Glucose Transport through N-Acetylgalactosamine Phosphotransferase System in Escherichia coli C Strain

Abstract

When ptsG, a glucose-specific phosphotransferase system (PTS) component, is deleted in Escherichia coli, growth can be severely poor because of the lack of efficient glucose transport. We discovered a new PTS transport system that could transport glucose through the growth-coupled experimental evolution of ptsG-deficient E. coli C strain under anaerobic conditions. Genome sequencing revealed mutations in agaR, which encodes a repressor of N-acetylgalactosamine (Aga) PTS expression in evolved progeny strains. RT-qPCR analysis showed that the expression of Aga PTS gene increased because of the loss-of-function of agaR. We confirmed the efficient Aga PTS-mediated glucose uptake by genetic complementation and anaerobic fermentation. We discussed the discovery of new glucose transporter in terms of different genetic backgrounds of E. coli strains, and the relationship between the pattern of mixed-acids fermentation and glucose transport rate.

Strategies to Enhance l-Isoleucine Synthesis by Modifying the Threonine Metabolism Pathway in Escherichia coli

“…The EMP pathway, the PPP pathway, and the TCA cycle generate precursors and energy required for the synthesis of l -isoleucine. , In the mutant strain NXU101, ptsG and murP gene expressions were up-regulated, implying that more glucose had entered the E. coli cells through the phosphotransferase system . It is important to highlight again that the EMP pathway, the PPP pathway, and the TCA cycle are key pathways for the synthesis of the l -isoleucine precursor, such as oxaloacetate, aspartate, and NADPH, and the TCA cycle is a major pathway in microbial oxidative metabolism.…”

“… 21 , 22 In the mutant strain NXU101, ptsG and murP gene expressions were up-regulated, implying that more glucose had entered the E. coli cells through the phosphotransferase system. 23 It is important to highlight again that the EMP pathway, the PPP pathway, and the TCA cycle are key pathways for the synthesis of the l -isoleucine precursor, such as oxaloacetate, aspartate, and NADPH, 24 and the TCA cycle is a major pathway in microbial oxidative metabolism. The sdhABCD genes encode four subunits of succinate dehydrogenase, whose expression was found to be down-regulated in the mutant strain NXU101 in this study.…”