Speaker: Neha Amatya, ISU

Title: Allosteric regulation of BTK

Abstract: Bruton Tyrosine kinase (BTK) is a cytoplasmic non-receptor tyrosine kinase that is predominantly found in B-cells and is targeted for the treatment of auto-immune diseases and immune cancers. The conformational organization of the BTK Src module (SH2-SH3-kinase domains) in its autoinhibitory form has been well characterized. However, there is still some ambiguity with regards to the role of BTK pleckstrin homology–Tec homology (PHTH) domain. In addition to its phospholipid targeting function, previous studies have also highlighted the autoinhibitory role of the PH domain. We used NMR spectroscopy to map where and how the PHTH domain affects the kinase domain of BTK. For this we partially assigned the backbone resonance amide of the BTK kinase domain and titrated unlabeled BTK PHTH domain into the 15N-BTK kinase domain. In addition, we used hydrogen/deuterium exchange mass spectroscopy and evolutionary sequence comparison to further complement the results obtained from NMR titration studies. Our results indicate that the PHTH binding interface on the kinase domain is localized on the activation loop face of the kinase domain. Our results provide a more complete picture of the autoinhibitory conformation of full length BTK. As patients experience drug resistance to existing active site inhibitors, our results define a new regulatory site that can be exploited for drug discovery. We also used this and other information available about BTK regulation to screen for and characterize allosteric modulators of BTK.