MOLECULAR EVOLUTION OF CYTOCHROME C OXIDASE

细胞色素c氧化酶(COX)由13个亚基组成：3个亚基编码在 线粒体DNA(MtDNA)，10个在细胞核内。在十个核国家中 亚基，有三个(亚基VIA、VIIa和VIIIviii)具有肌肉特异性 异构体。众所周知，线粒体基因的进化速度要快十倍 而不是高等灵长类动物的单拷贝核基因。因此，考克斯提供了 一个理想的系统，在其中确定增加的突变率是如何 线粒体DNA影响核基因的突变率。长期目标 这个项目的评估是混乱的进化(序列)比较 环氧合酶核编码亚基的功能及其调控 核基因。通过确定选定的COX基因的哪些区域发生变化 只是非常慢，因此显得进化上受到限制，而且 地区发展迅速，与获得新的或改变的 功能。追求这一目标的具体目标是：目标1。 确定在高等灵长类动物进化过程中何时发生更替 在人类身上观察到的替换。COX4基因是否发生，以及是否 不是这些变化是由于与COX亚基II的相互作用。 确定在灵长类进化中COX5B、COX7X和 出现了COX7AL基因。目的3.应用系统发育学方法 足迹法在鉴定保守顺式调控序列元件中的应用 组成性表达和组织表达的调节区- 特异的CO：X核基因。目的4.研究基因的作用 确定哺乳动物COX复合体进化的重复性 基因复制导致组织特异性基因的时间 COX6AH COX7AH和COX8H。目标5.确定生物进化的速度 酵母同源物中COX6AH基因编码序列的内含子1。 因为COX是线粒体电子的末端酶复合体 运输链，它是至关重要的氧化代谢在 有氧组织。COX缺乏症已被确认为分子 几种类型的线粒体肌病和脑肌病的缺陷。 应用进化的方法来定义细胞的功能和调节 哺乳动物COX核基因将提供对亚单位功能的见解 和组织特异性基因调控，特别是肌肉特异性基因调控 异构体。这些见解对我们理解这一点至关重要 关键酶复合体，最终将使我们能够设计出合理的 这些分子缺陷患者的治疗。

Cytochrome c oxidase (COX) comprises 13 subunits: 3 encoded in mitochondrial DNA (mtDNA), ten in the nucleus. Of the ten nuclear subunits, three (subunits VIa, VIIa, and VIII) have muscle-specific isoforms. The mitochondrial genes are known to evolve ten times faster than single copy nuclear genes in higher primates. Thus, COX provides an ideal system in which to determine how the increased mutation rate in mtDNA affects the mutation rate of the nuclear genes. The long-term goal of this project is tousle evolutionary (sequence) comparisons to assess the function of COX nuclear-coded subunits and the regulation of COX nuclear genes. By determining which regions of selected COX genes change only very slowly and thus appear evolutionarily constrained, and which regions have evolved rapidly, consistent with acquiring new or altered functions. The specific aims in pursuit of this goal are: Aim 1. To determine when in the evolution of higher primates the replacement substitutions observed in the human. COX4 gene occurred, and whether or not these changes are due to interaction with COX subunit II. Aim 2. To determine when in primate evolution the changes in the COX5B, COX7X and COX7AL gene occurred. Aim 3. To use the method of phylogenetic footprinting to identify conserved cis-regulatory sequence elements in the regulatory regions of both constitutively expressed and tissue- specific CO:X nuclear genes. Aim 4. To investigate the role of gene duplication on the evolution of the mammalian COX complex by determining the time of the gene duplication leading to the tissue-specific genes COX6AH COX7AH, and COX8H. Aim 5. To determine the rates of evolution of intron 1 of the COX6AH gene from coding sequence in the yeast homologue. Because COX is the terminal enzyme complex of the mitochondrial electron transport chain, it is critically important for oxidative metabolism in aerobic tissues. COX deficiency has been identified as the molecular defect in several types of mitochondrial myopathy and encephalomyopathy. Applying evolutionary approaches to define function and regulation of mammalian COX nuclear genes will provide insights into subunit function and tissue-specific gene regulation, particularly of the muscle-specific isoforms. These insights are critical to our understanding of this essential enzyme complex and will enable us eventually to design rational therapy for patients with these molecular defects.