Mechanism of initiation of lipid binding of apolipoprotein A-I

载脂蛋白 A-I 脂质结合的启动机制

• 批准号: 10436238
• 负责人: PAUL Michiel WEERS
• 金额: $ 11.06万
• 依托单位: CALIFORNIA STATE UNIVERSITY LONG BEACH
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-01-01 至 2024-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10436238
• 关键词: Affinity; Amino Acids; Amphipathic Alpha Helix; Antiatherogenic; Apolipoprotein A-I; Apolipoproteins; Atherosclerosis; Binding; Binding Sites; Biophysics; C-terminal; Cell membrane; Chimera organism; Chimeric Proteins; Cholesterol; Conflict (Psychology); Data; Dissociation; Engineering; Glutamine; Goals; Heart Diseases; High Density Lipoproteins; Human; Hydrophobicity; Individual; Invertebrates; Investigation; Lead; Lecithin; Length; Lipid Binding; Lipids; Liver; Location; Lysine; Modeling; Molecular Conformation; Molecular Sieve Chromatography; Mutagenesis; Mutation; N-terminal; Peripheral; Phospholipids; Plasma; Play; Process; Property; Proteins; Resolution; Role; Side; Site; Site-Directed Mutagenesis; Structure; Structure-Activity Relationship; Surface; System; Tissues; Transferase; Variant; alpha helix; biophysical analysis; dimer; improved; insight; macrophage; monomer; prevent; receptor binding; reverse cholesterol transport

Project Summary Apolipoprotein (apo) A-I is a multifunctional protein with a well-established role in reverse cholesterol transport and is an important player in heart disease. It is the main protein component of high-density lipoprotein (HDL), which circulates through plasma promoting cholesterol efflux. While a high-resolution structure is not known yet, extensive biophysical analysis has suggested that the 28 kDa protein is made of two domains, each of which contain amphipathic α-helices for association with lipid surfaces. The C-terminal (CT) domain contains helical segments that initiate lipid binding, and is also the site responsible for self-association. It is a critical part of the protein needed for maturation of lipid-free apoA-I into HDL. Conflicting data exist about the role of the N-terminal (NT) helices in this process, as well as the precise helical segments of the CT domain. We have recently discovered that CT lysine residues are critical for self-association, and were able to create a monomeric version of the protein. To identify apoA-I helical segments important for initiation of lipid binding and self-association, which are closely connected, we developed a chimeric protein. This chimera will be used to identify which helical segments of apoA-I, both NT and CT α-helices, are required for initiation of lipid binding and self-association. To identify the specific amino acid residues of the CT domain required in self-association, site-directed mutagenesis will be employed. All proteins will be expressed in a bacterial expression system, purified by affinity and size-exclusion chromatography, and characterized for structure and function. The results of this study will lead to a much better understanding in the domain organization of this critical apolipoprotein, their structure function relationship, and may also provide opportunities for high-resolution structural analysis using monomeric apoA-I.

项目概要 载脂蛋白 (apo) A-I 是一种多功能蛋白质，在逆转 胆固醇运输是心脏病的重要参与者。它是主要蛋白质 高密度脂蛋白（HDL）的成分，通过血浆促进循环 胆固醇外流。虽然高分辨率结构尚不清楚，但广泛的生物物理 分析表明，28 kDa 的蛋白质由两个结构域组成，每个结构域都包含 与脂质表面结合的两亲性 α-螺旋。 C 端 (CT) 结构域包含 启动脂质结合的螺旋片段，也是负责自缔合的位点。它 是无脂 apoA-I 成熟为 HDL 所需蛋白质的关键部分。冲突 存在有关 N 末端 (NT) 螺旋在此过程中的作用的数据，以及精确的 CT 域的螺旋段。我们最近发现 CT 赖氨酸残基 对于自缔合至关重要，并且能够创建该蛋白质的单体版本。到 识别对启动脂质结合和自缔合很重要的 apoA-I 螺旋片段， 它们紧密相连，我们开发了一种嵌合蛋白。该嵌合体将用于 确定 apoA-I 的哪些螺旋片段（NT 和 CT α 螺旋）是启动 脂质结合和自缔合。鉴定CT结构域的特定氨基酸残基 如果自关联需要，将采用定点诱变。所有的蛋白质都会 在细菌表达系统中表达，通过亲和力和尺寸排阻纯化 色谱法，并表征其结构和功能。这项研究的结果将引领 为了更好地理解这种关键载脂蛋白的结构域组织， 结构功能关系，也可能为高分辨率结构提供机会 使用单体 apoA-I 进行分析。