Recovery of photosystem II activity in photoinhibited synechocystis cells: light-dependent translation activity is required besides light-independent synthesis of the D1 protein.
Irreversible photoinactivation of photosystem II (PSII) results in the degradation of the reaction center II D1 protein. In Synechocystis PCC 6714 cells, recovery of PSII activity requires illumination. The rates of photoinactivation and recovery of PSII activity in the light are similar in cells grown in minimal (MM) or glucose-containing medium (GM). Reassembly of PSII with newly synthesized proteins requires degradation of the D1 protein of the photoinactivated PSII. This process may occur in darkness in both types of cells. The degraded D1 protein is, however, only partially replaced by newly synthesized protein in MM cells in darkness while a high level of D1 protein synthesis occurs in darkness in the GM cells. The newly synthesized D1 protein in darkness appears to be assembled with other PSII proteins. However, PSII activity is not recovered in such cells. Illumination of the cells in absence but not in the presence of protein synthesis inhibitors allows recovery of PSII activity.
Constant
S
S
Laboratoire de Photoregulation et Dynamique des Membranes Vegetales, UMR 8543, CNRS, Ecole Normale Superieure, 46 rue d'Ulm, 75230 Paris Cedex 05, France.
Eisenberg-Domovitch
Y
Y
Ohad
I
I
Kirilovsky
D
D
D002734:Chlorophyll / Q000378:metabolism; D000458:Cyanobacteria / Q000502:physiology*; D005470:Fluorometry; D005947:Glucose / Q000494:pharmacology; D007700:Kinetics; D008027:Light; D045342:Light-Harvesting Protein Complexes; D010100:Oxygen / Q000378:metabolism; D045322:Photosynthetic Reaction Center Complex Proteins / Q000096:biosynthesis* / Q000378:metabolism*; D045332:Photosystem II Protein Complex; D014176:Protein Biosynthesis; D020524:Thylakoids / Q000378:metabolism; D013997:Time Factors
D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D002734:Chlorophyll; D005947:Glucose; D010100:Oxygen