The stromal chloroplast Deg7 protease participates in the repair of photosystem II after photoinhibition in Arabidopsis.
Light is the ultimate source of energy for photosynthesis; however, excessive light leads to photooxidative damage and hence reduced photosynthetic efficiency, especially when combined with other abiotic stresses. Although the photosystem II (PSII) reaction center D1 protein is the primary target of photooxidative damage, other PSII core proteins are also damaged and degraded. However, it is still largely unknown whether degradation of D1 and other PSII proteins involves previously uncharacterized proteases. Here, we show that Deg7 is peripherally associated with the stromal side of the thylakoid membranes and that Deg7 interacts directly with PSII. Our results show that Deg7 is involved in the primary cleavage of photodamaged D1, D2, CP47, and CP43 and that this activity is essential for its function in PSII repair. The double mutants deg5 deg7 and deg8 deg7 showed no obvious phenotypic differences under normal growth conditions, but additive effects were observed under high light. These results suggest that Deg proteases on both the stromal and luminal sides of the thylakoid membranes are important for the efficient PSII repair in Arabidopsis (Arabidopsis thaliana).
Sun
Xuwu
X
Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
Fu
Tingjiao
T
Chen
Ning
N
Guo
Jinkui
J
Ma
Jinfang
J
Zou
Meijuan
M
Lu
Congming
C
Zhang
Lixin
L
D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D004269:DNA, Bacterial / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D008027:Light; D016254:Mutagenesis, Insertional; D009154:Mutation; D010447:Peptide Hydrolases / Q000235:genetics / Q000378:metabolism*; D010788:Photosynthesis; D045332:Photosystem II Protein Complex / Q000378:metabolism* / Q000528:radiation effects; D020524:Thylakoids / Q000201:enzymology* / Q000235:genetics
D029681:Arabidopsis Proteins; D004269:DNA, Bacterial; D018744:DNA, Plant; D045332:Photosystem II Protein Complex; C036483:T-DNA; D010447:Peptide Hydrolases