Investigating the Cytsolic Heme Pool in P. falciparum

研究恶性疟原虫胞质血红素池

• 批准号: 6915712
• 负责人: JACQUIN C NILES
• 金额: $ 5.15万
• 依托单位: UNIVERSITY OF CALIFORNIA BERKELEY
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-06-01 至 2007-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6915712
• 关键词: Plasmodium falciparum; SDS polyacrylamide gel electrophoresis; chloroquine; cytoplasm; drug resistance; heme; host organism interaction; malaria; oligonucleotides; pathologic process; peptide library; polymerase chain reaction; postdoctoral investigator; protein binding; protein degradation; protein structure function

DESCRIPTION (provided by applicant): During malarial infection by Plasmodium falciparum, significant, amounts of hemoglobin are degraded by the intraerythrocytic parasite in a specialized food vacuole. The released amino acids are utilized to support growth, but heme is mostly detoxified to hemozoin in the food vacuole. However, it is unclear how much heme partitions to the parasite's cytosol, and the role it plays in parasite physiology. Furthermore, chloroquine, a commonly used anti-malarial drug has been suggested to increase cytosolic heme flux, but this has not been proven. We will address these issues by using a functional approach rather than mass balance measurements that are prone to large errors in biological systems. Our goals are to (1) develop high affinity RNA aptamers to heme using SELEX, and, (2) introduce them into P. falciparum, and determine their impact on parasite survival in the presence and absence of chloroquine. The aptamers are expected to be cytosolic given their negative charge, and should not interfere with heme polymerization in the food vacuole, thus providing a tool to selectively investigate the heme pool in the cytosol. These studies are important to advance our understanding of how P. falciparum disposes and/or utilizes host-derived heme, and to specifically investigate a potential mechanism by which the commonly used anti-malarial drugs exert their toxicity. Resistance to chloroquine is becoming increasingly widespread, and occurs via efflux mechanisms that prevent drug accumulation within the parasite. If parasite survival is intricately associated with the status of a physiologic cytosolic heme pool, this may represent another drug development target that circumvents the known resistance mechanism.

描述（由申请人提供）：在恶性疟原虫疟原虫感染期间，大量的血红蛋白量会在专门的食物液泡中被肉毒内寄生虫降解。释放的氨基酸用于支持生长，但血红素主要被排毒以在食物液泡中进行血液毒素。但是，目前尚不清楚寄生虫的细胞质及其在寄生虫生理学中的作用有多少血红素分区。此外，已经提出了一种常用的抗疟疾药物来增加胞质血红素的通量，但尚未证明这一点。我们将通过使用功能性方法而不是容易遇到生物系统中大误差的质量平衡测量方法来解决这些问题。我们的目标是（1）使用SELEX开发高亲和力RNA适体，并将其引入恶性疟原虫，并确定它们在存在和不存在氯喹的情况下对寄生虫生存的影响。预计适体鉴于其负电荷为胞质，并且不应干扰食物液泡中的血红素聚合，从而提供了一种工具来选择性地研究细胞质中的血红素池。这些研究对于促进我们对恶性疟原虫如何处置和/或利用宿主衍生的血红素的理解非常重要，并专门研究了一种潜在的机制，通常使用常用的抗疟疾药物施加其毒性。对氯喹的耐药性正变得越来越普遍，并且通过排出机制发生，从而防止药物在寄生虫中积累。如果寄生虫的生存与生理胞质血红素池的状态相关，则可能代表了绕过已知抗性机制的另一个药物发育靶标。