Effects of colicin Ia on transport and respiration in Escherichia coli.

Treatment of Escherichia coli with colicin Ia leads to an inhibition in the active transport of exogenously supplied proline, thiomethyl-beta-D-galactoside and potassium ion. Furthermore, the addition of colicin Ia to cells preloaded with these substances leads to their almost immediate efflux. In contrast, colicin tia treatment enhances by as much as 10-fold the level of accumulation of alpha-methyl-D-glucoside. The colicin Ia-induced stimulation of glucoside accumulation is mediated by the phosphotransferase system. Cells treated with colicin Ia exhibit an increased rate of respiration when glucose is the substrate and a decreased rate when glycerol or succinate is the substrate; The decreased rate of succinate-dependent respiration is probably due to the failure of Ia-treated cells to accumulate succinate.