Ddp1 Cooperates with Ppx1 to Counter a Stress Response Initiated by Nonvacuolar Polyphosphate
Liam McCarthy, Iryna Abramchuk, Gamal Wafy, Alix Denoncourt, Mathieu Lavallée‐Adam, Michael Downey
Abstract
Cells from bacteria to humans have a molecule called polyphosphate (polyP) that functions in diverse processes. In many microbes, polyP is sequestered in granules or lysosome-related organelles such as vacuoles. In this study, we use an ectopic expression system to force budding yeast to accumulate polyP outside the vacuole. We use proteomics to demonstrate that this nonvacuolar polyP initiates a stress response mediated by a signaling cascade involving the Yak1 and Hog1 kinases and the Msn2 and Msn4 transcription factors. This response is countered by a pair of polyphosphatases with different enzymatic activities that function in concert to degrade polyP. Our results provide new insights into why polyP is confined to specific cell locations in many microbial cells.