The regulation of Taxol production in Taxus suspension cell culture
Plant-derived specialized metabolites are used as pharmaceuticals, dyes and fragrances. Due to the complex nature of these compounds, the continued dependence on plants to synthesize these products has persisted. Many of these products are found at low abundance in plants, so increasing the production of these compounds through metabolic engineering is desirable. An example of a plant-derived pharmaceutical found at low abundance is taxol (Taxol® - Bristol-Myers Squib). Taxol is an anti-cancer agent that is in high demand. Plants in the genus Taxus produce Taxol. Taxus cell suspension cultures are currently being used to meet the demands, however, taxol accumulation is limited. The low yield found in Taxus cultures has prompted biologists and engineers to attempt increasing production of this valuable metabolite.
In order to increase taxol accumulation, a better understanding of the metabolic pathway is required. There are unknown steps in the biosynthetic pathway, so cloning the genes involved with these steps is needed. Also, information regarding factors that regulate of the biosynthetic pathway must be collected. In this dissertation, novel genes are identified and the expression profiles of the known genes after methyl jasmonate (MJ) elicitation are revealed. The expression profiles of these genes are directly correlated with the taxol precursor accumulation. Transcription of these pathway genes occurs with MJ elicitation, demonstrating that the response to MJ elicitation is at the level of transcription; thus, taxol production is correlated with taxol pathway gene transcription.
A transcription factor has been cloned from Taxus and characterized. This transcription factor is similar to regulators of the MJ-inducible responses in other plants. This Taxus transcription factor, TcJAMYC, activates transcription of taxol pathway gene and also binds to DNA elements found in the promoters of these pathway genes. This transcription factor has the potential to increase taxol accumulation in transgenic Taxus cultures.
0542: Chemical engineering