roseus, CrNPF2.9, that exports strictosidine, the central intermediate of this pathway, into the cytosol from the vacuole. This discovery highlights the role that intracellular localization plays in specialized metabolism, and sets the stage for understanding and controlling the central branch point of this pharmacologically important group of compounds.
Herewith we report the use of modern hyphenated LC/SPE/NMR and LC/MS techniques in the characterization of constituents of Greek
Hypericum perforatum, mainly naphtodianthrones, flavonoids and ...phenolic acids and two phloroglucinols (hyperfirin and adhyperfirin).
The newly established hyphenated instrumentation of LC/DAD/SPE/NMR and LC/UV/(ESI)MS techniques have been applied for separation and structure verification of the major known constituents present in Greek
Hypericum perforatum extracts. The chromatographic separation was performed on a C18 column. Acetonitrile-water was used as a mobile phase. For the on-line NMR detection, the analytes eluted from column were trapped one by one onto separate SPE cartridges, and hereafter transported into the NMR flow-cell. LC/DAD/SPE/NMR and LC/UV/MS allowed the characterization of constituents of Greek
H. perforatum, mainly naphtodianthrones (hypericin, pseudohypericin, protohypericin, protopseudohypericin), phloroglucinols (hyperforin, adhyperforin), flavonoids (quercetin, quercitrin, isoquercitrin, hyperoside, astilbin, miquelianin, I3,II8-biapigenin) and phenolic acids (chlorogenic acid, 3-
O-coumaroylquinic acid). Two phloroglucinols (hyperfirin and adhyperfirin) were detected for the first time, which have been previously reported to be precursors in the biosynthesis of hyperforin and adhyperforin.
Summary
The meroterpenoid hyperforin is responsible for the antidepressant activity of St John's wort extracts, but the genes controlling its biosynthesis are unknown.
Using genome mining and ...biochemical work, we characterize two biosynthetic gene clusters (BGCs) that encode the first three steps in the biosynthesis of hyperforin precursors.
The findings of syntenic and phylogenetic analyses reveal the parallel assembly of the two BGCs. The syntenous BGC in Mesua ferrea indicates that the first cluster was assembled before the divergence of the Hypericaceae and Calophyllaceae families. The assembly of the second cluster is the result of a coalescence of genomic fragments after a major duplication event. The differences between the two BGCs – in terms of gene expression, response to methyl jasmonate, substrate specificity and subcellular localization of key enzymes – suggest that the presence of the two clusters could serve to generate separate pools of precursors.
The parallel assembly of two BGCs with similar compositions in a single plant species is uncommon, and our work provides insights into how and when these gene clusters form. Our discovery helps to advance our understanding of the evolution of plant specialized metabolism and its genomic organization. Additionally, our results offer a foundation from which hyperforin biosynthesis can be more fully understood, and which can be used in future metabolic engineering applications.
The presence of anticancer clerodane diterpenoids is a chemotaxonomic marker for the traditional Chinese medicinal plant Scutellaria barbata, although the molecular mechanisms behind clerodane ...biosynthesis are unknown. Here, we report a high-quality assembly of the 414.98 Mb genome of S. barbata into 13 pseudochromosomes. Using phylogenomic and biochemical data, we mapped the plastidial metabolism of kaurene (gibberellins), abietane, and clerodane diterpenes in three species of the family Lamiaceae (Scutellaria barbata, Scutellaria baicalensis, and Salvia splendens), facilitating the identification of genes involved in the biosynthesis of the clerodanes, kolavenol, and isokolavenol. We show that clerodane biosynthesis evolved through recruitment and neofunctionalization of genes from gibberellin and abietane metabolism. Despite the assumed monophyletic origin of clerodane biosynthesis, which is widespread in species of the Lamiaceae, our data show distinct evolutionary lineages and suggest polyphyletic origins of clerodane biosynthesis in the family Lamiaceae. Our study not only provides significant insights into the evolution of clerodane biosynthetic pathways in the mint family, Lamiaceae, but also will facilitate the production of anticancer clerodanes through future metabolic engineering efforts.
In this work, the authors assemble the genome of medicinal skullcap Scutellaria barbata at the chromosome level to deconvolute the biosynthesis of cytotoxic clerodane diterpenoids. Genome mining, biochemical data, and phylogenomic analysis indicate the polyphyletic origins of the clerodane biosynthetic pathway between the Scutellaria and Salvia genera in the family Lamiaceae.
Plants and fungi have provided, or inspired, key pharmaceuticals for global health challenges, including cancer, heart disease, dementia, and malaria, and are valued as traditional medicines ...worldwide. Global demand for medicinal plants and fungi has threatened certain species, contributing to biodiversity loss and depletion of natural resources that are important for the health of humanity. We consider the evolving role of plants and fungi in global healthcare as new challenges to human health and to biodiversity arise. We present current and emerging scientific approaches, to uncover and preserve nature‐based health solutions for the future, through harmonization with biodiversity conservation strategies.
Societal Impact Statement
Plants and fungi have provided, or inspired, key pharmaceuticals for global health challenges, including cancer, heart disease, dementia, and malaria, and are valued as traditional medicines worldwide. Global demand for medicinal plants and fungi has threatened certain species, contributing to biodiversity loss and depletion of natural resources that are important for the health of humanity. We consider the evolving role of plants and fungi in global healthcare as new challenges to human health and to biodiversity arise. We present current and emerging scientific approaches, to uncover and preserve nature‐based health solutions for the future, through harmonization with biodiversity conservation strategies.
Summary
Non‐communicable diseases, including cardiovascular disease, cancer, and diabetes, are the main causes of deaths globally, and communicable diseases such as malaria and tuberculosis affect billions of people. Plants and fungi have provided key pharmaceuticals in our armory against these global health challenges, while in some regions of the world, they continue to have a central role in healthcare systems as traditional medicines. Consequently, global demand for plants and fungi in healthcare has threatened certain medicinal species, and is a driving factor in biodiversity loss. Yet the future of therapeutics from nature is evolving. Scientific advances are enabling the untapped potential of the world's plants and fungi to be explored for their medicinal value, and to reveal other roles they may have for improving health and well‐being; this demonstrates the value of natural capital as an incentive for biodiversity conservation. Emerging technologies also offer new hope for safeguarding essential medicines for the future, by revealing more sustainable solutions for sourcing key natural products. This review discusses recent developments and future approaches for the discovery of natural products as medicines, for health and well‐being, and strategies to harmonize the therapeutic use of biodiversity with its proactive conservation through nature‐based solutions.
Nudicaulins, a unique group of indole alkaloids, are responsible for the petal color of three yellow-blooming papaveraceous species, Papaver nudicaule, Papaver alpinum and Meconopsis cambrica. The ...petal color of orange cultivars of P. nudicaule and P. alpinum is conferred by the co-occurrence of nudicaulins with pelargonidin derivatives and the petal color of a red P. nudicaule cultivar is due to pelargonidins alone. Two acylated nudicaulins have been found in M. cambrica. Display omitted
•Petals of two out of seven examined Papaver species and Meconopsis cambrica contain nudicaulins.•Nudicaulins from M. cambrica bear an uncommon 3-hydroxy-3-methyl-glutaryl group.•Nudicaulins and pelargonidins control the flower color of Papaver nudicaule and Papaver alpinum.•The nudicaulins occur as scalemic mixtures of diastereomeric pairs.
The intense color of yellow Papaver nudicaule flowers is conferred by the presence of nudicaulins, a group of alkaloids with a unique pentacyclic skeleton composed of an indole ring and a polyphenolic moiety. Petals from eight different Papaveraceae species composed of different color varieties were probed for the presence of nudicaulins. In addition to their occurrence in yellow P. nudicaule flowers, nudicaulins I–VIII were detected and quantified in orange flowers of P. nudicaule, and in yellow and orange Papaver alpinum flowers. Meconopsis cambrica petals showed a divergent nudicaulin spectrum, with compounds having an attached 3-hydroxy-3-methyl-glutaryl group (HMG) instead of a malonyl unit at one of the glucose units. Flavonols and anthocyanins that accompany nudicaulins were identified. The taxonomical significance of the occurrence of nudicaulins is briefly discussed.
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