Characterization of Phosphopantetheine Adenylyltransferase: A Potential, Novel Antibacterial Target

Phosphopantetheine adenylyltransferase (PPAT) catalyzes the penultimate step in the CoA biosynthetic pathway, reversibly transferring an adenylyl group from ATP to 4’-phosphopantetheine (PhP) to form dephosphocoenzyme A (dPCoA). This reaction sits at the branch point between the de novo and salvage pathways and has been shown to be a rate-limiting step in the biosynthesis. Importantly, the bacterial and mammalian PPAT share little sequence homology making the enzyme a potential target for antibiotic development. Therefore, we hypothesized that inhibiting PPAT would disrupt the CoA biosynthetic pathway and decrease the virulence and replicative potential of a broad range of pathogenic bacteria. Our overall goals for this dissertation project were to understand how the potential drug target, PPAT, regulates its respective reaction within a gram-positive and an acid-fast pathogenic bacteria, to discover small, organic, molecular probes against PPAT through high-throughput enzymatic screening, and to optimize these probes for further antibacterial applications. To achieve these goals, this dissertation presented the kinetic, thermodynamic, and structural characterization of M.tuberculosis and B.anthracis PPAT as well as the results of high-throughput screening campaigns against M.tuberculosis PPAT.