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Function and Inhibition of Plasmodium Lipid Decarboxylases

疟原虫脂质脱羧酶的功能和抑制

基本信息

批准号：
9088297
负责人：
CHOUKRI BEN MAMOUN
金额：
$ 40.95万
依托单位：
YALE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2012
资助国家：
美国
起止时间：
2012-07-01 至 2018-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9088297
关键词：
Affect Amino Acids Ammonium Compounds Anabolism Antimalarials Applications Grants Biochemical Biochemical Genetics Biological Assay CDP ethanolamine Carboxy-Lyases Catabolism Cells Cessation of life Codon Nucleotides Complement Complementary DNA Data Daughter Decarboxylation Development Diglycerides Disease Drug Targeting Enzymes Erythrocytes Ethanolamines Eukaryota Fatty Acids Fostering Genes Genetic Genetic Screening Genetic study Genome Genomics Globin Growth Hemoglobin Homologous Gene Human Label Lecithin Libraries Life Cycle Stages Lipids Malaria Membrane Metabolic Names Organism Parasites Pathway interactions Phosphatidylethanolamine Phosphatidylserines Phospholipid Metabolism Phospholipids Phosphotransferases Physiological Plants Plasmodium Plasmodium falciparum Plasmodium knowlesi Play Process Production Property Proteins Reaction Research Role Serine Signal Transduction System Work Yeasts cDNA Library combat design drug sensitivity enzyme activity expression vector genetic analysis genetic approach inhibitor/antagonist insight killings lipid metabolism macromolecule metabolic abnormality assessment mutant novel novel therapeutics promoter reverse genetics small molecule libraries

项目摘要

DESCRIPTION (provided by applicant): During its life cycle within human erythrocytes, Plasmodium falciparum undergoes major developmental and metabolic changes and multiplies to produce up to 36 new daughter parasites. This rapid multiplication requires an active synthesis of structural and signaling lipids important for many essential parasite functions such as the production of new membranes following parasite multiplication, and the synthesis of diacylglycerol for activation of parasite kinases, to name only a few. The metabolic machineries that govern the synthesis of these macromolecules are fueled by precursors such as serine, ethanolamine and fatty acids scavenged from the host. These machineries have long been regarded as excellent targets for the development of novel antimalarial drugs. To date only a few of these machineries have been thoroughly characterized in Plasmodium parasites and pharmacological studies targeting some of them have successfully resulted in the production of highly potent antimalarial drugs. Serine obtained from the host serves as the primary precursor for the synthesis of the major phospholipids phosphatidylcholine and phosphatidylethanolamine. Serine is decarboxylated by a parasite specific serine decarboxylase (PfSD) to form ethanolamine, which is subsequently used as a precursor for the synthesis of both phosphatidylcholine and phosphatidylethanolamine. Serine is also incorporated into phosphatidylserine, which serves as an alternate precursor for the synthesis of phosphatidylethanolamine, via a reaction catalyzed by a parasite phosphatidylserine decarboxylase (PfPSD). Because of their predicted essential functions, PfSD and PfPSD are regarded as potential targets for the development of new antimalarial drugs. Moreover, human cells do not contain SD enzymes thereby making SD a species-specific vulnerability of the parasite. Using a Plasmodium cDNA library constructed in a yeast expression vector we have successfully complemented a yeast mutant lacking PSD activity and identified the malarial PSD gene. Available data suggest that the malarial PSD plays an essential role in the intraerythrocytic life cycle of the parasite and is an excellent target for the development of nove antimalarial drugs. The malarial SD gene, however, remains to be identified. The overall objectives of this grant application are to complete the biochemical and genetic characterization of the PfPSD gene in P. falciparum (Aim 1); to take advantage of the newly developed and successful functional complementation assay using yeast as a surrogate system to screen a library of antimalarial active compounds to search for inhibitors of PfPSD activity (Aim 2); and employ genetic and biochemical analyses to identify the malarial serine decarboxylase gene and characterize its importance in P. falciparum intraerythrocytic development and survival (Aim 3). These studies hold the potential for elucidating the importance of PfSD and PfPSD specifically, and phospholipid metabolism in general during P. falciparum development as well as fostering the design of specific inhibitors. This work will provide new therapeutic insights for combating a disease that affects 250 million people worldwide and causes 1 million deaths each year.

描述（由申请人提供）：在人类红细胞内的生命周期中，恶性疟原虫经历了重大的发育和代谢变化并繁殖，产生多达 36 种新的子寄生虫。这种快速增殖需要主动合成对许多重要寄生虫功能很重要的结构和信号脂质，例如寄生虫增殖后新膜的产生，以及用于激活寄生虫激酶的二酰基甘油的合成，仅举几例。控制这些大分子合成的代谢机制由从宿主清除的丝氨酸、乙醇胺和脂肪酸等前体提供燃料。这些机器长期以来一直被认为是开发新型抗疟药物的极好目标。迄今为止，只有少数这些机器在疟原虫寄生虫中得到了彻底的表征，针对其中一些机器的药理学研究已成功生产出高效的抗疟药物。从宿主获得的丝氨酸是合成主要磷脂磷脂酰胆碱和磷脂酰乙醇胺的主要前体。丝氨酸被寄生虫特异性丝氨酸脱羧酶 (PfSD) 脱羧形成乙醇胺，随后用作合成磷脂酰胆碱和磷脂酰乙醇胺的前体。丝氨酸还可通过寄生虫磷脂酰丝氨酸脱羧酶 (PfPSD) 催化的反应掺入磷脂酰丝氨酸中，磷脂酰丝氨酸可作为合成磷脂酰乙醇胺的替代前体。由于其预测的基本功能，PfSD 和 PfPSD 被视为开发新型抗疟药物的潜在靶点。此外，人类细胞不含 SD 酶，因此使 SD 成为寄生虫的物种特异性脆弱性。使用在酵母表达载体中构建的疟原虫 cDNA 文库，我们成功地补充了缺乏 PSD 活性的酵母突变体，并鉴定了疟疾 PSD 基因。现有数据表明，疟疾 PSD 在寄生虫的红细胞内生命周期中发挥着重要作用，是开发新型抗疟药物的绝佳靶点。然而，疟疾 SD 基因仍有待鉴定。本次拨款申请的总体目标是完成恶性疟原虫 PfPSD 基因的生化和遗传表征（目标 1）；利用新开发的成功的功能互补测定法，使用酵母作为替代系统来筛选抗疟活性化合物库，以寻找 PfPSD 活性的抑制剂（目标 2）；并采用遗传和生化分析来鉴定疟疾丝氨酸脱羧酶基因并表征其在恶性疟原虫红细胞内发育和存活中的重要性（目标 3）。这些研究有可能阐明 PfSD 和 PfPSD 的重要性，以及恶性疟原虫发育期间一般磷脂代谢的重要性，并促进特定抑制剂的设计。这项工作将为以下疾病提供新的治疗见解抗击这种每年影响全球 2.5 亿人并导致 100 万人死亡的疾病。