ROLE OF PFHO-1 IN P. FALCIPARUM INTRAERYTHROCYTIC DEVELOPMENT

描述（申请人提供）：对恶性疟原虫红细胞内生长发育控制的探索尚处于起步阶段。了解寄生虫进展的信号和效应将增强我们对这种寄生虫如何在宿主细胞中生存的认识，并将发现化疗的新靶点。PfHO-1是一种在红细胞内疟原虫中表达的功能未知的血红素加氧酶样蛋白。我们发现PfHO-1具有响应卟啉的DNA结合活性，并优先与参与蛋白质合成的基因结合。我们的假设是PfHO-1响应血红蛋白降解产生的血红素积累，对红细胞内恶性疟原虫的发展至关重要。本研究的目的是验证这一假设。我们将评估PfHO-1对红细胞内恶性疟原虫和大肠杆菌报告系统中细胞内卟啉水平扰动的反应。我们将通过一种新的双阳性选择基因敲除方法和有条件地表达卟啉无反应版本的蛋白来削弱PfHO-1的作用。这些研究将使我们能够确定PfHO-1是否在感知细胞卟啉水平和参与细胞稳态的关键方面发挥重要作用。拟议的实验还将开发新的技术来控制卟啉和选择有害表型的反向基因工程寄生虫。

DESCRIPTION (provided by applicant): Exploration of the control of Plasmodium falciparum intraerythrocytic growth and development is in its infancy. Understanding the signals and effectors of parasite progression will enhance our knowledge of how this parasite survives in its host cell and will uncover new targets for chemotherapy. PfHO-1 is a heme oxygenase-like protein of unknown function expressed in intraerythrocytic malaria parasites. We have found that PfHO-1 has a porphyrin-responsive DNA- binding activity and associates preferentially with genes that are involved in protein synthesis. Our hypothesis is that PfHO-1 responds to heme accumulation from hemoglobin degradation and is crucial for intra-erythrocytic P. falciparum development. The goal of the study proposed here is to test this hypothesis. We will assess the response of PfHO-1 to perturbation of intracellular porphyrin levels in intraerythrocytic P. falciparum and in an E. coli reporter system. We will impair PfHO-1 action by a new double-positive selection gene knockout approach and by conditional expression of a porphyrin-unresponsive version of the protein. These studies will allow us to establish whether PfHO-1 plays an important role in sensing cellular porphyrin levels and participating in critical aspects f cellular homeostasis. The proposed experiments will also develop new technologies for porphyrin manipulation and for selection of deleterious phenotypes in reverse genetically engineered parasites.