Publications

• Lovastatin biosynthesis in Aspergillus terreus: characterization of blocked mutants, enzyme activities and a multifunctional polyketide synthase gene.

  Hendrickson L., Davis C.R., Roach C., Nguyen D.K., Aldrich T., McAda P.C., Reeves C.D.

  <h4>Background</h4>Lovastatin, an HMG-CoA reductase inhibitor produced by the fungus Aspergillus terreus, is composed of two polyketide chains. One is a nonaketide that undergoes cyclization to a hexahydronaphthalene ring system and the other is a simple diketide, 2-methylbutyrate. Fungal polyketi ... >> More

  <h4>Background</h4>Lovastatin, an HMG-CoA reductase inhibitor produced by the fungus Aspergillus terreus, is composed of two polyketide chains. One is a nonaketide that undergoes cyclization to a hexahydronaphthalene ring system and the other is a simple diketide, 2-methylbutyrate. Fungal polyketide synthase (PKS) systems are of great interest and their genetic manipulation should lead to novel compounds.<h4>Results</h4>An A. terreus mutant (BX102) was isolated that could not synthesize the nonaketide portion of lovastatin and was missing a approximately 250 kDa polypeptide normally present under conditions of lovastatin production. Other mutants produced lovastatin intermediates without the methylbutyryl sidechain and were missing a polypeptide of approximately 220 kDa. The PKS inhibitor cerulenin reacted covalently with both polypeptides. Antiserum raised against the approximately 250 kDa polypeptide was used to isolate the corresponding gene, which complemented the BX102 mutation. The gene encodes a polypeptide of 269 kDa containing catalytic domains typical of vertebrate fatty acid and fungal PKSs, plus two additional domains not previously seen in PKSs: a centrally located methyltransferase domain and a peptide synthetase elongation domain at the carboxyl terminus.<h4>Conclusions</h4>The results show that the nonaketide and diketide portions of lovastatin are synthesized by separate large multifunctional PKSs. Elucidation of the primary structure of the PKS that forms the lovastatin nonaketide, as well as characterization of blocked mutants, provides new details of lovastatin biosynthesis. << Less

  Chem. Biol. 6:429-439(1999) [PubMed] [EuropePMC]

• Complete reconstitution of a highly reducing iterative polyketide synthase.

  Ma S.M., Li J.W., Choi J.W., Zhou H., Lee K.K., Moorthie V.A., Xie X., Kealey J.T., Da Silva N.A., Vederas J.C., Tang Y.

  Highly reducing iterative polyketide synthases are large, multifunctional enzymes that make important metabolites in fungi, such as lovastatin, a cholesterol-lowering drug from Aspergillus terreus. We report efficient expression of the lovastatin nonaketide synthase (LovB) from an engineered strai ... >> More

  Highly reducing iterative polyketide synthases are large, multifunctional enzymes that make important metabolites in fungi, such as lovastatin, a cholesterol-lowering drug from Aspergillus terreus. We report efficient expression of the lovastatin nonaketide synthase (LovB) from an engineered strain of Saccharomyces cerevisiae, as well as complete reconstitution of its catalytic function in the presence and absence of cofactors (the reduced form of nicotinamide adenine dinucleotide phosphate and S-adenosylmethionine) and its partner enzyme, the enoyl reductase LovC. Our results demonstrate that LovB retains correct intermediates until completion of synthesis of dihydromonacolin L, but off-loads incorrectly processed compounds as pyrones or hydrolytic products. Experiments replacing LovC with analogous MlcG from compactin biosynthesis demonstrate a gate-keeping function for this partner enzyme. This study represents a key step in the understanding of the functions and structures of this family of enzymes. << Less

  Science 326:589-592(2009) [PubMed] [EuropePMC]

• Modulation of polyketide synthase activity by accessory proteins during lovastatin biosynthesis.

  Kennedy J., Auclair K., Kendrew S.G., Park C., Vederas J.C., Hutchinson C.R.

  Polyketides, the ubiquitous products of secondary metabolism in microorganisms, are made by a process resembling fatty acid biosynthesis that allows the suppression of reduction or dehydration reactions at specific biosynthetic steps, giving rise to a wide range of often medically useful products. ... >> More

  Polyketides, the ubiquitous products of secondary metabolism in microorganisms, are made by a process resembling fatty acid biosynthesis that allows the suppression of reduction or dehydration reactions at specific biosynthetic steps, giving rise to a wide range of often medically useful products. The lovastatin biosynthesis cluster contains two type I polyketide synthase genes. Synthesis of the main nonaketide-derived skeleton was found to require the previously known iterative lovastatin nonaketide synthase (LNKS), plus at least one additional protein (LovC) that interacts with LNKS and is necessary for the correct processing of the growing polyketide chain and production of dihydromonacolin L. The noniterative lovastatin diketide synthase (LDKS) enzyme specifies formation of 2-methylbutyrate and interacts closely with an additional transesterase (LovD) responsible for assembling lovastatin from this polyketide and monacolin J. << Less

  Science 284:1368-1372(1999) [PubMed] [EuropePMC]

  This publication is cited by 2 other entries.

• LovG: the thioesterase required for dihydromonacolin L release and lovastatin nonaketide synthase turnover in lovastatin biosynthesis.

  Xu W., Chooi Y.H., Choi J.W., Li S., Vederas J.C., Da Silva N.A., Tang Y.

  Angew. Chem. Int. Ed. Engl. 52:6472-6475(2013) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.