Fig. 1
From: Improving l-threonine production in Escherichia coli by elimination of transporters ProP and ProVWX
a The pathways and respective enzymes or genes to show the metabolic engineering strategy applied to create recombinant E. coli strains in this study. Osmosensing transporters ProP and ProVWX are responsible for the transport of betaine and proline. BetA and BetB are responsible for the synthesis of betaine, and BetT is driven by proton-motive-force to transport the betaine precursor choline into the cell. BetI regulates the expression of bet operon. EIIAGlc encoded by crr and EIIBCGlc encoded by ptsG are key enzymes in the phosphotransferase system. b The comparison of mutations on the chromosome of different E. coli strains used in this study