Singlet oxygen- and EXECUTER1-mediated signaling is initiated in grana margins and depends on the protease FtsH2.
Formation of singlet oxygen ((1)O2) has been implicated with damaging photosystem II (PSII) that needs to undergo continuous repair to maintain photosynthetic electron transport. In addition to its damaging effect, (1)O2 has also been shown to act as a signal that triggers stress acclimation and an enhanced stress resistance. A signaling role of (1)O2 was first documented in the fluorescent (flu) mutant of Arabidopsis It strictly depends on the chloroplast protein EXECUTER1 (EX1) and happens under nonphotoinhibitory light conditions. Under severe light stress, signaling is initiated independently of EX1 by (1)O2 that is thought to be generated at the acceptor side of active PSII within the core of grana stacks. The results of the present study suggest a second source of (1)O2 formation in grana margins close to the site of chlorophyll synthesis where EX1 is localized and the disassembly of damaged and reassembly of active PSII take place. The initiation of (1)O2 signaling in grana margins depends on EX1 and the ATP-dependent zinc metalloprotease FtsH. As FtsH cleaves also the D1 protein during the disassembly of damaged PSII, EX1- and (1)O2-mediated signaling seems to be not only spatially but also functionally associated with the repair of PSII.
Boyce Thompson Institute, Ithaca, NY 14853-1801;
Liangsheng
L
Wang
Boyce Thompson Institute, Ithaca, NY 14853-1801; Chinese Academy of Sciences Center for Excellence in Molecular Plant Sciences, Shanghai Center for Plant Stress Biology, Chinese Academy of Sciences, 201602 Shanghai, China;
Chanhong
C
Kim
Boyce Thompson Institute, Ithaca, NY 14853-1801;
Xia
X
Xu
Boyce Thompson Institute, Ithaca, NY 14853-1801;
Urszula
U
Piskurewicz
Chinese Academy of Sciences Center for Excellence in Molecular Plant Sciences, Shanghai Center for Plant Stress Biology, Chinese Academy of Sciences, 201602 Shanghai, China;
Vivek
0000-0003-1853-8274
V
Dogra
Chinese Academy of Sciences Center for Excellence in Molecular Plant Sciences, Shanghai Center for Plant Stress Biology, Chinese Academy of Sciences, 201602 Shanghai, China;
Somesh
S
Singh
Swiss Federal Institute of Technology, CH 8092 Zurich, Switzerland.
Hanno
H
Mahler
Boyce Thompson Institute, Ithaca, NY 14853-1801; kha24@cornell.edu.
Klaus
K
Apel
D049069:ATP-Dependent Proteases / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002734:Chlorophyll / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D045332:Photosystem II Protein Complex / Q000378:metabolism*; D036226:Seedlings / Q000378:metabolism; D015398:Signal Transduction; D026082:Singlet Oxygen / Q000378:metabolism*
D049069:ATP-Dependent Proteases; D029681:Arabidopsis Proteins; D002734:Chlorophyll; D008565:Membrane Proteins; D045332:Photosystem II Protein Complex; D026082:Singlet Oxygen; C521350:EXECUTER1 protein, Arabidopsis; C478633:FLU protein, Arabidopsis; C402651:AT2G30950 protein, Arabidopsis
EXECUTER1-dependent signaling; photosystem II; singlet oxygen; stress; thylakoid FtsH protease