Compositional and Structural Analyses of the Photosystem Ⅱ Isolated from the Red Alga Cyanidioschyzon Merolae
Members of the rhodophytan order Cyanidiales are unique among phototrophs in their ability to live in extremely low pH levels and moderately high temperatures. The photosynthetic apparatus of the red alga Cyanidioschyzon merolae represents an intermediate type between cyanobacteria and higher plants, suggesting that this alga may provide the evolutionary link between prokaryotic and eukaryotic phototrophs. While red algal PSI resembles that of the higher plants, the PSⅡ complex is more reminiscent of the cyanobacterial ancestor in that it contains phycobilisomes as the light-harvesting system instead of Chla/b binding proteins of green algae and higher plants, as well as the PsbU and PsbV subunits stabilising the oxygen evolving complex (OEC). The most remarkable feature of the red algal PSⅡ is the presence of the fourth extrinsic protein of 20 kDa (PsbQ) which is not found in the cyanobacterial OEC and which is distantly related with the green algal PsbQ. This feature together with some differences in the structural cooperation between the OEC subunits suggests that the lumenal side of red algal PSⅡ may vary from the prokaryotic ancestor. In order to elucidate the structural differences between cyanobacterial and eukaryotic PSⅡ, we have isolated highly active and stable dimeric complexes of the C. merolae PSⅡ and subjected them to high throughput crystallization and mass spectrometry analyses. Here we report the full subunit composition and preliminary results of 3D crystallization of the dimeric C. merolae PSⅡ.
PSⅡ structure Cyanidioschyzon merolae X-ray diffraction Mass spectrometry
Joanna Kargul Marko Boehm Nina Morgner Carol V. Robinson Peter J. Nixon James Barber
Division of Molecular Biosciences, Faculty of Natural Sciences, Imperial College London, London, SW7 Division of Biology, Faculty of Natural Sciences, Imperial College London, London, SW7 2AZ, UK Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford
国际会议
15th International Conference on Photosynthesis(第15届国际光合作用大会)
北京
英文
59-63
2010-08-22（万方平台首次上网日期，不代表论文的发表时间）