Ferreira Kristina N, Iverson Tina M, Maghlaoui Karim, Barber James, Iwata So
Department of Biological Sciences, Imperial College London, London, SW7 2AZ, UK.
Science. 2004 Mar 19;303(5665):1831-8. doi: 10.1126/science.1093087. Epub 2004 Feb 5.
Photosynthesis uses light energy to drive the oxidation of water at an oxygen-evolving catalytic site within photosystem II (PSII). We report the structure of PSII of the cyanobacterium Thermosynechococcus elongatus at 3.5 angstrom resolution. We have assigned most of the amino acid residues of this 650-kilodalton dimeric multisubunit complex and refined the structure to reveal its molecular architecture. Consequently, we are able to describe details of the binding sites for cofactors and propose a structure of the oxygen-evolving center (OEC). The data strongly suggest that the OEC contains a cubane-like Mn3CaO4 cluster linked to a fourth Mn by a mono-micro-oxo bridge. The details of the surrounding coordination sphere of the metal cluster and the implications for a possible oxygen-evolving mechanism are discussed.
光合作用利用光能驱动光系统II（PSII）中氧释放催化位点处水的氧化。我们报道了嗜热栖热放线菌PSII在3.5埃分辨率下的结构。我们已确定了这个650千道尔顿二聚体多亚基复合物的大部分氨基酸残基，并对结构进行了优化以揭示其分子结构。因此，我们能够描述辅因子结合位点的细节，并提出氧释放中心（OEC）的结构。数据有力地表明，OEC包含一个类似立方烷的Mn3CaO4簇，通过一个单μ-氧桥与第四个锰相连。讨论了金属簇周围配位球的细节以及对可能的氧释放机制的影响。
