Biosynthesis of Lovastatin in a Heterologous Host

Suzanne M. Ma, Xinkai Xie, Wladyslaw A. Wojcicki, and Yi Tang. Chemical and BioMolecular Engineering, University of California, Los Angeles, 420 Westwood Plaza, Los Angeles, CA 90095

Hypercholesterolemia is the primary risk factor for coronary heart diseases. Globally, cardiovascular diseases caused by high blood cholesterol account for 29% of all deaths. By inhibiting 3-hydroxy-3-methylglytaryl coenzyme A (HMG-CoA) reductase, the enzyme responsible for catalyzing the committed step in cholesterol biosynthesis, serum levels of cholesterol can be effectively lowered, thus lowering plaque accumulation in the arteries of the heart and lowering the risk for coronary heart disease. The cholesterol lowering statins are the drug therapy of choice in effectively treating hypercholesterolemia. Lovastatin is biosynthesized in its natural host, Aspergillus terreus by a type I fungal polyketide. It is attractive to seek a heterologous host for lovastatin production because, slow organism growth times, low yields in reference to secondary metabolite production, and difficulty of genetic manipulation in the natural host inhibit facile commercial production. We have cloned and expressed the lovastatin gene cluster in the genetically well-characterized hosts Escherichia coli and Saccharomyces cerevisiae. We have seen functional soluble expression of several of the key proteins in the lovastatin gene cluster from heterologous expression in E. coli. Specifically, the megasynthases LovB and LovF, as well as the transferase, LovD, and the dissociated enoyl reductase domain, LovC. In addition, we have also transformed the lovastatin gene cluster into S. cerevisiae for heterologous expression of the LovB, LovC, LovD, and lovF genes. This poster will discuss the reconstitution of the lovastatin pathway in the heterologous hosts to metabolically engineer E. coli, and S. cerevisiae to produce lovastatin and possibly therapeutic analogs to lovastatin.