Peroxide detection system

Homes are safeguarded by smoke detectors and carbon monoxide detectors. On page 779, Phalen et al. find that cells are likewise protected by a peroxide-monitoring system. Instead of beeping, this detector forms oligomers to alert cells to dangerous levels of H₂O₂.

H₂O₂ is a helpful signaling molecule, but at high concentrations it can also be a damaging reactive oxygen species. One family of antioxidant enzymes that hydrolyze—and thus neutralize—H₂O₂ is the peroxiredoxins (Prxs). The 2-Cys class of Prxs are inhibited by H₂O₂-mediated hyperoxidation. Scientists originally thought this negative feedback permitted H₂O₂ to accumulate to signaling-competent concentrations.

The new results show that signaling occurs at H₂O₂ concentrations...