title: Photosystem II core phosphorylation and photosynthetic acclimation require two different protein kinases.
abstract: Illumination changes elicit modifications of thylakoid proteins and reorganization of the photosynthetic machinery. This involves, in the short term, phosphorylation of photosystem II (PSII) and light-harvesting (LHCII) proteins. PSII phosphorylation is thought to be relevant for PSII turnover, whereas LHCII phosphorylation is associated with the relocation of LHCII and the redistribution of excitation energy (state transitions) between photosystems. In the long term, imbalances in energy distribution between photosystems are counteracted by adjusting photosystem stoichiometry. In the green alga Chlamydomonas and the plant Arabidopsis, state transitions require the orthologous protein kinases STT7 and STN7, respectively. Here we show that in Arabidopsis a second protein kinase, STN8, is required for the quantitative phosphorylation of PSII core proteins. However, PSII activity under high-intensity light is affected only slightly in stn8 mutants, and D1 turnover is indistinguishable from the wild type, implying that reversible protein phosphorylation is not essential for PSII repair. Acclimation to changes in light quality is defective in stn7 but not in stn8 mutants, indicating that short-term and long-term photosynthetic adaptations are coupled. Therefore the phosphorylation of LHCII, or of an unknown substrate of STN7, is also crucial for the control of photosynthetic gene expression.
authors.affiliation: Botanisches Institut, Department Biologie I, Ludwig-Maximilians-Universität, Menzinger Strasse 67, 80638 München, Germany.
authors.forename: Vera
authors.initials: V
authors.lastname: Bonardi
authors.forename: Paolo
authors.initials: P
authors.lastname: Pesaresi
authors.forename: Thomas
authors.initials: T
authors.lastname: Becker
authors.forename: Enrico
authors.initials: E
authors.lastname: Schleiff
authors.forename: Raik
authors.initials: R
authors.lastname: Wagner
authors.forename: Thomas
authors.initials: T
authors.lastname: Pfannschmidt
authors.forename: Peter
authors.initials: P
authors.lastname: Jahns
authors.forename: Dario
authors.initials: D
authors.lastname: Leister
mesh_terms: D000064:Acclimatization / Q000502:physiology*; D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D045342:Light-Harvesting Protein Complexes / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D010766:Phosphorylation; D010788:Photosynthesis / Q000502:physiology*; D045332:Photosystem II Protein Complex / Q000235:genetics / Q000378:metabolism*; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases
chemical_list: D029681:Arabidopsis Proteins; D045342:Light-Harvesting Protein Complexes; D045332:Photosystem II Protein Complex; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; C497212:STN7 protein, Arabidopsis; C504925:STN8 protein, Arabidopsis