title: Analysis of the radiation-damage-free X-ray structure of photosystem II in light of EXAFS and QM/MM data.
abstract: A recent femtosecond X-ray diffraction study produced the first high-resolution structural model of the oxygen-evolving complex of photosystem II that is free of radiation-induced manganese reduction (Protein Data Bank entries 4UB6 and 4UB8 ). We find, however, that the model does not match extended X-ray absorption fine structure and QM/MM data for the S1 state. This is attributed to uncertainty about the positions of oxygen atoms that remain partially unresolved, even at 1.95 Å resolution, next to the heavy manganese centers. In addition, the photosystem II crystals may contain significant amounts of the S0 state, because of extensive dark adaptation prior to data collection.
authors.affiliation: Department of Chemistry, Yale University , New Haven, Connecticut 06520-8107, United States .
authors.forename: Mikhail
authors.initials: M
authors.lastname: Askerka
authors.forename: David J
authors.initials: DJ
authors.lastname: Vinyard
authors.forename: Jimin
authors.initials: J
authors.lastname: Wang
authors.forename: Gary W
authors.initials: GW
authors.lastname: Brudvig
authors.forename: Victor S
authors.initials: VS
authors.lastname: Batista
mesh_terms: D018360:Crystallography, X-Ray; D008345:Manganese / Q000737:chemistry; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D045332:Photosystem II Protein Complex / Q000737:chemistry* / Q000145:classification / Q000378:metabolism; D011487:Protein Conformation; D055503:Protein Multimerization; D021122:Protein Subunits / Q000737:chemistry; D011789:Quantum Theory; D056928:X-Ray Absorption Spectroscopy / Q000379:methods*; D014961:X-Ray Diffraction
chemical_list: D045332:Photosystem II Protein Complex; D021122:Protein Subunits; D008345:Manganese