The present disclosure is directed to the biosynthetic pathway for a nonribosomal peptide synthetase (NRPS) derived drug and analogs thereof. The invention provides polynucleotide sequences useful for heterologous expression in a convenient microbial host for the synthesis of the NRPS-derived drug, the polypeptides encoded by such polynucleotides, expression vectors comprising the polynucleotides, host cells comprising the polynucleotides or expression vectors, and kits comprising a host cell. Also provided is a method for the production of ET-743, the NRPS-derived drug.