Electron-paramagnetic resonance (EPR) measurements for studying the assembly and structural dynamics of the light-harvesting chlorophyll a/b complex LHCII

• Applicant: Professor Dr. Harald Paulsen
• Co-Applicant: Professor Dr. Gunnar Jeschke
• Subject Area: Plant Biochemistry and Biophysics
• Term: from 2010 to 2014
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 170056744

The major light-harvesting complex (LHCII) is a main component of the photosynthetic apparatus in plants and among the most abundant membrane proteins on Earth. Electronparamagnetic resonance (EPR) will be used to measure the structure and structural dynamics of LHCII in vitro in various functional states. Since LHCII can be assembled in vitro from its recombinant apoprotein, spin labels are site-specifically attached to the protein. Therefore, the protein structure can be characterized by measuring distances between or the water accessibility of labelled protein domains. The structure of LHCII in various functional states will be compared to its known crystal structure, answering the question of whether LHCII exhibits structural changes in some of these functional states. The same approach will be used unravel the folding pathway of the LHCII apoprotein during its spontaneous assembly with pigments in vitro. This will not only help to understand LHCII biogenesis in plants but also yield information about how membrane protein folding is influenced by cofactor binding in a protein containing an exceptional number of cofactors. LHCII biogenesis will be more closely modelled by including the chloroplast signal recognition particle (cpSRP) in the protein folding studies.

• DFG Programme: Research Grants
• International Connection: Switzerland