Analysis of the chloroplast protein kinase Stt7 during state transitions
| Autor: | Roberto Bassi, Sylvain Lemeille, Jean-David Rochaix, Adrian Willig, Nathalie Depège-Fargeix, Christian Delessert |
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| Přispěvatelé: | Reproduction et développement des plantes (RDP), École normale supérieure - Lyon (ENS Lyon)-Institut National de la Recherche Agronomique (INRA)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de la Recherche Agronomique (INRA)-École normale supérieure - Lyon (ENS Lyon), Maggio, Stéphanie, École normale supérieure de Lyon (ENS de Lyon)-Institut National de la Recherche Agronomique (INRA)-Université Claude Bernard Lyon 1 (UCBL) |
| Jazyk: | angličtina |
| Rok vydání: | 2009 |
| Předmět: |
0106 biological sciences
Chloroplasts Photosystem II Light Protein Conformation Light-Harvesting Protein Complexes Plant Biology State transitions STT7 photosyntesis 01 natural sciences chemistry.chemical_compound [SDV.BV] Life Sciences [q-bio]/Vegetal Biology Photosynthesis Biology (General) ComputingMilieux_MISCELLANEOUS Photosystem ddc:616 0303 health sciences Cytochrome b6f complex General Neuroscience Adaptation Physiological Chloroplast Transmembrane domain ddc:580 Biochemistry Thylakoid General Agricultural and Biological Sciences Research Article QH301-705.5 Plastoquinone Biology Photosystem I General Biochemistry Genetics and Molecular Biology 03 medical and health sciences Structure-Activity Relationship ddc:570 Animals [SDV.BV]Life Sciences [q-bio]/Vegetal Biology 030304 developmental biology General Immunology and Microbiology Photosystem I Protein Complex Algal Proteins Chlamydomonas Photosystem II Protein Complex Cytochrome b6f Complex chemistry Biophysics Protein Kinases 010606 plant biology & botany |
| Zdroj: | PLoS Biology PLoS Biology, Public Library of Science, 2009, 7, pp.664-675 PLoS Biology, Vol 7, Iss 3, p e45 (2009) PLOS Biology, Vol. 7, No 3 (2009) pp. 0664-0675 HAL PLoS Biology, 2009, 7, pp.664-675 |
| ISSN: | 1544-9173 1545-7885 |
| Popis: | State transitions allow for the balancing of the light excitation energy between photosystem I and photosystem II and for optimal photosynthetic activity when photosynthetic organisms are subjected to changing light conditions. This process is regulated by the redox state of the plastoquinone pool through the Stt7/STN7 protein kinase required for phosphorylation of the light-harvesting complex LHCII and for the reversible displacement of the mobile LHCII between the photosystems. We show that Stt7 is associated with photosynthetic complexes including LHCII, photosystem I, and the cytochrome b 6 f complex. Our data reveal that Stt7 acts in catalytic amounts. We also provide evidence that Stt7 contains a transmembrane region that separates its catalytic kinase domain on the stromal side from its N-terminal end in the thylakoid lumen with two conserved Cys that are critical for its activity and state transitions. On the basis of these data, we propose that the activity of Stt7 is regulated through its transmembrane domain and that a disulfide bond between the two lumen Cys is essential for its activity. The high-light–induced reduction of this bond may occur through a transthylakoid thiol–reducing pathway driven by the ferredoxin-thioredoxin system which is also required for cytochrome b 6 f assembly and heme biogenesis. Author Summary To grow optimally, photosynthetic organisms need to constantly adjust to changing light conditions. One of these adjustments, called state transitions, allows light energy to be redistributed between the two photosynthetic reaction center complexes in a cell's chloroplasts. These complexes act in concert with other components of the photosynthetic machinery to turn light energy into cellular energy. A key component in the regulation of state transitions is the chloroplast protein Stt7 (also known as STN7), which can modify other proteins by adding a phosphate group. When light levels change, the oxidation level of a pool of another chloroplast component, plastoquinone, changes, which in turn activates Stt7, inducing it to phosphorylate specific proteins of the light-harvesting complex of one reaction center. As a result, a portion of this light-harvesting complex is transferred from one photosynthetic reaction center to the other, thereby optimizing photosynthetic efficiency. Here, we have addressed the configuration of Stt7 within the thylakoid membrane of the chloroplast and the molecular mechanisms underlying its activation. Our data reveal that the level of Stt7 protein changes drastically under specific environmental conditions, that the protein does not need to be present in a one-to-one ratio with its targets for activity, and that it associates directly with a number of components of the photosynthetic machinery. The protein-modifying domain of Stt7 is exposed to the outer side of the thylakoid membrane, whereas the domain critical for regulation of its activity lies on the inner side of the thylakoid membrane. These results shed light on the molecular mechanisms that allow photosynthetic organisms to adjust to fluctuations in light levels. The Stt7/STN7 chloroplast protein is involved in the phosphorylation and remodeling of the light-harvesting apparatus of photosynthetic organisms and plays a key role in the acclimation of the photosynthetic machinery following changes in light levels. |
| Databáze: | OpenAIRE |
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