Abstract
2-Cys peroxidredoxin (2-Cys Prx) reduces reactive oxygen species (ROS) such as hydrogen peroxide through the S-S/-SH catalytic cycle which requires the active cysteine to be regenerated by reductant. To date, no electron donor reducing the cyanobacterial 2-Cys Prx has been identified. In this work, a peroxiredoxin reductase (PrxR) was co-purified with 2-Cys Prx from a thermophilic cyanobacterium Thermosynechococcus elongatus cells as an NADPH dehydrogenase induced by oxidative stress. This result indicated that the PrxR interacts with the 2-Cys Prx. An in vitro assay with purified recombinant 2-Cys Prx and PrxR revealed that both proteins were essential for the efficient electron transport from NADPH to hydrogen peroxide. These results suggested that the PrxR transfers reducing power from NADPH to 2-Cys Prx, which reduces ROS in cyanobacteria grown under oxidative stress conditions.
