State transitions in Chlamydomonas reinhardtii strongly modulate the functional size of photosystem II but not of photosystem I
Plants and green algae optimize photosynthesis in changing light conditions by balancing the amount of light absorbed by photosystems I and II. These photosystems work in series to extract electrons from water and reduce NADP+ to NADPH. Light-harvesting complexes (LHCs) are held responsible for maintaining the balance by moving from one photosystem to the other in a process called state transitions. In the green alga Chlamydomonas reinhardtii, a photosynthetic model organism, state transitions are thought to involve 80% of the LHCs. Here, we demonstrate with picosecond-fluorescence spectroscopy on C. reinhardtii cells that, although LHCs indeed detach from photosystem II in state 2 conditions, only a fraction attaches to photosystem I. The detached antenna complexes become protected against photodamage via shortening of the excited-state lifetime. It is discussed how the transition from state 1 to state 2 can protect C. reinhardtii in high-light conditions and how this differs from the situation in plants.
| Main Authors: | , , , |
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| Format: | Article/Letter to editor biblioteca |
| Language: | English |
| Subjects: | alga scenedesmus-obliquus, angstrom resolution, arabidopsis-thaliana, charge separation, excitation-energy transfer, light-harvesting-complex, protein-phosphorylation, resolved chlorophyll fluorescence, supramolecular organization, thylakoid membrane, |
| Online Access: | https://research.wur.nl/en/publications/state-transitions-in-chlamydomonas-reinhardtii-strongly-modulate- |
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