BIOENERGETICS AND PROTON PUMPS IN MALARIA PARASITES

疟疾寄生虫中的生物能量学和质子泵

• 批准号: 6760043
• 负责人: AKHIL B VAIDYA
• 金额: $ 33.75万
• 依托单位: DREXEL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-07-01 至 2007-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6760043
• 关键词: BIOENERGETICS; PROTON; PUMPS; MALARIA; PARASITES

DESCRIPTION (provided by the applicant): Transport across the plasma membrane is a critical feature of all cellular physiology. Many gatekeepers at the plasma membrane are assisted by ionic and electric gradients across the membrane. Cells expend enormous energy-- up to 50% of intracellular ATP-- for maintenance of such electrochemical gradients. Energy economics of charging the plasma membrane with an electrochemical gradient for such transport remains virtually unknown in malaria parasites. The fact that erythrocytic stages of malaria parasites derive their ATP mainly through substrate-level phosphorylation, eking out a mere two ATP molecules per glucose molecule, must place significant constraints on parasite energy utilization. This project seeks to explore an alternate and/or adjunct energy source for malaria parasites. Recent evidence shows that Plasmodium species contains two members (PfVP1 and PfVP2) of the plant-like energyconserving, membrane-associated H*-pumping pyrophosphatases. The vacuolar pyrophosphatases (V-PPases) of plants couple the energy generated by hydrolysis of the phosphoanhydride bond of inorganic pyrophosphate (PPi) to pump Hv across the vacuolar membrane. In malaria parasites, preliminary data suggest that the enzyme is located within the parasite plasma membrane. This location would suggest that Hv translocation across the parasite plasma membrane could be energized through PPi hydrolysis by the PPases in concert with ATP hydrolysis by the V-type ATPase. Because animal cells do not possess homologues of V-PPases, the presence of these enzymes in malaria parasites offers candidates for devising selectively toxic inhibitors. This project will undertake basic investigations on the biochemistry and cell biology of PfVP1 and PfVP2. Gene disruption approaches will be undertaken to assess contributions made by these molecules to the parasite physiology. The possibility that V-ATPase of malaria parasites may function work in reverse to synthesize ATP by using the proton motive force generated by the V-PPases under high-energy demand will be explored. Furthermore, an unusual subunit configuration observed for the FoF1-ATP synthase of malaria parasites will be investigated to assess the contribution of this usually mitochondrial proton pumping complex to parasite physiology. Results from this project have a potential to require a major revision of our view of malaria parasite bioenergetics. Unique features of proton homeostasis and bioenergetics in malaria parasites likely to be uncovered in this project could form the basis for devising novel approaches to malaria control.

描述（由申请方提供）：跨质膜转运是所有细胞生理学的关键特征。质膜上的许多看门人都受到跨膜离子和电梯度的帮助。细胞消耗巨大的能量-高达50%的细胞内ATP-以维持这种电化学梯度。在疟疾寄生虫中，用电化学梯度为质膜充电以进行这种运输的能量经济学仍然几乎未知。疟疾寄生虫的红细胞阶段主要通过底物水平的磷酸化来获得ATP，每个葡萄糖分子只需要两个ATP分子，这一事实必须对寄生虫的能量利用产生重大限制。该项目旨在探索疟疾寄生虫的替代和/或辅助能源。最近的证据表明，疟原虫物种包含两个成员（PfVP 1和PfVP 2）的植物样节能，膜相关的H* 泵焦磷酸酶。植物的液泡焦磷酸酶（V-PPases）通过偶联无机焦磷酸盐（PPi）的磷酸酐键水解产生的能量来泵送Hv穿过液泡膜。在疟疾寄生虫中，初步数据表明这种酶位于寄生虫质膜内。该位置表明，Hv穿过寄生虫质膜的易位可以通过PPi水解而被PPases激活，同时通过V型ATP酶水解ATP。由于动物细胞不具有V-PPases的同源物，这些酶在疟疾寄生虫中的存在为设计选择性毒性抑制剂提供了候选者。该项目将对PfVP 1和PfVP 2的生物化学和细胞生物学进行基础研究。基因破坏的方法将进行评估这些分子的寄生虫生理学的贡献。疟原虫的V-ATP酶在高能量需求下利用V-PPases产生的质子动力反向工作合成ATP的可能性将被探索。此外，观察到的疟疾寄生虫的FoF 1-ATP合酶的一个不寻常的亚基配置将进行调查，以评估这种通常线粒体质子泵复合物寄生虫生理的贡献。这个项目的结果有可能需要我们对疟原虫生物能量学的看法进行重大修改。在这个项目中可能发现的疟疾寄生虫的质子稳态和生物能量学的独特特征可以形成设计疟疾控制新方法的基础。