Hybrid PKS-NRPS synthetase; part of the gene cluster that mediates the biosynthesis of trichosetin, a trans-fused decalin-containing tetramic acid with antimicrobial activity (PubMed:28379186). The PKS module of PKS-NRPS1 together with the enoylreductase (ER) catalyze the formation of the polyketide unit which is then conjugated to L-serine by the condensation domain of the PKS-NRPS1 NRPS module (By similarity). Activity of the Dieckmann cyclase domain (RED) results in release of the Dieckmann product intermediate (By similarity). Diels-Alderase (DA) is involved in endo-selective Diels-Alder cycloaddition to form the decalin ring, leading to the production of N-desmethylequisetin also called trichosetin (By similarity). The cluster does not contain the equisetin N-methyltransferase and consequently, trichosetin is isolated as final product (PubMed:28379186). acetyl-CoA + ATP + 11 H(+) + L-serine + 7 malonyl-CoA + 8 NADPH + 2 S-adenosyl-L-methionine = (5S)-3-[(2E,6R,8E,10E,12E)-2,6-dimethyltetradeca-2,8,10,12-tetraenoyl]-5-(hydroxymethyl)pyrrolidine-2,4-dione + AMP + 7 CO2 + 8 CoA + diphosphate + 6 H2O + 8 NADP(+) + 2 S-adenosyl-L-homocysteine Mycotoxin biosynthesis. Expression is positively regulated by the trichosetin cluster-specific transcription activator TF22 (PubMed:28379186). 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 (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, epimerase (E) domains (responsible for l- to d-amino acid conversion) are present within the NRP synthetase (By similarity). EqxS contains also a polyketide synthase module (PKS) consisting of several catalytic domains including a ketoacyl synthase domain (KS), an acyl transferase domain (AT), a dehydratase domain (DH), a methyltransferase domain (MT), and a ketoreductase domain (KR) (PubMed:28379186). Instead of a thioesterase domain (TE), eqxS finishes with a reductase-like domain (R) for peptide release (PubMed:28379186). EqxS has the following architecture: KS-AT-DH-KR-PCP-C-A-T-R (PubMed:28379186). Completely abolishes trichosetin production (PubMed:28379186). In the C-terminal section; belongs to the NRP synthetase family.