Xu Wen, Yang Shuiyun, Zhao Junchao, Su Tingting, Zhao Liangrui, Liu Jiankang
Institute of Mitochondrial Biology and Medicine, Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology, Xi'an Jiao tong University, Xi'an, 710049, Shaanxi, China.
J Ind Microbiol Biotechnol. 2014 Aug;41(8):1297-303. doi: 10.1007/s10295-014-1458-8. Epub 2014 Jun 8.
Coenzyme Q (CoQ) is a medically valuable compound and a high yielding strain for CoQ will have several benefits for the industrial production of CoQ. To increase the CoQ(8) content of E. coli, we blocked the pathway for the synthesis of menaquinone by deleting the menA gene. The blocking of menaquinone pathway increased the CoQ(8) content by 81 % in E. coli (ΔmenA). To study the CoQ producing potential of E. coli, we employed previous known increasing strategies for systematic metabolic engineering. These include the supplementation with substrate precursors and the co-expression of rate-limiting genes. The co-expression of dxs-ubiA and the supplementation with substrate precursors such as pyruvate (PYR) and parahydroxybenzoic acid (pHBA) increased the content of CoQ(8) in E. coli (ΔmenA) by 125 and 59 %, respectively. Moreover, a 180 % increase in the CoQ(8) content in E. coli (ΔmenA) was realized by the combination of the co-expression of dxs-ubiA and the supplementation with PYR and pHBA. All in all, CoQ(8) content in E. coli increased 4.06 times by blocking the menaquinone pathway, dxs-ubiA co-expression and the addition of sodium pyruvate and parahydroxybenzoic acid to the medium. Results suggested a synergistic effect among different metabolic engineering strategies.
辅酶Q（CoQ）是一种具有医学价值的化合物，高产辅酶Q的菌株将对辅酶Q的工业化生产有诸多益处。为了提高大肠杆菌中辅酶Q8的含量，我们通过缺失menA基因来阻断甲萘醌的合成途径。甲萘醌途径的阻断使大肠杆菌（ΔmenA）中的辅酶Q8含量提高了81%。为了研究大肠杆菌产生辅酶Q的潜力，我们采用了先前已知的系统代谢工程增产策略。这些策略包括添加底物前体以及共表达限速基因。dxs-ubiA的共表达以及添加丙酮酸（PYR）和对羟基苯甲酸（pHBA）等底物前体，分别使大肠杆菌（ΔmenA）中的辅酶Q8含量提高了125%和59%。此外，通过dxs-ubiA共表达与添加PYR和pHBA相结合，大肠杆菌（ΔmenA）中的辅酶Q8含量提高了180%。总体而言，通过阻断甲萘醌途径、共表达dxs-ubiA以及向培养基中添加丙酮酸钠和对羟基苯甲酸，大肠杆菌中的辅酶Q8含量提高了4.06倍。结果表明不同代谢工程策略之间存在协同效应。
