The Thylakoid FtsH Protease Plays a Role in the Light-Induced Turnover of the Photosystem II D1 Protein

• Published in: The Plant cell 2000-03, Vol.12 (3), p.419-431
• Main Authors: Lindahl, Marika, Spetea, Cornelia, Hundal, Torill, Oppenheim, Amos B., Adam, Zach, Andersson, Bertil
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphate - metabolism; Adenosine Triphosphate - pharmacology; Arabidopsis - drug effects; Arabidopsis - enzymology; Arabidopsis Proteins; ATP; ATP-Dependent Proteases; Biodegradation; Caseins - metabolism; Catalytic Domain; Cations - pharmacology; Cell membranes; Chlorophylls; Chloroplasts; D1 protein; Escherichia coli; Escherichia coli - genetics; Gels; Gene Expression Regulation, Enzymologic; Glutathione Transferase - genetics; Glutathione Transferase - metabolism; Light; MEDICIN; MEDICINE; Membrane Proteins - genetics; Membrane Proteins - metabolism; Membrane Proteins - physiology; Metalloendopeptidases - genetics; Metalloendopeptidases - metabolism; Metalloendopeptidases - physiology; Photosynthetic Reaction Center Complex Proteins - metabolism; Photosynthetic Reaction Center Complex Proteins - radiation effects; Photosystem II Protein Complex; Plant cells; Proteins; Quantification; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; Recombinant Proteins - metabolism; Thylakoids; Thylakoids - drug effects; Thylakoids - enzymology
• ISSN: 1040-4651; 1532-298X; 1532-298X
• DOI: 10.1105/tpc.12.3.419

The photosystem II reaction center D1 protein is known to turn over frequently. This protein is prone to irreversible damage caused by reactive oxygen species that are formed in the light; the damaged, nonfunctional D1 protein is degraded and replaced by a new copy. However, the proteases responsible for D1 protein degradation remain unknown. In this study, we investigate the possible role of the FtsH protease, an ATP-dependent zinc metalloprotease, during this process. The primary light-induced cleavage product of the D1 protein, a 23-kD fragment, was found to be degraded in isolated thylakoids in the dark during a process dependent on ATP hydrolysis and divalent metal ions, suggesting the involvement of FtsH. Purified FtsH degraded the 23-kD D1 fragment present in isolated photosystem II core complexes, as well as that in thylakoid membranes depleted of endogenous FtsH. In this study, we definitively identify the chloroplast protease acting on the D1 protein during its light-induced turnover. Unlike previously identified membrane-bound substrates for FtsH in bacteria and mitochondria, the 23-kD D1 fragment represents a novel class of FtsH substrate-functionally assembled proteins that have undergone irreversible photooxidative damage and cleavage.