STRUCTURAL STUDIES OF THE LACTOSE REPRESSOR OF E COLI

大肠杆菌乳糖抑制剂的结构研究

• 批准号: 2872627
• 负责人: CHARLES E BELL
• 金额: $ 3.67万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-01-06 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/2872627
• 关键词: Escherichia coli; X ray crystallography; bacterial genetics; bacterial proteins; gene induction /repression; lactose; microorganism culture; nucleic acid sequence; operon; protein structure function; transcription factor

Transcriptional gene regulation is an intense field of research in biology and in medicine. The lac operon of E. coli is the paradigm for transcriptional gene regulation. Its key component, the lac repressor (lacR), is one of the most intensely studied proteins both genetically and biochemically. Recent crystal structures of the uncomplexed tetrameric lacR, lacR bound to the inducer IPTG, and lacR bound to operator DNA have provided a framework for understanding how lacR functions as a genetic switch. The research in this proposal will extend our current structural understanding of lacR. Of paramount importance is extending the resolution of the structure of lacR bound to operator DNA. Since the structure was determined at only 4.8Angstrom units resolution, the current model for the operator-bound, repressed conformation of lacR does not include side chains. A major premise of this proposal is that a dimeric version of lacR, when complexed to operator DNA, will grow crystals which diffract to higher resolution than has so far been achieved for the tetramer of lacR. Dimeric lacR will also be used to achieve: (1) a structural comparison of lacR bound to both wild-type and symmetric operator sequences, (2) a structural basis for the action of allolactose, the natural inducer of lacR, and orthonitrophenylfucoside, an anti-inducer of lacR, and (3) a structural basis for single point mutations in lacR which lead to 100-fold increased affinity for operator.

转录基因调控是一个强烈的研究领域 生物学和医学。 大肠杆菌的拉丝操纵子是 转录基因调控。 它的关键组件，lac阻遏物 （LACR）是遗传学上最深入研究的蛋白质之一 和生化。 未复杂的最新晶体结构 四聚体湖泊，与诱导剂IPTG结合的长核长，并结合到LACR与 操作员DNA提供了一个框架，以了解LACR如何 充当遗传开关。 该提议中的研究将 扩展我们当前对LACR的结构理解。 派拉蒙 重要性是扩展了LACR结构的结构的分辨率 到操作员DNA。 由于仅确定4.8 Angstrom的结构 单位分辨率是运营商结合的当前模型，被压制 长型的构象不包括侧链。 一个主要的前提 该提议是二聚体的lacr，当复合到 操作员DNA，将生长出衍射到更高分辨率的晶体 比迄今为止的LACR四聚体已经实现了。 二聚体湖泊 还将用于实现：（1）laCR结合的结构比较 对于野生型和对称操作员序列，（2）结构 同种乳糖的作用的基础，LACR的天然诱导剂和 正硝基苯基氟糖苷，LACR的抗诱导剂和（3）结构 在湖泊中单点突变的基础，导致100倍 对操作员的亲和力增加。