REGULATION OF GENE EXPRESSION BY OXYGEN

氧气对基因表达的调节

• 批准号: 6519447
• 负责人: PATRICIA J KILEY
• 金额: $ 31.68万
• 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 2004-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6519447
• 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: (Applicant's abstract) Determining how cells sense and adapt to fluctuating O2 levels in their environment is a fundamental problem in biology. For many prokaryotic and eucaryotic organism, the sensing of oxygen levels is essential to ensure an adequate supply of energy as well as to avoid the toxic effects of oxygen. In recent years, it has been shown that many members of the FNR family of transcription factors that play a key role in the anaerobic lifestyle of a wide group of prokaryotes, function in oxygen sensing. Thus by deciphering how FNAR activity responds to oxygen availability, we will obtain fundamental information on a process that is critical to the growth and survival of facultative microbes. In addition, our studies should provide key insights into some general properties of oxygen sensing that can be applied to both eucaryotic and prokaryotic cells. In the best-studies case of Escherichia coli, FNR contains a [4Fe-4S]+2 cluster that is required for dimerization and site-specific DNA binding. This [4Fe-4S]+2 cluster is oxygen sensitive and its conversion to a [2Fe-21S]+2 decreases dimerization and DNA binding in vitro. To explain how FNR activity is regulated in vivo, we propose that FNR is largely active under anaerobic conditions because the [4Fe-4S]+2 cluster is stable whereas, in the presence of oxygen, we propose that FNR is largely inactive due to its conversion to a [2Fe-2S]+2 intermediate or possibly an apo-FNR form that lacks a cluster. To determine whether the [4Fe-4S]+2 cluster conversion is sufficient to explain how FNR is inactivated under aerobic conditions in vivo, we will define the pathway of FNR inactivation in vivo. To determine how the presence of the [4Fe-4S]+2 cluster increases FNR activity, we will test the hypothesis that the [4Fe-4S]+2 cluster is required to achieve a conformation that is competent for dimerization. To further define the role of FNR as a global regulator of transcription we will characterize the regions of FNR involved in transcription activation. Our studies should rovide insights into conserved regulatory strategies for sensing changes in oxygen tension by a wide variety of prokaryotes including several pathogenic organisms.

描述：（申请人的摘要） 确定细胞如何感知和适应体内氧气水平的波动 环境是生物学的一个基本问题。对于许多原核生物和 对于真核生物来说，氧水平的传感对于确保 充足的能量供应以及避免氧气的毒性作用。在 近年来，研究表明 FNR 家族的许多成员 转录因子在广泛的无氧生活方式中发挥关键作用 原核生物群，具有氧传感功能。因此，通过破译 FNAR 活性对氧气可用性做出反应，我们将获得基本的 有关对生长和生存至关重要的过程的信息 兼性微生物。此外，我们的研究应该提供以下方面的重要见解： 氧传感的一些一般特性可应用于两者 真核细胞和原核细胞。 在大肠杆菌的最佳研究案例中，FNR 包含 [4Fe-4S]+2 簇 这是二聚化和位点特异性 DNA 结合所必需的。这个[4Fe-4S]+2 簇对氧敏感，其向 [2Fe-21S]+2 的转化减少 体外二聚化和 DNA 结合。解释 FNR 活动如何受到监管 在体内，我们认为 FNR 在厌氧条件下主要是活跃的，因为 [4Fe-4S]+2 簇是稳定的，而在有氧存在的情况下，我们建议 FNR 由于转化为 [2Fe-2S]+2 中间体而基本上没有活性，或者 可能是缺少簇的 apo-FNR 形式。来判断是否 [4Fe-4S]+2簇转化足以解释FNR如何失活 在体内有氧条件下，我们将定义FNR失活的途径 体内。确定 [4Fe-4S]+2 簇的存在如何增加 FNR 活性，我们将测试 [4Fe-4S]+2 簇需要的假设 获得能够进行二聚化的构象。为了进一步定义 FNR 作为转录全局调节因子的作用，我们将描述以下区域的特征： FNR 参与转录激活。我们的研究应该提供以下见解： 通过广泛的感知氧分压变化的保守调节策略 多种原核生物，包括几种病原生物。