Mode of action of the staphylococcinlike peptide Pep 5: voltage-dependent depolarization of bacterial and artificial membranes

Abstract

(19). This result, and the fact that cytoplasmic membranes of Mycoplasma cells, human lung fibroblasts, and erythrocytes could not be impaired (17), led us to assume that Pep 5 requires a membrane potential for disruption of cytoplasmic membranes. Such a requirement has been shown for the channel-forming colicins (7, 16), alamethicin (5), and the bee venom constituent melittin (15). To substantiate the potential dependence for the membranedisrupting activity of Pep 5, we investigated its influence on bacterial cells artificially energized by a valinomycin-induced potassium diffusion potential. Planar lipid membranes were used to elucidate the processes of Pep 5 action on energized membranes in detail.

Bacterial membrane injuries induced by lactacin F and nisin

“…The observation that lactacin F forms channels at low voltage is consistent with studies on different Lactobacillus strains and on Enterococcus faecalis cells, in which it has been demonstrated that uncouplers, which decrease the proton-motive force, do not stop the lactacin-F-mediated loss of potassium out of the cells [1]. The action of nisin and Pep 5 on de-energized cells, however, is very small or even absent at low membrane potential [21,[28][29][30].…”

“…This result indicates that the voltage shifts the equilibrium between non-conductive monomers and conductive oligomers in favor of the latter. This type of voltage-dependence is similar to that reported for nisin and other lantibiotics [9,21,29,31], except that lantibiotics often show asymmetric voltage-dependence in w hich the membrane conductance increases only when the trans-side is negative. Similar results have also been found for other bacteriocidins such as colicins [13,27].…”

“…The response to uncouplers of oxidative phosphorylation suggests that the proton-motive force is not essential for lactacin F action on target cells. This is in contrast to the effect of other bacteriocidins, such as lantibiotics, in which membrane potential plays an essential role [21,29].…”

The bacteriocin lactococcin A specifically increases permeability of lactococcal cytoplasmic membranes in a voltage-independent, protein-mediated manner

“…Lactococcin A specifically inhibits the growth of lactococcal strains (10). Since lactococcin A is a small hydrophobic polypeptide like several peptide antibiotics permeabilizing the cytoplasmic membrane (7,8,17,26,28), a likely target for its action could be the cytoplasmic membrane. To investigate its mode of action, the effect of increasing concentrations of lactococcin A on the membrane potential was measured in sensitive L. lactis IL1403 cells (Fig.…”

Characterization and purification of mesentericin Y105, an anti-Listeria bacteriocin from Leuconostoc mesenteroides

“…It is not yet known whether a specific membrane receptor is involved as described for colicins (Pattus et al, 1990) and recently suggested by Van Belkum et al (1991) for lactococcin A produced by a Lactococcus lactis, or, like some lantibiotics, targeting is driven by a particular phospholipid composition of cytoplasmic membranes (Kordel et al, 1988;Gao et al, 1991). Flow cytometry and oxymetry analysis (unpublished results) indicate that mesentericin Y 105 decreases membrane potential and oxygen consumption of Listeria cells.…”