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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：
8686736
负责人：
CHOUKRI BEN MAMOUN
金额：
$ 40.98万
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/8686736
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 Targeting 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 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.

描述(申请人提供)：恶性疟原虫在人类红细胞内的生命周期中，经历了重大的发育和新陈代谢变化，并繁殖产生多达36种新的子寄生虫。这种快速增殖需要结构和信号脂的活性合成，这些脂对寄生虫的许多基本功能非常重要，例如在寄生虫繁殖后产生新的膜，以及合成二酰甘油以激活寄生虫激酶，仅举几例。控制这些大分子合成的代谢机制是由前体推动的，如丝氨酸、乙醇胺和从宿主中清除的脂肪酸。长期以来，这些机制一直被认为是开发新型抗疟疾药物的极佳靶点。到目前为止，这些机制中只有几个在疟疾寄生虫中得到了彻底的表征，针对其中一些机制的药理学研究成功地导致了高度有效的抗疟疾药物的生产。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)脱羧基，生成乙醇胺，乙醇胺随后被用作合成磷脂酰胆碱和磷脂酰乙醇胺的前体。通过寄生虫磷脂酰丝氨酸脱羧酶(PfPSD)的催化反应，丝氨酸也被结合到磷脂酰丝氨酸中，磷脂酰丝氨酸作为合成磷脂酰乙醇胺的替代前体。PfSD和PfPSD由于其预测的基本功能，被认为是开发抗疟疾新药的潜在靶点。此外，人类细胞不包含SD酶，从而使SD成为寄生虫的一种特定物种的脆弱性。利用构建在酵母表达载体中的疟原虫cDNA文库，我们成功地补充了一株缺乏PSD活性的酵母突变株，并鉴定了疟疾PSD基因。现有数据表明，疟疾的PSD在寄生虫的红细胞内生命周期中发挥着重要作用，是开发新的抗疟疾药物的极佳靶点。然而，疟疾的SD基因仍有待鉴定。这项赠款申请的总体目标是完成恶性疟原虫PfPSD基因的生化和遗传学特征(目标1)；利用以酵母为替代系统的新开发和成功的功能互补分析来筛选抗疟疾活性化合物文库，以寻找PfPSD活性的抑制物(目标2)；以及利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生存中的重要性(目标3)。这些研究有可能阐明PfSD和PfPSD在恶性疟原虫发育过程中的重要性，以及磷脂代谢的一般情况，并促进特定抑制物的设计。这项工作将为临床治疗提供新的见解与这种每年影响全球2.5亿人并导致100万人死亡的疾病作斗争。