posted on 2021-10-28, 20:04authored byYan Wang, Shenting Zhou, Qian Liu, Seong-Hee Jeong, Liyan Zhu, Xiangming Yu, Xiaojian Zheng, Gongyuan Wei, Seon-Won Kim, Chonglong Wang
α-Santalene belongs to a class
of natural compounds with
many physiological functions and medical applications. Advances in
metabolic engineering enable non-native hosts (e.g., Escherichia coli) to produce α-santalene, the
precursor of sandalwood oil. However, imbalances in enzymatic activity
often result in a metabolic burden on hosts and repress the synthetic
capacity of the desired product. In this work, we manipulated ribosome
binding sites (RBSs) to optimize an α-santalene synthetic operon
in E. coli, and the best engineered E. coli NA-IS3D strain could produce α-santalene
at a titer of 412 mg·L–1. Concerning the observation
of the inverse correlation between indole synthesis and α-santalene
production, this study speculated that indole-associated amino acid
metabolism would be competitive to the synthesis of α-santalene
rather than indole toxicity itself. The deletion of tnaA could lead to a 1.5-fold increase in α-santalene production
to a titer of 599 mg·L–1 in E. coli tnaA– NA-IS3D. Our results suggested that the optimization of RBS sets
of the synthetic module and attenuation of the competitive pathway
are promising approaches for improving the production of terpenoids
including α-santalene.