1. EXECUTER2 modulates the EXECUTER1 signalosome through its singlet oxygen-dependent oxidation.
- Author
-
Dogra V, Singh RM, Li M, Li M, Singh S, and Kim C
- Subjects
- Cell Nucleus metabolism, Chloroplasts metabolism, Phylogeny, Arabidopsis genetics, Arabidopsis metabolism, Singlet Oxygen metabolism
- Abstract
Oxidative post-translational modifications of specific chloroplast proteins contribute to the initiation of retrograde signaling. The Arabidopsis thaliana EXECUTER1 (EX1) protein, a chloroplast-localized singlet oxygen (
1 O2 ) sensor, undergoes tryptophan (Trp) 643 oxidation by1 O2 , a chloroplast-derived and light-dependent reactive oxygen species. The indole side chain of Trp is vulnerable to1 O2 , leading to the generation of oxidized Trp variants and priming EX1 for degradation by a membrane-bound FtsH protease. The perception of1 O2 via Trp643 oxidation and subsequent EX1 proteolysis facilitate chloroplast-to-nucleus retrograde signaling. In this study, we discovered that the EX1-like protein EX2 also undergoes1 O2 -dependent Trp530 oxidation and FtsH-dependent turnover, which attenuates1 O2 signaling by decelerating EX1-Trp643 oxidation and subsequent EX1 degradation. Consistent with this finding, the loss of EX2 function reinforces EX1-dependent retrograde signaling by accelerating EX1-Trp643 oxidation and subsequent EX1 proteolysis, whereas overexpression of EX2 produces molecular phenotypes opposite to those observed in the loss-of- function mutants of EX2. Intriguingly, phylogenetic analysis suggests that EX2 may have emerged evolutionarily to attenuate the sensitivity of EX1 toward1 O2 . Collectively, these results suggest that EX2 functions as a negative regulator of the EX1 signalosome through its own1 O2 -dependent oxidation, providing a new mechanistic insight into the regulation of EX1-mediated1 O2 signaling., (Copyright © 2021 The Author. Published by Elsevier Inc. All rights reserved.)- Published
- 2022
- Full Text
- View/download PDF