Cytochrome c oxidase subunit IV is essential for assembly and respiratory function of the enzyme complex
Cytochrome c oxidase subunit IV is essential for assembly and respiratory function of the enzyme complex
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DOI：
10.1007/s10863-006-9052-z
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发表时间：
2006-12-01
影响因子：
3
通讯作者：
Bai, Yidong
中科院分区：
文献类型：
--
作者：
Li, Youfen;Park, Jeong-Soon;Bai, Yidong
细胞色素C氧化酶或复合体IV催化线粒体电子转移链的最后一步，被认为是氧化磷酸化的主要调控位点之一。这种酶由核基因组和线粒体基因组共同控制。在其13个亚基中，3个由线粒体DNA编码，10个由核DNA编码。在这项工作中，采取了RNA干扰的方法，导致了小鼠A9细胞衍生物的产生，并抑制了该复合体的核编码亚基IV(COX IV)的表达。这个亚基的含量比正常水平下降了86%到94%。对几个COX IV表达受抑制的细胞系进行了详细的生物合成和功能分析，发现细胞色素c氧化酶复合体的组装丢失，相应地，细胞色素c氧化酶依赖的呼吸和总呼吸减少。此外，细胞中的细胞色素c氧化酶功能障碍导致线粒体膜电位受损，ATP水平下降，无法在半乳糖介质中生长。有趣的是，抑制COX IV的表达也会使细胞对凋亡敏感。这些观察结果证明了COX IV亚基对细胞色素c氧化酶复合体的重要作用，同时也证明了细胞色素c氧化酶对氧化磷酸化的严格控制。最后，我们的研究结果进一步揭示了细胞色素C氧化酶复合体功能失调所致疾病的发病机制。
Cytochrome c oxidase or complex IV, catalyzes the final step in mitochondrial electron transfer chain, and is regarded as one of the major regulation sites for oxidative phosphorylation. This enzyme is controlled by both nuclear and mitochondrial genomes. Among its 13 subunits, three are encoded by mitochondrial DNA and ten by nuclear DNA. In this work, an RNA interference approach was taken which led to the generation of mouse A9 cell derivatives with suppressed expression of nuclear-encoded subunit IV (COX IV) of this complex. The amounts of this subunit are decrease by 86% to 94% of normal level. A detail biosynthetic and functional analysis of several cell lines with suppressed COX IV expression revealed a loss of assembly of cytochrome c oxidase complex and, correspondingly, a reduction in cytochrome c oxidase-dependent respiration and total respiration. Furthermore, dysfunctional cytochrome c oxidase in the cells leads to a compromised mitochondrial membrane potential, a decreased ATP level, and failure to grow in galactose medium. Interestingly, suppression of COX IV expression also sensitizes the cells to apoptosis. These observations provide the evidence of the essential role of the COX IV subunit for a functional cytochrome c oxidase complex and also demonstrate a tight control of cytochrome c oxidase over oxidative phosphorylation. Finally, our results further shed some insights into the pathogenic mechanism of the diseases caused by dysfunctional cytochrome c oxidase complex.