The uptake and cellular distribution of zinc in Saccharomyces cerevisiae

C. White, G. M. Gadd (Lead / Corresponding author)

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    Abstract

    Zn2+ uptake by Saccharomyces cerevisiae was biphasic. The first phase was independent of metabolic energy, consisting of adsorption to the cell surface, and followed a Freundlich isotherm. The second phase was dependent on metabolic energy, ATPase activity and the transmembrane proton gradient, and consisted of uptake into the cell. Energy-dependent uptake showed Michaelis-Menten kinetics with a K(m) of 3.7 μM-Zn2+ and a V(max) of 1.6 nmol min-1 per 107 cells at Zn2+ concentrations below 80 μM but deviated at higher concentrations. K+ and Mg2+ inhibited energy-dependent Zn2+ uptake while Na+ and Ca2+ did not. The effect of heavy metals was complex and included both inhibition and stimulation of Zn2+ uptake. K+ efflux accompanied Zn2+ uptake at all Zn2+ concentrations but there was no simple stoichiometric relationship between the two. Toxic effects of Zn2+ such as inhibition of H+ efflux and K+ uptake and reduction of viability were observed at all Zn2+ concentrations and toxicity appeared to be a major factor in K+ efflux. Toxicity also affected the kinetics of Zn2+ uptake, being a major cause of deviation from Michaelis-Menten kinetics. Zn2+ was compartmented within the cell: 56% of the total intracellular pool was in the soluble vacuolar fraction, 39% was bound to insoluble components and only 5% was found in the cytosol. Isolated yeast vacuoles possessed an ATP-dependent Zn2+ uptake system whose properties were consistent with a Zn2+/H+ antiport.

    Original languageEnglish
    Pages (from-to)727-737
    Number of pages11
    JournalJournal of General Microbiology
    Volume133
    Issue number3
    DOIs
    Publication statusPublished - 1 Mar 1987

    ASJC Scopus subject areas

    • Microbiology

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