Human disease-related mutations in cytochrome b studied in yeast
Human disease-related mutations in cytochrome b studied in yeast
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DOI：
10.1074/jbc.m313866200
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发表时间：
2004-03-26
影响因子：
4.8
通讯作者：
Meunier, B
中科院分区：
文献类型：
--
作者：
Fisher, N;Castleden, CK;Meunier, B
在患者中已经报道了经尿道编码的细胞色素B的几种突变。为了表征它们的作用，我们在高度相似的酵母细胞色素B中引入了六个“人类”突变，即G33 S、S152 P、G252 D、Y279 C、G291 D和Delta 252 - 259。G252 D在标准条件下显示野生型行为。然而，Asp- 252可能干扰结构脂质，从而使酶组装不稳定，这可以解释突变的致病性。突变G33 S、S152 P、G291 D和Delta 252 - 259明显具有致病性。它们引起呼吸功能的严重下降，并改变了铁硫蛋白在bc（1）复合物中的组装，正如免疫检测所观察到的那样。抑制突变，部分恢复呼吸功能受损的S152 P或G291 D被发现在或接近铁-硫蛋白的铰链区，这表明该地区可能发挥作用的稳定结合的亚基的bc 1复合物。Y279 C引起bc 1功能的显著降低，并扰乱了醌醇结合。EPR谱显示改变的信号，指示Q（o）位点的较低占据。残基279的人类突变的影响通过另一种变化Y279 A得到证实，Y279 A对Q（o）位点性质具有更严重的影响。因此，通过使用酵母作为模型系统，我们确定了由细胞色素B中的疾病突变引起的呼吸缺陷的分子基础。
Several mutations in the mitochondrially encoded cytochrome b have been reported in patients. To characterize their effect, we introduced six " human" mutations, namely G33S, S152P, G252D, Y279C, G291D, and Delta 252 - 259 in the highly similar yeast cytochrome b. G252D showed wild type behavior in standard conditions. However, Asp- 252 may interfere with structural lipid and, in consequence, destabilize the enzyme assembly, which could explain the pathogenicity of the mutation. The mutations G33S, S152P, G291D, and Delta 252 - 259 were clearly pathogenic. They caused a severe decrease of the respiratory function and altered the assembly of the iron- sulfur protein in the bc(1) complex, as observed by immunodetection. Suppressor mutations that partially restored the respiratory function impaired by S152P or G291D were found in or close to the hinge region of the iron- sulfur protein, suggesting that this region may play a role in the stable binding of the subunit to the bc1 complex. Y279C caused a significant decrease of the bc1 function and perturbed the quinol binding. The EPR spectra showed an altered signal, indicative of a lower occupancy of the Q(o) site. The effect of human mutation of residue 279 was confirmed by another change, Y279A, which had a more severe effect on Q(o) site properties. Thus by using yeast as a model system, we identified the molecular basis of the respiratory defect caused by the disease mutations in cytochrome b.