Out of the shadows: Illuminating mammalian histidine phosphorylation

Project Summary Protein histidine phosphorylation plays an important role in several key signaling pathways in mammals but is very poorly understood. The main reasons for this dearth of information about histidine phosphorylation are the relative instability of pHis as compared to pSer, pThr, and pTyr and a complete lack of chemical tools available to monitor and modulate the enzymes involved in histidine phosphorylation and dephosphorylation. The Barrios laboratory is working to develop fluorogenic assays that can be applied to monitoring cellular histidine phosphatase and histidine kinase activity and to develop the first inhibitors of mammalian histidine phosphatase and histidine kinase activity. We will investigate the structural and sequence contexts that facilitate histidine phosphorylation and stabilize the resulting pHis residue and characterize the effects that histidine phosphorylation has on protein structure and function, including enzymatic activity and ability to bind metal ions. The tools, fundamental insights, and specific examples developed in this work will facilitate future research into the biological roles of the histidine phosphatases and kinases and are expected to revolutionize the field. The ultimate goal of the work is to elucidate the roles that histidine kinases and phosphatases play in cellular signaling, health, and disease and to identify promising therapeutic targets and lead compounds that act on histidine phosphorylation pathways.