The Regulation of Gene Expression by Oxygen

描述(申请人提供)：含铁S簇的蛋白质普遍存在，参与多种和必要的细胞功能。有氧代谢导致的铁-S簇的破坏给细胞带来了负担(称为铁-S应激)，以取代必要的蛋白质并处理由此产生的氧化损伤。氧化损伤是慢性和迟发性疾病的根本原因，因此，破译细胞对铁-S应激的反应是重要的。一个长期的目标是确定细胞对铁-S压力做出反应的途径，并避免由于簇破坏或基本功能丧失而造成的潜在致命的氧化损伤。本研究计划对大肠杆菌中铁-S胁迫进行研究，因为对铁-S簇合成途径和活性氧(ROS)介导的铁-S蛋白损伤机制有丰富的知识。这项拟议的研究将揭示在大肠杆菌中由铁-S转录因子Iscr指导的铁-S应激反应的成分。[2Fe-2S]-Iscr的生化和细胞特性将被研究，以确定氧和ROS在感受Fe-S胁迫中的作用。这些研究将验证这样的模型，即铁-S胁迫通过改变铁-S簇的占有率来改变Iscr的功能，从而改变靶基因的套数来响应Iscr的Fe-S占有率。我们将研究Iscr的DNA结合特性，以及在铁-S存在或不存在的情况下该蛋白识别的不同类别的DNA位点，以了解铁-S占据如何调节靶基因识别。目的基因在减轻铁-S应激中的作用将用遗传和分子方法进行研究。这些研究将确定铁-S蛋白如何作为O2或ROS的感受器发挥作用，以及它们如何控制靶基因的转录，以响应铁-S胁迫。我们从拟议的研究中获得的基本见解将促进我们对铁-S动态平衡机制和跨生物系统对有毒ROS的响应的理解。与公共健康相关：铁和氧的不经意反应会损害细胞成分，并在长期内导致疾病。我们正在研究将一类铁蛋白维持在细胞功能所需的适当水平的途径，以及当这些途径出错时减轻细胞损伤的机制。

DESCRIPTION (provided by applicant): Fe-S cluster containing proteins are ubiquitous and participate in diverse and essential cellular functions. The destruction of Fe-S clusters that occurs as a consequence of aerobic metabolism places a burden on cells (termed Fe-S stress) to replace essential proteins and deal with the resulting oxidative damage. Oxidative damage is an underlying cause of chronic and late onset diseases and therefore, it is important to decipher cellular responses to Fe-S stress. A long-term goal is to identify the pathways by which cells respond to Fe-S stress and avoid the potentially lethal oxidative damage caused by cluster destruction or loss of essential functions. This research plan studies Fe-S stress in the bacterium E. coli because there is a wealth of knowledge about the pathways of Fe-S cluster synthesis and the mechanisms of reactive oxygen species (ROS)-mediated Fe-S protein damage. The proposed studies will reveal the components of a Fe-S stress response that is directed by the Fe-S transcription factor, IscR in E. coli. The biochemical and cellular properties of [2Fe-2S]-IscR will be investigated to determine the role of oxygen and ROS in sensing Fe-S stress. These studies will test the model that Fe-S stress alters the function of IscR by changing the occupancy of the Fe-S cluster, thereby switching the suites of target genes in response to Fe-S occupancy of IscR. The DNA binding properties of IscR and the different classes of DNA sites recognized by this protein in the presence or absence of the Fe-S will be studied to understand how target genes recognition is regulated by Fe-S occupancy. The role of target genes in attenuating Fe-S stress will be investigated using genetic and molecular approaches. These studies will define how Fe-S proteins function as sensors of O2 or ROS and how they control transcription of target genes in response to Fe-S stress. The fundamental insights that we gain from the proposed studies will advance our understanding of Fe-S homeostatic mechanisms and the response to toxic ROS across biological systems. PUBLIC HEALTH RELEVANCE: Inadvertent reactions of iron and oxygen damage cellular components and over the long term lead to disease. We are studying the pathways that maintain a class of iron proteins at their appropriate levels for cell function and the mechanisms that attenuate cell damage when the pathways go awry.