FIG 10.

EI^Ntr and NPr are phosphorylated by PEP. Results of an in vitro phosphorylation assay of EI^Ntr, NPr, and PmrA are shown. Wild-type His₆-tagged EI^Ntr without its GAF domain (His₆-EI^NtrΔGAF), NPr-His₆, and His₆-PmrA were overexpressed and purified. Different combinations of the purified proteins were incubated with or without PEP and separated on 15% SDS-polyacrylamide gels, as described in Materials and Methods. Phosphorylated proteins were specifically detected by the Pro-Q Diamond phosphoprotein gel stain technique, while total protein was visualized by Coomassie blue.