FIG. 6.
Expression of S107A52G and S107C51S in trans to S105. (A) The inhibitory effect of the mutant S107 protein was tested in trans to S105. MC4100(λCmS105) cells carrying the plasmids pKB1 (Sam7) (○), pS107 (□), pS107C51S (●), or pS107A52G (■) were induced and monitored for turbidity. (B) Expression and stability of S107 and S107C51S were analyzed by Western blotting as described in Materials and Methods. Samples from the induced cultures were taken 30, 60, or 90 min after induction. Lane 1, molecular weight standards; lanes 2, 4, and 6, S107; lanes 3, 5, and 7, S107C51S. Time points when samples were taken are indicated below the panel. Total protein (12.8, 21, or 28 μg) was loaded for the 30, 60, or 90 min time points, respectively. Labeling of the panel is as described in the legend to Fig. 3. (C) Aliquots (5 ml) of the induced cultures were taken 50 min after induction. Oxidation and sample preparation for Western blot analysis were performed as described in Materials and Methods. Lane 1, molecular weight standards; lane 2, MC4100(λCmS105τ94) + pS107A52G; lane 3, MC4100(λCmS105τ94) + pS107. Labeling of the panel is as described in the legend to Fig. 3.