Nucleoredoxin guards against oxidative stress by protecting antioxidant enzymes.

Kneeshaw, Sophie; Keyani, Rumana; Delorme-Hinoux, Valérie; Imrie, Lisa; Loake, Gary J; Le Bihan, Thierry; Reichheld, Jean-Philippe; Spoel, Steven H · Proc Natl Acad Sci U S A · 2017

basic_science · Level V

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Abstract

Cellular accumulation of reactive oxygen species (ROS) is associated with a wide range of developmental and stress responses. Although cells have evolved to use ROS as signaling molecules, their chemically reactive nature also poses a threat. Antioxidant systems are required to detoxify ROS and prevent cellular damage, but little is known about how these systems manage to function in hostile, ROS-rich environments. Here we show that during oxidative stress in plant cells, the pathogen-inducible oxidoreductase Nucleoredoxin 1 (NRX1) targets enzymes of major hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>)-scavenging pathways, including catalases. Mutant <i>nrx1</i> plants displayed reduced catalase activity and were hypersensitive to oxidative stress. Remarkably, catalase was maintained in a reduced state by substrate-interaction with NRX1, a process necessary for its H<sub>2</sub>O<sub>2</sub>-scavenging activity. These data suggest that unexpectedly H<sub>2</sub>O<sub>2</sub>-scavenging enzymes experience oxidative distress in ROS-rich environments and require reductive protection from NRX1 for optimal activity.