Quinolinic acid (QA) is a key intermediate of nicotinic acid (Niacin) which is an essential human nutrient and widely used in food and pharmaceutical industries. In this study, a quinolinic acid producer was constructed by employing comprehensive engineering strategies. Firstly, the quinolinic acid production was improved by deactivation of NadC (to block the consumption pathway), NadR (to eliminate the repression of L-aspartate oxidase and quinolinate synthase), and PtsG (to slow the glucose utilization rate and achieve a more balanced metabolism, and also to increase the availability of the precursor phosphoenolpyruvate). Further modifications to enhance quinolinic acid production were investigated by increasing the oxaloacetate pool through overproduction of phosphoenolpyruvate carboxylase and deactivation of acetate-producing pathway enzymes. Moreover, quinolinic acid production was accelerated by assembling NadB and NadA as an enzyme complex with the help of peptide-peptide interaction peptides RIAD and RIDD, which resulted in up to 3.7 g/L quinolinic acid being produced from 40 g/L glucose in shake-flask cultures. A quinolinic acid producer was constructed in this study, and these results lay a foundation for further engineering of microbial cell factories to efficiently produce quinolinic acid and subsequently convert this product to nicotinic acid for industrial applications.

喹啉酸 (QA) 是烟酸 (Niacin) 的关键中间体，烟酸是人体必需的营养素，广泛应用于食品和制药行业。在这项研究中，采用综合工程策略构建了一个喹啉酸生产商。首先，通过失活 NadC（阻断消耗途径）、NadR（消除 L-天冬氨酸氧化酶和喹啉酸合酶的抑制）和 PtsG（减缓葡萄糖利用率并实现更平衡）提高喹啉酸产量代谢，并增加前体磷酸烯醇丙酮酸的可用性）。通过磷酸烯醇丙酮酸羧化酶的过量产生和乙酸产生途径酶的失活来增加草酰乙酸池，研究了进一步修饰以提高喹啉酸的产生。此外，在肽-肽相互作用肽 RIAD 和 RIDD 的帮助下，通过将 NadB 和 NadA 组装成酶复合物来加速喹啉酸的产生，这导致在摇动中从 40 g/L 葡萄糖产生高达 3.7 g/L 喹啉酸-烧瓶培养物。本研究构建了喹啉酸生产装置，这些结果为进一步工程化微生物细胞工厂以高效生产喹啉酸并将该产品转化为烟酸用于工业应用奠定了基础。