Nonribosomal peptide synthetase; part of the gene cluster that mediates the biosynthesis of the mycotoxin cyclochlorotine, a hepatotoxic and carcinogenic cyclic chlorinated pentapeptide (PubMed:26954535). Cyclochlorotine is formed by the nonproteinogenic amino acids L-2-aminobutyrate (2Abu), L-beta-phenylalanine (beta-Phe), the unique L-cis-3,4-dichloroproline Pro(Cl(2)) and two L-serines (Ser) (PubMed:26954535). The condensation of the 5 building blocks is performed by the cyclochlorotine synthetase cctN, a nonribosomal peptide synthetase (PubMed:26954535). The assembled linear pentapeptide is then assumed to be released through cyclization by the terminal condensation-like domain of cctN (PubMed:26954535). Incorporation of the alternative substrates allo-threonine or alanine by the domains A3 or A1 respectively may lead to the production of the variants hydroxy-cyclochlorotine and deoxy-cyclochlorotine, respectively (PubMed:26954535). CctP probably acts as a phenylalanine aminomutase and provides the uncommon building block beta-Phe (PubMed:26954535). Furthermore, 2Abu can be synthesized from threonine by one of the threonine dehydratases and transaminases localized outside of the cluster (PubMed:26954535). The biosynthesis of the unusual dichloroproline moiety remains elusive since the actual halogenase still awaits to be detected, with the possibility that proline halogenation is accomplished by a so far unknown type of halogenase (PubMed:26954535). Finally, the cluster encoded transporters cctQ and cctS are most likely responsible for cyclochlorotine secretion and thereby may contribute to intrinsic resistance (PubMed:26954535). The functions of the remaining proteins encoded by the cluster (cctM, cctO, cctR and cctG) have not been identified yet (PubMed:26954535). Mycotoxin 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 (PubMed:26954535). 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. VlmS has the following 7 module architecture: A-T-C-A-T-C-A-T-C-A-T-C-A-T-C (PubMed:26954535). The assembled linear pentapeptide, tethered to domain T5 of module 5, is then assumed to be released through cyclization by the terminal condensation-like domain which shows the characteristic variations in the first histidine residue of the highly conserved HHxxxDGxS motif of C domains (PubMed:26954535). Leads to complete loss of production of cyclochlorotine and its variants such as hydroxy-cyclochlorotine and deoxy-cyclochlorotine (PubMed:26954535). Belongs to the NRP synthetase family.