The significance of photosystem II supercomplexes in light acclimation of Arabidopsis thaliana

点击翻译按钮获取中文摘要

Photosynthesis is the major energy fixing process on earth. Higher plants as the model plant Arabidopsis thaliana regulate their photosynthetic capacity very fast and efficiently in order to allow for high photosynthetic performance and at the same time protection from oxidative damage. Photosystem (PS) II supercomplexes are of substantial importance for regulation of photosynthesis. Although the structure of PSII supercomplexes has been determined, the process of PSII supercomplex assembly and PSII supercomplex remodeling during light acclimation is poorly understood. We revealed in own previous work that the PSII associated protein Psb27 is required for assembly and/or stability of PSII supercomplexes while PSII supercomplex remodeling is induced by PSII core protein phosphorylation. Interestingly, the major phosphorylation site of the PSII subunit CP43 might be a putative Psb27 binding site. Within this project we aim to elucidate the assembly and regulation of PSII supercomplexes. To this end i) we will utilize immuno-biochemical approaches to determine the localization and function of the PSII associated factor Psb27. Additionally, we will use in planta tagged Psb27 lines in order to identify interacting proteins. ii) We will investigate the kinetics of PSII core phosphorylation in relation to the altered functionality of PSII supercomplexes. With fluorometrical and spectroscopical methods we will assess concomitant changes in light harvesting, light energy distribution and transfer. To this end we will use mutant lines with altered thylakoid complex phosphorylation in combination with defined light regimes. By this means we will be able to assign physiological functions of differentially phosphorylated PSII supercomplexes. iii) We will investigate the physiological impact of PSII remodeling on the ability to acclimate to different light environments using Arabidopsis lines impaired in assembly or regulation of PSII supercomplexes. These mutants will be subjected to fluctuating light conditions and tested for their photosynthetic performance. The knowledge obtained about PSII supercomplexes and their remodeling will enable us to evaluate the effects of the light environment on plant growth and yield. In the future the productivity of agricultural important plants might benefit from this knowledge.