Quantitative Redox Proteomics Links Thioredoxin to Heavy Ion Resistance in Deinococcus Radiodurans

Heavy ion radiotherapy is an effective treatment for tumors, but its therapeutic efficacy is limited in cancer cells with radiation resistance. Deinococcus radiodurans, well known for its extremely resisting various stresses, was used to explore radioresistant mechanism. We used quantitative redox proteomics to track the dynamic changes in the global redox state after 12C6+ irradiation. The redox-relevant metabolic signaling pathway was significantly changed, where thioredoxin 2 (DrTrx2) was found to shift towards more reduced status than other redox proteins, promoting great interest to explore the role of DrTrx2 redox in radioresistance. Both the reduction ratio and expression level of DrTrx2 were shown to affect the radioresistant phenotype under varying doses of 60Co irradiation. Additionally, the reduction at the active site was confirmed to provide the radioresistance to DrTrx2, further revealing the universality of DrTrx2 in radiation protection. Furthermore, we used radiation-sensitive Escherichia coli strain as host cells to analyze change of DrTrx2 interactome after UV radiation. Compared with the control, UV radiation induction altered the interaction of DrTrx2 with substrate proteins. The significantly altered proteins were enriched in DNA repair, base analogs metabolism, mitochondrial metabolism, RNA metabolism, transcription, translation, antioxidation, and so on. Therefore, DrTrx2 improved radioresistance by changing interaction with substrate proteins and their reduced states. Overall, this study provides a landscape of the radiation-induced dynamic change of redox state and the protein interaction, which provides novel insights for better understanding radioresistant mechanism and improving therapeutic efficiency of heavy ion irradiation for cancers.