Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign , 405 North Mathews Avenue, Urbana, Illinois 61801, United States.
Department of Physics, University of Illinois at Urbana-Champaign , 1110 West Green Street, Urbana, Illinois 61801, United States.
J Am Chem Soc. 2016 Sep 21;138(37):12077-89. doi: 10.1021/jacs.6b01193. Epub 2016 Sep 7.
Small diffusible redox proteins facilitate electron transfer in respiration and photosynthesis by alternately binding to their redox partners and integral membrane proteins and exchanging electrons. Diffusive search, recognition, binding, and unbinding of these proteins often amount to kinetic bottlenecks in cellular energy conversion, but despite the availability of structures and intense study, the physical mechanisms controlling redox partner interactions remain largely unknown. The present molecular dynamics study provides an all-atom description of the cytochrome c2-docked bc1 complex in Rhodobacter sphaeroides in terms of an ensemble of favorable docking conformations and reveals an intricate series of conformational changes that allow cytochrome c2 to recognize the bc1 complex and bind or unbind in a redox state-dependent manner. In particular, the role of electron transfer in triggering a molecular switch and in altering water-mediated interface mobility, thereby strengthening and weakening complex formation, is described. The results resolve long-standing discrepancies between structural and functional data.
小分子可扩散氧化还原蛋白通过交替与氧化还原伴侣和整合膜蛋白结合并交换电子，从而促进呼吸和光合作用中的电子传递。这些蛋白质的扩散搜索、识别、结合和脱附通常是细胞能量转换中的动力学瓶颈，但尽管有结构和深入研究，控制氧化还原伴侣相互作用的物理机制在很大程度上仍然未知。本分子动力学研究以一系列有利的对接构象集的形式，提供了关于 Rhodobacter sphaeroides 中细胞色素 c2 对接 bc1 复合物的全原子描述，并揭示了一系列复杂的构象变化，使细胞色素 c2 能够识别 bc1 复合物，并以氧化还原状态依赖的方式结合或脱附。特别是，描述了电子转移在触发分子开关以及改变水介导的界面流动性从而增强和削弱复合物形成中的作用。结果解决了结构和功能数据之间长期存在的差异。
