STRUCTURAL BIOLOGY OF CYTOCHROME C REDUCTASE BC1 COMPLEX

这项拟议中的研究将确定 细胞色素c还原酶从线粒体呼吸循环， 单晶X射线衍射研究。 细胞色素c还原酶是一种 寡聚线粒体内膜蛋白复合物， 电子从泛醇转移到细胞色素c， 质子跨膜转移。 这中间的一段 呼吸循环极其重要，许多线粒体 肌病是由这种蛋白质复合物的缺陷引起的。 三 细胞色素c还原酶的三维结构，有和没有 抑制剂结合，将有助于阐明其机制， 行动，从而提供初步了解其功能， 缺陷相关 尽管这个建筑群的部分结构 不到一年前发表的一篇关于四氢呋喃晶体形式的文章中， 其三个关键反应中心仍然没有得到解决， 难以捉摸。 为了解决完整的结构与这些 关键的缺失反应中心完好无损，我们已经获得了不同的 Bc1配合物的六方晶体形式。 最近，获得了3埃单位的本地数据集， 六边形形式和相位问题已经解决了使用多个 同晶置换法 模型的建立和细化 这些独特的六边形形态的阶段计划为 不久的将来。 此外，还将收集更多数据 扩展到当前的最大分辨率到2.5埃单位 利用快速冷却方法和同步加速器的改进 源和探测器技术。抑制剂结合的晶体也将是 试图推断出不同的构象是如何联系在一起的 与BC1复合物的功能机制有关。

The proposed research will determine the structural biology of cytochrome c reductase from the mitochondrial respiratory cycle by single crystal X-ray diffraction studies. Cytochrome c reductase is an oligomeric inner mitochondrial membrane protein complex which couples the transfer of electrons from ubiquinol to cytochrome c with the translocation of protons across the membrane. This middle segment of the respiratory cycle is extremely important and many mitochondrial myopathies result from defects of this protein complex. The three dimensional structure of cytochrome c reductase, with and without inhibitors bound, would facilitate the elucidation of its mechanism of action and thereby provide initial understanding for its function and defect correlation. Even though a partial structure of this complex from a tetragonal crystal form was published less than a year ago, two of its three crucial reactive centers still remain unresolved and elusive. In an effort to resolve the complete structure with these crucial missing reactive centers intact, we have obtained different hexagonal crystal forms of the bc1 complex. Recently, native data sets to 3 Angstrom units were obtained for these hexagonal forms and the phase problem has been solved using multiple isomorphous replacement methods. The model building and refinement stages for these unique hexagonal morphologies are planned for the immediate future. Furthermore, additional data will be collected extending to the current maximum resolution to 2.5 Angstrom units utilizing improvements in flash-cooling methodology and synchrotron source and detector technologies. Inhibitor bound crystals will also be studied in an effort to deduce how different conformations are related with the functional mechanism of the bc1 complex.