Kinase mediated tyrosine phosphorylation is a crucial component of cellular signaling cascades. Precise regulatory control over kinase activity must be maintained during signaling as evidenced by numerous human diseases that arise upon dysregulation of protein kinases. Given the crucial role of kinases in cell signaling, these enzymes are key targets in treating numerous diseases. Traditional approaches for therapeutic targeting of kinases have involved small molecules that exert their effect directly on the kinase active site. Given the increasing instances of resistance to such drugs there is a need for devising new ways to target kinase activity. In our work on the Tec family tyrosine kinases (immunological kinases involved in signaling downstream of antigen receptors), we have characterized a number of specific allosteric sites and interactions that modulate the chemistry of the active site. These allosteric pockets are sometimes 30 angstrom removed from the active site or involve domains far from the kinase domain in primary sequence. The current application lays out specific aims to identify and characterize allosteric small molecule modulators of the Tec family kinases, Itk and Btk. In addition, we continue to move our understanding of Tec structure forward by solving the crystal structure of full length Btk. This will be the first strucure of any full length Tec kinase and the insight gained will facilitate further development of allosteric regulators for this family. We have established strong collaborations with immunologists that have extensive T- and B-cell signaling expertise (in particular as related to Itk and Btk). These colleagues are eager to test our small molecule reagents in their cellular and animal systems. Thus, this project spans basic structural biology and enzymology to small molecule discovery to physiological assays that will ultimately reveal the utility of the reagents we are developing to treat human disease.

Public Health Relevance

This proposal aims to exploit specific allosteric mechanisms that control the Tec family of tyrosine kinases within the immune response. The public health relevance of the project relates to developing new ways to either limit or enhance the immune response in the face of autoimmunity, immunosuppression or immunological diseases.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
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Study Section
Cellular and Molecular Immunology - A Study Section (CMIA)
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Leitner, Wolfgang W
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Iowa State University
Schools of Arts and Sciences
United States
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Devkota, Sujan; Joseph, Raji E; Boyken, Scott E et al. (2017) An Autoinhibitory Role for the Pleckstrin Homology Domain of Interleukin-2-Inducible Tyrosine Kinase and Its Interplay with Canonical Phospholipid Recognition. Biochemistry 56:2938-2949
Joseph, Raji E; Wales, Thomas E; Fulton, D Bruce et al. (2017) Achieving a Graded Immune Response: BTK Adopts a Range of Active/Inactive Conformations Dictated by Multiple Interdomain Contacts. Structure 25:1481-1494.e4
Roberts, Justin M; Tarafdar, Sreya; Joseph, Raji E et al. (2016) Dynamics of the Tec-family tyrosine kinase SH3 domains. Protein Sci 25:852-64
Chopra, Nikita; Wales, Thomas E; Joseph, Raji E et al. (2016) Dynamic Allostery Mediated by a Conserved Tryptophan in the Tec Family Kinases. PLoS Comput Biol 12:e1004826
Xie, Qian; Fulton, D Bruce; Andreotti, Amy H (2015) A selective NMR probe to monitor the conformational transition from inactive to active kinase. ACS Chem Biol 10:262-8
Devkota, Sujan; Joseph, Raji E; Min, Lie et al. (2015) Scaffold Protein SLP-76 Primes PLC?1 for Activation by ITK-Mediated Phosphorylation. J Mol Biol 427:2734-47
Boyken, Scott E; Chopra, Nikita; Xie, Qian et al. (2014) A conserved isoleucine maintains the inactive state of Bruton's tyrosine kinase. J Mol Biol 426:3656-69
Wang, Xinxin; Boyken, Scott E; Hu, Jiancheng et al. (2014) Calmodulin and PI(3,4,5)P? cooperatively bind to the Itk pleckstrin homology domain to promote efficient calcium signaling and IL-17A production. Sci Signal 7:ra74
Xie, Qian; Joseph, Raji E; Fulton, D Bruce et al. (2013) Substrate recognition of PLC?1 via a specific docking surface on Itk. J Mol Biol 425:683-96
Joseph, Raji E; Kleino, Iivari; Wales, Thomas E et al. (2013) Activation loop dynamics determine the different catalytic efficiencies of B cell- and T cell-specific tec kinases. Sci Signal 6:ra76

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