Production of nonproteinaceous amino acids using recombinant Escherichia coli cells expressing cysteine synthase and related enzymes with or without the secretion of O-acetyl-L-serine

β-(Pyrazol-1-yl)-L-alanine (β-PA), a model nonproteinaceous amino acid, was specifically synthesized by two methods using recombinant Escherichia coli cells that express cysteine syathase, comprising serine acetyltransferase (SAT) and O-acetylserine sulfhydrylase-A (OASS-A) and related enzymes firooi E. coli. In the first method (method A), recombinant cells that express wildtype SAT, OASS-A, acetate kinase (AK), and phosphotransacetylase (PTA) showed the highest β-PA production. β-PA was produced at 140 mM from 200 mM L-serine and 200 mM pyrazole under optimum conditions. Using the cells expressing SATΔC20 (truncated SAT), OASS-A, AK, and PTA, β-PA was produced at a level of only 80 mM, whereas O-acetyl-serine (OAS) was found to be secreted into the broth. Under optimum conditions, OAS accumulated at levels of around 105 mM from 300 mM L-serine. Thus, in the second method (method B), the secreted OAS was used as the substrate for the syntheses of β-PA and β-(triazol-1-yl)-L-alanine (β-TA). The OAS that accumulated in the broth was efficiently converted to β-PA and β-TA at levels of around 90 mM from 105 mM OAS using free OASS-A. In both methods A and B, the addition of glucose was essential for the efficient production of β-PA and OAS, respectively.