Tracing the tail of ubiquinone in mitochondrial complex I
Tracing the tail of ubiquinone in mitochondrial complex I
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DOI：
10.1016/j.bbabio.2012.03.021
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发表时间：
2012-10-01
影响因子：
4.3
通讯作者：
Brandt, Ulrich
中科院分区：
文献类型：
--
作者：
Angerer, Heike;Nasiri, Hamid R.;Brandt, Ulrich
线粒体复合体I(质子泵NADH：泛醌氧化还原酶)是呼吸电子传递链中最大、最复杂的组成部分。尽管它在生物能量转换中起着核心作用，但这种膜整合多蛋白复合体的结构和功能仍然知之甚少。最近通过X射线结晶学对配合物I结构的研究表明，泛醌的直接电子供体--铁硫簇合物N_2位于膜结构域上方约30A处，诱变研究表明疏水底物的活性中心位于这个氧化还原中心附近。为了追踪泛醌的疏水尾巴进入络合物I的外围臂的路径，我们对解脂耶罗维菌的络合物I进行了广泛的结构/功能分析，监测了定点突变体与5个带有不同尾巴的泛醌衍生物的相互作用。突变体子集的催化活性严格依赖于尾部是否存在完整的类异戊二烯基团。总体而言，出现了一致的图像，表明泛醌的尾部通过49-kDa和Psst亚基之间的一条狭窄路径进入。最值得注意的是，我们鉴定了一组蛋氨酸，它们似乎形成了通往活性部位的疏水门，这让人想起参与与疏水靶向序列与内质网信号识别颗粒相互作用的M-结构域。有趣的是，在牛复合体I中，与泛醌尾巴相互作用的两个关键氨基酸是不同的，我们可以证明其中一个交换是解脂耶尔森菌复合体I对鱼藤酮抑制剂敏感性较低的原因。本文是题为：第17届欧洲生物能量学会议(EBEC 2012)特刊的一部分。(C)2012爱思唯尔B.V.保留所有权利。
Mitochondrial complex I (proton pumping NADH:ubiquinone oxidoreductase) is the largest and most complicated component of the respiratory electron transfer chain. Despite its central role in biological energy conversion the structure and function of this membrane integral multiprotein complex is still poorly understood. Recent insights into the structure of complex I by X-ray crystallography have shown that iron-sulfur cluster N2, the immediate electron donor for ubiquinone, resides about 30 A above the membrane domain and mutagenesis studies suggested that the active site for the hydrophobic substrate is located next to this redox-center. To trace the path for the hydrophobic tail of ubiquinone when it enters the peripheral arm of complex I, we performed an extensive structure/function analysis of complex I from Yarrowia lipolytica monitoring the interaction of site-directed mutants with five ubiquinone derivatives carrying different tails. The catalytic activity of a subset of mutants was strictly dependent on the presence of intact isoprenoid moieties in the tail. Overall a consistent picture emerged suggesting that the tail of ubiquinone enters through a narrow path at the interface between the 49-kDa and PSST subunits. Most notably we identified a set of methionines that seems to form a hydrophobic gate to the active site reminiscent to the M-domains involved in the interaction with hydrophobic targeting sequences with the signal recognition particle of the endoplasmic reticulum. Interestingly, two of the amino acids critical for the interaction with the ubiquinone tail are different in bovine complex I and we could show that one of these exchanges is responsible for the lower sensitivity of Y. lipolytica complex I towards the inhibitor rotenone. This article is part of a Special Issue entitled: 17th European Bioenergetics Conference (EBEC 2012). (C) 2012 Elsevier B.V. All rights reserved.