Dissecting the roles of protein O-GlcNAcylation in Toxoplasma gondii

描述（由申请方提供）：弓形虫是顶复门中的一种专性细胞内寄生虫。这种寄生虫会导致艾滋病患者和免疫力低下者患上危及生命的疾病，并在妇女怀孕期间感染时导致出生缺陷或流产。T.人体内的弓形虫是快速分裂的速殖子和潜伏的缓殖子之间的相互转化。尽管它的病理意义，信号分子和机制的基础上，这一过程是知之甚少。 近年来，在T.刚地。OGT将单个<$-N-乙酰葡糖胺添加到细胞内蛋白质的丝氨酸或苏氨酸残基。因为在哺乳动物生物体中，O-GlcNAc是响应细胞营养或应激的细胞内信号传导、转录调节和蛋白质运输的介体，我们假设O-GlcNAc可能在T.通过动态修饰胞内蛋白质实现弓形虫速殖子和缓殖子之间的生命周期转换。为了验证这一假设，我们将使用化学酶的方法来鉴定T.弓形虫速殖子（Aim 1）。接下来，我们将应用这种方法对T.弓形虫速殖子-缓殖子转变我们将把我们的研究重点放在参与这一过程的基因调控蛋白上。一旦确定，我们将 表征O-GlcNAc在介导这些经修饰的蛋白质在该生命周期转变中的生物学功能中的作用（目的2）。最后，我们将描述如何在全球变化 OGT介导的蛋白O-GlcNAc化影响T.弓形虫（Aim 3）。

DESCRIPTION (provided by applicant): Toxoplasma gondii is an obligate intracellular parasite in the phylum Apicomplexa. This parasite causes life-threatening diseases in AIDS patients and immune-compromised individuals, and birth defects or abortions when women are infected during pregnancy. An essential process for pathogenesis and persistence of T. gondii in human hosts is the interconversion between the rapidly dividing tachyzoites and latent bradyzoites. Despite its pathological significance, the signaling molecules and the mechanisms underlying this process are poorly understood. Recently, ubiquitous O-GlcNAcylation and O-GlcNAc transferase (OGT), the enzyme that catalyzes this process, have been identified in T. gondii. OGT adds a single ¿-N-acetylglucosamine to serine or threonine residues of intracellular proteins. Because in mammalian organisms, O-GlcNAc is a mediator of intracellular signaling, transcription regulation, and protein trafficking in response to cellular nutrients or stress, we hypothesize that O-GlcNAc may serve as an active player in T. gondii's life cycle transition between tachyzoites and bradyzoites by dynamically modifying intracellular proteins. To test this hypothesis, we will use a chemoenzymatic approach to identify O-GlcNAc-modified proteins in T. gondii tachyzoites (Aim 1). Next, we will apply this approach for comparative analysis of changes in protein O-GlcNAc status in T. gondii tachyzoite-bradyzoites transition. We will focus our studies on gene-regulatory proteins that are involved in this process. Once identified, we will characterize the role of O-GlcNAc in mediating the biological functions of these modified proteins in this life-cycle transition (Aim 2). Finally, we will characterize how changes in global protein O-GlcNAcylation mediated by OGT influence the life-cycle transition of T. gondii (Aim 3).