Glutamate decarboxylase (GAD) catalyzes the conversion of glutamate to γ-aminobutyric acid (GABA), which is significant for human health and industrial GABA production. This study demonstrates that sulfate acts as an activator for Bacteroides thetaiotaomicron GAD (BTGAD) in the absence of its cofactor pyridoxal-5'-phosphate (PLP), enhancing enzymatic activity by approximately 1.4-fold. However, sulfate competitively inhibits PLP binding and suppresses BTGAD-PLP activity to 36.15%. Structural studies revealed that sulfate binds in a bipartite manner to BTGAD at PLP-binding site and N-terminal sequence. Mutagenesis studies confirm that both binding sites are essential for sulfate-dependent regulation of BTGAD. The mutants H273A and ∆N increased the activation fold of Na2SO4 on BTGAD and enhanced the inhibitory effects of Na2SO4 on BTGAD-PLP. These results establish sulfate as a bifunctional modulator with potential applications in the enzymatic production of GABA.
The red bibenzoquinone oosporein, a promising biocontrol agent with potential to replace conventional pesticides in insect pest management in crops, was produced by the Basidiomycota Phlebia centrifuga P. Karst isolated from the Black Forest National Park. A submerged system was established, yielding up to 1.60 g L–1 oosporein in the culture supernatant upon supplementation with the key intermediate orsellinic acid, which strongly induced oosporein-specific biosynthetic genes. Using a multiomics approach, genes encoding enzymes for all necessary conversions were predicted, including a type I polyketide synthase, two monooxygenases, and a heme peroxidase. Enzymatic functions were investigated by extensive docking analyses and molecular dynamics simulations, ultimately leading to the prediction of the underlying biosynthetic pathway. In summary, a spore-free, high-yield, scalable production platform for oosporein was established, highlighting the potential of rare, protected fungal species as sources for valuable enzymes and bioactive secondary metabolites for efficient microbial biomanufacturing systems.
Niklas Broel, F. V. Wengner, J. Stein et al.· Journal of Agricultural and...· 0 citations