Glutamate Decarboxylase from Lactic Acid Bacteria—A Key Enzyme in GABA Synthesis

• Main Authors: Ida Bagus Agung Yogeswara, Suppasil Maneerat, Dietmar Haltrich
• Format: Article
• Language: English
• Published: MDPI AG 2020-12-01
• Series: Microorganisms
• Subjects: γ-aminobutyric acid production; lactic acid bacteria; glutamate decarboxylase; fermented foods; <i>gad</i> genes
• Online Access: https://www.mdpi.com/2076-2607/8/12/1923

Glutamate decarboxylase (<span style="font-variant: small-caps;">l</span>-glutamate-1-carboxylase, GAD; EC 4.1.1.15) is a pyridoxal-5’-phosphate-dependent enzyme that catalyzes the irreversible α-decarboxylation of <span style="font-variant: small-caps;">l</span>-glutamic acid to γ-aminobutyric acid (GABA) and CO₂. The enzyme is widely distributed in eukaryotes as well as prokaryotes, where it—together with its reaction product GABA—fulfils very different physiological functions. The occurrence of <i>gad</i> genes encoding GAD has been shown for many microorganisms, and GABA-producing lactic acid bacteria (LAB) have been a focus of research during recent years. A wide range of traditional foods produced by fermentation based on LAB offer the potential of providing new functional food products enriched with GABA that may offer certain health-benefits. Different GAD enzymes and genes from several strains of LAB have been isolated and characterized recently. GABA-producing LAB, the biochemical properties of their GAD enzymes, and possible applications are reviewed here.