Supramolecular organization of the photosynthetic apparatus of Rhodobacter sphaeroides
Supramolecular organization of the photosynthetic apparatus of Rhodobacter sphaeroides
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DOI：
10.1093/emboj/18.3.534
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发表时间：
1999-02-01
期刊：
影响因子：
11.4
通讯作者：
Verméglio, A
中科院分区：
文献类型：
--
作者：
Jungas, C;Ranck, JL;Verméglio, A
天然管状膜从紫色非硫细菌球形红杆菌纯化。这些管状结构包含光合机构的所有膜成分，相对比例为一个细胞色素bc（1）复合物与两个反应中心，类似于每个反应中心24个细菌叶绿素分子。负染色膜的电子显微照片可显示高达25埃，并允许在20埃下计算投影图。晶胞（a = 198埃，B = 120埃和γ = 103度）包含呈现伪2重对称的细长S形超络合物。与孤立的反应中心和捕光复合物的密度图的比较允许的投影图的解释。每个超复合体由光捕获1复合体组成，该复合体采取两个外径类似于112埃的C形结构的形式，在开放侧彼此面对并包围两个反应中心。剩余的正密度暂时归因于一个细胞色素bc（1）复合物。这些特征揭示了反应中心和捕光复合物之间的联系。特别地，C形结构中的捕光复合物的组织确保了泛氢醌/泛醌在反应中心和细胞色素bc（1）复合物之间的有效交换。
Native tubular membranes were purified from the purple non-sulfur bacterium Rhodobacter sphaeroides. These tubular structures contain all the membrane components of the photosynthetic apparatus, in the relative ratio of one cytochrome bc(1) complex to two reaction centers, and similar to 24 bacteriochlorophyll molecules per reaction center. Electron micrographs of negative-stained membranes diffract up to 25 Angstrom and allow the calculation of a projection map at 20 Angstrom. The unit cell (a = 198 Angstrom, b = 120 Angstrom and gamma = 103 degrees) contains an elongated S-shaped supercomplex presenting a pseudo-2-fold symmetry. Comparison with density maps of isolated reaction center and light-harvesting complexes allowed interpretation of the projection map. Each supercomplex is composed of light-harvesting 1 complexes that take the form of two C-shaped structures of similar to 112 Angstrom in external diameter, facing each other on the open side and enclosing the two reaction centers. The remaining positive density is tentatively attributed to one cytochrome bc(1) complex. These features shed new light on the association of the reaction center and the light-harvesting complexes. In particular, the organization of the light-harvesting complexes in C-shaped structures ensures an efficient exchange of ubihydroquinone/ubiquinone between the reaction center and the cytochrome bc(1) complex.