STRUCTURAL STUDIES ON LIPOXYGENASES

脂加氧酶的结构研究

• 批准号: 8361694
• 负责人: MARCIA E. NEWCOMER
• 金额: $ 3.84万
• 依托单位: CORNELL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-04-01 至 2012-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8361694
• 关键词: Address; Animals; Arachidonate 5-Lipoxygenase; Arachidonic Acids; Carbon; Data; Eicosanoids; Enzymes; Funding; Grant; Hydrogen; Inflammatory; Leukotrienes; Life; Lipoxygenase; Modeling; Molecular; National Center for Research Resources; Phospholipase A2; Principal Investigator; Production; Protein Isoforms; Reaction; Regulation; Research; Research Infrastructure; Resources; Site; Source; Specificity; United States National Institutes of Health; base; cost; lipid mediator; mutant; peroxidation; prevent; programs; research study; structural biology; suicide inactivation

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The enzyme 5-lipoxygenase (5-LOX) initiates the synthesis of pro-inflammatory leukotrienes. These lipid mediators are synthesized from arachidonic acid (AA) released from the bilayer by the action of Ca2+-dependent phospholipase A2. 5-LOX activity is short-lived, and temporal control appears in part due to an intrinsic instability of the enzyme. This instability provides a mechanism for auto-regulation, preventing an over-production of pro-inflammatory leukotrienes. However, "programmed obsolescence" is not common to all lipoxygenases, and stable isoforms have been identified. We address two critical aspects of control of 5-LOX activity: (1) Product specificity The substrate for 5-LOX is the polyunsaturated eicosanoid arachidonic acid. The first step of the reaction is the abstraction of hydrogen from the central carbon of a pentadiene. AA has three pentadiene moieties (and six possible sites of peroxidation, each with either R- or S- chirality). Yet animal lipoxygenases generally produce a single, regio- and stereo- specific product. We will develop a model for 5-LOX specificity that is consistent with its product specificty. (2) Programmed obsolescence "Programmed obsolescence" in 5-LOX appears to have two components: structural instability and turnover-based suicide inhibition. Our data, including our stable mutant form of 5-LOX, suggest that features unique to 5-LOX result in a tenuously restrained C-terminus that contributes to 5-LOX instability. Experiments to define the molecular basis for non-turnover and turnover-based inactivation are proposed.

该子项目是利用资源的众多研究子项目之一 由 NIH/NCRR 资助的中心拨款提供。子项目的主要支持 并且子项目的主要研究者可能是由其他来源提供的， 包括其他 NIH 来源。 子项目可能列出的总成本 代表子项目使用的中心基础设施的估计数量， NCRR 赠款不直接向子项目或子项目工作人员提供资金。 5-脂氧合酶 (5-LOX) 启动促炎性白三烯的合成。这些脂质介质是由通过 Ca2+ 依赖性磷脂酶 A2 的作用从双层释放的花生四烯酸 (AA) 合成的。 5-LOX 活性是短暂的，并且时间控制的出现部分是由于该酶的内在不稳定性。这种不稳定性提供了一种自动调节机制，防止促炎性白三烯的过度产生。然而，“程序性报废”并非所有脂氧合酶都常见，并且已经鉴定出稳定的亚型。我们解决了控制 5-LOX 活性的两个关键方面： (1) 产品特异性 5-LOX 的底物是多不饱和类二十烷酸花生四烯酸。反应的第一步是从戊二烯的中心碳中提取氢。 AA 具有三个戊二烯部分（以及六个可能的过氧化位点，每个位点具有 R- 或 S- 手性）。然而动物脂氧合酶通常产生单一的、区域和立体特异性的产物。我们将开发一个与其产品特异性一致的 5-LOX 特异性模型。 (2) 程序性报废 5-LOX 中的“程序性报废”似乎有两个组成部分：结构不稳定和基于更新的自杀抑制。我们的数据，包括 5-LOX 的稳定突变体形式，表明 5-LOX 独特的特征导致 C 末端受到轻微限制，从而导致 5-LOX 不稳定。提出了定义非更新和基于更新的失活的分子基础的实验。