Grant: $299,724 - National Institutes of Health - May. 29, 2009
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Award Description: The double-stranded (ds) RNA-activated protein kinase, PKR, is one of several proteins induced by interferon and plays a pivotal role in the cellular antiviral response. PKR has also been implicated in other cellular processes including transformation, differentiation and apoptosis. There are also structural and functional connections between PKR and the RNA interference (RNAi) pathway. PKR is synthesized in a latent state and is activated upon binding to dsRNA to undergo autophosphorylation reactions that activate the kinase. In turn, activated PKR phosphorylates eukaryotic initiation factor 2-alpha, resulting in the inhibition of protein synthesis in virally-infected cells. The importance of this antiviral pathway is highlighted by the diverse mechanisms that viruses have evolved to combat PKR. PKR contains an N-terminal regulatory domain consisting of two dsRNA binding motifs and C-terminal kinase domain. X-ray and NMR structures are available for the isolated domains. However, these structures have proven insufficient to construct a model of how PKR is activated by RNA and inhibited by viral regulators. The broad objective of our research program is to define the molecular mechanisms that regulate the activity of PKR using quantitative biophysical and structural methods. We will define the interactions of PKR with complex RNA inhibitors and activators. Specifically, we will determine how adenovirus VAI RNA functions as a potent PKR inhibitor and characterize the interactions of PKR with 5-triphosphorylated RNA activators. Hepatitis C virus and influenza virus each produce proteins that interact with PKR to evade the antiviral pathway. We will define how these proteins inhibit PKR and correlate mutations that affect virulence or confer interferon resistance with PKR binding and inhibition. We will determine how short, heparin oligosaccharides function as PKR activators. Synthetic oligosaccharides and chemical libraries will be screened and structure-activity relationships will be generated to define novel small molecule activators of PKR. Small angle scattering methods will be used to determine the conformation of PKR in solution and to probe structural changes associated with enzymatic activation and dimerization. Contrast matching neutron scattering experiments will define the PKR conformational changes associated with binding to RNA activators and inhibitors. Conditions for crystallization of PKR-ligand complexes will be optimized for X-ray structural analysis. These studies will provide the foundation for the design of therapeutic agents that target PKR for the treatment of viral infections and cancer.
Project Description: See Award Description
Jobs Summary: There are 2.33 FTE(s) of professional staff (including Faculty and Postdocs) working on this project. There are 2.33 FTE(s) of students (Graduate and Undergraduate) working on this project. (Total jobs reported: 5)
Project Status: Less Than 50% Completed
This award's data was last updated on May. 29, 2009. Help expand these official descriptions using the wiki below.