ROLE OF CDS QUANTUM CRYSTALLITES IN CADMIUM RESISTANCE IN CANDIDA-GLABRATA

Glutathione-related peptides (gamma-Glu-Cys)(n)Gly, trivially known as phytochelatins (PCs), sequester Cd(II) and other heavy metals in all plants and some yeasts. However, the metal resistance levels may depen d on factors such as the PC concentrations, their chain length and abi lity to incorporate labile sulfide. We show here that a highly C(II)-r esistant mutant of yeast Candida glabrata exhibited Cd(II)-dependent f ormation of extremely high levels of PC-coated CdS quantum crystallite s. The CdS crystallites were formed in the cytosol but finally accumul ated in the vacuoles. Cd(II)-stimulated sulfide production required su lfate and was inhibited by both cysteine and methionine. GSH synthesis inhibition sensitized the resistant strain to Cd(II) indicating that GSH still provided primary defense against the metal ion. (C) 1994 Aca demic Press, Inc.