Reconstitution of monoterpene indole alkaloid biosynthesis in Nicotiana benthamiana

Abstract

AbstractMonoterpene indole alkaloids (MIAs) are a diverse and important class of plant natural products that include a number of medicinally significant compounds, often present at low concentrations within their native plant species. The complex biosynthesis of MIAs requires the assembly of tryptamine with a secoiridoid to produce the central intermediate, strictosidine, from which all known MIAs derive. Structural complexity makes chemical synthesis challenging, but recent efforts to identify the biosynthetic enzymes provide options for pathway reconstruction in a heterologous host. Previous attempts have had limited success, with yield in microorganisms limited by the poor expression of some enzymes. Here, we reconstitute the pathway for strictosidine biosynthesis from central metabolism without the need for supplementation of any metabolite precursors or intermediates in Nicotiana benthamiana. The best yields were obtained by the co-expression of 14 enzymes, of which a major latex protein-like enzyme (MLPL) from Nepeta (catmint) was critical for improving flux through the secoiridoid pathway. The production of strictosidine in planta expands the range of MIA products amenable to biological synthesis.