Light acclimation involves dynamic re-organization of the pigment-protein megacomplexes in non-appressed thylakoid domains
Autor: | Michele Grieco, Sari Järvi, Fikret Mamedov, Marjaana Rantala, Eva-Mari Aro, Maija Lespinasse, Andrea Trotta, Marjaana Suorsa, Mikko Tikkanen, Eerika Vuorio |
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Rok vydání: | 2014 |
Předmět: |
Light
Acclimatization Mutant Arabidopsis Light-Harvesting Protein Complexes macromolecular substances Plant Science Thylakoids Genetics Arabidopsis thaliana Photosystem biology Photosystem I Protein Complex Arabidopsis Proteins ta1183 Wild type food and beverages Photosystem II Protein Complex Far-red Cell Biology 15. Life on land biology.organism_classification Biochemistry Thylakoid Biophysics Phosphorylation |
Zdroj: | The Plant journal : for cell and molecular biology. 84(2) |
ISSN: | 1365-313X |
Popis: | Thylakoid energy metabolism is crucial for plant growth, development and acclimation. Non-appressed thylakoids harbor several high molecular mass pigment-protein megacomplexes that have flexible compositions depending upon the environmental cues. This composition is important for dynamic energy balancing in photosystems (PS) I and II. We analysed the megacomplexes of Arabidopsis wild type (WT) plants and of several thylakoid regulatory mutants. The stn7 mutant, which is defective in phosphorylation of the light-harvesting complex (LHC) II, possessed a megacomplex composition that was strikingly different from that of the WT. Of the nine megacomplexes in total for the non-appressed thylakoids, the largest megacomplex in particular was less abundant in the stn7 mutant under standard growth conditions. This megacomplex contains both PSI and PSII and was recently shown to allow energy spillover between PSII and PSI (Nat. Commun., 6, 2015, 6675). The dynamics of the megacomplex composition was addressed by exposing plants to different light conditions prior to thylakoid isolation. The megacomplex pattern in the WT was highly dynamic. Under darkness or far red light it showed low levels of LHCII phosphorylation and resembled the stn7 pattern; under low light, which triggers LHCII phosphorylation, it resembled that of the tap38/pph1 phosphatase mutant. In contrast, solubilization of the entire thylakoid network with dodecyl maltoside, which efficiently solubilizes pigment-protein complexes from all thylakoid compartments, revealed that the pigment-protein composition remained stable despite the changing light conditions or mutations that affected LHCII (de)phosphorylation. We conclude that the composition of pigment-protein megacomplexes specifically in non-appressed thylakoids undergoes redox-dependent changes, thus facilitating maintenance of the excitation balance between the two photosystems upon changes in light conditions. |
Databáze: | OpenAIRE |
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