Multiple oxidation events increase signal specificity in the Tpx1-Pap1 pathway for hydrogen peroxide.

Abstract

Oxidative stress can be split into two states: eustress is associated with beneficial physiological states and cell proliferation, and distress correlates with deleterious states, neurological disease, diabetes and disease. Many redox pathways in these physiological states across cellular life require multiple oxidation events for full activation. OxyR in E. coli needs four events, Nrf2-Keap1 in mammals requires three, Yap1 in baker’s yeast needs three to four and Pap1 in S. pombe requires two oxidation events. This study investigated the purpose of the multiple oxidation events in hydrogen peroxide signal transduction in redox pathways. To achieve this, we developed and analysed a single and double oxidation computational Pap1-Tpx1-Trr1 model to compare how they respond to different hydrogen peroxide concentrations. We also utilised in vitro recombinant proteins, Tpx1 and Pap1, to assemble the Tpx1-Pap1 system and assessed the signal output at different hydrogen peroxide concentrations. The computational analysis showed that adding an oxidative step increases the system’s capability to attenuate the signal at low hydrogen peroxide concentrations and amplify it at high concentrations. The in vitro system showed that a simplified Tpx1-Pap1 system can differentiate between different hydrogen peroxide concentrations. Multiple oxidation steps impart high pass filtering properties on the system, allowing systems to better differentiate between low and high signal inputs.