Characterization and heterologous reconstitution of <i>Taxus</i> biosynthetic enzymes leading to baccatin III
Bin Jiang, Lei Gao, Haijun Wang, Haijun Wang, Ya‐Ping Sun, Xiaolin Zhang, Ke Han, Shengchao Liu, Pengchen Ma, Qinggang Liao, Yue Wang, Huan Wang, Huan Wang, Yugeng Liu, Ran Du, Torben Rogge, Wei Li, Yi Shang, K. N. Houk, Xingyao Xiong, Daoxin Xie, Sanwen Huang, Xiaoguang Lei, Jianbin Yan
Abstract
Paclitaxel is a well known anticancer compound. Its biosynthesis involves the formation of a highly functionalized diterpenoid core skeleton (baccatin III) and the subsequent assembly of a phenylisoserinoyl side chain. Despite intensive investigation for half a century, the complete biosynthetic pathway of baccatin III remains unknown. In this work, we identified a bifunctional cytochrome P450 enzyme [taxane oxetanase 1 (TOT1)] in Taxus mairei that catalyzes an oxidative rearrangement in paclitaxel oxetane formation, which represents a previously unknown enzyme mechanism for oxetane ring formation. We created a screening strategy based on the taxusin biosynthesis pathway and uncovered the enzyme responsible for the taxane oxidation of the C9 position (T9αH1). Finally, we artificially reconstituted a biosynthetic pathway for the production of baccatin III in tobacco.