Branched Chain Amino Acid Metabolism

支链氨基酸代谢

• 批准号: 7480686
• 负责人: SUSAN M HUTSON
• 金额: $ 4.95万
• 依托单位: WAKE FOREST UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-02-01 至 2008-09-15
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7480686
• 关键词: 3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide); Acute; Affect; Amino Acids; Beta Catenin Staining Method; Biochemical; Branched-Chain Amino Acids; Cell model; Complex; Crystallography; Cysteine; Disulfides; End Point; Energy Metabolism; Energy Supply; Enzymes; Gastrointestinal tract structure; Goals; Hormones; Human; In Situ; Individual; Insulin; Internet; Isoenzymes; Keto Acids; Lead; Leucine; Link; Macronutrients Nutrition; Mass Spectrum Analysis; Measures; Metabolic; Metabolism; Mitochondria; Multienzyme Complexes; Neuraxis; Neurons; Numbers; Nutrient; Nutritional; Oxidation-Reduction; Oxidoreductase; Pathway interactions; Peroxides; Personal Satisfaction; Pharmaceutical Preparations; Phosphorylation; Phosphorylation Site; Plasma; Play; Principal Investigator; Protein Biosynthesis; Protein Dephosphorylation; Proteins; RNA Splicing; Rate; Rattus; Regulation; Research; Role; Secretory Cell; Serine; Signal Pathway; Signal Transduction; Signaling Protein; Site-Directed Mutagenesis; Structure; System; Techniques; Testing; Thinking; Tissues; Variant; X-Ray Crystallography; base; branched-chain-amino-acid transaminase; dithiol; gabapentin; in vivo; mTOR Signaling Pathway; nitrogen metabolism; oxidation; programs; protein function; transamination

In addition to their role as protein building blocks, amino acids have a significant role as nutritional signals. The BCAA leucine is a nutrient signal that stimulates increased protein synthesis in target tissues, and it Js our hypothesis that leucine signaling is linked to leucine metabolism. The first step in the catabolic pathway is reversible transamination catalyzed by the branched chain aminotransferase isozymes (BCAT). We have solved several structures of the human mitochondrial BCAT (hBCATm) and discovered that it contains a redox-active dithiol/disulfide center. The redox-linked regulation of activity by the CXXC center demonstrates that the cysteine residues are part of a peroxide-sensing mechanism that may have an in vivo role. We have discovered that hBCATm can associate with the BCKD complex and that this interaction is redox sensitive. The association between hBCATm and the mitochondrial BCKD complex suggests that BCAA catabolic enzymes form supramolecular complex called a metabolon. We will test the hypothesis that a protein web controls BCAA metabolism using the BCAT proteins as "bait" to identify protein components of the BCAA metabolon. Determination of the protein web for the BCAT, particularly of the neuron-specific cytosolic isozyme (BCATc) and a newly recognized alternatively spliced form of human BCATm (hBCATm- sp), is likely to allow identification of new functions for these proteins. The rate-limiting step in BCAA oxidation is catalyzed in mitochondria by the branched-chain alpha-keto acid dehydrogenase enzyme complex (BCKD). BCKD activity is regulated by phosphorylation and dephosphorylation of a specific serine residue on the Ela subunit. We will determine the role of BCATm in leucine signaling, that is, whether leucine or KIC is the signal that activates the mTOR-signaling pathway in leucine-sensitive tissues in vivo in the rat. Using a newly developed rapid and simple test system to measure acute regulation of BCKD, the role of BCATm and link between leucine activation of the mTOR signaling pathway and BCKD complex (metabolism) will be determined in vivo and in a 13-cell model. It is our hope that the ideas put forth in this proposal will bring new ways of thinking into the field of amino acid metabolism and will lead to exciting new research directions.

除了作为蛋白质构建块的作用外，氨基酸还具有营养信号的重要作用。 BCAA亮氨酸是一种养分信号，可刺激靶组织中蛋白质合成增加的增加，并且IT JS 我们的假设是亮氨酸信号传导与亮氨酸代谢有关。分解代谢途径的第一步 是由分支链氨基转移酶同工酶（BCAT）催化的可逆透明。我们有 解决了人类线粒体BCAT（HBCATM）的几个结构，并发现它包含一个 氧化还原活性二硫醇/二硫键中心。 CXXC中心对氧化还原连接的活性调节 证明半胱氨酸残基是过氧化物感应机制的一部分，可能具有体内 角色。我们发现HBCATM可以与BCKD复合物相关联，并且这种相互作用是 氧化还原敏感。 HBCATM与线粒体BCKD复合物之间的关联表明 BCAA分解代谢酶形成了称为代谢物的超分子复合物。我们将检验以下假设 蛋白质网络使用BCAT蛋白作为“诱饵”来控制BCAA代谢，以鉴定蛋白质成分 BCAA变质。确定BCAT的蛋白质Web，特别是神经元特异性的 胞质同工酶（BCATC）和新认识的人类BCATM（hbcatm-- SP），可能允许鉴定这些蛋白质的新功能。 BCAA的限速步骤 通过分支链α-酮酸脱氢酶在线粒体中催化氧化 复杂（BCKD）。 BCKD活性受特定丝氨酸的磷酸化和去磷酸化的调节 ELA亚基上的残留物。我们将确定BCATM在亮氨酸信号传导中的作用，也就是说 亮氨酸或KIC是激活体内亮氨酸敏感组织中MTOR信号途径的信号 大鼠。使用新开发的快速和简单的测试系统来测量BCKD的急性调节， BCATM的作用以及MTOR信号通路的亮氨酸激活与BCKD复合物之间的联系 （代谢）将在体内和13细胞模型中确定。我们希望在此提出的想法 提案将为氨基酸代谢领域带来新的思维方式，并将导致令人兴奋的新思维 研究方向。