Fluorescence lifetime imaging biosensors
We have collaborated with Joseph Irudayaraj (Purdue University) to develop a fluorescence lifetime imaging strategy for peptide kinase biosensors. In this work, we found that upon phosphorylation of a fluorophore-tagged Abltide substrate peptide, the fluorescence lifetime would increase. Through control experiments, we attributed this to peptide-protein interaction between the phosphorylated product peptide and the kinase (or other nearby proteins), most likely through phosphotyrosine peptide-binding SH2 domains. We have used this strategy to image the phosphorylation dynamics of the Abl substrate in live cells in the absence and presence of the Abl inhibitor imatinib.