Non-reducing polyketide synthase; part of the gene cluster that mediates the biosynthesis of zearalenone (ZEA), a nonsteroid estrogen that is a contaminant of cereal grains and causes estrogenic disorders in humans and animals (PubMed:16262793, PubMed:16517624, PubMed:18427109). The ZEA backbone is synthesized from a single acetyl-CoA molecule and eight malonyl-CoA molecules (PubMed:16262793, PubMed:16517624, PubMed:18427109). The reducing polyketide synthase ZEA2 is proposed to synthesize a reduced hexaketide intermediate by using different combinations of its reductive domains during each round of condensation (PubMed:16262793, PubMed:16517624, PubMed:16751498, PubMed:18427109). The hexaketide thioester is then transacylated to the non-reducing polyketide synthase ZEA1 and is further condensed with three malonyl-CoAs without reductive tailoring to yield a mixed reduced/unreduced nonaketide (PubMed:16262793, PubMed:16517624, PubMed:18427109). ZEA1 must be able to interact with ZEA2 to facilitate starter-unit acyltransfer and initiate polyketide biosynthesis (PubMed:18427109). ZEA1 also mediates the required C2-C7 cyclization to form the resorcylate core and catalyzes the formation of the macrolactone (PubMed:18427109). ZEA1 exhibits broad starter-unit specificities toward fatty acyl-CoAs ranging in sizes between C6 and C16 and displays the highest activity toward decanoyl-CoA (PubMed:18427109). ZEB1 is then responsible for the chemical conversion of beta-zearalenonol (beta-ZOL) to ZEA in the biosynthetic pathway (PubMed:16262793). Mycotoxin biosynthesis. Expression is positively regulated by the zearalenone biosynthesis specific transcription factor ZEB2 (PubMed:16262793). Conditions for carbon-, nitrogen-, or phosphorus-starvations lead to very low expression (PubMed:16262793). Increase in pH results in gradual reduction of the gene expression (PubMed:16262793). Multidomain protein; including a starter unit:ACP transacylase (SAT) that selects the starter unit; a ketosynthase (KS) that catalyzes repeated decarboxylative condensation to elongate the polyketide backbone; a malonyl-CoA:ACP transacylase (MAT) that selects and transfers the extender unit malonyl-CoA; a product template (PT) domain that controls the immediate cyclization regioselectivity of the reactive polyketide backbone; and an acyl-carrier protein (ACP) that serves as the tether of the growing and completed polyketide via its phosphopantetheinyl arm (By similarity). The release of the polyketide chain from the non-reducing polyketide synthase is mediated by the thioesterase (TE) domain localized at the C-ter of the protein (By similarity). Results in the loss of zearalenone production but still produces beta-zearalenonol (PubMed:16262793, PubMed:16517624).