Jie Cheng

Mentor: Dr. Yan Kung

Chemistry Department

 

The purification and characterization of HMG-CoA reductases

 

The mevalonate(MEV) pathway is an important cellular metabolic pathway in all higher eukaryotes and many bacteria for the biosynthesis of steriods and isoprenoids, which have wide applications as pharmaceutics and biofuels. The structural and biochemical study of specific key enzyme in MEV pathway will provide insights in both synthetic biology for the microbial production of isoprenoids and in human medicine. HMG-CoA reductase (HMGR) catalyzes the rate-determining step of the MEV pathway, using a cofactor (NADPH or NADH) to reduce HMG-CoA to mevalonate. Although HMGR has been studied extensively, previous studies did not reveal the structural basis of HMGR cofactor specificity, which would have tremendous value for the production of isoprenoid drugs. My summer research will focus on the protein expression and crystallization of HMGRs with varying cofactor specificities, and the determination of crystal structures of HMGRs bound with cofactors to ultimately design HMGR mutants to increase the efficiency isoprenoid biosynthesis. The biochemical techniques applied in this research include molecular cloning, bacterial transformation, protein expression and purification, and protein crystallization. Finally the structures of HMGR homologs are expected to be solved by X-ray crystallography, and three-dimensional models will be established to better understand the interactions between HMGRs and its cofactors among different organisms.