Nonribosomal peptide synthase; part of the gene cluster that mediates the biosynthesis of asperphenamate, a rare linear amino acid ester that exhibits antitumor activity towards a number of cell lines (PubMed:29719714). The structure of asperphenamate contains two subunits, N-benzoylphenylalanine and N-benzoylphenylalaninol, which are connected by an inter-molecular ester bond (PubMed:29719714). The first step of asperphenamate biosynthesis is the generation of N-benzoylphenylalaninol by the nonribosomal peptide synthase apmA (PubMed:29719714). Using phenylalanine and benzoic acid as substrates, apmA catalyzes amide bond formation and tethers the intermediate into the NRPS chain. Then, the terminal R domain of apmA catalyzes the reduction reaction to get the shunt product N-benzoylphenylalaninol (PubMed:29719714). Subsequently, the nonribosomal peptide synthase apmB activates the same substrates as does apmA (phenylalanine and benzoic acid) to produce N-benzoylphenylalanine before condensing N-benzoylphenylalanine and N-benzoylphenylalaninol to release asperphenamate (PubMed:29719714). 2 AH2 + 2 ATP + benzoate + L-phenylalanine = 2 A + 2 AMP + 2 diphosphate + H(+) + N-benzoyl-L-phenylalaninol 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. Occasionally, methyltransferase domains (responsible for amino acid methylation) are present within the NRP synthetase. ApmA has the following architecture: A-T-C-A-T-R with a C-terminal reductase (R)-domain that acts in the reductive release of the shunt product N-benzoylphenylalaninol in the two-modular NRPS apmA. Completely abolishes the production of asperphenamate. Belongs to the NRP synthetase family.