Sunday, August 11, 2013
Pavilion (Sheraton San Diego)
Taxol is a potent and widely used antitumor agent isolated from the bark of the pacific yew tree. At the moment, plant cell culture is another route used for its commercial supply besides bark extraction. Therefore, there is a great attraction to develop a economical process for high production of this valuable drug. The biosynthesis of taxadiene, the first committed intermediate of taxol biosynthesis, starts from the formation of universal precursors isopentenyl diphosphate(IPP) and dimethylallyl pyrophosphate(DMAPP) which are generated from either the mevalonate(MVA) pathway or the 2C-methyl-D-erythritol-4-phosphate(MEP) pathway. Isoprenyl pyrophosphate synthase catalyzes the condensation of IPP and DMAPP to farnesyl pyrophosphate(FPP) by FPP synthase and then to geranylgeranyl pyrophosphate(GGPP) by GGPP synthase(GGPPS). GGPP is cyclized and rearranged by taxadiene synthase(TXS) to synthesize taxadiene. In this study, we assembled TXS with various GGPPS to construct the taxadiene synthase operons. The capacities of these operons were assessed in the background of the overexpression of the MVA pathway. The most productive operon is able to produce 20mg/L at 48 hour in DH5α strain. The following adaptive evolution led to obtain a high-productive strain. Using this strain, we have achieved approximately 10-fold increase in taxadiene production. This work was supported by a grant (NRF-2010-C1AAA001-0029084) from the National Research Foundation, the Intelligent Synthetic Biology Center of Global Frontier Project funded by the MEST (2011-0031964), and a grant from the Next-Generation BioGreen 21 Program (SSAC, grant#: PJ009522003), RDA, Korea.