The Medical Research Council Mitochondrial Biology Unit, University of Cambridge, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, UK.
Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK.
Nat Commun. 2020 Oct 16;11(1):5261. doi: 10.1038/s41467-020-18950-3.
Respiratory complex I (NADH:ubiquinone oxidoreductase) captures the free energy from oxidising NADH and reducing ubiquinone to drive protons across the mitochondrial inner membrane and power oxidative phosphorylation. Recent cryo-EM analyses have produced near-complete models of the mammalian complex, but leave the molecular principles of its long-range energy coupling mechanism open to debate. Here, we describe the 3.0-Å resolution cryo-EM structure of complex I from mouse heart mitochondria with a substrate-like inhibitor, piericidin A, bound in the ubiquinone-binding active site. We combine our structural analyses with both functional and computational studies to demonstrate competitive inhibitor binding poses and provide evidence that two inhibitor molecules bind end-to-end in the long substrate binding channel. Our findings reveal information about the mechanisms of inhibition and substrate reduction that are central for understanding the principles of energy transduction in mammalian complex I.
呼吸复合物 I（NADH：泛醌氧化还原酶）从氧化 NADH 和还原泛醌中捕获自由能，驱动质子穿过线粒体内膜，并为氧化磷酸化提供动力。最近的冷冻电镜分析已经产生了哺乳动物复合物的近乎完整模型，但它的长程能量耦合机制的分子原理仍存在争议。在这里，我们描述了结合底物样抑制剂 piericidin A 的来自小鼠心脏线粒体的复合物 I 的 3.0 Å 分辨率冷冻电镜结构。我们将结构分析与功能和计算研究相结合，证明了竞争性抑制剂结合构象，并提供了两个抑制剂分子在长底物结合通道中末端到末端结合的证据。我们的发现揭示了关于抑制和底物还原机制的信息，这些信息对于理解哺乳动物复合物 I 中的能量转导原理至关重要。
