Grant: Discovery Grants Program - Individual

The overall objective of my research program is understanding the molecular structure and function of a recently discovered family of enzymes (bacterial inositol polyphosphatases or PTP-IPPs) that are distantly related to protein tyrosine phosphatases. These enzymes remove one or more phosphates from many different inositol polyphosphates, an important class of signal transduction molecule that has known roles in many essential cellular processes including DNA repair, mRNA export, plant development, apotosis and bacterial pathogenicity. We utilize a variety of biochemical and molecular biology techniques to study the substrate specificity, kinetic and molecular mechanism of action of these enzymes. In particular, this research utilizes X-ray crystallographic techniques to determine atomic resolutions structures of PTP-IPPs alone and in complex with naturally occuring substrates. These studies allow us to visualize the enzyme and its interaction with substrate. Site-directed mutagenesis, fluorescense-based binding assays and steady-state kinetics are then utilized toextend and refine our understanding of the structure and function of these enzymes. Specific, interelated questions of interest that can be addressed using these techniques include: (1) How do these enzymes discriminate between the many naturally occuring InsPs? (2) What is their detailedkinetic mechanism and how does it differ from the well studied protein tyrosine phosphatases? And (3) Can these enzymes be utlized to cheaply produce biologically important InsPs? In turn, the answers to these questions will shed light upon their role in pathogenesis and the role of InsPs in eucaryotes.