Mao Jiwei, Liu Quanli, Song Xiaofei, Wang Hesuiyuan, Feng Hui, Xu Haijin, Qiao Mingqiang
The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, No. 94 Weijin Road, Nankai Distract, Tianjin, 300071, People's Republic of China.
Environmental Protection Technical Development Center, Tianjin, 300191, People's Republic of China.
Biotechnol Lett. 2017 Jul;39(7):977-982. doi: 10.1007/s10529-017-2322-5. Epub 2017 Mar 15.
To identify new enzymatic bottlenecks of L-tyrosine pathway for further improving the production of L-tyrosine and its derivatives.
When ARO4 and ARO7 were deregulated by their feedback resistant derivatives in the host strains, the ARO2 and TYR1 genes, coding for chorismate synthase and prephenate dehydrogenase were further identified as new important rate-limiting steps. The yield of p-coumaric acid in the feedback-resistant strain overexpressing ARO2 or TYR1, was significantly increased from 6.4 to 16.2 and 15.3 mg l, respectively. Subsequently, we improved the strain by combinatorial engineering of pathway genes increasing the yield of p-coumaric acid by 12.5-fold (from 1.7 to 21.3 mg l) compared with the wild-type strain. Batch cultivations revealed that p-coumaric acid production was correlated with cell growth, and the formation of by-product acetate of the best producer NK-M6 increased to 31.1 mM whereas only 19.1 mM acetate was accumulated by the wild-type strain.
Combinatorial metabolic engineering provides a new strategy for further improvement of L-tyrosine or other metabolic biosynthesis pathways in S. cerevisiae.
确定L-酪氨酸途径新的酶促瓶颈，以进一步提高L-酪氨酸及其衍生物的产量。
当宿主菌株中ARO4和ARO7被其反馈抗性衍生物解除调控时，编码分支酸合酶和预苯酸脱氢酶的ARO2和TYR1基因被进一步确定为新的重要限速步骤。在过表达ARO2或TYR1的反馈抗性菌株中，对香豆酸的产量分别从6.4显著提高到16.2和15.3 mg l。随后，我们通过对途径基因进行组合工程改造来改进菌株，与野生型菌株相比，对香豆酸的产量提高了12.5倍（从1.7提高到21.3 mg l）。分批培养表明，对香豆酸的产生与细胞生长相关，最佳生产菌株NK-M6的副产物乙酸盐形成增加至31.1 mM，而野生型菌株仅积累19.1 mM乙酸盐。
组合代谢工程为进一步改进酿酒酵母中L-酪氨酸或其他代谢生物合成途径提供了一种新策略。
