Mechanism of pyrithione-induced membrane depolarization in Neurospora crassa

Elena Petroff, D. Sanders

Research output: Contribution to journalArticleResearchpeer-review

48 Citations (Scopus)

Abstract

Pyrithione is a general inhibitor of membrane transport in fungi and is widely used in antidandruff shampoos as an antifungal agent. An electrophysiological approach has been used to determine the mode of action of pyrithione on the plasma membrane of the model ascomycete, Neurospora crassa. At pH 5.8, pyrithione induces a dramatic dose-dependent electrical depolarization of the membrane which is complete within 4 min, amounts to 110 mV at saturating pyrithione concentrations, and is half maximal between 0.6 and 0.8 mM pyrithione. Zinc pyrithione induces a similar response but exerts a half-maximal effect at around 0.3 mM. The depolarization is strongly dependent on external pH, being almost absent at pH 8.2, at which the concentration of the uncharged form of pyrithion-which might be expected to permeate the membrane freely-is markedly lowered. However, quantitative considerations based on cytosolic buffer capacity, the pK(a) of pyrithione, and the submillimolar concentration at which it is active appear to preclude significant cytosolic acidification on dissociation of the thiol proton from the uncharged form of pyrithione. Current-voltage analysis demonstrates that the depolarization is accompanied by a decrease in membrane electrical conductance in a manner consistent with inhibition of the primary proton pump and inconsistent with a mode of action of pyrithione on plasma membrane ion channels. We conclude that pyrithione inhibits membrane transport via a direct or indirect effect on the primary proton pump which energizes transport and that the site of action of pyrithione is likely to be intra- rather than extracellular.

Original languageEnglish
Pages (from-to)3385-3390
Number of pages6
JournalApplied and Environmental Microbiology
Volume61
Issue number9
StatePublished - 1 Jan 1995

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Neurospora crassa
proton pump
membrane
Membranes
mechanism of action
plasma membrane
antifungal agents
permeates
ion channels
thiols
Ascomycota
protons
acidification
buffers
Proton Pumps
zinc
pump
fungi
Ion Channels
plasma

Cite this

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title = "Mechanism of pyrithione-induced membrane depolarization in Neurospora crassa",
abstract = "Pyrithione is a general inhibitor of membrane transport in fungi and is widely used in antidandruff shampoos as an antifungal agent. An electrophysiological approach has been used to determine the mode of action of pyrithione on the plasma membrane of the model ascomycete, Neurospora crassa. At pH 5.8, pyrithione induces a dramatic dose-dependent electrical depolarization of the membrane which is complete within 4 min, amounts to 110 mV at saturating pyrithione concentrations, and is half maximal between 0.6 and 0.8 mM pyrithione. Zinc pyrithione induces a similar response but exerts a half-maximal effect at around 0.3 mM. The depolarization is strongly dependent on external pH, being almost absent at pH 8.2, at which the concentration of the uncharged form of pyrithion-which might be expected to permeate the membrane freely-is markedly lowered. However, quantitative considerations based on cytosolic buffer capacity, the pK(a) of pyrithione, and the submillimolar concentration at which it is active appear to preclude significant cytosolic acidification on dissociation of the thiol proton from the uncharged form of pyrithione. Current-voltage analysis demonstrates that the depolarization is accompanied by a decrease in membrane electrical conductance in a manner consistent with inhibition of the primary proton pump and inconsistent with a mode of action of pyrithione on plasma membrane ion channels. We conclude that pyrithione inhibits membrane transport via a direct or indirect effect on the primary proton pump which energizes transport and that the site of action of pyrithione is likely to be intra- rather than extracellular.",
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Mechanism of pyrithione-induced membrane depolarization in Neurospora crassa. / Petroff, Elena; Sanders, D.

In: Applied and Environmental Microbiology, Vol. 61, No. 9, 01.01.1995, p. 3385-3390.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Mechanism of pyrithione-induced membrane depolarization in Neurospora crassa

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AU - Sanders, D.

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AB - Pyrithione is a general inhibitor of membrane transport in fungi and is widely used in antidandruff shampoos as an antifungal agent. An electrophysiological approach has been used to determine the mode of action of pyrithione on the plasma membrane of the model ascomycete, Neurospora crassa. At pH 5.8, pyrithione induces a dramatic dose-dependent electrical depolarization of the membrane which is complete within 4 min, amounts to 110 mV at saturating pyrithione concentrations, and is half maximal between 0.6 and 0.8 mM pyrithione. Zinc pyrithione induces a similar response but exerts a half-maximal effect at around 0.3 mM. The depolarization is strongly dependent on external pH, being almost absent at pH 8.2, at which the concentration of the uncharged form of pyrithion-which might be expected to permeate the membrane freely-is markedly lowered. However, quantitative considerations based on cytosolic buffer capacity, the pK(a) of pyrithione, and the submillimolar concentration at which it is active appear to preclude significant cytosolic acidification on dissociation of the thiol proton from the uncharged form of pyrithione. Current-voltage analysis demonstrates that the depolarization is accompanied by a decrease in membrane electrical conductance in a manner consistent with inhibition of the primary proton pump and inconsistent with a mode of action of pyrithione on plasma membrane ion channels. We conclude that pyrithione inhibits membrane transport via a direct or indirect effect on the primary proton pump which energizes transport and that the site of action of pyrithione is likely to be intra- rather than extracellular.

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