FIGURE 7.
Characterization of the effects of mutant MtrA proteins on mtrB phenotype. Upper panel, shown is an autoradiogram evaluating the phosphorylation potential of MtrA proteins. MtrAWT, MtrAD13A, and MtrAY102C were incubated with EnvZ and [γ-32P]ATP, and products were resolved by SDS-PAGE and visualized by phosphorimaging. Lower panel, shown is morphology of ΔmtrB-producing mutant MtrA proteins. ΔmtrB transformed with plasmids producing MtrAWT (ΔmtrB + mtrAWT), phosphorylation-defective MtrA (ΔmtrB + mtrAD13A, ΔmtrB + mtrAD56N), or phosphorylation-proficient MtrA (ΔmtrB + mtrAY102C) were grown with acetamide for 16 h, and cells were visualized by brightfield microscopy. Note near restoration of WT phenotype with plasmids producing either mtrAY102C or mtrAD13A.