Elucidating the role of TSR glycosylation in Plasmodium parasites

项目概要_ 血小板反应蛋白1型重复序列（TSRs）是一种小的粘附蛋白结构域，在门中发现， 脊索动物、线虫和顶复体动物。携带TSR的蛋白质，通常定位于细胞 细胞表面或细胞外基质具有多种功能，包括细胞附着和运动。TSRs 通常在高度保守的基序处糖基化， 甘露糖和保守的丝氨酸或苏氨酸残基可以用O-连接的岩藻糖修饰。 疟原虫属的寄生虫，疟疾的病原体，表达10个保守的TSR- 在其生命周期的不同阶段携带蛋白质。破坏其中任何一个都会严重破坏或 阻止寄生虫的发育。研究最广泛的TSR携带蛋白是子孢子 表面蛋白CSP和TRAP。已经表明，这些蛋白质中的TSR含有结合到 蛋白聚糖，因此在寄生虫侵入宿主细胞中起作用。我们最近用质谱分析法 首次证明CSP和TRAP的TSR在体内被糖基化。这一发现 揭示了对这些研究得很好侵袭素理解上的一个缺口：携带TSR的蛋白质是关键的 疟原虫的生命周期，但没有人知道糖基化在维持其功能的作用 或毒性。 我们假设疟原虫中TSR的O-岩藻糖基化和C-甘露糖基化是疟原虫正常生长所必需的。 糖基化蛋白质的功能，我们预测，阻止这些蛋白质的糖基化将抑制 破坏疟原虫的生命周期。为了验证这一假设，我们将首先描述 恶性疟原虫中表达的所有携带TSR的蛋白质的糖基化状态。然后我们将生成 具有阻止特定蛋白质的TSR修饰的突变的转基因寄生虫系， 确定糖基化在这些毒力因子功能中的作用。

PROJECT SUMMARY _____ Thrombospondin type-1 repeats (TSRs) are small, adhesive protein domains that are found in phyla as diverse as chordates, nematodes, and apicomplexans. TSR-bearing proteins, which are typically localized to the cell surface or extracellular matrix, serve a wide variety of functions, including cell attachment and motility. TSRs are usually glycosylated at highly conserved motifs wherein tryptophans may be modified with a C-linked mannose and a conserved serine or threonine residue may be modified with an O-linked fucose. Parasites of the genus Plasmodium, the causative agent of the disease malaria, express ten conserved TSR- bearing proteins at various stages throughout their life cycle. Disrupting any one of them severely disrupts or halts parasite development. The most extensively studied of the TSR-bearing proteins are the sporozoite surface proteins CSP and TRAP. It has been shown that the TSRs in these proteins contain motifs that bind to proteoglycans and thus play a role in parasite invasion of host cells. We have recently used mass spectrometry to demonstrate for the first time that the TSRs of CSP and TRAP are glycosylated in vivo. This discovery revealed a gap in the understanding of these otherwise well-studied invasins: TSR-bearing proteins are critical to the Plasmodium life cycle, yet nothing is known about the role of glycosylation in maintaining their function or virulence. We hypothesize that the O-fucosylation and C-mannosylation of TSRs in Plasmodium is required for the proper function of the glycosylated proteins, and we predict that preventing glycosylation of these proteins will inhibit their function and disrupt the Plasmodium life cycle. In order to test this hypothesis, we will first characterize the glycosylation status of all TSR-bearing proteins expressed in P. falciparum. We will then generate transgenic parasite lines with mutations that prevent modification of the TSRs of specific proteins in order to determine the role of glycosylation in the function of these virulence factors.