Grant: Discovery Grants Program - Individual

Phosphorylation/dephosphorylation (i.e. the addition and removal of phosphate groups) is probably the most crucial chemical reaction taking place in living organisms. It is the basis for the regulatory control of many diverse biological events triggered by extracellular effectors. Moreover, it is a universal element of intracellular signal transduction pathways involved in the control of metabolism, gene expression, cell division and differentiation, development, contraction, transport, locomotion, and learning and memory. Phosphatases remove the phosphate group from phospho-containing substrates, including both small molecules and proteins, while kinases are involved in their addition. The long-term objective of this research proposal is to advance our understanding of the structure-function relationship of phosphatases/kinases, which are vital for many cellular processes. Specifically, we aim to understand the mechanisms of (de)phosphorylation by kinases and phosphatases, as well as, the structural basis for substrate recognition and specificity. The specific objectives of this proposal are: 1) structural determination of the bifunctional enzyme, AceK (containing both kinase and phosphatase activities), which is the first phosphorylating system found in bacteria, both in its native state and in complex with its natural substrate, isocitrate dehydrogenase; 2) extensive structural and functional characterization of myosin heavy chain kinase, a novel threonine-specific kinase involved in the control of contractility; 3) systematic characterization of Ham1/Maf pyrophosphatases and their specificity for ""abnormal"" nucleotides which allows them to serve a ""house-cleaning"" role in the cell. In all these studies, a combination of biochemical, biophysical and structural techniques will be utilized to uncover the structural basis and molecular mechanisms underlying substrate specificity, catalyitic activity and functional diversity. As such, it will be a means of providing high quality, diverse training to the trainees in our laboratory.