REVERSIBLE PROTEIN PHOSPHORYLATION IN APICOMPLEXANS

本提案的长期目标是表征可逆性蛋白磷酸化途径，参考寄生虫顶复合体群的生化和遗传调控。原生顶复合体寄生虫的典型例子是致命的病原体，如引起疟疾的疟原虫，以及引起艾滋病患者机会性感染的弓形虫和隐孢子虫。仅由蚊子传播的疟疾就在全世界造成150万至250万人死亡，其中大多数是幼儿。耐药寄生虫和耐杀虫剂蚊子的死灰复燃以及疟疾在全球的传播使人们迫切需要了解这种寄生虫的基本调控途径。尽管我们在这方面的知识还很初级，但在过去二十年中积累的大量证据表明，在高等动物中，可逆的蛋白质磷酸化提供了生化和遗传调控的主要机制。因此，本研究将采用生物化学和分子生物学相结合的方法来研究选定的疟原虫蛋白磷酸酶，这是负责特定磷酸化蛋白去磷酸化的关键酶。这些酶的性质和调控以及它们与特定生理抑制剂和药物的相互作用将被深入研究。抗寄生虫药物，如强效海洋毒素冈田酸和免疫抑制剂环孢素，将被用作分析寄生虫特定蛋白磷酸酶的结构和功能的工具。这些结果应该成为详细阐明调控途径和可能的药物-靶标相互作用的基础，特别是疟原虫，以及一般的顶复体。

The long-term goal of this proposal is to characterize the reversible protein phosphorylation pathways in reference to biochemical and genetic regulation in the Apicomplexan group of parasites. Protozan Apicomplexan parasites are exemplified by deadly pathogens such as Plasmodium that causes malaria, and Toxoplasma and Cryptosporidium that cause opportunistic infections in AIDS patients. Malaria, transmitted by mosquitoes, alone kills between 1.5 and 2.5 million people worldwide, mostly young children. The resurgence of drug-resistant parasites as well as pesticide-resistant mosquitoes and the global transmission of the disease have produced an urgent need to understand the fundamental regulatory pathways of the parasite. Although our knowledge in this area is still rudimentary, a large body of evidence accumulated over the last two decades has shown that in higher animals a reversible protein phosphorylation provides a major mechanism of biochemical and genetic regulation. In this proposal, therefore, a combination of biochemistry and molecular biology will be employed to study selected Plasmodium protein phosphatases, key enzymes that are responsible for the dephosphorylation of specific phosphoproteins. The properties and regulation of these enzymes and their interactions with specific physiological inhibitors and drugs will be studied in- depth. The anti-parasitic drugs such as okadaic acid, a potent marine toxin, and cyclosporin, an immunosuppressant, will be used as tools in the analysis of the structure and function of specific protein phosphatases of the parasite. These results should form the cornerstone in the detailed elucidation of the regulatory pathways and possible drug-target interactions in Plasmodium in particular, and Apicomplexans in general.