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

• 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
• 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

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.

项目总结/摘要 顶复门寄生虫通过以下疾病在世界范围内引起持续的死亡率和发病率， 疟疾弓形虫病和隐孢子虫病门成员弓形虫单独感染 约占世界人口的三分之一。T.弓形虫是一种机会致病菌， 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。 此外，怀孕期间胎儿感染弓形虫会导致先天性弓形虫病。一些外来的T. 在热带国家，弓形虫在免疫功能正常的人中引起严重的眼部疾病， 患者弓形虫病的治疗受到缺乏有效药物根除慢性感染的挑战 多达三分之一的艾滋病患者对这种疗法没有反应。目前使用的大多数药物是 它们在中枢神经系统中分布不良，并在大量患者中引发过敏反应。 迫切需要安全有效的弓形虫病治疗方法。 T.弓形虫和其他顶复门寄生虫是复制的关键， 主要的抗寄生虫药物，如阿托伐醌和endochin样喹诺酮，通过抑制 线粒体电子传递链上的辅酶Q：细胞色素c还原酶。辅酶Q（UQ） 分子由一个水溶性的醌头（对羟基苯甲酸酯或PHBA），可以接受或捐赠 两个电子和一个亲脂的类异戊二烯尾部，将UQ限制在膜上。PHBA部分的合成 在植物和酵母中，它是通过莽草酸途径合成的，但在顶复门中，它是如何合成的， 知道的类异戊二烯单元衍生自共同的前体异戊烯基焦磷酸（IPP），并且其 异构体，二甲基烯丙基焦磷酸（DMAPP），在哺乳动物细胞中通过甲羟戊酸合成 途径，但在T.而弓形虫则是通过顶质体定位的甲基磷酸盐（MEP）合成的。 通路IPP和DMAPP通过独特的法呢基二磷酸合酶（TgFPPS）的作用而缩合 转化为法呢基二磷酸（FPP）和香叶基香叶基二磷酸（GGPP）。我们实验室的工作 证明T.弓形虫能够从宿主中挽救GGPP和FPP， 寄生虫易受宿主类异戊二烯合成途径的抑制。在本项目中，我们建议 研究UQ的合成（补救点下游），并验证该途径作为新靶标。 我们的初步数据证明了三个酶促步骤的重要性和对其中一个步骤的抑制 一种新型化合物。我们的假设是UQ的合成代表了一个独特的和必要的途径 酶促步骤易于被特定化合物抑制，其中一些已经在临床上使用， 新的有待发现。我们预测，探索这一途径将揭示独特的和必要的酶 可以作为改善T.弓形虫和其他顶复门寄生虫。