Regulation of light-harvesting systems in plants: Flexible conformation of light-harvesting complex II trimer depending on its binding site

Photosynthesis is a fundamental energy conversion process that sustains the Earth's ecosystem. As the environment has changed, photosynthetic systems of photosynthetic organisms have been diversified and optimized. Recent studies indicate that photosynthesis has been designed not only for ‘efficiency’ in energy conversion but also for ‘flexibility' in sustaining itself in a changing environment. In particular, light-harvesting systems were found to have the greatest diversity and flexibility to cope with the changing light conditions. In this presentation, I would like to introduce my recent studies on the regulation of light-harvesting systems by protein-protein interactions in plants and green algae. Our results revealed that the conformation of a light-harvesting complex II (LHCII) trimer in the green alga Chlamydomonas reinhardtii was dependent on the binding site. We propose that this conformational flexibility of the LHCII trimer possibly modulates its light-harvesting properties by altering excitation-energy flow over the photosynthetic supercomplex.