Department of Microbiology and Immunology, University of Otago, Dunedin, 9054, New Zealand.
Mol Microbiol. 2014 Mar;91(5):950-64. doi: 10.1111/mmi.12507. Epub 2014 Jan 21.
Non-proton pumping type II NADH dehydrogenase (NDH-2) plays a central role in the respiratory metabolism of bacteria, and in the mitochondria of fungi, plants and protists. The lack of NDH-2 in mammalian mitochondria and its essentiality in important bacterial pathogens suggests these enzymes may represent a potential new drug target to combat microbial pathogens. Here, we report the first crystal structure of a bacterial NDH-2 enzyme at 2.5 Å resolution from Caldalkalibacillus thermarum. The NDH-2 structure reveals a homodimeric organization that has a unique dimer interface. NDH-2 is localized to the cytoplasmic membrane by two separated C-terminal membrane-anchoring regions that are essential for membrane localization and FAD binding, but not NDH-2 dimerization. Comparison of bacterial NDH-2 with the yeast NADH dehydrogenase (Ndi1) structure revealed non-overlapping binding sites for quinone and NADH in the bacterial enzyme. The bacterial NDH-2 structure establishes a framework for the structure-based design of small-molecule inhibitors.
非质子泵 II 型 NADH 脱氢酶（NDH-2）在细菌的呼吸代谢中发挥核心作用，在真菌、植物和原生生物的线粒体中也同样如此。哺乳动物线粒体中缺乏 NDH-2，而其在重要的细菌病原体中不可或缺，这表明这些酶可能成为对抗微生物病原体的潜在新药物靶点。在这里，我们报告了来自嗜热芽孢杆菌的细菌 NDH-2 酶在 2.5Å分辨率下的首个晶体结构。NDH-2 的结构揭示了一种具有独特二聚体界面的同源二聚体组织。NDH-2 通过两个分离的 C 端膜锚定区域定位于细胞质膜上，这两个区域对于膜定位和 FAD 结合是必需的，但对于 NDH-2 二聚化并非必需。将细菌 NDH-2 与酵母 NADH 脱氢酶（Ndi1）结构进行比较，揭示了细菌酶中存在与醌和 NADH 非重叠结合位点。细菌 NDH-2 的结构为基于结构的小分子抑制剂设计奠定了框架。
