Nonribosomal peptide synthetase; part of the gene cluster that mediates the biosynthesis of terreazepine, (PubMed:32843555). The first step of terreazepine biosynthesis is catalyzed by the indoleamine 2,3-dioxygenase tpzB which produces N-formyl-kynurenine through the catabolism of tryptophan (PubMed:32843555). The two-module NRPS tpzA then utilizes anthranilate and kynurenine to assemble terreazepine (PubMed:32843555). The first adenylation domain of tpzA (A1) loads anthranilate onto the T1 domain, while A2 loads kynurenine, generated through spontaneous nonenzymatic deformylation of the tzpB-supplied N-formyl-kynurenine (PubMed:32843555). TpzA produces a 2:1 mixture of S-R enantiomers, which suggests that the A2 domain accepts both D- and L-kynurenine (PubMed:32843555). The peptide bond formation between the tethered amino acids is catalyzed by the first condensation domain (C1) between anthranilate's carbonyl carbon and kynurenine's aliphatic primary amine (PubMed:32843555). The second C domain (C2) catalyzes the final cyclization event between the aromatic amine of kynurenine and the tethered carbonyl carbon, yielding the final terreazepine product (PubMed:32843555). The T3 domain may facilitate the interaction with downstream tailoring enzymes (PubMed:32843555). Secondary metabolite biosynthesis. NRP synthetases are composed of discrete domains (adenylation (A), thiolation (T) or peptidyl carrier protein (PCP) and condensation (C) domains) which when grouped together are referred to as a single module. Each module is responsible for the recognition (via the A domain) and incorporation of a single amino acid into the growing peptide product. Thus, an NRP synthetase is generally composed of one or more modules and can terminate in a thioesterase domain (TE) that releases the newly synthesized peptide from the enzyme. TpzA has the following architecture: A1-T1-C1-A2-T2-C2-T3. Belongs to the NRP synthetase family.