MOLECULAR EVOLUTION OF CYTOCHROME C OXIDASE

细胞色素c氧化酶（考克斯）包含13个亚基： 线粒体DNA（mtDNA），10个在细胞核中。 在10个核 亚基，三个（亚基VIa，VIIa和VIII）具有肌肉特异性 同种型。 众所周知，线粒体基因的进化速度要快十倍 比单拷贝核基因更重要。 因此，考克斯提供了 这是一个理想的系统，可以用来确定 mtDNA影响核基因的突变率。 远景目标 这个项目的一个重要部分是进行进化（序列）比较， 考克斯核编码亚单位的功能及其调控 核基因 通过确定选择的考克斯基因的哪些区域发生变化， 只是非常缓慢，因此显得受到进化的限制，而这 区域迅速演变，与获得新的或改变的 功能协调发展的 实现这一目标的具体目标是：目标1。 到 确定在高等灵长类动物的进化中， 在人类中观察到的取代。 COX 4基因是否发生，以及是否或 这些变化不是由于与考克斯亚基II的相互作用。目标2. 到 确定在灵长类动物进化过程中，COX 5 B，COX 7 X和 COX 7AL基因。 目标3.使用系统发育的方法 足迹法来鉴定保守的顺式调控序列元件， 组成型表达和组织- 特异性CO：X核基因 目标4。为了研究基因的作用 复制哺乳动物考克斯复合物的进化，通过确定 基因复制产生组织特异性基因的时间 COX 6AH、COX 7AH和COX 8H。目标5。为了确定进化的速度 COX 6AH基因的内含子1来自酵母同源物中的编码序列。 因为考克斯是线粒体电子传递的末端酶复合体， 运输链中，它对于氧化代谢至关重要 需氧组织 考克斯缺乏症已被确定为 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功能和调节 哺乳动物的考克斯核基因将提供亚基功能的见解 和组织特异性基因调控，特别是肌肉特异性 同种型。 这些见解对我们理解这一点至关重要 必不可少的酶复合物，并将使我们最终能够设计合理的 治疗有这些分子缺陷的患者。

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.