Expression of the H₂O₂ Biosensor roGFP-Tpx1.C160S in Fission and Budding Yeasts and Jurkat Cells to Compare...

Intracellular hydrogen peroxide (H₂O₂) levels can oscillate from low, physiological concentrations, to intermediate, signaling ones, and can participate in toxic reactions when overcoming certain thresholds. Fluorescent protein-based reporters to measure intracellular H₂O₂ have been developed in recent decades. In particular, the redox-sensitive green fluorescent protein (roGFP)-based proteins fused to peroxiredoxins are among the most sensitive H₂O₂ biosensors. Using fission yeast as a model system, we recently demonstrated that the gradient of extracellular-to-intracellular peroxides through the plasma membrane is around 300:1, and that the concentration of physiological H₂O₂ is in the low nanomolar range. Here, we have expressed the very sensitive probe roGFP2-Tpx1.C169S in two other model systems, budding yeast and human Jurkat cells. As in fission yeast, the biosensor is ~40-50% oxidized in these cell types, suggesting similar peroxide steady-state levels. Furthermore, probe oxidation upon the addition of extracellular peroxides is also quantitatively similar, suggesting comparable plasma membrane H₂O₂ gradients. Finally, as a proof of concept, we have applied different concentrations of zinc to all three model systems and have detected probe oxidation, demonstrating that an excess of this metal can cause fluctuations of peroxides, which are moderate in yeasts and severe in mammalian cells. We conclude that the principles governing H₂O₂ fluxes are very similar in different model organisms.