Zhao Hanjun, Zhou Feng, Xing Quan, Cao Zhengyu, Liu Jie, Zhu Guoping
The Research Center of Life Omics and Health, College of Life Sciences, Anhui Normal University, No.1 Beijing East Road, Wuhu 241000, Anhui, China.
The Research Center of Life Omics and Health, College of Life Sciences, Anhui Normal University, No.1 Beijing East Road, Wuhu 241000, Anhui, China
Biol Open. 2018 Sep 10;7(9):bio031856. doi: 10.1242/bio.031856.
The soluble transhydrogenase (UdhA) is one of two transhydrogenases that play a role in maintaining the balance between NAD(H) pools and NADP(H) pools in Although UdhA has been extensively used in metabolic engineering and biocatalysis for cofactor regeneration, its role in acid resistance has not been reported. Here we used DNA microarray to explore the impact of UdhA on transcript levels. We demonstrated that during growth on acetate, the expression of genes involved in the respiratory chain and Gad acid resistance system was inhibited in the -knockout strain. The deletion of significantly repressed the expression of six genes ( and ) which are involved in Gad acid resistance and resulted in low survival of the bacterium at a low pH of 4.9. Moreover, UdhA was essential for NADH production which is important for the adaptive growth of on acetate, while NADH concentration in the -knockout strain was quite low and supplemental NADH significantly increased the expression of acid resistance genes and survival of the -knockout strain. These results demonstrated that UdhA is an important source of NADH of growth on acetate and affects Gad acid resistance system under acetate stress.
可溶性转氢酶（UdhA）是两种转氢酶之一，在维持NAD（H）库和NADP（H）库之间的平衡中发挥作用。尽管UdhA已广泛用于代谢工程和生物催化中的辅因子再生，但其在耐酸性方面的作用尚未见报道。在此，我们使用DNA微阵列来探究UdhA对转录水平的影响。我们证明，在以乙酸盐为碳源生长期间，呼吸链和Gad耐酸系统相关基因的表达在UdhA基因敲除菌株中受到抑制。UdhA基因的缺失显著抑制了六个参与Gad耐酸系统的基因（和）的表达，并导致该细菌在pH 4.9的低pH环境下存活率较低。此外，UdhA对于NADH的产生至关重要，而NADH对于大肠杆菌在乙酸盐上的适应性生长很重要，而在UdhA基因敲除菌株中NADH浓度相当低，补充NADH可显著增加耐酸基因的表达和UdhA基因敲除菌株的存活率。这些结果表明，UdhA是大肠杆菌在乙酸盐上生长时NADH的重要来源，并在乙酸盐胁迫下影响Gad耐酸系统。
