Control of ATP concentration in Escherichia coli using synthetic small regulatory RNAs for enhanced S-adenosylmethionine production

ATP is the limiting precursor and driving force for S-adenosylmethionine (SAM) biosynthesis in Escherichia coli. In contrast to traditional optimization of fermentation processes, the synthetic sRNA-based repression strategy, which was developed as a highly efficient gene knockdown approach, has been applied for the regulation of the intracellular ATP concentration in order to enhance SAM production. In this work, proB, glnA and argB, all involved in the synthesis of ATP-dependent by-products in the S-adenosylmethionine production were selected as candidates for repression. The results show that the S-adenosylmethionine titer and yield in the recombinant strain were doubled compared with the control. The best-performing strain, Anti-argB, produced the highest SAM titer (1.21 mg L-1), and strain Anti-glnA gave the highest yield (0.13 mg g(-1), 12 h). Both the concentration of ATP and the ratio of ATP to ADP were shown to have a positive effect on the S-adenosylmethionine synthesis. Overall, the synthetic sRNA-based downregulation strategy has a high potential for cofactor regulation and will be useful for industrial ATP-driven bioprocesses.