Molecular architecture and mechanism of an icosahedral pyruvate dehydrogenase complex: a multifunctional catalytic machine
Molecular architecture and mechanism of an icosahedral pyruvate dehydrogenase complex: a multifunctional catalytic machine
复制标题
DOI：
10.1093/emboj/cdf574
复制
发表时间：
2002-11-01
期刊：
影响因子：
11.4
通讯作者：
Subramaniam, S
中科院分区：
文献类型：
--
作者：
Milne, JLS;Shi, D;Subramaniam, S
“单粒子”的电子冷冻显微镜是确定复杂细胞组装体的三维（3D）结构的有力方法。丙酮酸脱氢酶多酶复合物在丙酮酸的氧化脱羧中偶联三种组分酶（E1、E2和E3）的活性以产生乙酰辅酶A，连接糖酵解和三羧酸循环。我们在这里报告的3D模型为11 MDa，二十面体的丙酮酸脱氢酶子复合物，通过结合来自电子冷冻显微镜与先前确定的原子坐标的个别E1和E2组件的28埃的结构。一个关键特征是E1分子位于组件的外围，其取向允许60个移动的硫辛酰基结构域中的每一个连接到内部E2核心，以从二十面体复合物内部访问多个E1和E2活性位点。这种意想不到的架构提供了一个高效的机制，活性位点耦合和催化速率增强的运动的硫辛酰基域之间的内核和外壳的复杂的限制性环形区域。
Electron cryo-microscopy of 'single particles' is a powerful method to determine the three-dimensional (3D) architectures of complex cellular assemblies. The pyruvate dehydrogenase multi-enzyme complex couples the activity of three component enzymes (E1, E2 and E3) in the oxidative decarboxylation of pyruvate to generate acetyl-CoA, linking glycolysis and the tricarboxylic acid cycle. We report here a 3D model for an 11 MDa, icosahedral pyruvate dehydrogenase sub-complex, obtained by combining a 28 Angstrom structure derived from electron cryo-microscopy with previously determined atomic coordinates of the individual E1 and E2 components. A key feature is that the E1 molecules are located on the periphery of the assembly in an orientation that allows each of the 60 mobile lipoyl domains tethered to the inner E2 core to access multiple E1 and E2 active sites from inside the icosahedral complex. This unexpected architecture provides a highly efficient mechanism for active site coupling and catalytic rate enhancement by the motion of the lipoyl domains in the restricted annular region between the inner core and outer shell of the complex.