Department of Agricultural Biotechnology and Center for Agricultural Biomaterials, Seoul National University, Seoul, South Korea.
Appl Microbiol Biotechnol. 2012 Mar;93(6):2327-34. doi: 10.1007/s00253-011-3776-3. Epub 2011 Dec 13.
Guanosine 5'-triphosphate (GTP) is the key substrate for biosynthesis of guanosine 5'-diphosphate (GDP)-L-fucose. In this study, improvement of GDP-L-fucose production was attempted by manipulating the biosynthetic pathway for guanosine nucleotides in recombinant Escherichia coli-producing GDP-L-fucose. The effects of overexpression of inosine 5'-monophosphate (IMP) dehydrogenase, guanosine 5'-monophosphate (GMP) synthetase (GuaB and GuaA), GMP reductase (GuaC) and guanosine-inosine kinase (Gsk) on GDP-L-fucose production were investigated in a series of fed-batch fermentations. Among the enzymes tested, overexpression of Gsk led to a significant improvement of GDP-L-fucose production. Maximum GDP-L-fucose concentration of 305.5 ± 5.3 mg l(-1) was obtained in the pH-stat fed-batch fermentation of recombinant E. coli-overexpressing Gsk, which corresponds to a 58% enhancement in the GDP-L-fucose production compared with the control strain overexpressing GDP-L-fucose biosynthetic enzymes. Such an enhancement of GDP-L-fucose production could be due to the increase in the intracellular level of GMP.
鸟苷 5'-三磷酸（GTP）是合成鸟苷 5'-二磷酸（GDP）-L-岩藻糖的关键底物。在这项研究中，通过操纵重组大肠杆菌生产 GDP-L-岩藻糖的鸟苷核苷酸生物合成途径，尝试提高 GDP-L-岩藻糖的产量。在一系列分批补料发酵中，研究了过量表达肌苷 5'-单磷酸（IMP）脱氢酶、鸟苷 5'-单磷酸（GMP）合成酶（GuaB 和 GuaA）、GMP 还原酶（GuaC）和鸟苷肌苷激酶（Gsk）对 GDP-L-岩藻糖产量的影响。在所测试的酶中，过表达 Gsk 导致 GDP-L-岩藻糖产量显著提高。在过表达 Gsk 的重组大肠杆菌 pH -stat 分批补料发酵中，获得了 305.5±5.3mg l(-1)的 GDP-L-岩藻糖最大浓度，与过表达 GDP-L-岩藻糖生物合成酶的对照菌株相比，GDP-L-岩藻糖产量提高了 58%。这种 GDP-L-岩藻糖产量的提高可能是由于 GMP 细胞内水平的增加。
