Isoprenoid Pathway Optimization for Taxol Precursor Overproduction in <i>Escherichia coli</i>

TLDR

Taxol, a potent anticancer drug derived from the Pacific yew tree, remains difficult to produce cost‑efficiently. The authors partitioned the taxadiene pathway into a native MEP upstream module and a heterologous downstream module, then used systematic multivariate optimization to balance the two and engineered a P450 5α‑oxidase step to convert taxadiene to taxadien‑5α‑ol. This modular engineering raised taxadiene titers to about 1 g L⁻¹—roughly a 15,000‑fold increase—and demonstrated the MEP pathway’s potential for producing terpenoid natural products.

Abstract

Taxol (paclitaxel) is a potent anticancer drug first isolated from the Taxus brevifolia Pacific yew tree. Currently, cost-efficient production of Taxol and its analogs remains limited. Here, we report a multivariate-modular approach to metabolic-pathway engineering that succeeded in increasing titers of taxadiene--the first committed Taxol intermediate--approximately 1 gram per liter (~15,000-fold) in an engineered Escherichia coli strain. Our approach partitioned the taxadiene metabolic pathway into two modules: a native upstream methylerythritol-phosphate (MEP) pathway forming isopentenyl pyrophosphate and a heterologous downstream terpenoid-forming pathway. Systematic multivariate search identified conditions that optimally balance the two pathway modules so as to maximize the taxadiene production with minimal accumulation of indole, which is an inhibitory compound found here. We also engineered the next step in Taxol biosynthesis, a P450-mediated 5α-oxidation of taxadiene to taxadien-5α-ol. More broadly, the modular pathway engineering approach helped to unlock the potential of the MEP pathway for the engineered production of terpenoid natural products.