FIG. 4.

Effect of yjdE deletion on arginine-agmatine exchange during acid shock. Time courses of agmatine release to the extracellular medium were monitored for wild-type cells (open symbols), ΔyjdE cells (black symbols), or ΔyjdE cells transformed with the pRI-adiC1 rescue vector (grey symbols). The transport reactions were initiated by the addition of 1 mM arginine to the shock medium. Initial rates were determined by least-squares fitting (solid lines) and are 0.26 ± 0.02 and 0.005 ± 0.008 nmol/min for wild-type and ΔyjdE cells, respectively. In rescue experiments, cells were either uninduced (triangles) or induced with 1 mM IPTG (circles), giving initial rates of 0.05 ± 0.04 and 0.141 ± 0.002 nmol/min, respectively. Each data point represents the mean ± standard error of results from three to six independent experiments.