Structural insights into redox homeostasis

描述（由申请人提供）：有效的细胞内电子转移对使用氧气的生物体至关重要。氧化和还原酶和辅因子之间的微妙平衡，称为氧化还原稳态，必须仔细调节以维持细胞功能。氧化还原平衡的丧失是与衰老和年龄相关疾病相关的分子变化的基础。氧化还原稳态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，将检查保持细胞氧化还原电位的酶的结构和生物化学研究。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型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反应。这个目标的目的是使用结构分析和生化表征，以检查的硫氧还蛋白系统的机制细节，因为它属于线粒体氧化还原稳态。我们将确定线粒体硫氧还蛋白和谷氧还蛋白单独和与线粒体硫氧还蛋白还原酶复合的晶体结构。(ii)研究必需谷胱甘肽稳态酶的结构和机制特征。这个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的变构调节的分子细节，该酶催化谷胱甘肽双合成的关键步骤。我们还将研究谷胱甘肽补救所需的胞外酶g-谷氨酰转肽酶的自激活机制，以及自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提供新的见解细胞氧化还原稳态的机制。了解关键的细节可能会转化为新的治疗目标，在一系列困难的健康问题所造成的氧化损伤。

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.