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Production of 3-hydroxypropionic acid via malonyl-CoA pathway using recombinant Escherichia coli strains

Rathnasingh, Chelladurai, Raj, Subramanian Mohan, Lee, Youjin, Catherine, Christy, Ashok, Somasundar, Park, Sunghoon
Journal of biotechnology 2012 v.157 no.4 pp. 633-640
Chloroflexus aurantiacus, Escherichia coli, NAD (coenzyme), NADH or NADPH oxidoreductases, NADP (coenzyme), acetates, acetyl-CoA carboxylase, aerobic conditions, carbon, fatty acid metabolism, gene overexpression, genes, genetically engineered microorganisms, glucose, lactates, proteins, strains, tricarboxylic acid cycle
Malonyl-CoA is an intermediary compound that is produced during fatty acid metabolism. Our study aimed to produce the commercially important platform chemical 3-hydroxypropionic acid (3-HP) from its immediate precursor malonyl-CoA by recombinant Escherichia coli strains heterologously expressing the mcr gene of Chloroflexus aurantiacus DSM 635, encoding an NADPH-dependent malonyl-CoA reductase (MCR). The recombinant E. coli overexpressing mcr under the T5 promoter showed MCR activity of 0.015Umg⁻¹ protein in crude cell extract and produced 0.71mmol/L of 3-HP in 24h in shake flask cultivation under aerobic conditions with glucose as the sole source of carbon. When acetyl-CoA carboxylase and biotinilase, encoded by the genes accADBCb (ACC) of E. coli K-12 were overexpressed along with MCR, the final 3-HP titer improved by 2-fold, which is 1.6mM. Additional expression of the gene pntAB, encoding nicotinamide nucleotide transhydrogenase that converts NADH to NADPH, increased 3-HP production to 2.14mM. The strain was further developed by deleting the sucAB gene, encoding α-ketoglutarate dehydrogenase complex in tricarboxylic acid (TCA) cycle, or blocking lactate and acetate production pathways, and evaluated for the production of 3-HP. We report on the feasibility of producing 3-HP from glucose through the malonyl-CoA pathway.