[Formation of ion channels in the Escherichia coli cytoplasmic membrane after exposure to bacteriophages T4 and...

The effects of phage T4 and lambda on the ion permeability of the E. coli cytoplasmic membrane were studied. It was shown that the phage-induced depolarization of the membrane is coupled with a simultaneous increase in a transmembrane pH gradient. Hence, the total value of the proton-motive force remains unchanged at moderate multiplicity of infection. The rise in the pH gradient occurs due to an increase in the activity of the redox H+-pump of the E. coli membrane. Analysis of the temperature dependence showed that the stimulating effect of the phage is observed at 6-8 degrees C. Apart from the phages, gramicidin is also capable of stimulating the H+-pump under these conditions, while the stimulating effect of valinomycin is diminished. These data suggest that the ion-permeable channels are formed in the membrane during the interaction of E. coli cells with the phages. The experimental results demonstrate that the channels are permeable to ions of monovalent metals. The phage can also increase the permeability of cell membranes to protons; however, the permeability to monovalent ions is higher when these ions are in excess.