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。氧化和还原酶和辅助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。急性或慢性氧化还原稳态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电位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，考虑负责维持还原性硫氧还蛋白和谷胱甘肽池的酶促途径：(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。本目的目的是利用结构分析和生化表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稳态有关。我们将确定线粒体硫氧还蛋白和glutaredoxin单独和与线粒体硫氧还蛋白还原酶复合物的晶体结构。（ii）研究必需谷胱甘肽内稳态酶的结构和机制特征。这个目的的目标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，它催化谷胱甘肽生物合成的承诺步骤。我们还将研究g-谷氨酰转肽酶（谷胱甘肽回收所需的一种外酶）的自激活机制，以及自加工对催化活性的影响。这些关键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稳态机制提供新的见解。了解这些关键细节可能会转化为新的治疗靶点，以解决由氧化损伤引起的一系列困难的健康问题。

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.