DRUG TARGETS OF OPPORTUNISTIC PATHOGENS IN AIDS

尽管机会性感染并发症的治疗取得了进展， 艾滋病仍然是发病和死亡的主要原因。 测试 潜在的治疗剂被制备中的困难所混淆， 许多这些病原体的培养和动物的不可靠性 在新代理的测试模型。 为了规避这些 问题，我们计划克隆酶，这些酶是已知类别的目标， 抗生素，在异源中大量表达这些蛋白质， 系统（例如E.大肠杆菌和酵母），并表征酶学性质 目标的参数。 表达的蛋白质及其序列将 为三维结构的确定提供依据， 目标的分子建模。 结构信息将提供 合理药物设计和鉴定的基础。 类 具有新化合物所必需的结构成分的化合物 将测试抑制剂在体外抑制 目标 被选来研究的生物体是卡氏肺孢子虫， 新生隐球菌和刚地弓形虫。 这些有机体导致 大量危及生命的艾滋病感染者。 我们集团 卡氏肺孢子虫和新型隐球菌的经验。 许多 为这项研究选定的目标已经分离出来， 用于结构测定和分子建模。 其他目标 根据我们在这一领域的经验会很快被隔离 选择的目标是叶酸和胸苷酸中的关键酶 生物合成途径 由于抑制该途径的药剂已经被 在临床上用于卡氏肺孢子虫和刚地弓形虫时， 这些通路是化疗的合适靶点， 干预 已选定的目标是二氢叶酸 还原酶（DHFR;甲氧苄啶的靶标），二氢蝶酸合成酶 (DHPS;磺胺靶点）和胸苷酸合成酶（TS;可能的 5-氟胞嘧啶的靶标）。 丰富的动力学结构信息， 可用于两种酶（TS和DHFR），其中大部分已被 由这个群体的成员决定。 该集团共同提供了一个连续的药物开发系统， 克隆到表达到结构测定到分子建模。 该小组已经展示了以往富有成效的互动。 药物 机会致病菌的目标将不是一个全新的冒险，但 这些领域正在进行的项目的延伸。

Despite advances in the therapy of opportunistic infections complicating AIDS, they remain a leading cause of morbidity and mortality. Testing of potential therapeutic agents is confounded by the difficulties in the cultivation of many of these pathogens and the unreliability of animal models in the testing of new agents. In order to circumvent these problems, we plan to clone enzymes which are targets for known classes of antibiotics, expressing these proteins in large quantities in heterologous systems (e.g. E. Coli and yeast), and characterizing the enzymologic parameters of the targets. The expressed proteins and their sequences will provide the basis for the three-dimensional structure determination and molecular modeling of the targets. The structural information will provide the basis for rational drug design and identification. Classes of compounds which have the structural components necessary to be new inhibitors will be tested for their efficacy in the in vitro inhibition of the targets. The organisms that have been chosen for study are Pneumocystis carinii, Cryptococcus neoformans, and Toxoplasma gondii. These organisms cause the bulk of life-threatening infections in patients with AIDS. Our group has experience with Pneumocystis carinii and Cryptococcus neoformans. Many of targets selected for this study have already been isolated and are ready for structural determination and molecular modeling. The other targets will rapidly be isolated given our experience in this field. The targets chosen are crucial enzymes in the folate and thymidylate biosynthetic pathways. Since agents which inhibit this pathway are already in clinical use for Pneumocystis carinii and Toxoplasma gondii, we know that these pathways are appropriate targets for chemotherapeutic intervention. The targets that have been selected are dihydrofolate reductase (DHFR; the target of trimethoprim), dihydropteroate synthetase (DHPS; the sulfonamide target), and thymidylate synthase (TS; the likely target of 5-fluorocytosine). Abundant kinetic structural information is available for two these enzymes (TS and DHFR), much of which has been determined by members of this group. Together the group provides a continuous system of drug development from cloning to expression to structural determination to molecular modeling. The group has demonstrated previous productive interactions. The drug targets in opportunistic pathogens will not be an entirely new venture, but an extension of on-going projects in these fields.