The 30th International Conference on Arabidopsis Research (ICAR 2019)

415 / 2019-01-21 12:46:56

Oxidative post-translational modification: a step toward understanding the mode of action of EXECUTER1, a putative singlet oxygen sensor

Chloroplast, Retrograde Signaling, ROS, EXECUTER1, Singlet Oxygen, Arabidopsis

Plenary track > Abiotic Stress

Chloroplasts serve as environmental sensors translating the perceived information into various forms of signals, which alter the expression of nuclear genes via a process called retrograde signaling. Among these distinct signals, singlet oxygen (1O2) generated by photosystem II (PSII) has been implicated in photodamage of PSII as well as in retrograde signaling. We previously reported that a nuclear-encoded chloroplast FtsH2 metalloprotease coordinates 1O2-triggered retrograde signaling by promoting the degradation of the EXECUTER1 (EX1) protein, a putative 1O2 sensor. We now demonstrate that a 1O2-mediated oxidative post-translational modification of EX1 is essential for initiating 1O2-derived signaling. Specifically, the Trp643 residue in DUF3506 domain of EX1 is prone to oxidation by 1O2. Both the substitution of Trp643 with 1O2-insensitive amino acids and the deletion of the DUF3506 domain abolish the EX1-mediated 1O2 signaling. Here, we provide the first mechanistic clue to how EX1 senses 1O2 via Trp643 located in the DUF3506 domain.