Essential function of a putative glycosyltransferase in P. falciparum

项目摘要 致命的人类疟疾是由细胞内寄生虫恶性疟原虫引起的， 每年造成近45万人死亡这些寄生虫感染导致约2.5亿感染 每年.然而，目前还没有有效的疟疾疫苗， 对临床上使用的所有抗疟药物都有抗药性。此外，这些耐药菌株正在蔓延 在全世界都有。因此，确定寄生虫使用的基本药物途径至关重要 在人类宿主细胞中生长其中一个鲜为人知但至关重要的途径是 寄生虫蛋白质的糖分子或聚糖。在其他模式生物中， 蛋白质的功能，主要发生在分泌途径。疟原虫的最新研究 已经表明几种寄生虫表面配体的聚糖修饰在寄生虫中起重要作用， 传播及其在蚊媒中的发展。但我们对它的功能知之甚少， 在临床上重要的恶性疟原虫红细胞内生长过程中的糖基化。我们最近 确定了一个假定的糖基转移酶作为一个重要的相互作用的热休克蛋白居住在 内质网为了研究其在寄生虫生长的红细胞内阶段的功能，我们 产生了这种蛋白质的条件突变体。我们假设，糖基转移酶的功能， 该蛋白在恶性疟原虫红细胞内生长过程中起着重要作用。我们的初步 数据显示，这种蛋白质是人体红细胞内寄生虫生长所必需的， 用于在红细胞内生命周期结束时从宿主细胞排出子寄生虫。使用 细胞，生物化学和遗传学方法，我们将定义这个基因在出口过程中的功能。 寄生虫的女儿推测的糖基转移酶活性对寄生虫存活的重要性将 得到考验拟议的研究将使用重组酶来定义其酶活性 糖基转移酶邻近依赖性生物素化方法与质谱联用 将被用来确定相互作用以及推定的基板。这个项目的成功将揭示 寄生虫用于人红细胞无性扩增的新的和必需的糖基化途径 血细胞

Project Summary The lethal form of human malaria is caused by the intracellular parasite Plasmodium falciparum, which causes nearly 450,000 deaths every year. Infection by these parasites results in ~250 million infections each year. However, there are no effective vaccines against malaria and the parasite has gained resistance to all antimalarial drugs used in the clinic. Further, these drug-resistant strains are spreading throughout the world. Therefore, it is crucial to identify essential druggable pathways used by the parasite to grow within human host cells. One such poorly understood but essential pathway is the modification of parasite proteins by sugar molecules or glycans. In other model organisms, this process is essential for protein function and mostly occurs in the secretory pathway. Recent work in Plasmodium parasites has shown that glycan modification of several parasite surface ligands play an essential role in parasite transmission and its development within the mosquito vector. But little is known about the function, if any, of glycosylation during the clinically important intraerythrocytic growth of P. falciparum. We recently identified a putative glycosyltransferase as an essential interactor of a heat shock protein residing in the endoplasmic reticulum. To study its function during the intraerythrocytic stages of parasite growth, we generated conditional mutants for this protein. We hypothesize that the glycosyltransferase function of this protein plays an essential function during intraerythrocytic growth of P. falciparum. Our preliminary data show that this protein is essential for parasite growth within human red blood cells and is required for the egress of daughter parasites from the host cell at the end of the intraerythrocytic life cycle. Using cellular, biochemical, and genetic approaches, we will define the function of this gene during egress of daughter parasites. The essentiality of the putative glycosyltransferase activity for parasite survival will be tested. The proposed studies will use recombinant enzyme to define the enzymatic activity of this glycosyltransferase. Proximity-dependent biotinylation approaches combined with mass spectrometry will be used to identify interactors as well as putative substrates. The success of this project will reveal novel and essential glycosylation pathways used by the parasite for asexual expansion in human red blood cells.