The cadmium tolerance in Saccharomyces cerevisiae depends on inorganic polyphosphate

Abstract

The sensitivity to cadmium (Cd(II)), an important environmental pollutant, was studied in the cells of Saccharomyces cerevisiae strains with genetically altered polyphosphate metabolism. The strains overproducing polyphosphatases PPX1 or PPN1 were more sensitive to Cd(II) than the parent strain. The half maximal inhibitory concentrations were 0.02 and 0.05 mM for the transformants and the parent strain, respectively. Transformant strains cultivated in the presence of Cd(II) show a decrease in the content of short-chained cytosolic acid soluble polyphosphate. The role of this polyphosphate fraction in detoxification of heavy metal ions is discussed.

The Reduced Level of Inorganic Polyphosphate Mobilizes Antioxidant and Manganese-Resistance Systems in Saccharomyces cerevisiae

“…The acid-soluble polyphosphate was extracted from biomass samples by the twofold treatment, with 0.5 M HClO 4 at 0 °C for 15 min with continuous stirring. The cells were precipitated at 4000 g. In supernatants, the Pi and polyP amounts were assayed as described earlier [45]. The amount of acid-insoluble polyphosphate in the remaining biomass was assayed by the Pi content after twofold treatment with 0.5 M HClO 4 at 90 °C for 20 min.…”

Inorganic polyphosphate, a multifunctional polyanionic protein scaffold

“…Vacuolar polyP serves a central role in maintaining phosphate homeostasis, sequestering phosphate during growth in phosphate-rich environments (38), and releasing phosphate during the cell cycle to provide the building blocks for DNA replication (40). Moreover, polyP chelates metals, such as manganese and cadmium, thereby preventing metal-induced cellular damage (41,42), and sequesters arginine to increase nitrogen storage without affecting the osmotic pressure (43). One other eukaryotic polyP-generating system has been proposed to exist in Dictyostelium discoideum, which, in addition to a bacterial PPK homologue, contains a tripartite complex of actin-related proteins that was found to synthesize polyP ex vivo (44).…”

Protective role of l‐threonine against cadmium toxicity in Saccharomyces cerevisiae

“…Even worse, defects in Thr synthesis ( thr1 ∆ and thr4 ∆) made it hard for cells to survive under Cd stress. The decrease in the content of acid‐soluble inorganic polyphosphate was also observed in presence of Cd, which made the cell difficult to adapt well to heavy metal stress [63]. Thr feeds into the synthesis of other amino acids such as Gly, which is involved in the biosynthesis of the antioxidant glutathione.…”