Inorganic Polyphosphate and Physiological Properties of Saccharomyces cerevisiae Yeast Overexpressing Ppn2

The effect of the yeast endopolyphosphatase Ppn2 overproduction on the metabolism of inorganic polyphosphates in Saccharomyces cerevisiae yeast was studied. Expression of the PPN2 gene under control of the strong constitutive promoter of glyceraldehyde 3-phosphate dehydrogenase gene (PKG1) led to a significant increase in the endopolyphosphatase activity stimulated by cobalt/zinc ions. This activity was present in both soluble and membrane subcellular fractions; it was higher toward long-chain polyphosphates and could be stimulated by ADP. The content of short-chain polyphosphates in the cells of the overexpressing strain was ~2.5 times higher compared to the parent strain. The cells overexpressing Ppn2 were more resistant to peroxide and alkali. The role of short-chain polyphosphates in the adaptation to these stress factors is discussed.