REGULATION OF GENE EXPRESSION BY OXYGEN

氧气对基因表达的调节

• 批准号: 6636028
• 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 2005-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6636028
• 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：（申请人摘要） 确定细胞如何感知和适应体内波动的O2水平 环境问题是生物学中的一个基本问题。对于许多原核生物和 在真核生物中，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 转录因子在广泛的厌氧生活方式中起着关键作用， 一组原核生物，在氧传感中起作用。因此，通过破译FNAR 活动响应氧气供应，我们将获得基本的 信息的过程是至关重要的增长和生存 兼性微生物此外，我们的研究应该提供关键的见解， 氧感测的一些一般性质可以应用于 真核和原核细胞。 在大肠杆菌的最佳研究情况下，FNR含有[4Fe-4S]+2簇 这是二聚化和位点特异性DNA结合所必需的。[4Fe-4S]+2 团簇对氧敏感，向[2Fe-21 S]+2的转化率降低 二聚化和体外DNA结合。解释FNR活性是如何调节的 在体内，我们认为FNR在厌氧条件下具有很大的活性， [4Fe-4S]+2团簇是稳定的，而在氧的存在下，我们提出， FNR由于其转化为[2Fe-2S]+2中间体而在很大程度上无活性，或者 可能是缺乏簇的apo-FNR形式。以确定是否 [4Fe-4S]+2团簇转化率为 足以解释FNR如何失活 在体内需氧条件下， 我们将确定FNR失活的途径， in vivo.为了确定[4Fe-4S]+2簇的存在如何增加FNR 活动，我们将测试的假设，即[4Fe-4S]+2集群是必要的， 实现能够进行二聚化的构象。以进一步限定 FNR作为转录的全局调节器的作用，我们将描述 FNR参与转录激活。我们的研究应该让我们了解 保守的调节策略，用于通过广泛的 各种原核生物，包括几种病原生物。