Collaborative regulation of CO2 transport and fixation during succinate production in Escherichia coli.
Collaborative regulation of CO2 transport and fixation during succinate production in Escherichia coli.
复制标题
大肠杆菌生产琥珀酸过程中二氧化碳运输和固定的协同调控
DOI：
10.1038/srep17321
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发表时间：
2015-12-02
影响因子：
4.6
通讯作者：
Tang YJ
中科院分区：
文献类型：
--
作者：
Zhu LW;Zhang L;Wei LN;Li HM;Yuan ZP;Chen T;Tang YL;Liang XH;Tang YJ
在大肠杆菌中，琥珀酸是通过C3代谢产物的基于CO2固定的羧化来合成的。一个两步过程涉及CO2整合：CO2吸收到细胞和CO2固定的羧化酶。磷酸烯醇式丙酮酸（PEP）羧化酶（PPC）和羧激酶（PCK）是琥珀酸合成途径中两种重要的羧化酶，而SbtA和BicA是两种重要的碳酸氢盐转运蛋白。在这项研究中，我们采用了双表达系统，其中调节CO2吸收和固定的基因共过表达，或单独过表达，以提高琥珀酸的生物合成。通过SbtA或/和BicA的表达，观察到活性CO2吸收，但琥珀酸的生物合成减少。只有当CO2固定基因（ppc或pck）和CO2转运基因（sbtA或bicA）共表达时，琥珀酸产量才显着增加。pck和sbtA的共表达提供了所有菌株中最好的琥珀酸生产。最高琥珀酸产量为73.4 g L-1，分别比单独表达PCK、SbtA或使用空质粒获得的产量高13.3%、66.4%或15.0%。我们认为，CO2运输和固定的联合调节对琥珀酸生产至关重要。不平衡的基因表达可能会干扰细胞代谢和琥珀酸生产。
In Escherichia coli, succinic acid is synthesized by CO2 fixation-based carboxylation of C3 metabolites. A two-step process is involved in CO2 integration: CO2 uptake into the cell and CO2 fixation by carboxylation enzymes. The phosphoenolpyruvate (PEP) carboxylase (PPC) and carboxykinase (PCK) are two important carboxylation enzymes within the succinate synthetic pathway, while SbtA and BicA are two important bicarbonate transporters. In this study, we employed a dual expression system, in which genes regulating both CO2 uptake and fixation were co-overexpressed, or overexpressed individually to improve succinate biosynthesis. Active CO2 uptake was observed by the expression of SbtA or/and BicA, but the succinate biosynthesis was decreased. The succinate production was significantly increased only when a CO2 fixation gene (ppc or pck) and a CO2 transport gene (sbtA or bicA) were co-expressed. Co-expression of pck and sbtA provided the best succinate production among all the strains. The highest succinate production of 73.4 g L−1 was 13.3%, 66.4% or 15.0% higher than that obtained with the expression of PCK, SbtA alone, or with empty plasmids, respectively. We believe that combined regulation of CO2 transport and fixation is critical for succinate production. Imbalanced gene expression may disturb the cellular metabolism and succinate production.