title: The structure of a plant photosystem I supercomplex at 3.4 A resolution.
abstract: All higher organisms on Earth receive energy directly or indirectly from oxygenic photosynthesis performed by plants, green algae and cyanobacteria. Photosystem I (PSI) is a supercomplex of a reaction centre and light-harvesting complexes. It generates the most negative redox potential in nature, and thus largely determines the global amount of enthalpy in living systems. We report the structure of plant PSI at 3.4 A resolution, revealing 17 protein subunits. PsaN was identified in the luminal side of the supercomplex, and most of the amino acids in the reaction centre were traced. The crystal structure of PSI provides a picture at near atomic detail of 11 out of 12 protein subunits of the reaction centre. At this level, 168 chlorophylls (65 assigned with orientations for Q(x) and Q(y) transition dipole moments), 2 phylloquinones, 3 Fe(4)S(4) clusters and 5 carotenoids are described. This structural information extends the understanding of the most efficient nano-photochemical machine in nature.
authors.affiliation: Department of Biochemistry, The George S. Wise Faculty of Life Sciences, The Daniella Rich Institute for Structural Biology, Tel Aviv University, Tel Aviv, 69978, Israel.
authors.forename: Alexey
authors.initials: A
authors.lastname: Amunts
authors.forename: Omri
authors.initials: O
authors.lastname: Drory
authors.forename: Nathan
authors.initials: N
authors.lastname: Nelson
mesh_terms: D002338:Carotenoids / Q000737:chemistry / Q000378:metabolism; D002734:Chlorophyll / Q000737:chemistry / Q000378:metabolism; D018360:Crystallography, X-Ray; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D018532:Pisum sativum / Q000737:chemistry* / Q000378:metabolism; D010788:Photosynthesis; D045331:Photosystem I Protein Complex / Q000737:chemistry* / Q000378:metabolism*; D020836:Protein Structure, Quaternary; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism; D010837:Vitamin K 1 / Q000737:chemistry / Q000378:metabolism
chemical_list: D045342:Light-Harvesting Protein Complexes; D045331:Photosystem I Protein Complex; D021122:Protein Subunits; D002734:Chlorophyll; D002338:Carotenoids; D010837:Vitamin K 1