A phosphatase-centric mechanism drives stress signaling response.

ABSTRACT: Changing environmental cues lead to the adjustment of cellular physiology by phosphorylation signaling networks that typically center around kinases as active effectors and phosphatases as antagonistic elements. Here, we report a signaling mechanism that reverses this principle. Using the hyperosmotic stress response in Saccharomyces cerevisiae as a model system, we find that a phosphatase-driven mechanism causes induction of phosphorylation. The key activating step that triggers this phospho-proteomic response is the Endosulfine-mediated inhibition of protein phosphatase 2A-Cdc55 (PP2A^Cdc55 ), while we do not observe concurrent kinase activation. In fact, many of the stress-induced phosphorylation sites appear to be direct substrates of the phosphatase, rendering PP2A^Cdc55 the main downstream effector of a signaling response that operates in parallel and independent of the well-established kinase-centric stress signaling pathways. This response affects multiple cellular processes and is required for stress survival. Our results demonstrate how a phosphatase can assume the role of active downstream effectors during signaling and allow re-evaluating the impact of phosphatases on shaping the phosphorylome.

SUBMITTER: Hollenstein DM 

PROVIDER: S-EPMC8567219 | biostudies-literature | 2021 Nov

REPOSITORIES: biostudies-literature