title: Co-Localization of GABA Shunt Enzymes for the Efficient Production of Gamma-Aminobutyric Acid via GABA Shunt Pathway in Escherichia coli.
abstract: Gamma-aminobutyric acid (GABA) is a non-protein amino acid, which is an important inhibitor of neurotransmission in the human brain. GABA is also used as the precursor of biopolymer Nylon-4 production. In this study, the carbon flux from the tricarboxylic acid cycle was directed to the GABA shunt pathway for the production of GABA from glucose. The GABA shunt enzymes succinate-semialdehyde dehydrogenase (GabD) and GABA aminotransferase (GabT) were co-localized along with the GABA transporter (GadC) by using a synthetic scaffold complex. The co-localized enzyme scaffold complex produced 0.71 g/l of GABA from 10 g/l of glucose. Inactivation of competing metabolic pathways in mutant E. coli strains XBM1 and XBM6 increased GABA production 13% to reach 0.80 g/l GABA by the enzymes co-localized and expressed in the mutant strains. The recombinant E. coli system developed in this study demonstrated the possibility of the pathway of the GABA shunt as a novel GABA production pathway.
authors.affiliation: School of Chemical Engineering, University of Ulsan, Ulsan 44610, Republic of Korea.
authors.forename: Van Dung
authors.initials: VD
authors.lastname: Pham
authors.affiliation: School of Chemical Engineering, University of Ulsan, Ulsan 44610, Republic of Korea.
authors.forename: Sivachandiran
authors.initials: S
authors.lastname: Somasundaram
authors.affiliation: Department of Environmental Engineering and Energy, Myongji University, Yongin 17058, Republic of Korea.
authors.forename: Si Jae
authors.initials: SJ
authors.lastname: Park
authors.affiliation: Department of Biotechnology and Bioengineering, Chonnam National University, Gwangju 61186, Republic of Korea.
authors.forename: Seung Hwan
authors.initials: SH
authors.lastname: Lee
authors.affiliation: School of Chemical Engineering, University of Ulsan, Ulsan 44610, Republic of Korea.
authors.forename: Soon Ho
authors.initials: SH
authors.lastname: Hong
mesh_terms: D000612:4-Aminobutyrate Transaminase / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D057486:Carbon Cycle; D002952:Citric Acid Cycle; D004274:DNA, Recombinant; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D053858:Metabolic Networks and Pathways; D009154:Mutation; D050644:Succinate-Semialdehyde Dehydrogenase / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D004274:DNA, Recombinant; D029968:Escherichia coli Proteins; C491226:GadC protein, E coli; C103589:GadC protein, bacteria; D008565:Membrane Proteins; D005680:gamma-Aminobutyric Acid; D050644:Succinate-Semialdehyde Dehydrogenase; D000612:4-Aminobutyrate Transaminase; D005947:Glucose
keywords: Gamma-aminobutyric acid; carbon flux; co-localization; glucose; recombinant DNA; scaffold complex