title: A stable LHCII-PSI aggregate and suppression of photosynthetic state transitions in the psae1-1 mutant of Arabidopsis thaliana.
abstract: During photosynthetic state transitions, a fraction of the major light-harvesting complex (LHCII) shuttles between photosystems II (PSII) and I (PSI), depending on whether or not it is phosphorylated. Its phosphorylation state in turn depends on the relative activity of the two photosystems, which is a function of redox state and illumination parameters. In the psae1-1 mutant of Arabidopsis thaliana (L.) Heynh., amounts of the PSI subunits E, C, D, H and L are decreased. A fraction of LHCII is stably associated with PSI when plants are exposed to low light conditions, giving rise to a high-molecular-mass protein-pigment complex detectable in native protein gels. The formation of this abnormal LHCII-PSI complex is associated with an almost complete suppression of state transitions, a drastic increase in the levels of phosphorylated LHCII under all light regimes tested, and a permanent reduction in PSII antenna size. All these observations suggest that the altered polypeptide composition of PSI perturbs the docking of phosphorylated LHCII, making psae1-1 a unique mutant for the study of PSI-LHCII interactions and additional effects of the mutation, such as a decrease in grana stacking and increased adenylate kinase activity.
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins; D002734:Chlorophyll / Q000378:metabolism; D004579:Electron Transport / Q000502:physiology; D008027:Light; D045342:Light-Harvesting Protein Complexes; D009154:Mutation; D010766:Phosphorylation; D010788:Photosynthesis / Q000235:genetics / Q000502:physiology*; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics / Q000378:metabolism*; D045331:Photosystem I Protein Complex; D020524:Thylakoids / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D029681:Arabidopsis Proteins; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D045331:Photosystem I Protein Complex; C412446:psaE1 protein, Arabidopsis; D002734:Chlorophyll