Calcium ATPases in Apicomplexan Parasites as Potential D

顶复门寄生虫中的钙 ATP 酶具有潜力 D

• 批准号: 7140569
• 负责人: L. David Sibley
• 金额: $ 22.41万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-01 至 2008-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7140569
• 关键词: Apicomplexa; Cryptosporidium; Plasmodium; Toxoplasma gondii; active sites; alternative medicine; antiparasitic agents; calcium metabolism; calcium transporting ATPase; drug screening /evaluation; enzyme activity; enzyme inhibitors; gene expression; malaria; molecular cloning; parasite infection mechanism; protein localization; protein structure function; protozoal genetics; secretion

Toxoplasma gondii is a widespread apicomplexan parasite that is a common cause of serious food borne illness in the USA and which causes opportunistic disease in immunocompromised individuals. Toxoplasma gondii offers a number of advantages as a model system for studying the biology of related apicomplexan parasites including excellent animals models, robust in vitro systems, and forward and reverse genetics. Consequently, advances made in this system may also be relevant to other important human pathogens such as Cryptosporidium and Plasmodium (the causative agent of malaria). Apicomplexan parasites rely on active invasion to enter host cells and this obligatory step is controlled in part by the regulated secretion of adhesins from micronemes. Microneme secretion is a calcium-dependent process and agents that disrupt calcium signaling block secretion, motility, and invasion. Our previous studies have shown that calcium levels in the parasite undergo oscillations that correlate with motility. Disruption of these calcium oscillations prevents motility and cell invasion by the parasite. Recent evidence in malaria suggests that the Chinese herbal medicine Qinghaosu (Artemisinin) acts directly on one component of the calcium regulatory system, the sarcoplasmic-endoplasmic reticulum calcium ATPase (SERCA). To expand further on this discovery, we have recently cloned the SERCA gene from T. gondii. In AIM 1, we will characterize the expression and localization of SERCA in T. gondii and test the hypothesis that artemisinin binds to and inhibits the calcium pumping action of SERCA, thus disrupting parasite survival. In AIM2, we plan to use to robust genetic systems available in T. gondii to confirm the molecular target of artemisinin and to map the active site of the compound. This project addresses the need for greater understanding of fundamental processes in pathogens through the examination of regulatory pathways in calcium homeostasis. Knowledge gained through these studies may improve the ability to pharmacologically inhibit key calcium regulatory enzymes and hence block motility and invasion by this important group of parasites.

弓形虫是一种广泛分布的顶复门寄生虫，在美国是严重食源性疾病的常见原因，并在免疫功能低下的个体中引起机会性疾病。弓形虫作为研究相关顶复门寄生虫生物学的模型系统提供了许多优势，包括优良的动物模型、稳健的体外系统以及正向和反向遗传学。 因此，在这一系统中取得的进展也可能与其他重要的人类病原体有关，如隐孢子虫和疟原虫（疟疾的病原体）。 顶复门寄生虫依靠主动入侵进入宿主细胞，这一强制性步骤部分受到来自微丝的粘附素的调节分泌的控制。蛋白质分泌是一个钙依赖性过程，干扰钙信号传导的药物会阻断分泌、运动和侵袭。我们以前的研究表明，寄生虫中的钙水平经历与运动相关的振荡。这些钙振荡的破坏可以防止寄生虫的运动和细胞入侵。最近在疟疾方面的证据表明，中草药青蒿素（青蒿素）直接作用于钙调节系统的一个组成部分，即肌质-内质网钙ATP酶（SERCA）。到 进一步扩展这一发现，我们最近从T.刚地。在AIM 1中，我们将描述SERCA在T.并测试青蒿素结合并抑制SERCA的钙泵作用，从而破坏寄生虫存活的假设。在AIM 2中，我们计划使用T.以确定青蒿素的分子靶点并定位化合物的活性位点。 本项目旨在通过研究钙稳态的调节途径，更好地了解病原体的基本过程。通过这些研究获得的知识可能会提高抑制关键钙调节酶的能力，从而阻断这一重要寄生虫群的运动和入侵。