The Regulation of Gene Expression by Oxygen

描述（由申请人提供）：含Fe-S簇的蛋白质普遍存在，并参与多种基本细胞功能。由于有氧代谢而发生的Fe-S簇的破坏对细胞造成负担（称为Fe-S应激），以取代必需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Fe-S应激的反应是重要的。一个长期的目标是确定细胞对Fe-S应激的反应途径，并避免由簇破坏或基本功能丧失引起的潜在致命的氧化损伤。本研究计划研究细菌E.由于对Fe-S簇的合成途径和活性氧（ROS）介导的Fe-S蛋白损伤机制有着丰富的认识，因此，本论文对Fe-S簇在大肠杆菌中的表达进行了研究。这些研究将揭示E.杆菌[2Fe-2S]-IscR的生化和细胞特性将被研究以确定氧和ROS在感知Fe-S胁迫中的作用。这些研究将测试Fe-S胁迫通过改变Fe-S簇的占据来改变IscR的功能的模型，从而响应于IscR的Fe-S占据来切换靶基因的套件。将研究IscR的DNA结合特性以及在存在或不存在Fe-S的情况下由该蛋白识别的不同类别的DNA位点，以了解Fe-S占据如何调节靶基因识别。目的基因在减轻铁硫胁迫中的作用将通过遗传学和分子生物学方法进行研究。这些研究将确定Fe-S蛋白如何作为O2或ROS的传感器，以及它们如何控制靶基因的转录以响应Fe-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Fe-S稳态机制和生物系统对有毒ROS的反应的理解。公共卫生相关性：铁和氧的意外反应会损害细胞成分，长期下来会导致疾病。我们正在研究维持一类铁蛋白在其适当水平的细胞功能的途径，以及当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.