T.gondii pyrimidine synthesis as a chemotherapy target

描述(由申请人提供)： 弓形虫慢性感染了大约30%的美国人口。化疗主要基于抗叶酸，可用于感染速殖子的急性感染，但需要终生治疗才能预防艾滋病感染。不幸的是，高频率的不良反应与慢性治疗有关，经常使弓形虫的临床治疗复杂化。因此，开发新的和改进的治疗策略来治疗艾滋病中的弓形虫感染是当务之急。这笔赠款的重点是开发新的方法，以针对寄生虫氨甲酰磷酸合成酶II(CPSII)活性为基础，开发改进的治疗弓形虫感染的方法，这是从头合成嘧啶所需的。初步的生化和遗传学研究表明，弓形虫表达一种新的CPSII，它可以被干扰以诱导对尿苷一磷酸(UMP)和其他寄生虫RNA和DNA合成所需的嘧啶核苷酸的饥饿。破坏弓形虫中的CPSII活性会在体外阻止寄生虫的复制，迅速导致寄生虫生存能力的丧失。破坏CPSII可以消除缺乏干扰素的小鼠的寄生虫生长和毒力。目前的建议将扩大我们对CPSII的研究，将重点放在这种重要寄生虫酶的特定抑制剂的开发上。我们将描述CPSII的基本活动和调控，以获得有关CPSII功能的信息，这些功能可以有效地针对化疗。我们将测定具有活性的弓形虫CPSII酶(S)的晶体结构，为药物开发奠定结构基础。我们将评估弓形虫CPSII的先导抑制剂化合物，并将寻找或合成新的抑制剂。我们的假设是靶向CPSII和从头开始的嘧啶生物合成可以导致改进的治疗。这项拟议的研究正式汇集了达特茅斯大学三个研究小组的专业知识。David Bzik博士是一名分子寄生虫学家，曾接受过遗传学和生物化学方面的培训。艾米·安德森博士是一名结构生物化学家，曾受过生物化学和结晶学方面的培训。戈登·格里布尔博士是一名药物/合成化学家，接受过治疗疾病的化合物化学合成方面的培训。这三个研究小组的专业知识加在一起，将为开发和评估基于抑制寄生虫CPSII的弓形虫感染治疗新药提供一个独特的机会。

DESCRIPTION (provided by applicant): Toxoplasma gondii chronically infects approximately 30% of the United States population. Chemotherapy, largely based on anti-folates, is available for acute infection with tachzyzoites, but life-long treatment is required to protect against infections in AIDS. Unfortunately, a high frequency of adverse reactions are associated with chronic treatment, frequently complicating clinical treatment of T. gondii. Thus it is a high priority to develop new and improved treatment strategies for T. gondii infection in AIDS. This grant focuses on new approaches to develop improved treatments for T. gondii infection based on targeting the parasite carbamoyl phosphate synthetase II (CPSII) activity required for de novo pyrimidine biosynthesis. Preliminary biochemical and genetic studies indicate that T. gondii expresses a novel CPSII that can be disrupted to induce starvation for uridine monophosphate (UMP), and other pyrimidine nucleotides required for parasite RNA and DNA synthesis. Disruption of CPSII activity in T. gondii blocks parasite replication in vitro, rapidly resulting in loss of parasite viability. Disruption of CPSII abolished parasite growth and virulence in mice that lack interferon-y. The present proposal will expand our studies of CPSII to focus on the development of specific inhibitors of this essential parasite enzyme. We will characterize the essential activities and regulation to gain information on CPSII functions that can be effectively targeted for chemotherapy. We will determine the crystal structure of active T. gondii CPSII enzyme(s) to establish a structural basis for drug development. We will evaluate lead inhibitor compounds of T. gondii CPSII, and will identify or synthesize new inhibitors. It is our hypothesis that targeting CPSII and de novo pyrimidine biosynthesis can lead to improved treatments. The proposed research formally brings together expertise from three research groups at Dartmouth. Dr. David Bzik is a molecular parasitologist with training in genetics and biochemistry. Dr. Amy Anderson is a structural biochemist with training in biochemistry and crystallography. Dr. Gordon Gribble is a medicinal/synthetic chemist with training in chemical synthesis of compounds for the treatment of disease. Together, the expertise of these three research groups will provide a unique opportunity to develop and evaluate new drugs for treatment of T. gondii infection based on inhibition of parasite CPSII.