Regulation of gene expression by oxygen

氧对基因表达的调节

• 批准号: 7082218
• 负责人: PATRICIA J KILEY
• 金额: $ 33.98万
• 依托单位: UNIVERSITY OF WISCONSIN-MADISON
• 依托单位国家: 美国
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-04-01 至 2009-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7082218
• 关键词: DNA directed RNA polymerase; Escherichia coli; aerobiosis; bacterial genetics; conformation; gene expression; iron compounds; microorganism culture; microorganism metabolism; nucleic acid sequence; oxygen tension; polymerase chain reaction; protein purification; transcription factor

DESCRIPTION (provided by applicant): Determining how cell sense and adapt to fluctuating O2 levels in their environment is a fundamental problem in biology. Our studies focus on the regulatory strategies used by the facultative anaerobe E. coli to respond to O2 availability. These studies have led us to investigate two Fe-S cluster transcription factors, FNR and IscR. A picture is emerging that utilization of Fe-S proteins as sensors of O2 and other biologically relevant oxidants has taken advantage of the special properties of these metal centers and involves both regulation of cluster destruction and/or cluster synthesis. Thus, our studies should advance our understanding of how Fe-S clusters function as sensors of O2 and other important oxidants. The global regulator FNR controls transcription of genes under anaerobic growth conditions and serves as a paradigm for sensing cellular O2 levels. FNR is inactivated by cluster destruction upon the O2 dependent removal of its [4Fe-4S]2+ cluster that is required to maintain an active conformation. In this grant period, the fate of apoFNR that is produced from this reaction will be studied in order to develop a comprehensive model for how FNR is regulated at the cellular level. We will test whether apoFNR is the form of FNR that is proteolyzed by the CIpXP protease under aerobic growth conditions. In addition, we will determine whether apoFNR can be reactivated when O2 becomes limiting. Lastly, structural studies of FNR will be initiated to determine how the Fe-S cluster of FNR alters its conformation. IscR contains a [2Fe-2S] cluster and is a represser of genes encoding functions for Fe-S cluster biogenesis (isc operon). Our hypothesis is that IscR is a sensor of cellular demands for Fe-S cluster biogenesis and it is also involved in O2 regulation of gene expression. The role of the [2Fe-2S] cluster of IscR in sensing the Fe-S cluster status of cells will be investigated. To gain new insights into how these transcription factors reprogram metabolism under aerobic and anaerobic conditions, we will study the regulation of FNR and IscR target genes that we recently identified using a genome-wide approach. In particular, we will investigate the mechanism by which FNR antagonizes IscR function under anaerobic conditions to impart a new strategy for the O2 regulation of gene expression. Our studies should provide important new insights into the conserved regulatory strategies for sensing O2 that are used by a wide variety of bacteria including pathogenic organisms and provide fundamental mechanisms of O2 sensing and Fe-S based sensing that apply to all organisms, which when gone awry can cause human disease.

描述（由申请人提供）：确定细胞如何感知和适应环境中波动的氧气水平是生物学中的一个基本问题。我们的研究重点是兼性厌氧菌大肠杆菌响应氧气可用性的调节策略。这些研究引导我们研究了两种 Fe-S 簇转录因子：FNR 和 IscR。正在出现的情况是，利用 Fe-S 蛋白作为 O2 和其他生物相关氧化剂的传感器，利用了这些金属中心的特殊性质，并涉及簇破坏和/或簇合成的调节。因此，我们的研究应该加深我们对 Fe-S 簇如何作为 O2 和其他重要氧化剂传感器的理解。 全局调节因子 FNR 在厌氧生长条件下控制基因转录，并​​作为传感细胞 O2 水平的范例。 FNR 因依赖 O2 去除其 [4Fe-4S]2+ 簇（维持活性构象所需）而被簇破坏而失活。在此资助期内，我们将研究该反应产生的 apoFNR 的命运，以便开发一个关于如何在细胞水平上调节 FNR 的综合模型。我们将测试 apoFNR 是否是在有氧生长条件下被 CIpXP 蛋白酶水解的 FNR 形式。此外，我们将确定当 O2 受到限制时是否可以重新激活 apoFNR。最后，将启动 FNR 的结构研究，以确定 FNR 的 Fe-S 簇如何改变其构象。 IscR 包含一个 [2Fe-2S] 簇，是编码 Fe-S 簇生物发生功能的基因（isc 操纵子）的抑制子。我们的假设是 IscR 是 Fe-S 簇生物发生的细胞需求传感器，并且还参与基因表达的 O2 调节。将研究 IscR 的 [2Fe-2S] 簇在感知细胞 Fe-S 簇状态中的作用。为了获得关于这些转录因子如何在有氧和无氧条件下重编程代谢的新见解，我们将研究我们最近使用全基因组方法鉴定的 FNR 和 IscR 靶基因的调节。特别是，我们将研究厌氧条件下 FNR 拮抗 IscR 功能的机制，为 O2 基因表达调控提供新策略。我们的研究应该为包括病原生物在内的多种细菌使用的传感 O2 的保守调控策略提供重要的新见解，并提供适用于所有生物体的 O2 传感和基于 Fe-S 传感的基本机制，当出现问题时可引起人类疾病。