Highly efficient production of L-homoserine in Escherichia coli by engineering a redox balance route
Highly efficient production of L-homoserine in Escherichia coli by engineering a redox balance route
复制标题
DOI：
10.1016/j.ymben.2021.07.011
复制
发表时间：
2021-07-29
影响因子：
8.4
通讯作者：
Yu, Bo
中科院分区：
文献类型：
--
作者：
Mu, Qingxuan;Zhang, Shasha;Yu, Bo
L-高丝氨酸是一种非必需的手性氨基酸，是L-苏氨酸和L-蛋氨酸的前体。它在制药、农业、化妆品和香料工业中具有巨大的潜力。然而，目前L-高丝氨酸发酵过程中的低效率提高了成本，因此限制了应用。在这里，我们系统地分析了L-高丝氨酸生产网络在大肠杆菌中，以设计一个氧化还原平衡的路线，L-高丝氨酸发酵从葡萄糖。通过还原三羧酸循环中间体草酰乙酸从L-天冬氨酸生产L-高丝氨酸缺乏还原能力。这种缺陷可以通过激活乙醛酸分流并以过量的还原力驱动从富马酸到L-天冬氨酸的通量来纠正。这种氧化还原平衡途径降低了细胞生长压力，并且L-高丝氨酸的理论产率为1.5 mol/mol葡萄糖而没有碳损失。我们微调了从富马酸到L-天冬氨酸的通量，删除了竞争和降解途径，增强了L-高丝氨酸的流出，并在补料分批发酵中产生了84.1 g/L的L-高丝氨酸，生产率为1.96 g/L/h，葡萄糖产量为0.50 g/g。本研究提出了一种新的平衡氧化还原代谢网络策略，用于高效生产L-高丝氨酸及其衍生物氨基酸。
L-Homoserine is a nonessential chiral amino acid and the precursor of L-threonine and L-methionine. It has great potential to be used in the pharmaceutical, agricultural, cosmetic, and fragrance industries. However, the current low efficiency in the fermentation process of L-homoserine drives up the cost and therefore limits applications. Here, we systematically analyzed the L-homoserine production network in Escherichia coli to design a redox balance route for L-homoserine fermentation from glucose. Production of L-homoserine from L-aspartate via reduction of the tricarboxylic acid cycle intermediate oxaloacetate lacks reducing power. This deficiency could be corrected by activating the glyoxylate shunt and driving the flux from fumarate to L-aspartate with excess reducing power. This redox balance route decreases cell growth pressure and the theoretical yield of L-homoserine is 1.5 mol/mol of glucose without carbon loss. We fine-tuned the flux from fumarate to L-aspartate, deleted competitive and degradative pathways, enhanced L-homoserine efflux, and generated 84.1 g/L Lhomoserine with 1.96 g/L/h productivity and 0.50 g/g glucose yield in a fed-batch fermentation. This study proposes a novel balanced redox metabolic network strategy for highly efficient production of L-homoserine and its derivative amino acids.