Chanhong Kim's research group reveals new progress of chloroplast ROS sensor proteins EXECUTER1 and EXECUTER2

On December 28, 2021, the research group of Chanhong Kim, Research Center for Stress Biology, Center for Excellence in Molecular Plant Science, Chinese Academy of Sciences , published a research paper entitled "EXECUTER2 modulates the EXECUTER1 signalosome through its singlet oxygen-dependent oxidation" on Molecular Plant

Under photooxidative stress conditions, photosystem II (PSII) produces a harmful oxygen molecule, ¹ O ₂

The current study found that, as a similar protein of EX1, the tryptophan residue (Trp530) at position 530 of EX2 protein also undergoes ¹ O ₂ -dependent oxidation

One might ask why the chloroplast needs such a system in which the function of its homologue (EX1) is antagonized by one of its closely related proteins (EX2)? _{Given that EX1 -} mediated ¹ O signaling is capable of inducing cell death, it appears that EX2 may regulate EX1 's sensitivity to ¹ O through this system to prevent chloroplast hypersensitivity responses to ₁ O ⁽ such as growth inhibition and cell death ₎ ) (Kim et al.

_{Post -}translational oxidative modification of Trp residues in EX1 and EX2 regulates ¹ O signaling .

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