Monoterpenoid Indole Alkaloid Biosynthesis

Abstract

A unique feature of MIA assembly is the participation of separate pathways that distinguish tryptamine from the tryptophan branch of the shikimate pathway and secologanin from the 2-C-methyl-D-erythritol-4-phosphate (MEP) pathway rather than the mevalonic acid (MVA) pathway (Figure 10.2). Many biochemical studies on tryptophan decarboxylase (TDC) involved in tryptamine formation from tryptophan have been conducted with Catharanthus roseus cell cultures and in intact plants. The cDNA for this gene was the first to be identified and functionally characterised in Catharanthus , with the recombinant protein being able to decarboxylate tryptophan but not tyrosine or phenylalanine. Labelling studies using Catharanthus roseus (Contin et al., 1998) and Ophiorrhiza pumila (Yamazaki et al., 2004) cell cultures with [1-13 C]-glucose showed that the MEP pathway, rather than the mevalonic pathway, contributes to the formation of this key precursor. While many of the Catharanthus genes for the MEP pathway, including deoxyxylulose 5-phosphate synthase (DXS), deoxyxylulose 5-phosphate reductoisomerase (DXR), CO 2 Primary Carbon Metabolism 3PGA + Pyruvate Pyruvate E-4-P + PEP Plastid Shikimate Pathway Plastid MEP Pathway Cytosol Mevalonic acid Pathway ? Sesquiterpenes, Triterpenes MIAs Monoterpenes Diterpenes Tetraterpenes Figure 10.2 Linking primary metabolism and MIA biosynthesis. Primary metabolism converts CO 2 fixed during photosynthesis to erythrose-4-phosphate (E-4-P), phospoenolpyruvate (PEP), 3-phosphoglycerate (3PGA) and pyruvate which are used to elaborate the plastid-localised shikimate and MEP pathways together with the cytosol localised mevalonic acid pathway for biosynthesis of MIAs, as well as different terpenes. The shikimate pathway provides the tryptophan that is then converted in the cytosol to tryptamine which is utilised in the biosynthesis of MIAs. It is not clear how much crosstalk takes place between the MEP and mevalonic acid pathways

Cell-specific localization of alkaloids in Catharanthus roseus stem tissue measured with Imaging MS and Single-cell MS

“…Approximately 20% of plant species are known to contain alkaloids (1). The significant value of alkaloids as medicines or luxury items in human life has attracted widespread interest from researchers in a range of scientific fields.…”

Indole alkaloids from the Marquesan plant Rauvolfia nukuhivensis and their effects on ion channels

“…They are mainly produced by plants belonging to families such as Apocynaceae, Loganiaceae, Rubiaceae and Nyssaceae and, currently, their biosynthesis is under acute examination (De Luca, 2011;St-Pierre et al, 2013). Among the Apocynaceae family, plants of the genus Rauvolfia have been largely investigated for their alkaloid content (Ganapaty et al, 2001).…”

Transcriptional Responses and Gentiopicroside Biosynthesis in Methyl Jasmonate-Treated Gentiana macrophylla Seedlings

“…This pathway has been well studied and reviewed in Catharanthus roseus [14,15], and most steps have been identified. In the first step within higher plants, isopentenyl diphosphate (IPP), a precursor of terpenoids, is formed through either the plastidial 2-C-methyl-D-erythritol-4-phosphate (MEP) pathway or the cytosolic mevalonic acid (MVA) pathway.…”