Exploring the ubiquinone binding cavity of respiratory complex I
Exploring the ubiquinone binding cavity of respiratory complex I
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DOI：
10.1074/jbc.m704519200
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发表时间：
2007-10-05
影响因子：
4.8
通讯作者：
Brandt, Ulrich
中科院分区：
文献类型：
--
作者：
Tocilescu, Maja A.;Fendel, Uta;Brandt, Ulrich
质子泵呼吸复合物I是线粒体能量转换的主要参与者。然而，人们对这种大型膜蛋白复合物的分子机制知之甚少。了解泛醌还原的细节将是阐明这一机制的先决条件。基于最近发表的部分结构的细菌酶，我们扫描了建议泛醌结合腔的复合物I在严格的好氧酵母解脂耶氏酵母定点诱变。所观察到的催化活性和抑制剂敏感性的变化遵循一致的模式，并允许我们定义三个功能上重要的区域附近的泛醌还原铁硫簇N2。我们确定了一个可能的进入路径的底物泛醌和定义一个区域参与抑制剂结合内的空腔。最后，我们能够突出的功能关键的结构基序的活性位点，由Tyr-144在49 kDa的亚基，由三个保守的疏水残基包围。
Proton pumping respiratory complex I is a major player in mitochondrial energy conversion. Yet little is known about the molecular mechanism of this large membrane protein complex. Understanding the details of ubiquinone reduction will be prerequisite for elucidating this mechanism. Based on a recently published partial structure of the bacterial enzyme, we scanned the proposed ubiquinone binding cavity of complex I by site-directed mutagenesis in the strictly aerobic yeast Yarrowia lipolytica. The observed changes in catalytic activity and inhibitor sensitivity followed a consistent pattern and allowed us to define three functionally important regions near the ubiquinone-reducing iron-sulfur cluster N2. We identified a likely entry path for the substrate ubiquinone and defined a region involved in inhibitor binding within the cavity. Finally, we were able to highlight a functionally critical structural motif in the active site that consisted of Tyr-144 in the 49-kDa subunit, surrounded by three conserved hydrophobic residues.