Engineering the intracellular metabolism of Escherichia coli to produce gamma-aminobutyric acid by co-localization of GABA shunt enzymes

Objectives: To direct the carbon flux from Krebs cycle into the gamma-aminobutyric acid (GABA) shunt pathway for the production of GABA by protein scaffold introduction in Escherichia coli. Results: Escherichia coli was engineered to produce GABA from glucose by the co-localization of enzymes succinate semialdehyde dehydrogenase (GadD), GABA aminotransferase (PuuE) and GABA transporter (GadC) by protein scaffold. 0.7 g GABA l⁻¹ was produced from 10 g glucose l⁻¹ while no GABA was produced in wild type E. coli. pH 6 and 30 °C were optimum for GABA production, and GABA concentration increased to 1.12 g GABA l⁻¹ when 20 g glucose l⁻¹ was used. When competing metabolic networks were inactivated, GABA increased by 24 % (0.87 g GABA l⁻¹). Conclusions: The novel GABA production system was constructed by co-localization of GABA shunt enzymes.