Federica Cariti

Light regulation of photosynthetic electron transfer.

All organisms on earth are continually exposed to changes in their environment, such as the atmospheric conditions or nutrient availability. Their survival depends on their ability to react and adapt to new conditions. Photosynthetic organisms are continuously required to acclimate rapidly to changes in the quality and quantity of light. Plants and green algae have developed a sophisticated mechanism to best exploit light in a dynamic environment. The organization of the photosynthetic apparatus, located in the thylakoid membranes of the chloroplast, is rapidly modified in response to different metabolic and light conditions. In particular, the light harvesting complex II (LHCII) is dynamically allocated between PSII and PSI in order to redistribute light energy between the two photosystems. This process is known as state transition. The main objective of the project is to investigate in detail state transitions in Chlamydomonas reinhardtii. The allocation of the LHCII complex is finely regulated by reversible phosphorylation. The specific roles of kinases and phosphatases involved in this process will investigated and the kinetics of state transitions will be studied in detail. Moreover, the data obtained will be used to refine a mathematical model of the regulation of photosynthesis, in collaboration with A. Matuszynska and O. Ebenhöh.