MurA and EPSPS are the only known members of the enolpyruvyl transferase family of enzymes. They are attractive targets for the development of new antibiotic drugs. The MurA reaction forms the first committed step in the biosynthesis of the bacterial cell wall. EPSP synthase is the sixth enzyme in the shikimate pathway towards the synthesis of aromatic amino acids and of other aromatic compounds in numerous microorganisms and plants. Both these pathways are absent from mammals but essential for microbial growth. The central hypothesis to the proposed project is that the use of selected mutant enzymes of MurA and EPSPS together with substrate, product and intermediate state analogs will allow for a complete understanding of the entire reaction pathway of enolpyruvyl transfer, starting from free enzyme to the enzyme products complex. The rationale for the proposed research is that once the prerequisites for the enzymatic reaction are identified, this information will be ultimately utilized to design potent inhibitors that selectively target both enzymes. In order to test our hypothesis and accomplish the objective of this project, two specific aims, which integrate techniques such as protein crystallography, enzyme kinetics, fluorescence spectroscopy, molecular cloning, and synthetic organic chemistry, will be pursued: (i) the identification of the prerequisites for the catalysis of enolpyruvyl transfer, and (ii) the identification of the prerequisites for the induced-fit mechanism. These studies will substantially contribute to our understanding of the relationship between the structure and activity of enolpyruvyl transferases. Moreover, they will provide a solid basis for the rational design of novel broad-spectrum antimicrobial drugs targeting these important enzymes.
