Peroxiredoxin Biochemistry and Redox Regulation in Metabolic Stress and Signaling

SUMMARY While hydrogen peroxide has long been understood as a toxin used by the human immune system to kill infectious organisms, only recently has it become well accepted that it serves as a second messenger in eukaryotes, produced in response to growth factors, cytokines and immune system effectors and modulating downstream signal transduction pathways. Through insights contributed in part by the work of the PI, a family of cysteine-dependent, peroxide-reducing enzymes known as the peroxiredoxins (Prxs) have become widely recognized not just as one of the primary oxidant removal systems in all organisms, but also as key modulators of cell signaling pathways. PI Poole’s work on the enzymology, structures and dynamics of Prxs has contributed greatly to understanding the mechanism and regulation of this widespread and highly abundant family of enzymes. In 2003, PI Poole and collaborator Andy Karplus published a Science paper in which the “floodgate hypothesis” explaining the potential benefits of a peroxide-mediated “off switch” (hyperoxidation or other modification) was proposed; under conditions where peroxide levels begin to rise (e.g. NADPH oxidase activation), Prx inactivation would promote the local accumulation of peroxide near the source, allowing for the oxidation of alternative protein targets. This intriguing perspective remains a topic of debate, while in the meantime several examples of Prx-mediated signaling through redox relays initiated by Prx oxidation have come to light. In fact, the “off switch” of hyperoxidation is not the only modification modulating Prx activity and hyperoxidation sensitivity. Proteomics evidence suggests a number of posttranslational modifications (PTMs) occurring on Prxs, but much remains to be discovered regarding the molecular and biological consequences of the PTMs that may be present and may be associated with disease states. Recently, in collaboration with Ana Denicola in Uruguay, we reported that nitration near the C-terminus of Prx2, caused by peroxynitrite treatment, led to a more resilient (less hyperoxidation prone) peroxidase. As shown by kinetics data and modeling by this same team, a threshold effect due to a change in rate limiting step as peroxide levels rise leads to accumulation of oxidized forms above a peroxide set point which is distinct for each Prx studied. We are also increasingly discovering that Prxs play key metabolic and signaling roles in multiple areas important to disease progression and treatment, including radiation resistance, chemotherapy toxicities and inflammatory signaling. In the next years, we will continue investigations of the contributions of varying levels and posttranslational modifications to modulating the antioxidant activity and signaling capacity of Prx3, the key Prx in mitochondria. Also continuing will be our biophysical and kinetic analyses of Prxs amenable to high resolution studies by X- ray crystallography and NMR. Together, these efforts will address areas important to Prx function, protein oxidation and biomedical applications, enabling further research and biomedical interventions. Project Number: 1R35GM161816-01 | Fiscal Year: 2026 | NIH Institute/Center: National Institute of General Medical Sciences (NIGMS) | Principal Investigator: LESLIE POOLE | Institution: WAKE FOREST UNIVERSITY HEALTH SCIENCES, WINSTON-SALEM, NC | Award Amount: $432,844 | Activity Code: R35 | Study Section: Special Emphasis Panel[ZRG1 MBBC-A (57)] View on NIH RePORTER: https://reporter.nih.gov/project-details/11260628