Arginine phosphorylation is an emerging post-translational protein modification, however its overall prevalence could not been studied by mass spectrometry. One major complication is the great abundance of serine/threonine phosphorylations that outcompetes phosphoarginine by several orders of magnitude. We thus developed a “trapping mutant” of the YwlE arginine phosphatase that can bind pArg proteins but not transform them. Indeed, the YwlE trap allows the selective enrichment of pArg proteins in the cellular pool dominated by O-phosphorylations, as is now published in the journal of Molecular & Cellular Proteomics.
pArg sites located for ClpC. Surface presentation of the ClpC hexamer with highlighted pArgs. Those shown in orange are only accessible in the monomeric state.