Structure-Function Relationship of CAR

CAR的结构-功能关系

• 批准号: 6925954
• 负责人: ELIAS J FERNANDEZ
• 金额: $ 24.6万
• 依托单位: UNIVERSITY OF TENNESSEE KNOXVILLE
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-05-01 至 2009-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6925954
• 关键词: X ray crystallography; androstane compound; crystallization; fluorescence spectrometry; protein protein interaction; protein structure function; receptor binding; steroid hormone receptor; structural biology

DESCRIPTION (provided by applicant): The long-term goal of this proposal is to understand the structural mechanism of the constitutive androstane receptor (CAR). CAR belongs to the nuclear receptor superfamily of proteins. These are hormone-modulated transcription factors that direct almost every aspect of human physiology. CAR is constitutively active in the absence of ligand. Small molecules have been identified that modulate CAR activity. The steroidal molecule, androstanol, functions as an inverse agonist and inhibits the constitutive activity of CAR. Another molecule, TCPOBOP, rescues CAR from the androstanol-mediated repression and can enhance CAR activity. We hypothesize that the CAR structure employs unique, but subtle, modifications from the canonical nuclear receptor structural fold that results in this distinctive behavior. We hypothesize that the three states of CAR, the inactive, androstanol-bound, the active, apo, and the TCPOBOP-bound highly active states are linked by an allosteric mechanism. In Specific Aim 1 we propose to compare the structures of apo CAR with androstenol-bound CAR. In Specific Aim 2, we will compare the CAR:TCPOBOP to apo and androstanol-bound CAR structures. In Specific Aim 3, we will study the mechanism of CAR allosterism by performing structure-based point mutations and binding and activity assays on these mutants. CAR has been shown to direct the transcription of the CYP2 and CYP3 gene products, which belong to the cytochrome P50 class of enzymes. These enzymes are responsible for the metabolism of xenobiotics such as pharmaceutical drugs. CAR has been directly implicated in the metabolism of the analgesic, acetaminophen (commercial nomenclature: Tylenol) other pharmaceutical products. Understanding the CAR molecular mechanism is of great significance in nuclear receptor biology with broad implications in the pharmacology of these proteins. Because of its involvement in metabolism of therapeutics, CAR is itself an attractive target for the design of small molecule ligands that can both enhance or diminish its transcriptional activity.

描述（由申请人提供）：本提案的长期目标是了解组成型雄甾受体（CAR）的结构机制。CAR属于核受体超家族蛋白。这些是激素调节的转录因子，几乎指导着人类生理的各个方面。在没有配体的情况下，CAR具有组成性活性。已经确定了调节CAR活性的小分子。甾体分子，雄甾醇，作为一种逆激动剂，抑制CAR的组成活性。另一种分子TCPOBOP可以将CAR从雄甾醇介导的抑制中解救出来，并可以增强CAR的活性。我们假设CAR结构采用了独特的，但微妙的，来自典型核受体结构折叠的修饰，导致这种独特的行为。我们假设CAR的三种状态，即无活性、雄甾醇结合、活性、载脂蛋白和tcpobop结合的高活性状态是通过变构机制联系在一起的。在Specific Aim 1中，我们建议比较载脂蛋白CAR和雄烯醇结合CAR的结构。在Specific Aim 2中，我们将比较CAR:TCPOBOP与载脂蛋白和雄甾醇结合的CAR结构。在Specific Aim 3中，我们将通过对这些突变体进行基于结构的点突变和结合和活性分析来研究CAR变构的机制。