Nonribosomal peptide synthetase; part of the gene cluster that mediates the biosynthesis of the antifungal antibiotic FR901469, an inhibitor of beta-1,3-glucansynthase, exerting antifungal activity against the pathogenes Candida albicans and Aspergillus fumigatus (PubMed:27660098). FR901469 is a cyclic depsipeptide containing 12 amino acid residues and a fatty acid chain (PubMed:27660098). The NRPS frbI contains 12 modules responsible for the formation of the depsipeptide backbone which is denoted as Acyl-Thr-Ala-Tyr-Val-4OHPro-Thr-Thr-3OHPro-threo3OHGln-Gly-Thr-Orn-OH (C71H116N14O23) (Probable). The PKS frbB is probably involved in the production of the hydrocarbon chain, and the acyl-CoA ligase frbC might be involved in the transport of the chain to the peptide ptoduct of frbI (Probable). Because FR901469 contains 3 hydroxylated amino acid residues, the 3 oxygenases frbA, frbH, and frbJ might be participating in amino acid hydroxylation (Probable). As no thioesterase domains were detected in frbI or frbB, the thioesterases frbD and frbE may instead release and cyclize the products of the NRPS and PKS, respectively (Probable). Antifungal biosynthesis. Expression is positively regulated by the cluster-specific transcription factor frbF. 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. FrbI has the following architecture: T-C-A-T-E-C-A-T-E-C-A-T-C-A-T-C-A-T-C-A-T-E-C-A-T-C-A-T-C-A-T-C-A-T-C-A-T-E-C-A-T-C. FR901469 inhibits the activity of 1,3-beta-glucan synthase from Candida albicans and Aspergillus fumigatus (PubMed:11099224, PubMed:11099225). With minimal inhibitory concentrations (MICs) against Candida albicans and Aspergillus fumigatus of 0.63 ug/ml and 0.16 ug/ml, repectively, FR901469 displays greater inhibitory activity than other 1,3-beta-glucan synthase inhibitors such as, WF11899A, echinocandin B, aculeacin A, and papulacandin B (PubMed:11099224, PubMed:11099225). Belongs to the NRP synthetase family.