Biochemical Engineering School, Pontificia Universidad Católica de Valparaíso, Av. Brasil 2085, Casilla 4059,, Valparaíso, Chile.
Dirección de Investigación y Postgrado, Universidad tecnológica de Chile INACAP, Av. Cóndor Norte 720, Ciudad Empresarial, Huechuraba, Santiago, Chile.
Bioprocess Biosyst Eng. 2019 Jul;42(7):1143-1149. doi: 10.1007/s00449-019-02111-y. Epub 2019 Mar 26.
Coenzyme Q (CoQ) plays an important role as an electron transporter in the respiratory chain. It is formed from a benzoquinone ring and an isoprenoid chain of a specific length depending on the organism. We constructed an engineered Escherichia coli strain (menF) unable to produce demethylmenaquinone and menaquinone, compounds that compete for both chorismate, precursor of the benzoquinone ring, and the isoprenoid chain involved in CoQ biosynthesis. In addition, a mutant strain (entC) unable to produce enterobactin, high-affinity siderophore, synthesized from chorismate, and a double mutant (entC-menF) were constructed. The use of glucose or glycerol as carbon sources was also evaluated for the production of CoQ in these strains. The double mutant (entC-menF) showed 18% increase in CoQ-specific content compared to the control strain; however, the single-mutant strains did not show statistically significant differences in CoQ-specific content respect to the control, in glucose medium in bioreactor experiments. Glycerol was significantly superior compared to glucose for the production of CoQ in E. coli, where the CoQ-specific content increased 126% and 53% in the control and double-mutant strain, respectively. The expression of genes related to CoQ biosynthesis is reported, where the entC-menF double-mutant strain showed a significant increase in the expression of CoQ biosynthesis-related genes when glycerol was used as sole carbon source. The control strain did not show gene expression difference between both carbon sources, indicating a possible regulation at a different level.
辅酶 Q（CoQ）在呼吸链中作为电子传递体发挥着重要作用。它由一个苯醌环和一个特定长度的异戊二烯链组成，具体取决于生物体。我们构建了一种不能产生脱甲基甲萘醌和甲萘醌的工程大肠杆菌菌株（menF），这两种化合物都与苯醌环的前体分支酸和参与 CoQ 生物合成的异戊二烯链竞争。此外，还构建了一种不能产生高亲和力铁载体肠杆菌素的突变株（entC），该铁载体由分支酸合成，以及一种双突变株（entC-menF）。还评估了在这些菌株中使用葡萄糖或甘油作为碳源生产 CoQ 的情况。与对照菌株相比，双突变株（entC-menF）的 CoQ 特异性含量增加了 18％；然而，在生物反应器实验中，在葡萄糖培养基中，单突变株的 CoQ 特异性含量与对照相比没有统计学上的显著差异。与葡萄糖相比，甘油在大肠杆菌中生产 CoQ 具有明显优势，对照菌株和双突变株的 CoQ 特异性含量分别增加了 126％和 53％。报告了与 CoQ 生物合成相关的基因表达情况，其中当甘油作为唯一碳源时，entC-menF 双突变株的 CoQ 生物合成相关基因表达显著增加。对照菌株在两种碳源之间没有表现出基因表达差异，表明可能在不同水平上进行了调控。
