AUTHOR=Hong Eun Young , Lee Sun-Gu , Yun Hyungdon , Kim Byung-Gee TITLE=Improving the Stability and Activity of Arginine Decarboxylase at Alkaline pH for the Production of Agmatine JOURNAL=Frontiers in Catalysis VOLUME=1 YEAR=2021 URL=https://www.frontiersin.org/journals/catalysis/articles/10.3389/fctls.2021.774512 DOI=10.3389/fctls.2021.774512 ISSN=2673-7841 ABSTRACT=

Agmatine, involved in various modulatory actions in cellular mechanisms, is produced from arginine (Arg) by decarboxylation reaction using arginine decarboxylase (ADC, EC 4.1.1.19). The major obstacle of using wild-type Escherichia coli ADC (ADCes) in agmatine production is its sharp activity loss and instability at alkaline pH. Here, to overcome this problem, a new disulfide bond was rationally introduced in the decameric interface region of the enzyme. Among the mutants generated, W16C/D43C increased both thermostability and activity. The half-life (T1/2) of W16C/D43C at pH 8.0 and 60°C was 560 min, which was 280-fold longer than that of the wild-type, and the specific activity at pH 8.0 also increased 2.1-fold. Site-saturation mutagenesis was subsequently performed at the active site residues of ADCes using the disulfide-bond mutant (W16C/D43C) as a template. The best variant W16C/D43C/I258A displayed a 4.4-fold increase in the catalytic efficiency when compared with the wild-type. The final mutant (W16C/D43C/I258A) was successfully applied to in vitro synthesis of agmatine with an improved yield and productivity (>89.0% yield based on 100 mM of Arg within 5  h).