Purine Pathways and Inhibitor Design in Plasmodium

疟原虫中的嘌呤途径和抑制剂设计

• 批准号: 7619060
• 负责人: Vern L. Schramm
• 金额: $ 48.22万
• 依托单位: ALBERT EINSTEIN COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-08-01 至 2013-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7619060
• 关键词: Adenosine; Adenosine Kinase; Affinity; Anabolism; Animal Disease Models; Antibiotic Resistance; Antimalarials; Biochemical; Biological; Biological Availability; Blood; Bypass; Cause of Death; Cell Culture Techniques; Cellular biology; Cessation of life; Chemistry; Child; Clinical; Coformycin; Collaborations; Communicable Diseases; Complex; Coupling; Crystallography; Culicidae; Cultured Cells; Disease; Elements; Enzymatic Biochemistry; Enzymes; Erythrocyte Survival; Erythrocytes; Generations; Genetic; Genome; Goals; Human; Hypoxanthines; Immucillin-H; Infection; Inosine; Interruption; Ions; Isotopes; Kinetics; Label; Life; Malaria; Mass Spectrum Analysis; Measures; Metabolic; Metabolism; Methods; Mouse Strains; Mus; Muscle Form Glycogen Phosphorylase; Nucleic Acid Precursors; Nucleosides; Orotate Phosphoribosyltransferase; Parasites; Pathway interactions; Pattern; Pharmaceutical Preparations; Phosphorylases; Physiological; Plasmodium; Plasmodium falciparum; Plasmodium yoelii; Purine Nucleoside Phosphorylase Inhibitor; Purine Nucleotides; Purine-Nucleoside Phosphorylase; Purines; Pyrimidine; Pyrimidine Nucleotides; Pyrimidines; Radioisotopes; Research; Resistance; Source; Specificity; Structure; Synthesis Chemistry; Technology; Testing; Therapeutic; Validation; accelerator mass spectrometry; adenosine deaminase; analog; base; comparative; design; enzyme structure; frontier; hypoxanthine-guanine-xanthine phosphoribosyltransferase; in vivo; inhibitor/antagonist; killings; metabolic abnormality assessment; mouse model; nucleotide metabolism; overexpression; phosphonate; professor; programs; public health relevance; purine; pyrimidine analog; quantum chemistry; research study; ribosyltransferase; theories; uptake

DESCRIPTION (provided by applicant): Plasmodium falciparum is the leading cause of death from malaria, taking the lives of over a million children and causing clinical illness in 300 to 500 million people each year. The parasite has acquired resistance against most antimalarials and new drugs are required. P. falciparum is a purine auxotroph, requiring purine salvage from human erythrocytes for survival. Using the frontier technology of transition state analysis, the transition state structures of P. falciparum purine nucleoside phosphorylase (PNP) and adenosine deaminase (ADA) have been solved and used to design transition state analogue inhibitors to match a their transition states. These inhibitors block their respective pathways and kill parasites cultured in human erythrocytes, but do not cure infections of Plasmodium yoelii in mice, an animal model of the disease. Metabolite labeling patterns and mouse studies have established that new pathways remain to be discovered and targeted. Inhibitor design against two critical targets will be assisted by solving the transition state structures of P. falciparum hypoxanthine-guanine-xanthine phosphoribosyltransferase (HGXPRT), the most critical step in purine synthesis. In the essential pathway of malarial de novo pyrimidine biosynthesis, orotate phosphoribosyltransferase (OPRT) is the essential first step to form all pyrimidine nucleotides. These transition state structures will be solved by frontier methods coupling kinetic isotope effects and quantum chemistry. A new generation of inhibitors will be patterned on these transition states and tested against parasites cultured in human erythrocytes and in the mouse model of P. yoelii infection. Purine salvage and synthetic pathways in parasites and their interruption with inhibitors will be investigated with purine precursors with specific radioisotope labels. The ultrasensitive method of accelerator mass spectrometry (AMS) will be used to follow normal pathways of purine salvage without perturbing normal pools in cultured cells and in mouse infections. The AMS approach has revealed uncharacterized pathways of purine salvage and these will be defined in metabolic, enzymatic and inhibitor approaches. Antimalarials that block purine salvage or pyrimidine synthesis may be useful therapeutics as single agents or in combination with agents targeted against other pathways. Simultaneous blocking of two targets decreases the ability of mutational escape by the parasite. PUBLIC HEALTH RELEVANCE Malaria is an infectious disease cause by parasites spread by mosquitoes in tropical regions of the developing world. Approximately one million children die each year from the disease and current drugs are losing their efficiency because of acquired antibiotic resistance by the parasites. This research proposes new ways to treat malaria by discovered new ways to kill the parasites without harming the human host and by exploring new drugs.

描述（由申请人提供）：恶性疟原虫是疟疾死亡的主要原因，夺走了超过一百万儿童的生命，并每年300至5亿人造成临床疾病。该寄生虫已经获得了对大多数抗疟疾药物的抵抗力，需要新药。恶性疟原虫是一种嘌呤型菌群，需要人类红细胞的嘌呤挽救才能生存。使用过渡状态分析的前沿技术，已解决了恶性疟原虫嘌呤核苷磷酸化酶（PNP）和腺苷脱氨酶（ADA）的过渡状态结构，并用于设计过渡态模拟抑制剂以匹配其过渡状态。这些抑制剂阻止了它们各自的途径并杀死在人红细胞中培养的寄生虫，但不能治愈小鼠的疟原虫感染，这是该疾病的动物模型。代谢产物标记模式和小鼠研究已经确定，新途径仍有待发现和靶向。针对两个关键靶标的抑制剂设计将通过解决恶性疟原虫甲黄嘌呤 - 瓜氨酸 - 黑甘氨酸磷酸糖基转移酶（HGXPRT）的过渡状态结构，这是嘌呤合成中最关键的一步。在疟疾新嘧啶生物合成的基本途径中，甲状腺磷酸磷酸糖基转移酶（OPRT）是形成所有嘧啶核苷酸的必不可少的第一步。这些过渡状态结构将通过耦合动力学同位素效应和量子化学的边界方法来解决。新一代的抑制剂将在这些过渡态上进行图案化，并针对在人类红细胞和P. yoelii感染的小鼠模型中培养的寄生虫进行测试。寄生虫中的嘌呤挽救和合成途径将使用具有特定的放射性同位素标签的嘌呤前体研究。加速器质谱法（AMS）的超敏感方法将用于遵循嘌呤挽救的正常途径，而不会扰动培养细胞和小鼠感染中的正常池。 AMS方法揭示了嘌呤打捞的未表征，这些途径将以代谢，酶和抑制剂方法定义。阻断嘌呤挽救或嘧啶合成的抗疟药可能是单一药物，或与针对其他途径靶向的药物结合使用的抗菌素。同时阻止两个靶标会降低寄生虫突变逃逸的能力。公共卫生相关性疟疾是一种传染病，这是由于蚊子在发展中国家的热带地区传播的寄生虫。每年大约有100万儿童因疾病而死亡，目前的药物由于寄生虫获得了抗生素的耐药性而失去了效率。这项研究提出了新的方法来治疗疟疾，从而发现了新的方法来杀死寄生虫，而无需损害人类宿主并探索新药。