烟酰胺腺嘌呤二核苷酸合成相关酶有助于1,4-丁二醇转化为4-羟基丁酸

Enzymes related with NAD synthesis promote conversion of 1,4-butanediol to 4-hydroxybutyrate

摘要:

4-羟基丁酸 (4-HB) 不仅具有医学应用价值，而且是合成生物材料P3HB4HB的重要前体。在烟酰胺腺嘌呤二核苷酸 (NAD) 参与情况下，大肠杆菌Escherichia coli S17-1 (pZL-dhaT-aldD) 可以把1,4-丁二醇 (1,4-BD) 转化为4HB。为提高4HB产率，通过过表达烟酸磷酸核糖转移酶 (PncB) 和烟酰胺腺嘌呤二核苷酸合成酶 (NadE) 增加胞内NAD含量，从而加速1,4-BD转化反应的进行。结果表明，PncB-NadE的表达使1,4-BD转化率比对照组增加13.03％，由10 g/L的1,4-BD得到4.87 g/L的4HB，单位细胞的4HB产量由1.32 g/g提高40.91％至1.86 g/g。因此PncB和NadE可用于促进1,4-BD转化为4HB。

Abstract:

Besides medical application, 4-hydroxybutyrate (4-HB) is a precursor of P3HB4HB, a bioplastic showing excellent physical properties and degradability. Escherichia coli S17-1 (pZL-dhaT-aldD) can transform 1, 4-butanediol (1,4-BD) into 4HB with participation of cofactor NAD. To enhance productivity, nicotinic acid phosphoribosyltransferase (PncB) and nicotinamide adenine dinucleotide synthetase (NadE) were overexpressed to increase intracellular nicotinamide adenine dinucleotide concentration and promote reaction process. The shake flask fermentation result showed that the conversion rate increased by 13.03% with help of PncB-NadE, leading to 4.87 g/L 4HB from 10 g/L 1,4-BD, and productivity was increased by 40.91% to1.86 g/g. These results demonstrated that expression of PncB and NadE is beneficial for conversion of 1,4-BD to 4HB.