Validation of the ubiquinone synthesis pathway of Toxoplasma gondii as a novel drug target

弓形虫泛醌合成途径作为新药物靶点的验证

基本信息

批准号：
10608408
负责人：
Silvia N Moreno
金额：
$ 41.57万
依托单位：
UNIVERSITY OF GEORGIA
依托单位国家：
美国
项目类别：
财政年份：
2022
资助国家：
美国
起止时间：
2022-09-19 至 2027-07-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10608408
关键词：
Acquired Immunodeficiency Syndrome Allergic Reaction Anabolism Antiparasitic Agents Bone Diseases Cells Chemicals Chemotherapy-Oncologic Procedure Chronic Clinic Clinical Congenital Toxoplasmosis Country Cryptosporidiosis Cyst Data Diphosphates Disease Drug Kinetics Drug Targeting Drug usage Electron Transport Electron Transport Complex III Electrons Enzymes Fetus Future Genetic Geranyltranstransferase Growth HIV Head Human Immunocompetent Immunocompromised Host Immunosuppression In Vitro Infection Isomerism Laboratories Lead Malaria Mammalian Cell Membrane Mitochondria Modeling Morbidity - disease rate Mus Neuraxis Organ Transplantation Outcome Parasites Pathogenesis Pathway interactions Patients Persons Pharmaceutical Preparations Pharmacology Phenotype Plants Population Pregnancy Property Quinolones Quinones Research Resistance Supplementation Tail Techniques Testing Tissues Toxoplasma gondii Toxoplasmosis Treatment Failure Ubiquinone Validation Water Work Yeasts acute infection atovaquone bisphosphonate chemotherapy chronic infection cytotoxicity effective therapy experience farnesyl pyrophosphate fosmidomycin gene complementation geranylgeranyl diphosphate hydroxybenzoate hypercholesterolemia improved inhibitor inorganic phosphate isopentenyl pyrophosphate isoprenoid knock-down lipophilicity member mevalonate mortality mouse model new therapeutic target novel opportunistic pathogen shikimate small molecule libraries tool ubiquinone 6

项目摘要

PROJECT SUMMARY/ABSTRACT Apicomplexan parasites cause persistent mortality and morbidity worldwide through diseases including malaria, toxoplasmosis, and cryptosporidiosis. The phylum member Toxoplasma gondii alone infects approximately one third of the world population. T. gondii is an opportunistic pathogen that causes serious disease in immunocompromised patients. Most human infections are asymptomatic but immunosuppression due to organ transplant, cancer chemotherapy, or infection with HIV can lead to re-activation of the infection. In addition, infection of the fetus during pregnancy causes congenital toxoplasmosis. Some exotic strains of T. gondii have been described in tropical countries that cause severe ocular disease in immunocompetent patients. Treatment for toxoplasmosis is challenged by lack of effective drugs to eradicate the chronic infection and as many as one-third of AIDS patients do not respond to the therapy. Most of the drugs currently used are poorly distributed to the central nervous system and they trigger allergic reactions in a large number of patients. There is a compelling need for safe and effective treatments for toxoplasmosis. The mitochondrion of T. gondii and of other apicomplexan parasites is critical for replication and several major antiparasitic drugs, such as atovaquone and endochin-like quinolones, act through inhibition of the mitochondrial electron transport chain at the coenzyme Q:cytochrome c reductase. The coenzyme Q (UQ) molecule consists of a water soluble quinone head (para-hydroxybenzoate or PHBA) that can accept or donate two electrons and a lipophilic isoprenoid tail that confines the UQ to membranes. Synthesis of the PHBA moiety in plants and yeast occurs through the shikimate pathway, but how it is synthesized in apicomplexan is not known. The isoprenoid unit derives from a common precursor, isopentenyl pyrophosphate (IPP), and its isomer, dimethylallyl pyrophosphate (DMAPP), which are synthesized in mammalian cells via the mevalonate pathway, but in T. gondii instead is synthesized via an apicoplast localized methylerythritol phosphate (MEP) pathway. IPP and DMAPP are condensed by the action of a unique farnesyl diphosphate synthase (TgFPPS) into farnesyl diphosphate (FPP) and geranylgeranyl diphosphate (GGPP). Work from our laboratory demonstrated that T. gondii is able to salvage GGPP and FPP from the host and therefore intracellular parasites are vulnerable to inhibition of the host isoprenoid synthesis pathway. In this project we propose to investigate the synthesis of UQ (downstream to the salvage point) and validate the pathway as a novel target. Our preliminary data demonstrates the essentiality of three enzymatic steps and the inhibition of one of them by a novel compound. Our hypothesis is that the synthesis of UQ represents a unique and essential pathway with enzymatic steps liable to inhibition by specific compounds, some already in use in the clinics and potential new ones to be discovered. We predict that exploring this pathway will reveal unique and essential enzymes that could be targeted for improved chemotherapy against T. gondii and other apicomplexan parasites.

项目概要/摘要顶复门寄生虫通过以下疾病在世界范围内导致持续的死亡和发病：疟疾、弓形体病和隐孢子虫病。弓形虫门成员单独感染约占世界人口的三分之一。弓形虫是一种机会致病菌，可导致严重的感染免疫功能低下患者的疾病。大多数人类感染无症状但免疫抑制由于器官移植、癌症化疗或艾滋病毒感染可能导致感染重新激活。另外，怀孕期间胎儿感染会导致先天性弓形虫病。一些外来菌株 T. 在热带国家，弓形虫已被描述，可在免疫功能正常的人中引起严重的眼部疾病患者。由于缺乏根除慢性感染的有效药物，弓形虫病的治疗面临挑战多达三分之一的艾滋病患者对这种疗法没有反应。目前使用的药物大部分是它们很难分布到中枢神经系统，并引发大量患者的过敏反应。迫切需要安全有效的弓形体病治疗方法。弓形虫和其他顶复门寄生虫的线粒体对于复制至关重要，并且有一些主要的抗寄生虫药物，例如阿托伐醌和内啡肽样喹诺酮类药物，通过抑制辅酶Q：细胞色素c还原酶处的线粒体电子传递链。辅酶Q (UQ) 分子由水溶性醌头（对羟基苯甲酸酯或 PHBA）组成，可以接受或捐赠两个电子和一个将 UQ 限制在膜上的亲脂性类异戊二烯尾部。 PHBA 部分的合成在植物和酵母中，它是通过莽草酸途径发生的，但它在 apicomplexan 中的合成方式尚不清楚已知。类异戊二烯单元源自常见的前体异戊烯焦磷酸 (IPP)，其异构体二甲基烯丙基焦磷酸 (DMAPP)，通过甲羟戊酸在哺乳动物细胞中合成途径，但在弓形虫中是通过顶端质体局部甲基赤藓糖醇磷酸酯 (MEP) 合成的途径。 IPP 和 DMAPP 在独特的法尼基二磷酸合酶 (TgFPPS) 的作用下缩合分为法呢基二磷酸（FPP）和香叶基香叶基二磷酸（GGPP）。在我们的实验室工作证明弓形虫能够从宿主体内回收 GGPP 和 FPP，从而在细胞内寄生虫容易受到宿主类异戊二烯合成途径的抑制。在这个项目中我们建议研究 UQ 的合成（抢救点下游）并验证该途径作为新靶点。我们的初步数据证明了三个酶促步骤的重要性以及其中之一的抑制由一种新颖的化合物。我们的假设是 UQ 的合成代表了一条独特且重要的途径酶促步骤容易被特定化合物抑制，其中一些已经在临床中使用并且具有潜力新的有待发现。我们预测探索这条途径将揭示独特且必需的酶可以作为改进针对弓形虫和其他顶复门寄生虫的化疗的目标。