Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden.
Chem Rev. 2021 Aug 11;121(15):9644-9673. doi: 10.1021/acs.chemrev.1c00140. Epub 2021 Jun 29.
In the final steps of energy conservation in aerobic organisms, free energy from electron transfer through the respiratory chain is transduced into a proton electrochemical gradient across a membrane. In mitochondria and many bacteria, reduction of the dioxygen electron acceptor is catalyzed by cytochrome oxidase (complex IV), which receives electrons from cytochrome (complex III), via membrane-bound or water-soluble cytochrome . These complexes function independently, but in many organisms they associate to form supercomplexes. Here, we review the structural features and the functional significance of the nonobligate IIIIV mitochondrial supercomplex as well as the obligate IIIIV supercomplex from actinobacteria. The analysis is centered around the Q-cycle of complex III, proton uptake by CytO, as well as mechanistic and structural solutions to the electronic link between complexes III and IV.
在需氧生物的能量守恒的最后步骤中，通过呼吸链传递的电子的自由能被转化为跨膜的质子电化学梯度。在线粒体和许多细菌中，二氧电子受体的还原是由细胞色素氧化酶（复合物 IV）催化的，它通过膜结合或水溶性细胞色素从细胞色素（复合物 III）接收电子。这些复合物独立发挥作用，但在许多生物体中它们会结合形成超复合物。在这里，我们回顾了非必需的 IIIIV 线粒体超复合物以及来自放线菌的必需的 IIIIV 超复合物的结构特征和功能意义。分析集中在复合物 III 的 Q 循环、 CytO 的质子摄取以及复合物 III 和 IV 之间电子连接的机制和结构解决方案上。
