FIG. 7.

Expression of ¹⁵N-labeled ICP27 N terminus and S16,18,114A and S16,18,114E phosphorylation point mutants. Rosetta E. coli cells were transformed with either the pET21b wild-type ICP27 N terminus or phosphorylation point mutant S16,18,114A or S16,18,114E expression plasmids. Cells were grown in Neidhart's minimal media supplemented with ¹⁵NH₄Cl. Protein expression was induced with IPTG, and 6× His-tagged proteins were purified using Ni-NTA agarose under native protein purification conditions. A portion of the elution fractions from the Ni-NTA column was separated on a 10 to 20% Tris gradient gel, and the gel was stained with Coomassie blue.