Membrane Potential and Gentamicin Uptake in Staphylococcus aureus
At pH 5.0, the electrical potential (Δ Ψ , interior negative) across the plasma membrane of Staphylococcus aureus exhibits a minimum of -85 to -90 mV; the pH gradient (Δ pH, interior alkaline) across the membrane approximates a maximum of about -100 mV. Under these conditions, uptake of the aminogly...
Gespeichert in:
Veröffentlicht in: | Proceedings of the National Academy of Sciences - PNAS 1982-11, Vol.79 (21), p.6693-6697 |
---|---|
Hauptverfasser: | , , , , , |
Format: | Artikel |
Sprache: | eng |
Schlagworte: | |
Online-Zugang: | Volltext |
Tags: |
Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
|
Zusammenfassung: | At pH 5.0, the electrical potential (Δ Ψ , interior negative) across the plasma membrane of Staphylococcus aureus exhibits a minimum of -85 to -90 mV; the pH gradient (Δ pH, interior alkaline) across the membrane approximates a maximum of about -100 mV. Under these conditions, uptake of the aminoglycoside gentamicin is negligible, and viability of the organism is not impaired by the antibiotic. In contrast, at pH 7.5, at which Δ Φ is about -130 mV and Δ pH is 0, gentamicin uptake is observed and the drug markedly decreases viability. Dramatically, when the ionophore nigericin is added at pH 5.0, gentamicin uptake is induced, there is a striking decrease in viability, and the effect is associated with an increase in Δ Φ at the expense of Δ pH. Consistently, valinomycin, which dissipates Δ Φ in the presence of potassium, abolishes gentamicin uptake and killing. In addition, from pH 5.0 to pH 7.5, there is a direct relationship between the magnitude of Δ Φ and both gentamicin uptake and its bactericidal effect. However, a threshold Δ Φ of -75 to -90 mV is apparently necessary to initiate uptake and killing. These observations provide a strong indication that Δ Φ plays a critical role in the uptake and antibacterial action of gentamicin and suggest that nigericinlike ionophores may be clinically useful in synergy with aminoglycosides. |
---|---|
ISSN: | 0027-8424 1091-6490 |
DOI: | 10.1073/pnas.79.21.6693 |