CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, 100101, Beijing, China.
University of Chinese Academy of Sciences, 100049, Beijing, China.
Nat Commun. 2024 Mar 15;15(1):2372. doi: 10.1038/s41467-024-46655-4.
Tricarboxylic acid cycle (TCA cycle) plays an important role for aerobic growth of heterotrophic bacteria. Theoretically, eliminating TCA cycle would decrease carbon dissipation and facilitate chemicals biosynthesis. Here, we construct an E. coli strain without a functional TCA cycle that can serve as a versatile chassis for chemicals biosynthesis. We first use adaptive laboratory evolution to recover aerobic growth in minimal medium of TCA cycle-deficient E. coli. Inactivation of succinate dehydrogenase is a key event in the evolutionary trajectory. Supply of succinyl-CoA is identified as the growth limiting factor. By replacing endogenous succinyl-CoA dependent enzymes, we obtain an optimized TCA cycle-deficient E. coli strain. As a proof of concept, the strain is engineered for high-yield production of four separate products. This work enhances our understanding of the role of the TCA cycle in E. coli metabolism and demonstrates the advantages of using TCA cycle-deficient E. coli strain for biotechnological applications.
三羧酸循环(TCA 循环)在异养细菌的需氧生长中起着重要作用。从理论上讲,消除 TCA 循环可以减少碳耗散,有利于化学品的生物合成。在这里,我们构建了一种缺乏功能性 TCA 循环的大肠杆菌菌株,可作为化学品生物合成的通用底盘。我们首先使用适应性实验室进化来恢复 TCA 循环缺陷型大肠杆菌在最小培养基中的需氧生长。琥珀酸脱氢酶的失活是进化轨迹中的一个关键事件。琥珀酰辅酶 A 的供应被确定为生长的限制因素。通过替换内源性依赖琥珀酰辅酶 A 的酶,我们获得了优化的 TCA 循环缺陷型大肠杆菌菌株。作为概念验证,该菌株被工程化为高效生产四种不同产品。这项工作增强了我们对 TCA 循环在大肠杆菌代谢中的作用的理解,并展示了使用 TCA 循环缺陷型大肠杆菌菌株进行生物技术应用的优势。