Nature2014-06-19 2:25 PM

一个细菌集光复合物的结构 Structure of the LH1–RC complex fromThermochromatium tepidum at 3.0??


光合作用生物能将太阳能转化成细胞可以利用的一种形式。现在,Kunio Miki及同事获得了与Ca2+和各种辅因子结合在一起的一个完整的细菌“集光天线-反应中心”(LH1–RC)复合物的第一个接近原子水平的结构。LH1亚单元形成围绕反应中心的一个环,细菌叶绿素和螺菌黄素辅因子位于该环内,Ca2+离子在LH1的周质(periplasmic)侧。该结构显示了能量是怎样被高效地从集光天线传递到反应中心的,同时也为了解泛醌怎样穿过一个封闭的LH1屏障提供了信息。


The light-harvesting core antenna (LH1) and the reaction centre (RC) of purple photosynthetic bacteria form a supramolecular complex (LH1–RC) to use sunlight energy in a highly efficient manner. Here we report the first near-atomic structure, to our knowledge, of a LH1–RC complex, namely that of a Ca2+-bound complex from Thermochromatium tepidum, which reveals detailed information on the arrangement and interactions of the protein subunits and the cofactors. The RC is surrounded by 16 heterodimers of the LH1 αβ-subunit that form a completely closed structure. The Ca2+ ions are located at the periplasmic side of LH1. Thirty-two bacteriochlorophyll and 16 spirilloxanthin molecules in the LH1 ring form an elliptical assembly. The geometries of the pigment assembly involved in the absorption characteristics of the bacteriochlorophyll in LH1 and excitation energy transfer among the pigments are reported. In addition, possible ubiquinone channels in the closed LH1 complex are proposed based on the atomic structure.






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