(5bg) Metabolic Engineering of the Terpenoid and Indole Pathways in Catharanthus roseus Hairy Roots

Plants produce a wide variety of secondary metabolites many of which are economically important in the areas of pharmaceuticals, nutrition, flavors and fragrances, fine chemicals, cosmetics, etc. In most cases, production of these compounds are limited to plants because synthetic routes of producing these structurally complex molecules are often more expensive than producing them natively within the plant even though the yields within the plant are small. Thus it is desirable to use the techniques of metabolic engineering to increase the yield of specific metabolites within the plant.

We have chosen to study the terpenoid indole alkaloid (TIA) pathway in Catharanthus roseus hairy roots as a model system because it produces two pharmaceutically important anticancer drugs vinblastine and vincristine which are used in the treatment of cancers such as lymphoma and leukemia. Over the course of my research, our focus has been to increase the flux down the terpenoid pathway and to combine those efforts with our previous success of increasing the flux down the indole pathway to increase the overall availability of the precursors to the TIAs. We have used the tools of precursor feeding studies, elicitor studies, and expression profiling of target genes by Q RT PCR to better understand the bottlenecks within the indole and terpenoid pathways. Using this information, we then constructed transgenic C. roseus hairy root lines by using molecular biology tools to overexpress one or more strategic genes in the terpenoid and/or indole pathway under the control of an inducible promoter system. In addition, we determined the effects of these genetic manipulations on TIA production by focusing on the levels of 6 TIA compounds, where the authentic standards were available. We have begun to further characterize additional metabolites from these transgenic hairy root lines using LCMS and tandem LSMS/MS data.