UIS2 function in establishing transport mechanisms at the malaria parasite-host cell interface

项目摘要 疟疾仍然是一个严重的公共卫生问题。疟疾控制进展缓慢 近年来，虽然在最受影响的地区出现了对一线抗疟药物的耐药性， 强调迫切需要破译寄生虫的基本生物学， 治疗选择在致病性血液阶段，疟原虫在一个 宿主红细胞内的保护性空泡。效应蛋白从液泡重塑中输出 宿主细胞创造了一个复制的小生境，而营养物质的运输穿过这个屏障， 寄生虫快速生长这两个过程都依赖于一个液泡膜孔， 寄生虫蛋白EXP 2，它允许宿主胞质溶胶和 空泡，也组装成PTEX复合物，介导效应子的易位。 蛋白质进入宿主细胞。虽然这些机制对寄生虫的生存和疾病至关重要， 发病机制，目前还不清楚EXP 2/PTEX功能是如何具体建立在液泡 膜的我们最近发现了EXP 2/PTEX和UIS 2之间的相互作用， 也定位于液泡的寄生虫蛋白质。初步观察表明，UIS 2是一个 疟原虫液泡膜整合蛋白与UIS 2的条件性敲低 恶性疟原虫在蛋白质输出方面具有重要功能。我们假设UIS 2是 需要在PVM中建立EXP 2功能，关键地使蛋白质输出和 养分吸收UIS 2含有紫色酸性磷酸酶结构域，但不太可能是 催化活性，因为它似乎缺少几个关键的金属配位残基。目标1将 研究了UIS 2的膜缔合和拓扑结构，并评价了其催化活性。 体外磷酸酶结构域及其对体内UIS 2功能的重要性。目标2将调查 通过测定UIS 2在跨液泡膜运输中的精确影响， EXP 2和营养孔的形成。这些研究将确定UIS 2在PVM中的作用 对寄生虫生存和疟疾病理学至关重要的运输过程。有趣的是，UIS 2广泛地 保守的空泡居住apicomplexans和弓形虫直系同源的UIS 2，已知 如GRA 44，对于类似但机制上不同的蛋白质输出途径也是关键的。 因此，UIS 2/GRA 44可能代表了这些细胞中液泡输出机制的统一特征。 不同的apicomplexans，可以提出新的，广泛适用的控制策略， 重要的病原体。

Project Summary Malaria disease remains a serious public health problem. Progress in Malaria control has slowed in recent years while resistance to frontline antimalarials is emerging in the most afflicted regions, underscoring a pressing need to decipher the fundamental biology of the parasite to provide novel therapeutic options. During the pathogenic blood stage, malaria parasites develop within a protective vacuole inside host erythrocytes. Export of effector proteins out of the vacuole remodels the host cell to create a niche for replication while transport of nutrients across this barrier fuels rapid parasite growth. Both of these processes depend on a vacuole membrane pore formed by the parasite protein EXP2, which allows small molecule exchange between the host cytosol and vacuole and is also assembled into the PTEX complex to mediate translocation of effector proteins into the host cell. While these mechanisms are critical to parasite survival and disease pathogenesis, it is unknown how EXP2/PTEX function is specifically established in the vacuole membrane. We recently identified an interaction between EXP2/PTEX and UIS2, a secreted parasite protein that also localizes to the vacuole. Preliminary observations suggest UIS2 is an integral protein of the vacuolar membrane and conditional knockdown of UIS2 in Plasmodium falciparum revealed an essential function in protein export. We hypothesize that UIS2 is required to establish EXP2 function in the PVM, critically enabling both protein export and nutrient uptake. UIS2 contains a purple acid phosphatase domain but is unlikely to be catalytically active as it appears to be missing several key metal coordinating residues. Aim 1 will study the membrane association and topology of UIS2 and evaluate the catalytic activity of the phosphatase domain in vitro and its importance to UIS2 function in vivo. Aim 2 will investigate the function of UIS2 in transport across the vacuolar membrane by determining its precise impact on EXP2 and formation of the nutrient pore. These studies will define the role of UIS2 in PVM transport processes critical to parasite survival and Malaria pathology. Intriguingly, UIS2 is broadly conserved among vacuole-dwelling apicomplexans and the Toxoplasma ortholog of UIS2, known as GRA44, is also critical to an analogous but mechanistically distinct protein export pathway. Thus UIS2/GRA44 may represent a unifying feature of the vacuolar export machinery in these diverse apicomplexans that could suggest novel, widely applicable control strategies for this important group of pathogens.