Role of L-Histidine in Conferring Tolerance to Ni²⁺ in Sacchromyces cerevisiae Cells

Abstract

Ni²⁺ toxicity can be alleviated in yeast cells by exogenous L-histidine, but not by its enantiomer, D-histidine, nor by other natural L-amino acids tested. We studied the effect of L-histidine upon the accumulation and intracellular distribution of Ni²⁺ and found that moderate L-histidine concentrations (less than or equal to those of Ni²⁺) increased cell tolerance without decreasing Ni²⁺ accumulation. Although excess L-histidine appeared to lower Ni²⁺ accumulation, the concomitant presence of Ni²⁺ and L-histidine in the growth medium stimulated each other’s uptake.