Increasing the acetyl-CoA pool in the presence of overexpressed phosphoenolpyruvate carboxylase or pyruvate carboxylase enhances succinate production in Escherichia coli.
An in vivo strategy to apply the activation effect of acetyl-CoA on phosphoenolpyruvate carboxylase (PEPC) and pyruvate carboxylase (PYC) to increase succinate production in Escherichia coli was studied. This approach relies on the increased intracellular acetyl-CoA and CoA levels by overexpressing E. coli pantothenate kinase (PANK). The results showed that coexpression of PANK and PEPC, and PANK and PYC, did improve succinate production compared to the individual expression of PEPC and PYC, respectively. The intracellular acetyl-CoA and CoA levels were also measured, and each showed a significant increase when the PANK was overexpressed. Another effect observed was a decrease in lactate production. The least amount of lactate was produced when PANK and PEPC, and PANK and PYC, were coexpressed. This result showed increased competitiveness of the succinate pathway at the phosphoenolpyruvate and pyruvate nodes for the carbon flux, as a result reducing the carbon flux toward the lactate pathway. The study also demonstrates a feasible method for metabolic engineering to modulate enzyme activity in vivo through specific activators and inhibitors.
Lin
Henry
H
Department of Bioengineering, Rice University, Houston, Texas, USA.
Vadali
Ravishankar V
RV
Bennett
George N
GN
San
Ka-Yiu
KY
D000105:Acetyl Coenzyme A / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D005240:Feasibility Studies; D024861:Genetic Enhancement / Q000379:methods*; D019344:Lactic Acid / Q000096:biosynthesis; D010730:Phosphoenolpyruvate Carboxylase / Q000235:genetics / Q000378:metabolism*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics / Q000378:metabolism*; D015202:Protein Engineering / Q000379:methods*; D011766:Pyruvate Carboxylase / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D013386:Succinates / Q000378:metabolism*
D011994:Recombinant Proteins; D013386:Succinates; D019344:Lactic Acid; D000105:Acetyl Coenzyme A; D017853:Phosphotransferases (Alcohol Group Acceptor); C023088:pantothenate kinase; D010730:Phosphoenolpyruvate Carboxylase; D011766:Pyruvate Carboxylase