Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91, Stockholm, Sweden.
Nat Commun. 2024 Jun 20;15(1):5276. doi: 10.1038/s41467-024-49628-9.
Aerobic life is powered by membrane-bound redox enzymes that shuttle electrons to oxygen and transfer protons across a biological membrane. Structural studies suggest that these energy-transducing enzymes operate as higher-order supercomplexes, but their functional role remains poorly understood and highly debated. Here we resolve the functional dynamics of the 0.7 MDa IIIIV obligate supercomplex from Mycobacterium smegmatis, a close relative of M. tuberculosis, the causative agent of tuberculosis. By combining computational, biochemical, and high-resolution (2.3 Å) cryo-electron microscopy experiments, we show how the mycobacterial supercomplex catalyses long-range charge transport from its menaquinol oxidation site to the binuclear active site for oxygen reduction. Our data reveal proton and electron pathways responsible for the charge transfer reactions, mechanistic principles of the quinone catalysis, and how unique molecular adaptations, water molecules, and lipid interactions enable the proton-coupled electron transfer (PCET) reactions. Our combined findings provide a mechanistic blueprint of mycobacterial supercomplexes and a basis for developing drugs against pathogenic bacteria.
需氧生命由膜结合的氧化还原酶驱动，这些酶将电子传递到氧气并将质子跨生物膜转移。结构研究表明，这些能量转换酶作为更高阶的超复合体起作用，但它们的功能作用仍知之甚少，存在高度争议。在这里，我们解决了分枝杆菌属（Mycobacterium）必需超复合体的功能动态，分枝杆菌属是结核分枝杆菌（导致结核病的病原体）的近亲。通过结合计算、生化和高分辨率（2.3Å）冷冻电镜实验，我们展示了分枝杆菌超复合体如何催化从menaquinol 氧化位点到双核活性位点的长程电荷转移，用于氧气还原。我们的数据揭示了负责电荷转移反应的质子和电子途径、醌催化的机制原理以及独特的分子适应、水分子和脂质相互作用如何使质子耦合电子转移（PCET）反应成为可能。我们的综合发现为分枝杆菌超复合体提供了一个机械蓝图，并为开发针对致病性细菌的药物提供了基础。
