Fig 1: Modulating the coupling between H2O2 and matrix glutathione links matrix glutathione oxidation to cell death Hydrogen peroxide “acute stress” assay. ?prx1 cells co-transformed with an empty plasmid or a plasmid encoding Prx1, Tsa1, PRDX3, PRDX5, PRDX6, PfAOP, or PfAOP-L109M were grown in SD medium lacking the appropriate amino acids for plasmid selection and pre-treated with 0, 1, 5, 10, and 25 mM H2O2 for 30 min. Afterward, the cells were diluted, and a fixed volume was plated on YPD plates. The number of viable colonies was counted after 2 days of growth at 30°C, here represented as a percentage relative to the 0 mM pre-treatment. Error bars represent standard deviation (n = 3–8 biological replicates, with cells taken from independent cultures for each individual biological replicate). Significance was assessed with Student's 2-tailed, unpaired, t-test. *P < 0.05; **P < 0.01; and ***P < 0.001.The efficiency of transfer of oxidation from H2O2 to E GSH strongly correlates with cell death upon exposure to acute H2O2 stress. Data from viability and matrix Grx1-roGFP2 responses during acute H2O2 stress were correlated.