Vivian Chang

Mentor: Dr. Yan Kung

The mevalonate (MVA) pathway is an important metabolic pathway involved in the biosynthesis of isoprenoids, a class of naturally-occurring organic compounds that are essential in nearly all living organisms. Products of the MVA pathway also have applications in biofuel and drug production in engineered microorganisms. The structural and biochemical study of specific enzymes of this pathway will provide insight into how isoprenoids are synthesized in nature to give rise to these biologically-useful derivatives.

Figure 1

Figure 1. Competitive feedback inhibition in mevalonate kinase (green) by farnesyl thiophosphate (colored sticks) on the Mg2+-dependent ATP-binding pocket. PDB ID: 2R3V (1).

My research will focus on the key MVA pathway enzyme mevalonate kinase (MK), which catalyzes the ATP-dependent phosphorylation of mevalonic acid into mevalonate 5-phosphate. Previous studies have shown that MK is subject to inhibition by MVA pathway intermediates (Figure 1), which may be responsible for limiting the production of isoprenoid drugs and biofuels. To improve the efficiency of isoprenoid biosynthesis, our goals are to solve X-ray crystal structures of MK bound with different inhibitors and to design and test MK mutants to reduce inhibitory activity.

The biochemical techniques that will be applied include molecular cloning, bacterial transformation, protein expression and purification, protein activity and inhibition studies, and protein crystallization. X-ray crystallography will then be employed to solve structures of MK. Using these enzyme structures, we can develop three-dimensional models which will be valuable for understanding how structure affects the activity and inhibition of the enzyme, thus enabling us to synthesize modified MK enzymes with more favorable properties.

 

Reference:

1. Fu, Z., Voynova, N.E., Herdendorf, T.J., Miziorko, H.M., and Kim, J.P. (2008) Biochemical and Structural Basis for Feedback Inhibition of Mevalonate Kinase and Isoprenoid Metabolism. Biochemistry 47, 3715-3724.