In photosynthetic organisms, light absorption is essential for growth. Absorbed in excess however, it leads to cell damage. These organisms have thus developed a large array of photoprotective mechanisms, most of which target light-harvesting antennae. In plants, the main antenna is the Light-Harvesting Complex II (LHCII), a trimer of membrane, pigment-binding proteins, which is thus at the heart of the critical trade-off between light harvesting and photoprotection. There is a long-standing debate over the triggers of photoprotection and their effect on LHCII’s switch between light-harvesting and energy dissipative states. Yet, understanding this switch and its regulation is of major importance for fields ranging from crop stress resilience to reduction of energy loss in biotechnological applications.
This project aims to investigate which light acclimation-induced changes on the plant light-harvesting complex regulate its ability to cluster and / or interact with other complexes, and thus to modulate light capture and energy dissipation.
Our preliminary research has indeed evidenced a change in clustering properties of LHCII between complexes purified from dark- and light-adapted plants. Yet, an array of modifications on LHCII or its immediate surroundings, well-known (carotenoids) or little explored (lipids, surface charges modifications) can explain the change. Using biochemistry, fluorescence spectroscopy, and to some extent genetics and structural biology, we are now investigating if each of these parameters influences LHCII interacting properties – and how!