The present invention provides a recombinant cell for producing para-nitro-L-phenylalanine (pN-Phe). The recombinant cell comprises heterologous genes encoding heterologous enzymes. The recombinant cell expresses the heterologous enzymes and contains a native metabolite. The native metabolite is converted to the pN-Phe in the recombinant cell. The biosynthesized pN-Phe may be incorporated into a target polypeptide in the recombinant cell without requiring exposure of the recombinant cell to exogenous pN-Phe. A cell culture comprising the recombinant cell is also provided. Further provided is a method of producing pN-Phe by a recombinant cell comprising heterologous genes encoding heterologous enzymes. The method comprises expressing a native metabolite by the recombinant cell, expressing the heterologous enzymes, and converting the native metabolite to the pN-Phe in the recombinant cell. The method may further comprise incorporating the pN-Phe into the target polypeptide in the recombinant cell.