Researchers identified a redox-responsive protein called CATALASE-INTERACTING RCC1-LIKE 1 (CAIR1) that controls catalase localization and hydrogen peroxide detoxification in Arabidopsis, according to a study published in Nature Communications.
The research team identified CAIR1 through affinity purification of the UV-B photoreceptor UVR8 coupled with mass spectrometry. The protein interacts directly with all three Arabidopsis catalases and their chaperone NO CATALASE ACTIVITY 1 (NCA1). Inside cells, CAIR1 facilitates the peroxisomal import and proper localization of CAT2, which prevents the enzyme from aggregating and maintains its activity in detoxifying reactive oxygen species.
Plants lacking the CAIR1 protein exhibit reduced catalase activity alongside impaired root growth, alkaline sensitivity, and heightened vulnerability to oxidative stress. These defects closely mirror the physical and molecular characteristics observed in cat2 and nca1 plant mutants.
CAIR1 operates through reversible, redox-dependent oligomerization that boosts its binding affinity for catalases. When researchers mutated the Cys-356 and Cys-545 residues, the interaction weakened and failed to rescue oxidative stress sensitivity in cair1 mutants. In addition, exposure to UV-B light weakens the interaction between CAIR1 and catalases while suppressing catalase activity, linking environmental light signaling to cellular redox homeostasis.
Scientists from the University of Geneva, Ghent University, the VIB Center for Plant Systems Biology, and the Max Planck Institute for Plant Breeding Research conducted the research. Funding was provided by the Swiss National Science Foundation, the Research Foundation - Flanders (FWO), the Max Planck Society, the VIB, and the University of Geneva.
