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：
8373669
负责人：
CHOUKRI BEN MAMOUN
金额：
$ 42.58万
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 2017-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8373669
关键词：
1,2-diacylglycerol 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 Delivery Systems Enzyme Gene Enzymes Erythrocytes Ethanolamines Eukaryota Fatty Acids Fostering Genes Genetic Genetic Screening Genome Genomics Globin Growth Hemoglobin Homologous Gene Human Inhibitory Concentration 50 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 inhibitor/antagonist insight killings lipid metabolism macromolecule metabolic abnormality assessment mutant novel novel therapeutics phosphatidylethanolamine positional cloning promoter 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. PUBLIC HEALTH RELEVANCE: The main objectives of the proposed research are to identify and characterize two steps in the biosynthesis of the major phospholipids of P. falciparum, which are predicted to play an essential role in parasite development and survival within human erythrocytes, and search for inhibitors that block these steps and kill the parasite.

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，并乘以多达36个新的女儿寄生虫。这种快速的乘法需要对许多必需寄生虫功能重要的结构和信号脂质进行主动合成，例如寄生虫繁殖后的新膜产生新膜，以及仅举几例对寄生虫激酶激活的二酰基甘油的合成。控制这些大分子的合成的代谢机制是由丝氨酸，乙醇胺和脂肪酸从宿主那里清除的前体的助力。这些机器长期以来一直被认为是开发新型抗疟药的绝佳靶标。迄今为止，仅在疟原虫寄生虫和针对其中一些机器的药理学研究中，只有少数几个机器已得到了彻底的特征。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。丝氨酸还掺入了磷脂酰丝氨酸中，它是通过由寄生虫磷脂酰丙氨酸脱羧酶（PFPSD）催化的反应，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被认为是开发新抗疟药的潜在靶标。此外，人类细胞不含SD酶，从而使SD成为寄生虫的特定物种脆弱性。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。可用的数据表明，疟疾PSD在寄生虫的肉体内生命周期中起着至关重要的作用，并且是开发Nove抗疟药的绝佳靶标。然而，疟疾SD基因仍有待鉴定。该赠款应用的总体目标是完成pfpsd基因在恶性疟原虫中的生化和遗传表征（AIM 1）；利用酵母作为替代系统的新开发和成功的功能互补测定，以筛选抗菌活性化合物库，以搜索PFPSD活性的抑制剂（AIM 2）；并采用遗传和生化分析来识别疟疾丝氨酸脱羧酶基因，并表征其在恶性疟原虫内炎性发育和生存中的重要性（AIM 3）。这些研究具有阐明PFSD和PFPSD的重要性的潜力，以及在恶性疟原虫发育过程中总体而言，磷脂代谢以及促进特定抑制剂的设计。这项工作将为打击影响全球2.5亿人的疾病，每年造成100万人死亡。公共卫生相关性：拟议研究的主要目标是识别和表征恶性疟原虫主要磷脂的生物合成的两个步骤，预计该磷脂的主要磷脂将在人类红细胞内的寄生虫发育和生存中起着至关重要的作用，并寻找阻止这些步骤和杀死寄生虫的抑制剂。