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）：跨质膜运输是所有细胞生理学的一个关键特征。质膜上的许多看门人都受到跨膜离子和电场梯度的协助。细胞消耗大量能量（高达细胞内 ATP 的 50%）来维持这种电化学梯度。在疟原虫中，利用电化学梯度对质膜充电以实现这种运输的能源经济性实际上仍然未知。事实上，疟疾寄生虫的红细胞阶段主要通过底物水平磷酸化获得 ATP，每个葡萄糖分子仅产生两个 ATP 分子，这一事实必然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，疟原虫物种含有植物样能量保存、膜相关的 H* 泵焦磷酸酶的两个成员（PfVP1 和 PfVP2）。植物的液泡焦磷酸酶 (V-PPase) 耦合无机焦磷酸 (PPi) 磷酸酐键水解产生的能量，将 Hv 泵送穿过液泡膜。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，Hv 跨寄生虫质膜的易位可以通过 PPase 的 PPi 水解以及 V 型 ATPase 的 ATP 水解来激活。由于动物细胞不具有 V-PPase 同源物，因此疟原虫中这些酶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学的贡献。将探讨疟原虫的V-ATP酶在高能量需求下利用V-PPase产生的质子动力反向合成ATP的可能性。此外，还将研究在疟疾寄生虫的 FoF1-ATP 合酶中观察到的不寻常的亚基结构，以评估这种通常为线粒体的质子泵复合物对寄生虫生理学的贡献。该项目的结果有可能要求我们对疟疾寄生虫生物能学的观点进行重大修改。该项目可能会发现疟疾寄生虫的质子稳态和生物能学的独特特征，这可能成为设计疟疾控制新方法的基础。