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: 7002735
• 负责人: AKHIL B VAIDYA
• 金额: $ 32.96万
• 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/7002735
• 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（由申请人提供）：跨质膜的运输是所有细胞生理学的关键特征。质膜上的许多守门人都受到整个膜的离子和电梯度的帮助。细胞消耗巨大的能量（最多50％的细胞内ATP）来维持这种电化学梯度。用电化学梯度为这种运输的电化学梯度充电的能源经济学在疟疾寄生虫中几乎是未知的。疟疾寄生虫的红细胞阶段主要通过底物水平的磷酸化得出其ATP，每个葡萄糖分子只有两个ATP分子，必须对寄生虫能量利用施加重大约束。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，疟原虫含有植物样能量，与膜相关的H* - 倾斜的焦磷酸酶的两个成员（PFVP1和PFVP2）。植物的液泡焦磷酸酶（V-PPases）将无机焦磷酸盐（PPI）的磷酸氢键水解产生的能量泵送，以在整个液泡膜上泵送HV。在疟疾寄生虫中，初步数据表明该酶位于寄生虫质膜内。该位置表明，跨寄生虫质膜的HV易位可以通过PPASE与V型ATPase一起通过PPI水解通过PPI水解来通电。由于动物细胞不具有V-PPASE的同源物，因此疟疾寄生虫中这些酶的存在提供了制定选择性毒性抑制剂的候选者。该项目将对PFVP1和PFVP2的生物化学和细胞生物学进行基础研究。将采用基因破坏方法来评估这些分子对寄生虫生理的贡献。通过使用在高能需求下V-PPase产生的质子动力，疟疾寄生虫的V-ATPase可能会相反地合成ATP的可能性。此外，将研究针对疟疾寄生虫的FOF1-ATP合酶观察到的异常亚基构型，以评估该通常线粒体质子泵浦复合物对寄生虫生理的贡献。该项目的结果有可能对我们对疟疾寄生虫生物能学的看法进行重大修改。疟疾寄生虫中质子稳态和生物能学的独特特征可能在该项目中被发现可能是设计新型疟疾控制方法的基础。