Trans-enoyl reductase; part of the gene cluster that mediates the biosynthesis of the tetramic acids Sch210971 and Sch210972, potential anti-HIV fungal natural product that contain a decalin core (PubMed:25885659). The PKS module of tasS together with the enoylreductase tasC catalyze the formation of the polyketide unit which is then conjugated to 4-hydroxyl-4-methyl glutamate (HMG) by the condensation domain of the tasS NRPS module (PubMed:25885659). One unique structural feature of Sch210971 and Sch210972 is the tetramic acid motif proposed to be derived from the non-proteinogenic amino acid HMG, by a Dieckmann-type condensation catalyzed by the reductase domain of tasS (PubMed:25885659). The aldolase tasA catalyzes the aldol condensation of 2 molecules of pyruvic acid to yield the intermediate 4-hydroxyl-4-methyl-2-oxoglutarate (HMOG), which can then be stereoselectively transaminated, may be by tasG, to form HMG (PubMed:25885659). The Diels-Alderase tas3 then uses the Dieckmann product of tasS as substrate and catalyzes the Diels-Alder cycloaddition to form the decalin ring of Sch210971 and Sch210972 (PubMed:25885659). (2S,4S)-4-hydroxy-4-methylglutamate + ATP + 11 H(+) + 8 malonyl-CoA + 8 NADPH + 3 S-adenosyl-L-methionine = (2S)-3-[(2S)-3,5-dioxo-4-[(2E,4R,6R,8E,10E,12E)-4,6,12-trimethyltetradeca-2,8,10,12-tetraenoyl]pyrrolidin-2-yl]-2-hydroxy-2-methylpropanoate + AMP + 8 CO2 + 8 CoA + diphosphate + 6 H2O + 8 NADP(+) + 3 S-adenosyl-L-homocysteine (2S,4R)-4-hydroxy-4-methylglutamate + ATP + 11 H(+) + 8 malonyl-CoA + 8 NADPH + 3 S-adenosyl-L-methionine = (2R)-3-[(2S)-3,5-dioxo-4-[(2E,4R,6R,8E,10E,12E)-4,6,12-trimethyltetradeca-2,8,10,12-tetraenoyl]pyrrolidin-2-yl]-2-hydroxy-2-methylpropanoate + AMP + 8 CO2 + 8 CoA + diphosphate + 6 H2O + 8 NADP(+) + 3 S-adenosyl-L-homocysteine Secondary metabolite biosynthesis. Monomer. Belongs to the zinc-containing alcohol dehydrogenase family.