Abstract
Life on Earth depends on photosynthesis, the conversion of light energy from the Sun to chemical energy. In plants, green algae and cyanobacteria, this process is driven by the cooperation of two large protein–cofactor complexes, photosystems I and II, which are located in the thylakoid photosynthetic membranes. The crystal structure of photosystem I from the thermophilic cyanobacterium Synechococcus elongatus described here provides a picture at atomic detail of 12 protein subunits and 127 cofactors comprising 96 chlorophylls, 2 phylloquinones, 3 Fe4S4 clusters, 22 carotenoids, 4 lipids, a putative Ca2+ ion and 201 water molecules. The structural information on the proteins and cofactors and their interactions provides a basis for understanding how the high efficiency of photosystem I in light capturing and electron transfer is achieved.
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Acknowledgements
These studies are financially supported by Deutsche Forschungsgemeinschaft, by Bundesministerium für Bildung und Forschung and by Fonds der Chemischen Industrie. We thank D. DiFiore and H. Schmidt for technical assistance; W. Schroeder for supporting the analytical characterisation of the PSI preparations; B. Rasmussen and J. Lescar for long-term support during data collection at beamline ID2B at ESRF in Grenoble; and J. Hughes for reading and improving the manuscript. We particularly thank D. A. Bryant for discussions regarding PsaX and acknowledge R. Bittl, K. Brettel, M. Byrdin, P. Chitnis, J. Golbeck, B. Loll, W. Lubitz, E. Schlodder and D. Stehlik for discussions.
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Jordan, P., Fromme, P., Witt, H. et al. Three-dimensional structure of cyanobacterial photosystem I at 2.5 Å resolution. Nature 411, 909–917 (2001). https://doi.org/10.1038/35082000
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DOI: https://doi.org/10.1038/35082000
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