Rigid core and flexible terminus: Structure of solubilized light-harvesting chlorophyll a/b complex (LHCII) measured by EPR

Autor: Dockter, Christoph, Müller, André H., Dietz, Carsten, Volkov, Aleksei, Polyhach, Yevhen, Jeschke, Gunnar, Paulsen, Harald
Rok vydání: 2012
Předmět:
Zdroj: Journal of Biological Chemistry
Popis: The structure of the major light harvesting chlorophyll a/b complex (LHCII) was analyzed by pulsed EPR measurements and compared with the crystal structure. Site specific spin labeling of the recombinant protein allowed the measurement of distance distributions over several intra and intermolecular distances in monomeric and trimeric LHCII yielding information on the protein structure and its local flexibility. A spin label rotamer library based on a molecular dynamics simulation was used to take the local mobility of spin labels into account. The core of LHCII in solution adopts a structure very similar or identical to the one seen in crystallized LHCII trimers with little motional freedom as indicated by narrow distance distributions along and between a helices. However distances comprising the lumenal loop domain show broader distance distributions indicating some mobility of this loop structure. Positions in the hydrophilic N terminal domain upstream of the first trans membrane a helix exhibit more and more mobility the closer they are to the N terminus. The nine amino acids at the very N terminus that have not been resolved in any of the crystal structure analyses give rise to very broad and possibly bimodal distance distributions which may represent two families of preferred conformations. © 2012 by The American Society for Biochemistry and Molecular Biology Inc.
Databáze: OpenAIRE