Mehra R K, Mulchandani P, Hunter T C
Environmental Toxicology Graduate Program, University of California, Riverside 92521.
Biochem Biophys Res Commun. 1994 May 16;200(3):1193-200. doi: 10.1006/bbrc.1994.1577.
Glutathione-related peptides (gamma-Glu-Cys)nGly, trivially known as phytochelatins (PCs), sequester Cd(II) and other heavy metals in all plants and some yeasts. However, the metal resistance levels may depend on factors such as the PC concentrations, their chain length and ability to incorporate labile sulfide. We show here that a highly Cd(II)-resistant mutant of yeast Candida glabrata exhibited Cd(II)-dependent formation of extremely high levels of PC-coated CdS quantum crystallites. The CdS crystallites were formed in the cytosol but finally accumulated in the vacuoles. Cd(II)-stimulated sulfide production required sulfate 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.
谷胱甘肽相关肽（γ-谷氨酰-半胱氨酸）n甘氨酸，通常被称为植物螯合肽（PCs），在所有植物和一些酵母中螯合镉（II）和其他重金属。然而，金属抗性水平可能取决于多种因素，如PC的浓度、其链长以及结合不稳定硫化物的能力。我们在此表明，光滑念珠菌的一个高度抗镉（II）的酵母突变体表现出依赖镉（II）形成极高水平的PC包被的硫化镉量子微晶。硫化镉微晶在细胞质中形成，但最终积累在液泡中。镉（II）刺激的硫化物产生需要硫酸盐，并受到半胱氨酸和蛋氨酸的抑制。谷胱甘肽合成抑制使抗性菌株对镉（II）敏感，这表明谷胱甘肽仍然为抵御金属离子提供了主要防御。
