Wu Qiulin, Yang Aihua, Zou Wei, Duan Zuoying, Liu Jie, Chen Jian, Liu Liming
State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, 214122, China; Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi, Jiangsu, 214122, China; Laboratory of Food Microbial-Manufacturing Engineering, Jiangnan University, Wuxi, Jiangsu, 214122, China.
Biotechnol Prog. 2013 Sep-Oct;29(5):1140-9. doi: 10.1002/btpr.1777. Epub 2013 Jul 16.
The capsule polysaccharide (CPS) of Escherichia coli K4 (K4CPS) is identical to fructosylated chondroitin, which can be modified to chondroitin sulfate, a commercially valuable biopolymer commonly used in pharmaceutical applications. In this study, we homologously overexpressed the transcriptional regulator SlyA to enhance the expression of K4 capsule gene cluster and production of CPS. The iTRAQ quantificaton of proteomics revealed 77 up-regulated proteins and 143 down-regulated proteins in E. coli THslyA. Most enzymes of glycolysis and citrate cycle pathway were weakened, while proteins associated with K4CPS synthesis were up-regulated, showing a shift of carbon flux from cell growth to K4CPS production. Further, the production of K4CPS by the recombinant strain was 1 and 2.6 g/L in a shake flask and 7-L batch bioreactor, which was 1.85- and 1.53-fold higher than that of the wild-type strain, respectively. Thus, this study provides a viable strategy for improving the production of K4CPS through a transcriptional-level manipulation.
大肠杆菌K4的荚膜多糖（CPS，即K4CPS）与糖基化硫酸软骨素相同，后者可被修饰为硫酸软骨素，这是一种在制药应用中常用的具有商业价值的生物聚合物。在本研究中，我们通过同源过表达转录调节因子SlyA来增强K4荚膜基因簇的表达及CPS的产量。蛋白质组学的iTRAQ定量分析显示，在大肠杆菌THslyA中有77种上调蛋白和143种下调蛋白。糖酵解和柠檬酸循环途径的大多数酶活性减弱，而与K4CPS合成相关的蛋白上调，表明碳通量从细胞生长转向K4CPS生产。此外，重组菌株在摇瓶和7-L分批生物反应器中K4CPS的产量分别为1 g/L和2.6 g/L，分别比野生型菌株高1.85倍和1.53倍。因此，本研究提供了一种通过转录水平操作提高K4CPS产量的可行策略。
