Non-reducing polyketide synthase (NRPKS); part of the gene cluster that mediates the biosynthesis of asperthecin, an anthraquinone pigment (PubMed:18978088, PubMed:21866960). Catalyzes the formation of the aromatic polyketide from acetyl coenzyme A and seven malonyl coenzyme A molecules (PubMed:18978088, PubMed:21866960). Through its product template (PT) domain, catalyzes the cyclization of the polyketide backbone via C6-C11 aldolcondensation (PubMed:20479000). Polyketide is subsequently hydrolyzed from the NRPKS by the action of the hydrolase aptB into endocrocin-9-anthrone (PubMed:18978088). Endocrocin-9-anthrone is then oxidized into endocrocin by aptC (PubMed:18978088). Endocrocin is likely to decarboxylate spontaneously to form emodin which explains why there is no decarboxylase in the asperthecin biosynthesis cluster (PubMed:18978088). Finally, aptC or another endogenous oxygenase catalyzes additional oxidation steps to form asperthecin (PubMed:18978088). acetyl-CoA + 8 H(+) + holo-[ACP] + 8 malonyl-CoA = 3,6,8,9-tetrahydroxy-1-oxo-3-(2-oxopropyl)-1,2,3,4-tetrahydroanthracene-2-carboxyl-[ACP] + 8 CO2 + 9 CoA + 2 H2O Binds 1 phosphopantetheine covalently. Secondary metabolite biosynthesis. Expression is induced during late sexual development in the dark (PubMed:26773375). 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 (PubMed:18978088, PubMed:20479000). Fails to produce asperthecin (PubMed:18978088).