Fluorescent Probe for Dynamics of Arginine Phosphorylation

Abstract

Protein phosphorylation plays a crucial role in cell signaling and other physiological processes, thus dysregulated phosphorylation has been related to various human diseases. While protein phosphorylations on serine, threonine, and tyrosine have been studied extensively, protein arginine phosphorylation has been less explored because it is incompatible with current phosphoproteomic methods due to its chemical instability. However, recent studies discovered the novel roles of pArg’s regulatory function in cells. In gram positive bacteria, pArg was reported to modulate a stress regulator protein (CtsR heat shock regulator). Furthermore, pArg as a protein degradation tag in bacteria recognized by ClpCP protease, suggests that arginine kinases and phosphatase can be novel antibacterial drug targets. Here, we introduce real-time fluorescence based chemosensors to monitor the dynamics of protein arginine phosphorylation and dephosphorylation. These chemosensors enabled continuous measurement of both McsB (protein arginine kinase) and YwlE (protein phosphoarginine phosphatase) activities. Given the growing interest in the protein arginine phosphorylation, mainly in bacteria, we believe this tool will facilitate further understanding of this underappreciated form of protein phosphorylation, paving the way for future drug discovery.