ENTAMEBA HISTOLYTICA ADH2--A NEW TARGET FOR ANTI-AMEBIC THERAPY

阿米巴痢疾和阿米巴肝脏的溶组织内阿米巴 脓肿是寄生虫病的第三大致死原因。 全世界。侵袭性溶组织性肠杆菌感染用该药治疗 甲硝唑，但担心甲硝唑的诱变作用， 以及在一些生物体中甲硝唑耐药性的发展， 促使人们寻找治疗阿米巴病的替代药物。E 溶解组织缺乏线粒体，并从发酵中获得能量 葡萄糖转化为二氧化碳、醋酸盐和乙醇。这种糖酵解途径是一种 抗阿米巴化疗的有吸引力的靶点，因为它是 寄生虫的存在，它似乎利用了几种缺乏 大多数其他真核生物。最近，我们分离出了天然蛋白质， 并克隆了编码这一途径中的关键酶--双功能酶的基因 依赖NAD的酒精脱氢酶/乙酰辅酶A还原酶负责 乙酰辅酶A转化为乙醛，乙醛转化为乙醇。 这种酶，我们已经命名为组织裂解埃希氏菌酒精脱氢酶 2(EhADH2)，具有独特的结构，既含有乙醇脱氢酶 (ADH)和乙醛脱氢酶(ALDH)结构域，没有任何 已知的真核生物酶之间的同源物。中国的关键地位 阿米巴糖酵解途径中的EhADH2酶及其基础 与人类ADH和ALDH酶的不同，似乎使其成为理想的 化疗的目标。这项提案的目标是确定具体的 EhADH2酶的抑制剂。我们将通过研究 从分子水平了解EhADH2酶的结构和功能 关于这类新的酶，并提供必要的数据库 EhADH2分子抑制剂的合理设计。同时 时间，我们将开发一种检测系统，使我们能够迅速， 简单、廉价地筛选化合物的EhADH2抑制活性。 通过这一筛选和分子建模确定的抑制剂，然后 检测它们对溶组织性肠杆菌的生长和毒力的影响。 能够选择性抑制EhADH2酶的化合物可以 代表了一类对某些厌氧菌有效的新药物 原生动物和一些厌氧细菌。

Entamoeba histolytica, the agent of amebic dysentery and amebic liver abscess, is the third leading cause of death from parasitic diseases worldwide. Invasive E. histolytica infection is treated with the drug metronidazole, but concerns about the mutagenic effects of metronidazole, and the development of metronidazole resistance in a number of organisms, has fueled a search for alternative agents to treat amebiasis. E histolytica lack mitochondria, and obtain energy from the fermentation of glucose to CO2, acetate and ethanol. This glycolytic pathway is an attractive target for anti-amebic chemotherapy because it is essential for parasite existence, and it appears to utilize several enzymes lacking from most other eukaryotic organisms. Recently, we isolated the native protein, and cloned the gene encoding a key enzyme in this pathway, a bifunctional NAD-dependent alcohol dehydrogenase/acetyl-coA reductase responsible for the conversion of acetyl-coA to acetaldehyde and acetaldehyde to ethanol. This enzyme, which we have designated E. histolytica alcohol dehydrogenase 2 (EhADH2), has a unique structure containing both alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) domains, and does not have any homologues among known eukaryotic enzymes. The critical position of the EhADH2 enzyme in the amebic glycolytic pathway, and its fundamental differences from human ADH and ALDH enzymes, appear to make it an ideal target for chemotherapy. The goal of this proposal is to identify specific inhibitors of the EhADH2 enzyme. We will accomplish this by studying the structure and function of the EhADH2 enzyme at the molecular level to learn about this new class of enzymes, and to provide the data base necessary for the rational design of inhibitors of the EhADH2 molecule. At the same time, we will develop an assay system which will allow us to rapidly, simply, and inexpensively screen compounds for EhADH2 inhibitory activity. Inhibitors identified by this screen, and by molecular modeling, will then be assayed for their effects on E. histolytica growth and virulence. Compounds capable of selectively inhibiting the EhADH2 enzyme could represent a new class of agents effective against certain anaerobic protozoa and some anaerobic bacteria.