Crystal Structure of Monomeric Photosystem II from Thermosynechococcus elongatus at 3.6-Å Resolution

• DOI: 10.1074/jbc.m110.127589
• Publication Date: 2010-06-18T01:10:27Z
• Authors: Matthias Broser; Azat Gabdulkhakov; Jan Kern; Albert Guskov; Frank Müh; Wolfram Saenger; Athina Zouni
• Keywords: Molecular replacement

The membrane-embedded photosystem II core complex (PSIIcc) uses light energy to oxidize water in photosynthesis. Information about the spatial structure of PSIIcc obtained from x-ray crystallography was so far derived homodimeric thermophilic cyanobacteria. Here, we report first crystallization and structural analysis monomeric form with high oxygen evolution capacity, isolated Thermosynechococcus elongatus. crystals belong space group C222(1), contain one monomer per asymmetric unit, diffract a resolution 3.6 A. diffraction pattern PSIIcc-monomer exhibit less anisotropy (dependence on crystal orientation) compared dimeric PSIIcc, packing molecules within unit cell is different. In monomer, 19 protein subunits, 35 chlorophylls, two pheophytins, non-heme iron, primary plastoquinone Q(A), heme groups, 11 beta-carotenes, 22 lipids, seven detergent molecules, Mn(4)Ca cluster oxidizing could be assigned analogous dimer. Based new information, roles lipids subunits dimer formation are discussed. Due lack non-crystallographic symmetry orientation membrane normal perpendicular ( approximately 87 degrees ) crystallographic b-axis, further information expected become available orientation-dependent spectroscopy this form.