A chloroplast DegP2 protease performs the primary cleavage of the photodamaged D1 protein in plant photosystem II.
Although light is the ultimate substrate in photosynthesis, it can also be harmful and lead to oxidative damage of the photosynthetic apparatus. The main target for light stress is the central oxygen-evolving photosystem II (PSII) and its D1 reaction centre protein. Degradation of the damaged D1 protein and its rapid replacement by a de novo synthesized copy represent the important repair mechanism of PSII crucial for plant survival under light stress conditions. Here we report the isolation of a single-copy nuclear gene from Arabidopsis thaliana, encoding a protease that performs GTP-dependent primary cleavage of the photodamaged D1 protein and hence catalysing the key step in the repair cycle in plants. This protease, designated DegP2, is a homologue of the prokaryotic Deg/Htr family of serine endopeptidases and is associated with the stromal side of the non-appressed region of the thylakoid membranes. Increased expression of DegP2 under high salt, desiccation and light stress conditions was measured at the protein level.
Haussühl
K
K
Department of Biochemistry, Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-10691 Stockholm, Sweden.
Andersson
B
B
Adamska
I
I
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology; D029681:Arabidopsis Proteins; D001483:Base Sequence; D002736:Chloroplasts / Q000201:enzymology*; D017931:DNA Primers; D006358:Hot Temperature; D006868:Hydrolysis; D008027:Light; D008969:Molecular Sequence Data; D045322:Photosynthetic Reaction Center Complex Proteins / Q000378:metabolism*; D045332:Photosystem II Protein Complex; D017386:Sequence Homology, Amino Acid; D012697:Serine Endopeptidases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D029681:Arabidopsis Proteins; D017931:DNA Primers; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; C423318:DegP2 protein, Arabidopsis; D012697:Serine Endopeptidases