STRUCTURE OF TOXOPLASMA GONDII ADENOSINE KINASE

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目及 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 在艾滋病毒感染人群中，弓形虫感染引起的发病和死亡是一个日益严重的问题。这些患者中弓形虫病的管理由于最常用化合物的高副作用发生率以及这些化合物对寄生虫潜伏期的无活性而变得复杂。 因此，持续需要定义新的治疗靶标并开发针对该病原体的新治疗剂。 这些生物体的基本代谢的一个特征尚未被充分利用用于化疗，这是它们的腺苷激酶的特征及其在活化“破坏性”底物”中的独特特异性。 来自合作者的结果表明，寄生虫，而不是宿主，腺苷激酶可以独特地磷酸化某些6-取代嘌呤核苷作为“颠覆性”底物，从而选择性地杀死T。弓形虫体外感染，延长感染小鼠寿命。因此，T.克隆、过表达和纯化了弓形虫腺苷激酶（TgAK）。 构效关系以及比较代谢和分子研究表明，T。弓形虫腺苷激酶在底物特异性、结构和其他特性上确实与宿主的腺苷激酶有实质性的不同。与我们的合作者一起，我们将表征TgAK，并利用所获得的信息开发有效的和选择性的颠覆性底物作为潜在的抗弓形虫剂。 这种方法可能适用于其他机会性感染，这些感染与弓形虫一样具有嘌呤类似物代谢的独特特征。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Morbidity and mortality due to infections with Toxoplasma gondii are an increasing problem in the HIV-infected population. Management of toxoplasmosis in these patients is complicated by a high incidence of side effects with the most commonly used compounds and the inactivity of these compounds against the latent stage of the parasite. Hence, there is a continuing need to define novel therapeutic targets and develop new therapeutic agents for this pathogen. One feature of the basic metabolism of these organisms which has not been fully exploited for chemotherapy is the characteristics of their adenosine kinase and its unique specificity in the activation of "subversive" substrates". Results from a collaborator indicate that the parasite, but not the host, adenosine kinase can uniquely phosphorylate certain 6-substituted purine nucleosides as "subversive" substrates and thereby selectively kill T. gondii in vitro and extend the life span of infected mice. Therefore, T. gondii adenosine kinase (TgAK) was cloned, overexpressed and purified. Structure activity relationships as well as comparative metabolic and molecular studies indicate that T. gondii adenosine kinase is indeed substantially different from that of the host in substrate specificity, structure and other characteristics. In conjunction with our collaborator, we will characterize the TgAK and to use the information gained to develop potent and selective subversive substrates as potential anti-toxoplasmic agents. This approach may well apply to other opportunistic infections which share with toxoplasma this unique feature of purine analogue metabolism.