Polyphosphate Polymerase Knockout Increases Stress Resistance of Cells.

Inorganic polyphosphate (polyP) is an important factor of alkaline, heavy metal, and oxidative stress resistance in microbial cells. In yeast, polyP is synthesized by Vtc4, a subunit of the vacuole transporter chaperone complex. Here, we report reduced but reliably detectable amounts of acid-soluble and acid-insoluble polyPs in the Δ strain of , reaching 10% and 20% of the respective levels of the wild-type strain. The Δ strain has decreased resistance to alkaline stress but, unexpectedly, increased resistance to oxidation and heavy metal excess. We suggest that increased resistance is achieved through elevated expression of , which is implicated in stress response, and reduced expression of encoding a phosphate and divalent metal transporter. The decreased Mg-dependent phosphate accumulation in Δ cells is consistent with reduced expression of . We discuss a possible role that polyP level plays in cellular signaling of stress response mobilization in yeast.