REGULATION OF FATTY ACID BIOSYNTHESIS

脂肪酸生物合成的调节

• 批准号: 3285595
• 负责人: Charles O Rock
• 金额: $ 7.34万
• 依托单位: ST. JUDE CHILDREN'S RESEARCH HOSPITAL
• 依托单位国家: 美国
• 财政年份: 1984
• 资助国家: 美国
• 起止时间: 1984-12-01 至 1992-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3285595
• 关键词: Escherichia coli; acetyl coA acetyltransferase; acyl carrier protein; antibody; enzyme mechanism; enzyme structure; fatty acid biosynthesis; gel electrophoresis; genetic mapping; growth /development; high performance liquid chromatography; membrane lipids; microorganism metabolism; mutant; phospholipids; protein biosynthesis; structural genes; temperature sensitive mutant; tissue /cell culture

The overall goal of this research program is to elucidate the mechanisms that regulate membrane lipid production and coordinate this process with growth and protein synthesis. A considerable amount of metabolic energy is expended in the biogenesis of membrane lipid and organisms in general exert a high degree of control over the activity of this pathway. In Escherichia coli, the bulk of the available evidence indicates that the control point is at an early step in fatty acid biosynthesis; however, the identity of the rate-controlling enzyme and an understanding of how it is regulated remains one of the major unanswered questions about bacterial physiology. Comparable concentrations of malonyl- and acetyl-acyl carrier protein (ACP) are present in vivo, indicating that the first condensation reaction in fatty aid biosynthesis is rate-limiting. This reaction is catalyzed by a unique condensing enzyme, acetoacetyl-ACP synthase, that is biochemically and genetically distinct from the other beta-kito-acyl-ACP synthases. Acetoacetyl-ACP synthase is ideally positioned in the biochemical pathway to function as the pacemaker of fatty acid production in organisms and organelles that possess dissociated (Type II) fatty acid synthase systems. Nothing is known about the biochemical mechanism, regulatory properties, or genetics of this new condensing enzyme. The work proposed in this application will test the hypothesis that fatty acid biosynthesis, and hence bulk membrane phospholipid formation, is controlled by modulating the activity of acetoacetyl-ACP synthase. The specific experimental aims of the grant will be (1) to purify acetoacetyl-ACP synthase and characterize its biochemical mechanism and regulatory properties, and (2) to isolate mutants with defective or altered acetoacetyl-ACP synthase activity and examine the metabolic basis for any physiological imbalance promoted by these mutations. The results of this work will provide significant new information on the relationship between regulation at the level of fatty acid chain initiation and the overall rate of membrane phospholipid biogenesis.

该研究计划的总体目标是阐明 调节膜脂质产生的机制和 将该过程与生长和蛋白质合成协调。 一个 在 膜脂质和生物的生物发生一般施加A 对该途径活性的高度控制。 在 大肠杆菌，大部分可用证据表明 控制点是脂肪酸生物合成的早期一步。 但是，速率控制酶的身份和 了解如何调节仍然是主要的 关于细菌生理学的未解决问题。 可比 丙二酰基和乙酰基酰基载体蛋白（ACP）的浓度 在体内存在，表明第一个冷凝反应 在脂肪AID中，生物合成是限制的。 这个反应是 由独特的冷凝酶，乙酰乙酰基-ACP催化 合酶，在生化和遗传上与 其他β-KITO-acyl-ACP合酶。 乙酰乙酰基-ACP合酶 理想地将其定位在生化途径中，以作为 生物和细胞器中脂肪酸产生的起搏器 具有解离的（II型）脂肪酸合酶系统。 关于生化机制，调节性的尚无 该新凝结酶的特性或遗传学。 工作 在本应用中提出的将检验以下假设 酸性生物合成，因此大量的膜磷脂 形成，通过调节活性来控制 乙酰乙酰基-ACP合酶。 特定的实验目的 授予将是（1）净化乙酰乙酰基-ACP合酶和 表征其生化机制和调节性 属性，（2）分离出有缺陷或改变的突变体 乙酰乙酰基-ACP合酶活性并检查代谢 这些促进的任何生理失衡的基础 突变。 这项工作的结果将提供重要的新 有关调节之间关系的信息 脂肪酸链的启动和膜的整体速率 磷脂生物发生。