Structural insights into redox homeostasis

描述(由申请人提供)：有效的细胞内电子转移对于使用氧气的生物体是必不可少的。氧化和还原的酶和辅因子之间的微妙平衡，称为氧化还原动态平衡，必须仔细调节才能维持细胞功能。氧化还原平衡的丧失是与衰老和衰老相关疾病相关的分子变化的基础。氧化还原平衡的急性或慢性破坏的后果包括神经退行性疾病、癌症、糖尿病、动脉粥样硬化和类风湿性关节炎。为了研究控制氧化还原平衡的特定分子和化学事件，将研究保持细胞氧化还原潜力的酶的结构和生化研究。特别是，拟议的研究将通过解决以下具体目标来考虑负责维持还原的硫氧还蛋白和谷胱甘肽库的酶途径：(I)在分子水平上表征线粒体硫氧还蛋白还原酶催化的电子转移级联。这一目标的目的是使用结构分析和生化特征来检查硫氧还蛋白系统的机制细节，因为它与线粒体氧化还原动态平衡有关。我们将测定线粒体硫氧还蛋白和谷氧还蛋白单独以及与线粒体硫氧还蛋白还原酶复合体的晶体结构。(Ii)研究必需的谷胱甘肽稳态酶的结构和机制特征。这一目标的目的是深入了解谷胱甘肽水平的调节。我们将研究谷氨酸半胱氨酸连接酶变构调节的分子细节，该酶催化谷胱甘肽生物合成的关键步骤。我们还将研究谷氨酰转肽酶的自动激活机制，以及自我处理对催化活性的影响。这些关键的硫氧还蛋白和谷胱甘肽系统的结构特征将为细胞氧化还原动态平衡的机制提供新的见解。了解这些关键的细节可能会转化为氧化损伤造成的一系列棘手的健康问题中的新的治疗目标。

DESCRIPTION (provided by applicant): Efficient intracellular electron transfer is essential to organisms that use oxygen. An exquisite balance between oxidized and reduced enzymes and cofactors, termed redox homeostasis, must be carefully regulated to maintain cellular function. Loss of redox balance underlies molecular changes associated with aging and age related diseases. Consequences of acute or chronic disruption in redox homeostasis include neurodegenerative diseases, cancer, diabetes mellitus, atherosclerosis, and rheumatoid arthritis. To investigate the specific molecular and chemical events that govern redox balance, structural and biochemical studies of enzymes that preserve cellular redox potential will be examined. In particular, the proposed research will consider the enzymatic pathways responsible for the maintenance of reduced thioredoxin and glutathione pools by addressing the following specific aims: (i) Characterize the electron transfer cascade catalyzed by mitochondrial thioredoxin reductase at the molecular level. The goal of this aim is to use structural analysis and biochemical characterizations to examine the mechanistic details of the thioredoxin system as it pertains to mitochondrial redox homeostasis. We will determine the crystal structures of mitochondrial thioredoxin and glutaredoxin alone and in complex with mitochondrial thioredoxin reductase. (ii) investigate the structural and mechanistic features of essential glutathione homeostasis enzymes. The goal of this aim is to gain insight into the regulation of glutathione levels. We will examine the molecular details of allosteric regulation of glutamate cysteine ligase, which catalyzes the committed step of glutathione bisoynthesis. We will also examine the auto-activation mechanism of g-glutamyl transpeptidase, an ectoenzyme required for glutathione salvage, and the effects of self-processing on catalytic activity. Structural characterizations of these key thioredoxin and glutathione systems will provide new insights into mechanisms of cellular redox homeostasis. Understanding the crucial details may translate to new therapeutic targets in the array of difficult health problems caused by oxidative damage.