Efficient gamma-aminobutyric acid bioconversion by employing synthetic complex between glutamate decarboxylase and glutamate/GABA antiporter in engineered Escherichia coli

• Published in: Journal of industrial microbiology & biotechnology 2013-08, Vol.40 (8), p.927-933
• Main Authors: Le Vo, Tam Dinh, Ko, Ji-seun, Park, Si Jae, Lee, Seung Hwan, Hong, Soon Ho
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Amino acids; Analysis; Antiporters - chemistry; Antiporters - genetics; Antiporters - metabolism; Biochemistry; Bioconversions. Hemisynthesis; Bioinformatics; Biological and medical sciences; Biomedical and Life Sciences; Biopolymers; Biotechnology; biotransformation; Cell Engineering; Cloning; E coli; Enzymes; Escherichia coli; Escherichia coli - genetics; Escherichia coli - metabolism; Fundamental and applied biological sciences. Psychology; gamma-aminobutyric acid; gamma-Aminobutyric Acid - biosynthesis; Gene expression; Genes; Genetic Engineering; glutamate decarboxylase; Glutamate Decarboxylase - genetics; Glutamate Decarboxylase - metabolism; Glutamic Acid - metabolism; Inorganic Chemistry; Life Sciences; Ligands; Metabolic Engineering and Synthetic Biology; Metabolism; Methods. Procedures. Technologies; Microbiology; Molecular Sequence Data; monosodium glutamate; Plasmids; Polymers; Productivity; Proteins; Studies; Synthetic biology
• ISSN: 1367-5435; 1476-5535
• DOI: 10.1007/s10295-013-1289-z

Gamma-aminobutyric acid (GABA) is a precursor of one of the most promising heat-resistant biopolymers, Nylon-4, and can be produced by the decarboxylation of monosodium glutamate (MSG). In this study, a synthetic protein complex was applied to improve the GABA conversion in engineered Escherichia coli. Complexes were constructed by assembling a single protein–protein interaction domain SH3 to the glutamate decarboxylase (GadA and GadB) and attaching a cognate peptide ligand to the glutamate/GABA antiporter (GadC) at the N-terminus, C-terminus, and the 233rd amino acid residue. When GadA and GadC were co-overexpressed via the C-terminus complex, a GABA concentration of 5.65 g/l was obtained from 10 g/l MSG, which corresponds to a GABA yield of 93 %. A significant increase of the GABA productivity was also observed where the GABA productivity increased 2.5-fold in the early culture period due to the introduction of the synthetic protein complex. The GABA pathway efficiency and GABA productivity were enhanced by the introduction of the complex between Gad and glutamate/GABA antiporter.