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）：该提案的长期目标是了解构型雄激素受体（CAR）的结构机制。汽车属于蛋白质的核受体超家族。这些是激素调节的转录因子，几乎指导人类生理的各个方面。在没有配体的情况下，汽车具有组成性活跃。已经鉴定出小分子可以调节汽车活性。类固醇分子，雄烷醇作为反向激动剂起作用，并抑制CAR的组成活性。另一个分子TCPOBOP从雄烷醇介导的抑制中救出了汽车，并可以增强汽车活性。我们假设汽车结构采用了从规范的核受体结构折叠中进行独特但微妙的修饰，从而导致这种独特的行为。我们假设三种汽车，非活性，雄烷醇结合，活性，APO和TCPOBOP结合的高度活性状态与变构机制相连。在特定的目标1中，我们建议将Apo Car的结构与雄烯醇结合的汽车进行比较。在特定的目标2中，我们将比较汽车：TCPOBOP与Apo和Androstanol结合的汽车结构。在特定的目标3中，我们将通过对这些突变体进行基于结构的点突变以及结合和活性测定来研究CAR变构主义的机制。 已显示汽车指导CYP2和CYP3基因产物的转录，这些基因产物属于细胞色素P50类酶。这些酶负责异种生物（例如药物）的代谢。汽车已直接与止痛药（商业命名：Tylenol）其他药品的代谢有关。了解CAR分子机制在核受体生物学中具有重要意义，对这些蛋白质的药理学具有广泛的影响。由于它参与了治疗剂的代谢，因此CAR本身是设计小分子配体的有吸引力的目标，可以增强或减少其转录活性。