Production and transport of secondary metabolites in plants

Monoterpene indole alkaloids and Sesquiterpene lactones are secondary metabolites derived from terpenes. They are used for the treatment of different diseases in humans (e.g. cancers, vascular disease, migraines, fever, menstrual disorders and arthritic conditions). We are not only interested in identifying the genes involved in the biosynthesis of these compounds, but we also try to identify the genes related to the intra- and intercellular transport of these compounds.

Terpenes form a diverse class of plant secondary metabolites which are synthesized in specific cells and the different steps in the biosynthesis pathway are distributed over different subcellular compartments. Because terpenoid intermediates have different solubility in water or lipids it is assumed that active transport of terpenenoid intermediates from different sites within the cell and between cells is of importance for the total production of these compounds. However, very little is known about specific proteins involved in the transport of metabolites between compartments and over membranes.

In different projects we try to identify the different enzymatic steps in specific mono-, di- and sesqui-terpene synthesis and manipulate the subcellular location of enzymes from the pathway in homologous or heterologous plant species to study the role of subcellular compartments and to optimize production of certain medicinal compounds. 

Our approach:

The cDNA libraries from different plant species are screened for terpene biosynthesis genes and P450 (which may modify terpenes). Candidate genes are tested in transient plant assays and in bacterial expression systems. In many plant species, expression of terpene biosynthesis genes coincides with high expression of lipid transfer protein genes (LTP’s) suggesting that these proteins may not only be carriers of lipids but may also be involved in the transport of terpenoids.  Therefore we are manipulating LTP expression to study the effect on terpene production and we manipulate terpene synthesis to see the effect on LTP expression. In addition we test the effect of inhibitors of sub-cellular vesicle transport on terpene production.