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Fig. 1 | Biotechnology for Biofuels

Fig. 1

From: High-yield production of 1,3-propanediol from glycerol by metabolically engineered Klebsiella pneumoniae

Fig. 1

Engineered metabolic pathways and regulators in this study. a Metabolic pathways of K. pneumoniae for 1,3-propanediol (1,3-PDO) production and microbial growth. Eliminated pathways in this study on byproducts formation and glycerol assimilation are presented with dashed gray arrows. Pathways with multiple steps are presented with dotted arrows. The acronyms, 3-HPA, DHA, G3P, DHAP, and TCA, refer to 3-hydroxypropionaldehyde, dihydroxyacetone, glyceraldehyde 3-phosphate, dihydroxyacetone phosphate, and tricarboxylic acid, respectively. Genes involved in those pathways are in italics. b Engineering scheme of dha operon with its regulations. PdhaK, the promoter of dhaK, is transcriptionally repressed by DhaK and DhaM and activated by DhaL. ADP forms a complex with DhaL, which binds to the sensing domain of DhaR, thus activating DhaR. ADP and DhaL complexes are inactivated by DhaM-mediated phosphorylation. DhaK inactivates DhaR by binding. Activated DhaR by ADP-DhaL complex activates dhaT expression, while represses dhaB. Black solid arrows stand for activation and gray closed arrows stand for inhibition. Black dashed arrows indicate protein modification [14]. KMK-23M, KMK-46, and KMY on the right-hand side represent the engineered strains (Table 2)

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