Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin, China; Institute for Biochemical Engineering, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, 5 South Zhong Guancun Street, Beijing, PR China; College of Life Sciences, North China University of Science and Technology, 21 Bo Hai Road, Tangshan, PR China.
Institute for Biochemical Engineering, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, 5 South Zhong Guancun Street, Beijing, PR China.
Metab Eng. 2020 Nov;62:72-83. doi: 10.1016/j.ymben.2020.08.010. Epub 2020 Aug 22.
α-Amyrin is a plant-originated high-valued triterpene that is highly effective against several pathological ailments. α-Amyrin production by engineered Saccharomyces cerevisiae has been achieved by introducing α-amyrin synthase (αAS). However, the low yield of α-amyrin highly limits its industrial application; the low catalytic activity of αAS and the toxic effect of α-amyrin have been considered key elements. In this study, the highest yield of α-amyrin was obtained in engineered S. cerevisiae by remodeling α-amyrin synthase MdOSC1 and expanding the storage pool. The yield of α-amyrin was increased to 11-fold higher than that of the control by the triple mutant MdOSC1 obtained based on the modeling analysis. Furthermore, key genes of MVA pathway were overexpressed to provide sufficient precursors, and DGA1 (Diacylglycerol acyltransferase) was overexpressed to expand the intracellular storage capacity. Finally, the as-constructed aAM12 strain produced 213.7 ± 12.4 mg/L α-amyrin in the shake flask and 1107.9 ± 76.8 mg/L in fed-batch fermentation; the fermentation yield was 106-fold higher than that of the original aAM1 strain under the same conditions, representing the highest α-amyrin yield in yeast reported to date. Microbial production of α-amyrin with over 1 g/L will be suitable for commercialization and can accelerate the industrial production of α-amyrin in yeast.
α-香树醇是一种源自植物的高附加值三萜类化合物，对多种病理疾病具有显著疗效。通过引入 α-香树醇合酶（αAS），已实现了工程化酿酒酵母（Saccharomyces cerevisiae）产生 α-香树醇。然而，α-香树醇的低产量极大地限制了其工业应用；αAS 的低催化活性和 α-香树醇的毒性被认为是关键因素。在本研究中，通过重塑 α-香树醇合酶 MdOSC1 和扩大储存池，在工程化酿酒酵母中获得了 α-香树醇的最高产量。基于建模分析获得的三重突变体 MdOSC1 使 α-香树醇的产量比对照提高了 11 倍。此外，过量表达 MVA 途径的关键基因以提供足够的前体，并过量表达 DGA1（二酰基甘油酰基转移酶）以扩大细胞内储存能力。最终，构建的 aAM12 菌株在摇瓶中产生了 213.7±12.4mg/L 的 α-香树醇，在分批补料发酵中产生了 1107.9±76.8mg/L；在相同条件下，发酵产率比原始 aAM1 菌株高 106 倍，这是迄今为止报道的酵母中 α-香树醇产量最高的。超过 1g/L 的 α-香树醇的微生物生产将适合商业化，并能加速酵母中 α-香树醇的工业化生产。
