Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University, Nanjing 210037, China.
College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, China.
J Agric Food Chem. 2020 Sep 2;68(35):9513-9523. doi: 10.1021/acs.jafc.0c03689. Epub 2020 Aug 19.
UDP-rhamnose is the main type of sugar donor and endows flavonoids with special activity, selectivity, and pharmacological properties by glycosylation. In this study, several UDP-glucose synthesis pathways and UDP-rhamnose synthases were screened to develop an efficient UDP-rhamnose biosynthesis pathway in . Maximal UDP-rhamnose production reached 82.2 mg/L in the recombinant strain by introducing the cellobiose phosphorolysis pathway and UDP-rhamnose synthase (AtRHM). Quercitrin production of 3522 mg/L was achieved in the recombinant strain by coupling the UDP-rhamnose generation system with rhamnosyltransferase (AtUGT78D1) to recycle UDP-rhamnose. To further increase UDP-rhamnose supply, an NADPH-independent fusion enzyme was constructed, the UTP supply was improved, and NADPH regenerators were overexpressed in vivo. Finally, by optimizing the bioconversion conditions, the highest quercitrin production reached 7627 mg/L with the average productivity of 141 mg/(L h), which is the highest yield of quercitrin and efficiency of UDP-rhamnose supply reported to date in . Therefore, the method described herein for the regeneration of UDP-rhamnose from cellobiose may be widely used for the rhamnosylation of flavonoids and other bioactive substances.
UDP-鼠李糖是主要的糖供体，通过糖基化赋予黄酮类化合物特殊的活性、选择性和药理学特性。在本研究中，筛选了几种 UDP-葡萄糖合成途径和 UDP-鼠李糖合酶，以在 中开发高效的 UDP-鼠李糖生物合成途径。通过引入纤维二糖磷酸解途径和 UDP-鼠李糖合酶（AtRHM），重组菌株中 UDP-鼠李糖的最大产量达到 82.2mg/L。通过将 UDP-鼠李糖生成系统与鼠李糖基转移酶（AtUGT78D1）偶联，以回收 UDP-鼠李糖，重组菌株中实现了 3522mg/L 的槲皮苷产量。为了进一步增加 UDP-鼠李糖的供应，构建了一种 NADPH 非依赖性融合酶，提高了 UTP 的供应，并在体内过表达 NADPH 再生酶。最终，通过优化生物转化条件，槲皮苷的最高产量达到 7627mg/L，平均产率为 141mg/（L h），这是迄今为止在 中报道的槲皮苷和 UDP-鼠李糖供应的最高产量和效率。因此，本文所述的从纤维二糖再生 UDP-鼠李糖的方法可能广泛用于黄酮类化合物和其他生物活性物质的鼠李糖基化。
