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The evolution and regulation of DNA-binding by the nickel-dependent transcription factor NikR.

机译：镍依赖性转录因子NikR对DNA结合的进化和调控。

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摘要

Transition metal homeostasis is critical for all cells to balance cellular metal requirements with metal availability. One common homeostatic mechanism in bacteria is metal-dependent transcriptional regulation. The Ni 2+-dependent transcription factor NikR is a member of the ribbon-helix-helix (RHH) family of DNA-binding proteins and is widespread among bacteria and archea with vastly different nickel physiologies. The goal of this thesis was to better understand basic aspects of cellular transition metal homeostasis by examining the activity and regulatory properties of NikR family members from different bacterial species. One organism that exhibits a prominent and well-defined nickel physiology is Helicobacter pylori, making it an ideal system with which to examine various aspects of metal homeostasis. Genetic studies demonstrated that NikR activation is controlled by a hierarchy of nickel-trafficking in H. pylori, where nickel is preferentially trafficked to the urease assembly pathway. NikR differentially regulates multiple nickel-related genes in response to distinct extracellular nickel concentrations, functioning to coordinate multiple activities important for metal homeostasis. Differential gene regulation resulted from NikR binding to promoters from different genes with a range of affinities and in distinct conformations, due to a flexible N-terminal arm that makes different DNA contacts at two promoters. In addition, the arm expands the specific DNA interactions by NikR as compared to previously characterized RHH transcription factors. Examination of additional previously uncharacterized NikR family members revealed that the N-terminal arm has been adapted differently in some cases but is also critical for DNA-binding affinity and specificity. This structural feature provides a molecular basis for tuning NikR activity to the physiology of the cell. These studies provide insight into how multiple metal-dependent activities in cells are coordinated and controlled in response to fluctuations in environmental metal. Further, they establish a robust experimental system with which to further investigate the molecular details of the evolution of transcriptional regulation, an integral component of metal homeostasis.
机译：过渡金属稳态对于所有细胞平衡细胞金属需求与金属可用性至关重要。细菌中一种常见的稳态机制是金属依赖性转录调控。 Ni 2+依赖性转录因子NikR是DNA结合蛋白的Ribbon-Helix-Helix（RHH）家族的成员，广泛分布于镍生理差异很大的细菌和古细菌中。本文的目的是通过检查来自不同细菌物种的NikR家族成员的活性和调控特性，更好地了解细胞过渡金属稳态的基本方面。幽门螺杆菌是表现出杰出的镍生理特征的一种生物，使其成为检查金属稳态各个方面的理想系统。遗传研究表明，NikR激活受幽门螺杆菌中镍贩运的等级控制，其中镍优先贩运至脲酶组装途径。 NikR响应于不同的细胞外镍浓度，差异调节多种与镍相关的基因，起着协调对金属稳态重要的多种活动的作用。 NikR与具有不同亲和力和不同构象的不同基因的启动子结合，导致差异基因调控，这是由于N末端柔性臂在两个启动子上产生了不同的DNA接触。此外，与先前表征的RHH转录因子相比，该臂通过NikR扩展了特定的DNA相互作用。对其他以前未表征的NikR家族成员的检查表明，在某些情况下N末端臂的适应方式有所不同，但对于DNA结合亲和力和特异性也很关键。该结构特征为调节NikR活性使其适应细胞生理提供了分子基础。这些研究提供了洞察如何响应环境金属波动来协调和控制细胞中多种金属依赖性活动的见解。此外，他们建立了一个强大的实验系统，可用来进一步研究转录调控进化的分子细节，转录调控是金属稳态的一个组成部分。

著录项

  • 作者

    Benanti, Erin Lynn.;

  • 作者单位

    Washington University in St. Louis.;

  • 授予单位 Washington University in St. Louis.;
  • 学科 Biology Microbiology.;Chemistry Biochemistry.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 386 p.
  • 总页数 386
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

  • 入库时间 2022-08-17 11:38:25

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