Disruption of the interaction between the Rieske iron-sulfur protein and cytochrome b in the yeast bc1 complex owing to a human disease-associated mutation within cytochrome b
Disruption of the interaction between the Rieske iron-sulfur protein and cytochrome b in the yeast bc1 complex owing to a human disease-associated mutation within cytochrome b
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DOI：
10.1111/j.1432-1033.2004.04036.x
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发表时间：
2004-04-01
期刊：
影响因子：
--
通讯作者：
Meunier, B
中科院分区：
文献类型：
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作者：
Fisher, N;Bourges, I;Meunier, B
据报道，一名心肌病患者存在线粒体细胞色素 b 错义突变 G167E。残基 G167 位于靠近铁硫蛋白铰链区的膜外螺旋中。为了表征突变对bc(1)复合物结构和功能的影响，我们将G167E引入高度相似的酵母细胞色素b中。该突变对呼吸功能产生严重影响，bc(1)复合物的活性下降至野生型的百分之几。酶活性分析表明，该突变影响了其稳定性，这可能是铁硫蛋白在复合物上的结合发生改变的结果。从电子顺磁共振信号判断，G167E对铁硫蛋白头基和对苯二酚氧化位点之间的相互作用没有重大影响，对细胞色素b的还原速率只有很小的影响，但它严重降低了细胞色素c(1)的还原速率。这表明突变 G167E 可能通过扭曲铰链区的结构来阻碍铁硫蛋白的运动。 bc(1) 的功能通过靠近原发变化的突变（W164L 和 W166L）部分恢复，从而减少了 G167E 引起的空间位阻。综上所述，这些观察结果表明，n-硫蛋白铰链区和细胞色素 b 膜外 cd2 螺旋之间的蛋白质-蛋白质相互作用对于维持铰链区的结构非常重要，从而维持头基的运动和酶的完整性。
The mitochondrial cytochrome b missense mutation, G167E, has been reported in a patient with cardiomyopathy. The residue G167 is located in an extramembranous helix close to the hinge region of the iron-sulfur protein. In order to characterize the effects of the mutation on the structure and function of the bc(1) complex, we introduced G167E into the highly similar yeast cytochrome b. The mutation had a severe effect on the respiratory function, with the activity of the bc(1) complex decreased to a few per cent of the wild type. Analysis of the enzyme activity indicated that the mutation affected its stability, which could be the result of an altered binding of the iron-sulfur protein on the complex. G167E had no major effect on the interaction between the iron-sulfur protein headgroup and the quinol oxidation site, as judged by the electron paramagnetic resonance signal, and only a minor effect on the rate of cytochrome b reduction, but it severely reduced the rate of cytochrome c(1) reduction. This suggested that the mutation G167E could hinder the movement of the iron-sulfur protein, probably by distorting the structure of the hinge region. The function of bc(1) was partially restored by mutations (W164L and W166L) located close to the primary change, which reduced the steric hindrance caused by G167E. Taken together, these observations suggest that the protein-protein interaction between the n-sulfur protein hinge region and the cytochrome b extramembranous cd2 helix is important for maintaining the structure of the hinge region and, by consequence, the movement of the headgroup and the integrity of the enzyme.