Synthetic Metabolism in Plants: Elucidating Vinblastine Biosynthesis and Implementing Strategies to Overproduce Complex Plant Metabolites

Nature produces a spectacularly diverse array of complex molecules that are exploited for many industrial and pharmaceutical applications. Elucidating the biosynthetic pathways that are used to construct these molecules allows implementation of metabolic engineering or synthetic biology strategies that can dramatically improve production levels of these compounds. Moreover, identifying the biosynthetic genes facilitates study of the unprecedented biochemistry harboured within these specialised metabolic pathways. Unfortunately, research progress in plant specialised metabolism has lagged, in large part due to the complexities of plant systems. This has severely hampered the application of state-of-the-art approaches that can exploit this rich metabolism.

The availability of inexpensive sequence data makes this an outstanding time to revisit difficult questions in plant metabolism. My group has recently obtained RNA-seq data for 24 tissues for Catharanthus roseus, which produces vinblastine, an anti-cancer drug that is arguably one of the most complex natural products found in plants. We now have a clear path toward identifying the ~13 missing biosynthetic enzymes within the ~39,000 genes comprising the transcriptome of C. roseus.

In Objective 1, we outline a plan to identify vinblastine biosynthetic gene candidates using our transcriptome data and then screen these candidates for function in planta. We also propose a series of in vitro assays by which to characterise promising gene candidates biochemically. In Objective 2, we propose to reconstitute portions of the vinblastine pathway in the model plant Nicotiana benthamiana (tobacco) and Saccharomyces cerevisiae (yeast) and to create high-yielding platforms for production of valuable plant metabolites.