Nonribosomal peptide synthetase; part of the gene cluster that mediates the biosynthesis of gramillins A and B, bicyclic lipopeptides that induce cell death in maize leaves but not in wheat leaves (PubMed:30395461). The nonribosomal peptide synthetase GRA1 incorporates respectively a glutamic adic (Glu), a leucine (Leu), a serine (Ser), a hydroxyglutamine (HOGln), a 2-amino decanoic acid, and 2 cysteins (CysB and CysA) (Probable). The biosynthesis of 2-amino decanoic acid incorporated in gramillins could be initiated by a fatty acid synthase composed of the alpha and beta subunits FGSG_00036 and FGSG_11656 (Probable). The cytochrome P450 monooxygenase FGSG_15680 could hydroxylate the fatty acid chain (Probable). Subsequent oxidation to the ketone by the oxidoreductase FGSG_00048 and transamination by aminotransferase FGSG_00049 could form 2-amino-decanoic acid (Probable). On the other hand, FGSG_15680 could also be responsible for the HO-modified glutamine at the gamma-position (Probable). Whether hydroxylation occurs on the fully assembled product or on the Gln residue prior to assembly into the gramillins requires further proof (Probable). The thioredoxin FGSG_00043 could also be required for the disulfide-bond formation between CysA and CysB (Probable). The specific involvement of the remaining proteins from the cluster is more difficult to discern, but could have broader regulatory (FGSG_00040 and FGSG_11657) or enzymatic functions (FGSG_00044 and FGSG_00045) (Probable). The final C-domain of GRA1 does not possess the expected sequence of a termination CT domain, often implicated in macrocyclization and release of a cyclopeptidein fungal NRPs; and the thioesterase FGSG_00047 may act in concert with the terminal C-domain of GRA1 to catalyze the formation of the macrocyclic anhydride and release of the products (Probable). Mycotoxin biosynthesis. Expressed during infection of maize kernels and exhibits transient expression during barley and wheat spike infection (PubMed:26693688). Coexpressed alongside the trichothecene biosynthesis gene cluster (PubMed:26693688). 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, epimerase (E) domains (responsible for L- to D-amino acid conversion) are present within the NRP synthetase. GRA1 has the following architecture: A-T-C-A-T-C-A-T-C-A-T-C-A-T-C-A-T-C-A-T-C. Abolishes the production of gramillins A and B. Belongs to the NRP synthetase family.