Nonribosomal peptide synthase; part of the gene cluster that mediates the biosynthesis of aspercryptins, linear lipopeptides built from six amino acids including 2 highly unusual and nonproteogenic amino acids, 2-amino-octanoic acid (2aoa) and 2-amino-dodecanol (2adol) (PubMed:23248299, PubMed:27310134, PubMed:26563584). The core structure of aspercryptins is as follows: Ser/Ala-Thr-Ile/Val-2aoa-Asn-2adol (PubMed:27310134). The first step of aspercryptin biosynthesis is the generation of the fatty acid precursors, octanoic and dodecanoic acids, by the FAS subunits atnF and atnM (PubMed:27310134, PubMed:26563584). The fatty acid precursors are likely transformed into the corresponding alpha-amino fatty acids in three steps (PubMed:27310134, PubMed:26563584). First, they are hydroxylated by the cytochrome P450 monooxygenase atnE, then oxidized to the corresponding alpha-keto acids by the NAD(P)-dependent oxidoreductase atnD, and finally converted to the alpha-amino fatty acids by the PLP-dependent aminotransferases atnH or atnJ (PubMed:27310134, PubMed:26563584). the alpha-amino fatty acids, 2-amino-octanoic and 2-amino-dodecanoic acids, are recognized, activated, and covalently tethered to the NRPS atnA by its fourth and sixth adenylation domains (PubMed:27310134). The second module of atnA is the Thr module and contains an epimerase (E) domain responsible for the epimerization of Thr to D-allo-Thr (PubMed:26563584). Additionally, despite atnA having only one epimerase domain, the first amino acid of aspercryptin A1 is D-Ser, suggesting that serine is either loaded directly as D-Ser on the first module or that the epimerase domain in the threonine module epimerizes both L-Ser and L-Thr (PubMed:27310134). After condensation of the hexapeptide of aspercryptin, the C-terminal reductase (TE) domain might be involved in the reductive release and production of the aldehyde hexapeptide (PubMed:26563584). Further reduction would generate aspercryptins (PubMed:27310134, PubMed:26563584). The variety of aspercryptins produced reflects the flexibiliy of the atnA NRPS, allowing incorporation of alanine instead of serine, valine for isoleucine, and a C10 fatty amino alcohol instead of the C12 version (PubMed:27310134). AtnB seems to be involved in the selectivity for Ile versus Val by the third module (PubMed:26563584). Moreover, type B, C and D aspercryptins have an additional N-terminal cichorine, acetyl and propionyl group respectively (PubMed:27310134). Secondary metabolite biosynthesis. Expression is positively regulated by the aspercryptin cluser-specific transcription factor atnN (PubMed:27310134). 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 (By similarity). Each module is responsible for the recognition (via the A domain) and incorporation of a single amino acid into the growing peptide product (By similarity). 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 (By similarity). Occasionally, methyltransferase domains (responsible for amino acid methylation) are present within the NRP synthetase (By similarity). InpA has the following architecture: A-T-C-A-T-E-C-A-T-C-A-T-C-A-T-C-A-T-TE (PubMed:27310134). Eliminates the production of aspercryptin (PubMed:27310134, PubMed:26563584). Belongs to the NRP synthetase family.