STRUCTURAL BIOLOGY OF CYTOCHROME C REDUCTASE BC1 COMPLEX

这项拟议的研究将确定 线粒体呼吸循环中的细胞色素C还原酶 单晶X射线衍射研究。细胞色素c还原酶是一种 偶联的低聚内线粒体膜蛋白复合体 电子从泛喹酚到细胞色素c的转移 质子在膜上的转移。这中间的这段 呼吸周期是极其重要的，许多线粒体 肌病是由这种蛋白质复合体的缺陷引起的。三位一体 细胞色素c还原酶的空间结构 抑制剂的结合，将有助于阐明其作用机制 行动，从而对其功能和作用提供初步了解 缺陷相关性。即使这个建筑群的部分结构 在不到一年前发表了四方晶型，两个 它的三个关键反应中心中的一个仍然没有解决 难以捉摸。为了用这些来解析完整的结构 关键缺失的反应中心完好无损，我们得到了不同的 六方晶型的Bc1络合物。 最近，获得了3埃单位的原始数据集 六角形和位相问题已经用多个 同构替换法。模型的建立和求精 这些独特的六角形形态的阶段计划在 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至2.5埃 利用闪冷方法和同步加速器的改进 源和探测器技术。缓蚀剂结合的晶体也将 为了推断不同的构象如何相关而进行的研究 与Bc1复合体的作用机制有关。

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.