Metal Ion Homeostasis in Bacillus subtilis

枯草芽孢杆菌中的金属离子稳态

• 批准号: 7045981
• 负责人: John D Helmann
• 金额: $ 26.48万
• 依托单位: CORNELL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-02-01 至 2009-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7045981
• 关键词: Bacillus subtilis; bacterial genetics; bacterial proteins; cell wall; chelating agents; conformation; copper; detoxification; gene expression; gene mutation; genetic regulation; high throughput technology; homeostasis; ion transport; iron; manganese; metal metabolism; protein structure function; ribosomal proteins; site directed mutagenesis; transcription factor; zinc

DESCRIPTION (provided by applicant): The long-term objective of this research is to understand how bacterial cells maintain metal ion homeostasis. Essential metal ions must be obtained from the environment, transported into the cell, and trafficked to the correct intracellular destinations. When metal ions are limiting, high affinity uptake mechanisms are induced. When in excess, the cell induces the synthesis of efflux, detoxication, or storage mechanisms. The ability to obtain sufficient metal ions from the host is crucial to bacterial pathogens, metal uptake systems are highly expressed in vivo, and surface-exposed transport proteins are often targets for the host immune response. Disorders of metal ion homeostasis are also a major cause of human disease including anemias, Menkes', and Wilson's diseases, and several other neurodegenerative diseases. The genetic responses to changes in metal ion availability are coordinated by metalloregulatory proteins. In the Gram-positive bacterium Bacillus subtilis metal-specific regulators control the uptake of Mn (MntR), Fe (Fur), and Zn (Zur), and others regulate efflux mechanisms induced when metal ions are in excess (CueR, CzrA, ArsR, YdeT). We will measure the metal ion content and quotas needed for growth for both wild-type and mutants altered in metal ion homeostasis. We will test the hypothesis that adsorption of metal ions to the cell wall plays a role in both uptake and storage of metals and we will characterize pathways for Fe and Zn uptake. We will test the hypotheses that MrgA and Dps function in Fe storage and detoxification and that Zn-containing ribosomal proteins provide a major intracellular Zn store that can be mobilized under Zn limitation. Genetic and biochemical approaches will be used to further our understanding of metal-sensing by MntR, Fur, Zur, CueR, and ArsR family members by site-directed mutagenesis of metal ligands, in vivo analyses of altered function mutants, and structure-determination methods.

描述（由申请人提供）：本研究的长期目标是了解细菌细胞如何维持金属离子稳态。必需的金属离子必须从环境中获得，运输到细胞中，并运输到正确的细胞内目的地。当金属离子是有限的，高亲和力摄取机制诱导。当过量时，细胞诱导外排、解毒或储存机制的合成。从宿主获得足够的金属离子的能力对于细菌病原体是至关重要的，金属摄取系统在体内高度表达，并且表面暴露的转运蛋白通常是宿主免疫应答的靶标。金属离子体内平衡紊乱也是人类疾病的主要原因，包括贫血、门克斯病和威尔逊病以及几种其他神经退行性疾病。 对金属离子可用性变化的遗传反应由金属调节蛋白协调。在革兰氏阳性细菌枯草芽孢杆菌中，金属特异性调节剂控制Mn（MntR）、Fe（Fur）和Zn（Zur）的摄取，其他调节剂调节金属离子过量时诱导的外排机制（CueR、CzrA、ArsR、YdeT）。我们将测量金属离子的含量和配额的野生型和突变体的生长所需的金属离子稳态改变。我们将测试的假设，即吸附的金属离子的细胞壁中起着重要的作用，在吸收和储存的金属，我们将表征的Fe和Zn的吸收途径。我们将测试的假设，MrgA和DPS功能在铁的存储和解毒，含锌的核糖体蛋白提供了一个主要的细胞内锌存储，可以动员下锌限制。遗传和生物化学的方法将用于进一步了解金属传感MntR，毛皮，Zur，CueR，和ArsR家族成员的金属配体的定点诱变，在体内分析功能改变的突变体，和结构测定方法。