Energy-Dependent Transport of Manganese into Yeast Cells and Distribution of Accumulated Ions

Abstract

Mn transport into yeast [Saccharomyces cerevisiae and S. carlsbergensis] cells is energy-dependent. It is dependent on endogenous sources of energy and is inhibited by olygomycin (12.5-25 .mu.g/ml), 2,4-dinitrophenol (1 mM), 2-deoxyglucose (1-50 mM) and sodium azide (1-10 mM), but is stimulated by cyanide and glucose. The stimulating effect of glucose is eliminated by N-ethylmaleimide and iodoacetate, which apparently inhibit the transport of glucose itself. About 75% of the Mn accumulated in the presence of glucose is found in yeast protoplasts and nearly 25% in the cell walls. A major portion of the accumulated Mn is found in vacuoles. The concentration of osmotically free Mn in the cytosol did not exceed 2 mM, but the concentration in vacuoles was up to 14 mM. The tonoplast is assumed to have a transport system for divalent cations, thereby regulating their concentration in the cytosol.