Highly Efficient Synthesis of Glutathione via a Genetic Engineering Enzymatic Method Coupled with Yeast ATP Generation

Efficient synthesis of Ala-Tyr by L-amino acid ligase coupled with ATP regeneration system

The multi-enzyme coupling reaction system has become a promising biomanufacturing platform for biochemical production. Tyr is an essential amino acid, but the limited solubility restricts its use. Tyrosyl dipeptide has been paid more attention due to its higher solubility. In this study, an efficient enzymatic cascade of Ala-Tyr synthesis was developed by a L-amino acid ligase together with polyphosphate kinase (PPK). Two L-amino acid ligases from Bacillus subtilis and Bacillus pumilus were selected and applied for Ala-Tyr synthesis. The L-amino acid ligase from B. subtilis (Bs) was selected and coupled with the PPK from Sulfurovum lithotrophicum (PPKSL) for regenerating ATP to produce Ala-Tyr in one pot. In the optimization system, 40.1 mM Ala-Tyr was produced within 3 h due to efficient ATP regeneration with hexametaphosphate (PolyP(6)) as the phosphate donor. The molar yield was 0.89 mol/mol based on the substrates added, while the productivity of Ala-Tyr achieved 13.4 mM/h, which were the highest yield and productivity ever reported about Ala-Tyr synthesis with L-amino acid ligase.

Recombinant Production of Arginyl Dipeptides by l-Amino Acid Ligase RizA Coupled with ATP Regeneration

Arginyl dipeptides like Arg-Ser, Arg-Ala, and Arg-Gly are salt-taste enhancers and can potentially be used to reduce the salt content of food. The l-amino acid ligase RizA from B. subtilis selectively synthesizes arginyl dipeptides. However, industrial application is prevented by the high cost of the cofactor adenosine triphosphate (ATP). Thus, a coupled reaction system was created consisting of RizA and acetate kinase (AckA) from E. coli providing ATP regeneration from acetyl phosphate. Both enzymes were recombinantly produced in E. coli and purified by affinity chromatography. Biocatalytic reactions were varied and analyzed by RP-HPLC with fluorescence detection. Under optimal conditions the system produced up to 5.9 g/L Arg-Ser corresponding to an ATP efficiency of 23 g Arg-Ser per gram ATP. Using similar conditions with alanine or glycine as second amino acid, 2.6 g/L Arg-Ala or 2.4 g/L Arg Gly were produced. The RizA/AckA system selectively produced substantial amounts of arginyl dipeptides while minimizing the usage of the expensive ATP.