Cytochrome c Oxidase Assembly in Health and Disease

描述（由申请方提供）：细胞色素c氧化酶（考克斯）缺乏是人类线粒体脑肌病的最常见原因，也与神经变性和衰老相关。更好地了解考克斯生物起源是阐明这些疾病的分子基础。本研究的主要目的是以酿酒酵母和培养的人类细胞为研究模型，探讨参与考克斯生物合成的参与者和机制。我们的长期目标是完全了解导致考克斯组装的途径及其组分，这是开发治疗考克斯缺陷相关疾病的治疗方法的先决条件。 在上一期的研究中，我们在理解考克斯生物发生是如何调控方面取得了重大进展。真核考克斯酶是一种多聚体酶，由核和线粒体双重遗传来源的多肽组成，其组装涉及大量核编码的辅助因子。考克斯表现出其组成性亚基的协同积累。未组装的亚基具有产生活性氧的高风险，并且它们的积累受到翻译后降解的限制。我们揭示了考克斯生物发生过程中亚基化学计量积累的另一个贡献。我们的数据支持存在一种调节机制，通过该机制，线粒体DNA编码的考克斯亚基1（Cox 1）的合成受到其在酵母酿酒酵母中的组装伙伴的可用性的调节。因此，该提议的中心假设是存在Cox 1合成的考克斯组装依赖性调节，其独特的性质反过来提供了催化多亚基组装的手段。In S.在酿酒酵母中，调控系统涉及特定的COX 1 mRNA翻译激活剂，特定的Cox 1分子伴侣和组装因子以及一般分子伴侣在复杂的相互作用中共同作用，我们刚刚开始表征。调控系统的中心元件是双功能COX 1 mRNA翻译激活因子和Cox 1伴侣Mss 51，其从酵母到人类都是保守的。提出了三个具体的目标，以表征最近发现的新的Mss 51相互作用的球员（即Ssc 1和Cox 25）和水平的复杂性（即Mss 51是一个血红素结合蛋白）有关的翻译调控系统在S。酿酒酵母及其从酵母到人类的保护。目的#1-揭示Mss 51与血红素结合的机制和作用目的#2 -研究Mss 51与线粒体伴侣的相互作用调节Cox 1合成的机制目的#3-确定酵母和人Mss 51的功能等效性

DESCRIPTION (provided by applicant): Cytochrome c oxidase (COX) deficiency is the most frequent cause of mitochondrial encephalomyopathies in humans and has also been associated to neurodegeneration and aging. A better understanding of COX biogenesis is essential for elucidating the molecular basis underlying these groups of diseases. The main objective of the proposed research is to investigate the players and mechanisms involved in COX biogenesis using the yeast Saccharomyces cerevisiae and cultured human cells as research models. Our long-term goal is to attain a complete understanding of the pathways leading to COX assembly and their components as a prerequisite to the development of therapies for the management of disorders associated with COX deficiencies. In the previous term of our grant we made significant progress in the understanding of how COX biogenesis is regulated. Eukaryotic COX is a multimeric enzyme formed by polypeptides of dual genetic origin (nuclear and mitochondrial) which assembly involves a large number of nuclear-encoded auxiliary factors. COX display a concerted accumulation of its constitutive subunits. Unassembled subunits bear a high risk to produce reactive oxygen species and their accumulation is limited by posttranslational degradation. We have revealed another contribution to the stoichiometric accumulation of subunits during COX biogenesis. Our data support the existence of a regulatory mechanism by which the synthesis of mtDNA-encoded COX subunit 1 (Cox1) is regulated by the availability of its assembly partners in the yeast Saccharomyces cerevisiae. Thus, the central hypothesis of this proposal is the existence of a COX assembly dependent regulation of Cox1 synthesis, which unique properties, in turn, offer a means to catalyze multiple- subunit assembly. In S. cerevisiae, the regulatory system involves specific COX1 mRNA translational activators, specific Cox1 chaperones and assembly factors as well as general chaperones acting together in a sophisticated interplay that we are just beginning to characterize. The central element of the regulatory system is the bi-functional COX1 mRNA translational activator and Cox1 chaperone Mss51 which is conserved from yeast to humans. Three specific aims are proposed to characterize recently identified new Mss51-interacting players (i.e. Ssc1 and Cox25) and levels of complexity (i.e. Mss51 is a heme binding protein) concerning the translational regulatory system in S. cerevisiae and its conservation from yeast to humans. Aim # 1 - Disclose the mechanism and role of heme binding by Mss51 Aim #2 - Investigate the mechanism/s by which the interactions of Mss51 with mitochondrial chaperones regulate Cox1 synthesis Aim # 3 - Determine the functional equivalence of yeast and human Mss51