Targeting the Mitochondrion of P. falciparum

描述（由申请人提供）：恶性疟原虫的线粒体被剥夺了线粒体的许多典型功能，但保留了寄生虫生存所必需的途径。剩余的线粒体功能被证明是抗疟药物发现的一组非常有成效的目标。克服耐药性的一种方法是设计新药，使得耐药性的适应性成本限制突变寄生虫在联合治疗中存活或在没有选择的情况下持续存在的能力。通过全生物高通量筛选，我们发现了许多新的化学型，似乎作用于线粒体靶点。我们建议采取化学生物学的方法，以peculon和开发这些成一套试剂，用于表征线粒体功能的作用和阻力的一系列化学型，对peculon的作用机制。我们将研究抗性突变对靶标结构和功能的影响，以及这些突变和随后的生化变化对体外寄生虫生长和适应性的影响。我们将选择对一系列似乎靶向线粒体ETC的化学抑制剂的抗性，重点是DHODH。使用已被证明具有高生产力的方法，我们将表征抗性突变体，以确定化学抑制剂的靶点。我们建议进行足够深入的选择，并使用足够多样化的化学方法对影响线粒体ETC的可能靶点和机制的范围进行采样，并深入探索DHODH抑制剂的耐药突变范围，重点关注进入临床测试的化合物。我们将筛选先前鉴定的DHODH抑制剂筛选命中物，以获得对抗性寄生虫具有活性的那些。我们将绘制新分离的突变体的抗性突变，并通过测量突变对酶、线粒体功能和生物体生长的影响来评估生物学后果。

DESCRIPTION (provided by applicant): The mitochondrion of P. falciparum is stripped of many of the typical functions of mitochondria, yet retains pathways essential to the parasite survival. The remaining mitochondrial functions are proving to be an exceptionally productive set of targets for antimalarial drug discovery. One approach to overcoming drug resistance is to design new drugs such that the fitness cost of resistance restricts the ability of mutant parasites to survive combination therapy or to persist in the absence of selection. Through whole organism high-throughput screening we have discovered many new chemotypes that appear to act on mitochondrial targets. We propose to take a chemical biology approach to the mitochondrion and develop these into a suite of reagents useful in characterizing mitochondrial function by pinpointing mechanisms of action and resistance for a range of chemotypes that act against the mitochondrion. We will study the effects of the resistance mutations on the structure and function of the targets and the impact of those mutations and consequent biochemical changes on parasite growth and fitness in vitro. We will select resistance to a range of chemical inhibitors that appear to target the mitochondrial ETC, focusing on DHODH. Using an approach that has proven highly productive, we will characterize the resistant mutants to identify the target of the chemical inhibitor. We propose to conduct selections in sufficient depth and using a sufficiently diverse range of chemistry to sample the range of possible targets and mechanisms affecting the mitochondrial ETC, and to explore the range of resistance mutations to DHODH inhibitors intensively, focusing on the compound advancing to clinical testing. We will screen previously identified DHODH inhibitor screening hits for those active against the resistant parasites. We will map the resistance mutations of mutants newly isolated and assess the biological consequences by measuring the effects of the mutations on the enzyme, on mitochondrial function and on the growth of the organism.