Redox regulation of LSD1/CATALASE 2 phase separation condensates controls location and functions.

Area of Science:

• Plant molecular biology
• Cellular compartmentalization
• Protein phase separation

Background:

• Membraneless protein compartments regulate plant development and stress responses.
• Arabidopsis catalase 2 (CAT2) and LESION SIMULATING DISEASE1 (LSD1) are key proteins in plant stress signaling.
• Redox regulation influences protein localization and activity.

Purpose of the Study:

• To investigate the role of redox-dependent phase separation in CAT2 and LSD1 interactions.
• To elucidate the mechanism controlling CAT2 intracellular localization and activity.
• To understand how LSD1 regulates CAT2 function under stress conditions.

Main Methods:

• Recombinant protein complex formation assays
• Confocal microscopy for in vivo protein trafficking
• Analysis of protein-protein interactions and condensate fluidity

Main Results:

• CAT2 and LSD1 form redox-regulated ternary complexes with PEX5.
• LSD1's phase separation ability is linked to its zinc fingers.
• Redox state controls CAT2 trafficking to peroxisomes and nuclei, regulated by LSD1.
• LSD1 condensates exhibit redox-regulated fluidity.

Conclusions:

• Redox-dependent phase separation of CAT2, LSD1, and PEX5 regulates CAT2 activity and compartmentalization.
• LSD1 controls CAT2 localization between peroxisomes, cytosol, and nucleus.
• Nuclear relocation of CAT2 may protect nuclear processes during biotic stress.