Effects of cloacin DF13 on the functioning of the cytoplasmic membrane

Abstract

Adsorption of cloacin DF13 onto sensitive cells induces a leakage of potassium ions after a lag of 15–20 min. The rate of the potassium efflux is proportional to the bacteriocin concentration used. The extent of the potassium loss depends on the concentrations of bacteriocin and of extracellular potassium. Leakage of potassium ions is accompanied by an uptake of sodium ions. Cloacin DF13 does not affect the transport of magnesium ions, phosphate ions or amino acids. About 10 min after addition of the bacteriocin the ATP content of the cells begins to decrease gradually to about 25% of the original level. Anaerobiosis, lack of energy source and inhibition of oxidative phosphorylation may protect the cells if applied within 10 min after addition of the bacteriocin. The results suggest that the action of cloacin DF13 proceeds through at least two distinct phases. Phase I is a period after bacteriocin adsorption which is reversible and in some way depends on oxidative phosphorylation. This phase does not cause any cellular damage. Phase II is irreversible and results in a disturbance of several cellular functions.