Characterization of two new aromatic amino acid lyases from actinomycetes for highly efficient production of p -coumaric acid

p -Coumaric acid ( p -CA) is a bioactive natural product and an important industrial material for pharmaceuticals and nutraceuticals. It can be synthesized from deamination of l -tyrosine by tyrosine ammonia lyase (TAL). In this work, we discovered two aromatic amino acid lyase genes, Sas-tal and Sts-tal , from Saccharothrix sp. NRRL B-16348 and Streptomyces sp. NRRL F-4489, respectively, and expressed them in Escherichia coli BL21(DE3). The two enzymes were functionally characterized as TAL. The optimum reaction temperature for Sas-TAL and Sts-TAL is 55 °C and 50 °C, respectively; while, the optimum pH for both TALs is 11. Sas-TAL had a k cat / K m value of 6.2 μM −1 min −1 , while Sts-TAL had a much higher efficiency with a k cat / K m value of 78.3 μM −1 min −1 . Both Sts-TAL and Sas-TAL can also take l -phenylalanine as the substrate to yield trans -cinnamic acid, and Sas-TAL showed much higher phenylalanine ammonia lyase activity than Sts-TAL. Using E. coli /Sts-TAL as a whole-cell biocatalyst, the productivity of p -CA reached 2.88 ± 0.12 g (L h) −1 , which represents the highest efficiency for microbial production of p -CA. Therefore, this work not only reports the identification of two new TALs from actinomycetes, but also provides an efficient way to produce the industrially valuable material p -CA.