Lovastatin nonaketide synthase; part of the gene cluster that mediates the biosynthesis of lovastatin (also known as mevinolin, mevacor or monacolin K), a hypolipidemic inhibitor of (3S)-hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase (HMGR) (PubMed:10334994, PubMed:12929390, PubMed:21495633, PubMed:23023987). The first step in the biosynthesis of lovastatin is the production of dihydromonacolin L acid by the lovastatin nonaketide synthase lovB and the trans-acting enoyl reductase lovC via condensation of one acetyl-CoA unit and 8 malonyl-CoA units (PubMed:10334994, PubMed:10381407, PubMed:19900898, PubMed:22733743, PubMed:23023987). Dihydromonacolin L acid is released from lovB by the thioesterase lovG (PubMed:23653178). Next, dihydromonacolin L acid is oxidized by the dihydromonacolin L monooxygenase lovA twice to form monacolin J acid (PubMed:12929390, PubMed:21495633). The 2-methylbutyrate moiety of lovastatin is synthesized by the lovastatin diketide synthase lovF via condensation of one acetyl-CoA unit and one malonyl-CoA unit (PubMed:19530726, PubMed:21069965). Finally, the covalent attachment of this moiety to monacolin J acid is catalyzed by the transesterase lovD to yield lovastatin (PubMed:10334994, PubMed:17113998, PubMed:18988191, PubMed:19875080, PubMed:24727900). LovD has broad substrate specificity and can also convert monacolin J to simvastatin using alpha-dimethylbutanoyl-S-methyl-3-mercaptopropionate (DMB-S-MMP) as the thioester acyl donor, and can also catalyze the reverse reaction and function as hydrolase in vitro (PubMed:19875080). LovD has much higher activity with LovF-bound 2-methylbutanoate than with free diketide substrates (PubMed:21069965). 19 H(+) + holo-[lovastatin nonaketide synthase] + 9 malonyl-CoA + 11 NADPH + S-adenosyl-L-methionine = 9 CO2 + 9 CoA + dihydromonacolin L-[lovastatin nonaketide synthase] + 6 H2O + 11 NADP(+) + S-adenosyl-L-homocysteine Binds 1 phosphopantetheine covalently. Polyketide biosynthesis; lovastatin biosynthesis. Interacts with LovC. Multidomain protein; including 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 dehydratase (DH) domain that reduces hydroxyl groups to enoyl groups; a methyltransferase (CMeT) domain responsible for the incorporation of methyl groups; a ketoreductase (KR) domain that catalyzes beta-ketoreduction steps; and an acyl-carrier protein (ACP) that serves as the tether of the growing and completed polyketide via its phosphopantetheinyl arm (PubMed:22733743). A C-terminal thioesterase (TE) domain that is often found in polyketide synthase proteins is not present in this protein, but lovB contains insteado a C-terminal condensation (C) domain that has lost its condensation activity, but has gained a novel function that is necessary for release of the final product (PubMed:23023987). Lacks an enoylreductase (ER) domain that reduces enoyl groups to alkyl group which function is performed by the trans-acting enoyl reductase lovC. Lovastatin acts as a hypolipidemic agent that works as inhibitor of (3S)-hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase (HMGR) which reduces HMG-CoA to mevalonate and is the key step in cholesterol biosynthesis (PubMed:6933445). Lovastatin, simvastatin and related compounds are widely used to treat hypercholesteremia and reduce the risk of cardiovascular disease (PubMed:6933445). Furthermore, statins such as lovastatin were found to be anticancer agents (PubMed:29236027, PubMed:29932104).