title: Accumulation of the D2 protein is a key regulatory step for assembly of the photosystem II reaction center complex in Synechocystis PCC 6803.
abstract: Accumulation of monomer and dimer photosystem (PS) II reaction center core complexes has been analyzed by two-dimensional Blue-native/SDS-PAGE in Synechocystis PCC 6803 wild type and in mutant strains lacking genes psbA, psbB, psbC, psbDIC/DII, or the psbEFLJ operon. In vivo pulse-chase radiolabeling experiments revealed that mutant cells assembled PSII precomplexes only. In DeltapsbC and DeltapsbB, assembly of reaction center cores lacking CP43 and reaction center complexes was detected, respectively. In DeltapsbA, protein subunits CP43, CP47, D2, and cytochrome b559 were synthesized, but proteins did not assemble. Similarly, in DeltapsbD/C lacking D2, and CP43, the de novo synthesized proteins D1, CP47, and cytochrome b559 did not form any mutual complexes, indicating that assembly of the reaction center complex is a prerequisite for assembly with core subunits CP47 and CP43. Finally, although CP43 and CP47 accumulated in DeltapsbEFLJ, D2 was neither expressed nor accumulated. We, furthermore, show that the amount of D2 is high in the strain lacking D1, whereas the amount of D1 is low in the strain lacking D2. We conclude that expression of the psbEFLJ operon is a prerequisite for D2 accumulation that is the key regulatory step for D1 accumulation and consecutive assembly of the PSII reaction center complex.
authors.affiliation: Institute of Microbiology, Opatovický mlýn, 379 81 Trebon, Czech Republic.
authors.forename: Josef
authors.initials: J
authors.lastname: Komenda
authors.forename: Veronika
authors.initials: V
authors.lastname: Reisinger
authors.forename: Bernd Christian
authors.initials: BC
authors.lastname: Müller
authors.forename: Marika
authors.initials: M
authors.lastname: Dobáková
authors.forename: Bernhard
authors.initials: B
authors.lastname: Granvogl
authors.forename: Lutz Andreas
authors.initials: LA
authors.lastname: Eichacker
mesh_terms: D001345:Autoradiography; D002734:Chlorophyll / Q000737:chemistry; D000458:Cyanobacteria / Q000378:metabolism; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D017353:Gene Deletion; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry; D008954:Models, Biological; D009154:Mutation; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry; D045332:Photosystem II Protein Complex / Q000737:chemistry / Q000378:metabolism*; D046939:Synechocystis / Q000502:physiology*; D020524:Thylakoids / Q000378:metabolism
chemical_list: D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; C083100:photosystem II, chlorophyll binding protein, CP-43; C070970:photosystem II, chlorophyll-binding protein, CP-47; D002734:Chlorophyll