Polyamine and glutathione metabolism in trypanosomes.

锥虫中的多胺和谷胱甘肽代谢。

基本信息

批准号：
7325676
负责人：
Margaret A. Phillips
金额：
$ 32.65万
依托单位：
UT SOUTHWESTERN MEDICAL CENTER
依托单位国家：
美国
项目类别：
财政年份：
1994
资助国家：
美国
起止时间：
1994-12-01 至 2009-09-29
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7325676
关键词：
Active Sites Adenosylmethionine Decarboxylase Affect Affinity Africa African Trypanosomiasis Allosteric Site Anabolism Binding Binding Sites Blood Circulation Catalysis Cell Maintenance Cells Chagas Disease Chemistry Commit DL-alpha-Difluoromethylornithine Dimerization Disease Distant Drug Delivery Systems Drug Design Effectiveness Enzyme Inhibition Enzyme Inhibitor Drugs Enzyme Inhibitors Enzymes Equilibrium Foundations Future Gene Expression Genetic Glutamate-Cysteine Ligase Glutathione Glutathione Metabolism Pathway Growth Growth Factor Inhibition Growth Inhibitors Human Kinetics Ligand Binding Metabolic Metabolic Control Metabolism Mitoguazone Morbidity - disease rate Mutation Nature Numbers Ornithine Decarboxylase Ornithine Decarboxylase Inhibitor Oxidation-Reduction Parasites Parasitic Diseases Pathway interactions Peptides Pharmacotherapy Polyamines Process Proteins Protozoa Putrescine RNA RNA Interference Rate Reaction Regulation Research Personnel Roentgen Rays Role Screening procedure Site Site-Directed Mutagenesis South America Spermidine Stress Structure Sulfhydryl Compounds Trypanosoma Trypanosoma brucei brucei Trypanosoma cruzi X-Ray Crystallography Yeasts analog antibiotic G 418 base cell growth cofactor design dimer gamma-glutamylcysteine inhibitor/antagonist insight mortality mutant novel pathogen programs response trypanothione

项目摘要

DESCRIPTION (provided by applicant): The parasitic protozoa of the genus Trypanosoma are the causative agents of African sleeping sickness and of Chagas' disease in South America. These parasites cause significant mortality and drug therapy to combat these diseases is inadequate. Polyamines are essential growth factors, and inhibition of polyamine biosynthesis provides a mechanism to inhibit cell growth. The first committed step in the biosynthesis of polyamines is catalyzed by ornithine decarboxylase (ODC). This enzyme is one of the few validated targets for the treatment of parasitic diseases. A number of enzymes in the pathway are essential for cell growth, and inhibitors of several polyamine biosynthetic enzymes have anti-trypanosomal activity. In addition the parasites synthesize a unique cofactor that is a conjugate of spermidine and glutathione, termed trypanothione that functions to maintain the reduced thiol pool in the cell. In this proposal our planned studies focus on the three enzymes in the pathway (ODC, S-adenosylmethionine decarboxylase and gamma-glutamylcysteine synthetase) that catalyze the first committed steps in the biosynthesis of the polyamines and trypanothione. In the first two aims we will explore the structural basis for inhibition of these enzymes. These studies will lay the foundation for future inhibitor design. In Aim one we plan to explore the role of active site interactions in the energetics of ligand binding and catalysis, using site-directed mutagenesis and X-ray crystallography. In Aim two mechanisms of allosteric inhibition will be studied to explore the potential to develop novel mechanisms of inhibition that target regions outside of the active site. While ODC is a fully validated target, other enzymes in the pathway are not. The nature of the rate-determining steps in polyamine and trypanothione biosynthesis in T. brucei has not been fully elucidated. Understanding the metabolic flux through the pathway will provide insight into which additional enzymes are best targeted for drug design. Polyamine metabolism is highly regulated in most cells, yet no evidence for regulation has been described in trypanosomatids. If the parasite alters polyamine levels in response to pathway inhibitors this regulation may impact on the effectiveness of drugs targeted at these enzymes. In Aim 3 we propose to study the effects of both genetic and metabolic perturbations in the pathway on the levels of key enzymes and metabolites.

描述（由申请人提供）：锥虫属的寄生虫原生动物是南美洲疾病和查加斯病的病因。这些寄生虫会导致重大死亡率和药物治疗来打击这些疾病是不足的。多胺是基本生长因子，抑制多胺生物合成为抑制细胞生长提供了一种机制。多胺生物合成中的第一个投入步骤是由鸟氨酸脱羧酶（ODC）催化的。该酶是寄生疾病治疗的少数几个验证靶标之一。途径中的许多酶对于细胞生长至关重要，几种多胺生物合成酶的抑制剂具有抗肌体活性。此外，寄生虫合成了一种独特的辅助因子，该辅助因子是精子和谷胱甘肽的结合物，称为锥虫，该锥虫功能可维持细胞中的硫醇池。在这项建议中，我们的计划研究集中于途径中的三种酶（ODC，S-腺苷甲硫代脱羧酶和γ-谷氨基半胱氨酸合成酶），这些酶催化了在多胺和锥虫的生物合成中提出的第一个步骤。在前两个目标中，我们将探索抑制这些酶的结构基础。这些研究将为未来的抑制剂设计奠定基础。在目标中，我们计划使用位置定向的诱变和X射线晶体学探索活性位点相互作用在配体结合和催化的能量中的作用。在目标方面，将研究两种变构抑制的机制，以探索发展活性部位以外的靶向区域的新型抑制机制的潜力。虽然ODC是一个完全验证的目标，但途径中的其他酶却不是。多胺和锥虫生物合成的速率确定步骤的性质尚未完全阐明。了解通过途径的代谢通量将提供有关最适合药物设计的其他酶的洞察力。多胺代谢在大多数细胞中受到高度调节，但在锥虫中没有描述调节的证据。如果寄生虫根据途径抑制剂改变了多胺水平，则该调节可能会影响针对这些酶的药物的有效性。在AIM 3中，我们建议研究途径中遗传和代谢扰动对关键酶和代谢产物水平的影响。