Abstract: This study focused onEnterococcus lactisFSUH-1 to investigate the characteristics of its γ-aminobutyric acid （GABA） synthesis system. It demonstrated that FSUH-1 possessed the ability to produce glutamate decarboxylase （GAD）. Potential key functional genes in its genome were amplified, and were verified that FSUH-1 contained the key genesgadAandgadC, which were essential for GABA synthesis in lactic acid bacteria. Bioinformatics methods were employed to analyze and predict the structure and function of the proteins encoded bygadAandgadC. It was found that the GadA protein was a hydrophilic protein without transmembrane regions or a signal peptide, indicating that it was an intracellular protein. It contained the GAD （TIGR01788） domain and was confirmed to catalyze the production of GABA from glutamate. The GadC protein was identified as a hydrophobic protein with transmembrane regions but no signal peptide, and was classified as a transmembrane protein. It contained the GadC （TIGR00910） domain and was predicted to mediate functions such as substrate transport and signal transduction. The tertiary structures of the GadA and GadC proteins were superimposed on and compared with the corresponding protein structures fromEscherichia coliandLactobacillusCGMCC 1306. Results showed that the core regions of their tertiary structures were consistent, indicating that the GadA and GadC proteins in this strain were highly conserved and could mediate the catalytic synthesis of GABA.

Key words: Enterococcus lactis, glutamate decarboxylase, γ-aminobutyric acid, bioinformatics analysis