The control of the yeast H2O2 response by the Msn2/4 transcription factors

Area of Science:

• * Molecular biology
• * Yeast genetics
• * Stress response pathways

Background:

• * The yeast hydrogen peroxide (H2O2) response involves complex regulatory networks.
• * Transcription factors Msn2/4 and the Ras-cAMP-protein kinase A (PKA) pathway are implicated in cellular defense.
• * Understanding these pathways is key to deciphering oxidative stress tolerance in yeast.

Purpose of the Study:

• * To elucidate the distinct roles of Msn2/4 transcription factors and the Ras-cAMP-PKA pathway in the yeast H2O2 response.
• * To investigate the interplay between these two major oxidative stress response pathways.
• * To identify specific proteins regulated by Msn2/4 under H2O2 stress.

Main Methods:

• * Gene deletion analysis of MSN2 and MSN4.
• * Quantitative two-dimensional gel electrophoresis to analyze protein expression.
• * Assessment of H2O2 sensitivity and adaptation in various yeast strains.
• * Investigation of gene reporter induction under different cAMP conditions.

Main Results:

• * Strains lacking Msn2/4 exhibit hypersensitivity to H2O2 and fail to induce 27 H2O2-responsive proteins.
• * The Ras-cAMP pathway negatively regulates the H2O2 stress response via Msn2/4.
• * High intracellular cAMP levels inhibit Msn2/4-dependent gene induction but not Yap1-dependent induction.
• * Deletion of the PKA regulatory subunit Bcy1 leads to hypersensitivity, affecting both Msn2/4 and Yap1 pathways.

Conclusions:

• * Msn2/4 and the Ras-cAMP-PKA pathway represent distinct yet interconnected arms of the yeast H2O2 stress response.
• * The Ras-cAMP pathway acts as a negative regulator of the Msn2/4-mediated oxidative stress defense.
• * The PKA pathway influences both Msn2/4 and Yap1, suggesting a broader role in oxidative stress signaling.