Transcriptional Regulation in Giardia lamblia

描述：（由申请人提供）：贾第鞭毛虫是一个最 流行的寄生原生生物和世界范围内的疟疾疾病的主要原因。 一种寄生的生活方式和一种从真核生物 树允许Giardia开发独立的解决方案， 真核细胞问题。这种生物多样性有助于 他们致病的能力贾第虫生物学的显著特征是其两个 细胞核及其异常紧凑和可塑的基因组。我们的长期目标是 了解基因组结构对基因表达的影响。一 其基本出发点是对转录调控的研究。虽然 转录的“规则”已经在高等真核生物中被描绘出来， 在低等真核生物和古生菌中的研究清楚地表明， 基因表达的机制贾第鞭毛虫基因转录的研究 因此，作为理解蛋白质表达的先决条件， 参与发病机制，同时也进一步了解 转录机制的一部分。我们将检验两个关于RNA的假设 蓝氏贾第鞭毛虫中聚合酶II的转录：（I）贾第鞭毛虫将含有一个 简化和简并核心启动子。两个核心启动子元件，TATA 盒和启动器元件（Inr），将存在，尽管基于它们的 类似的序列特征，它们将能够独立地启动 转录。TATA结合蛋白的同源物将存在以指导 TATA盒和mnr的转录。(II)松弛序列 转录起始的限制和四倍体的存在 分布在两个细胞核之间的基因组表明， 在染色质和细胞核水平的调控。为了实验性地测试这些 假设，我们将总结四个具体目标：（1）表征的 在我们的模型启动子-α-2微管蛋白中核心启动子元件所起的作用。 (2)隐蔽启动子元件的表征。(3)功能 TATA结合蛋白（TBP）的同源物的表征。(4)考试 在染色质和核水平上的转录调控。这些研究 将建立对蓝氏贾第鞭毛虫转录的理解， 基因表达调控作用的研究基础 疾病

DESCRIPTION: (provided by the applicant): Giardia lamblia is one of the most prevalent parasitic protists and a major cause of diarrheal disease worldwide. A parasitic lifestyle and an extremely early divergence from the eukaryotic tree have permitted Giardia to develop independent solutions to common eukaryotic cellular problems. This biological diversity is instrumental in their ability to cause disease. Notable features of Giardia biology are its two nuclei and its unusually compact and plastic genome. Our long-term goal is to understand the consequences that genomic structure exerts on gene expression. A fundamental starting point is the study of transcriptional regulation. Although 'rules' of transcription have been delineated in higher eukaryotes, extensive work in lower eukaryotes and archaea have clearly indicated many differences in the mechanics of gene expression. Investigation of transcription in Giardia is therefore important both as a prerequisite to understand expression of proteins involved in pathogenesis and also to further our understanding of the evolution of transcriptional machinery. We will test two hypotheses regarding RNA Polymerase II transcription in Giardia lamblia: (I) Giardia will contain a simplified and degenerate core promoter. Two core promoter elements, the TATA box and initiator element (Inr), will be present, although based on their similar sequence profiles, they will be independently able to initiate transcription. A homologue of TATA binding protein will be present to direct transcription from both the TATA box and mnr. (II) The relaxed sequence constraints for transcription initiation and the presence of a tetraploid genome distributed between two nuclei suggests an enhanced role for gene regulation at the chromatin and nuclear level. To experimentally test these hypotheses we will ronduct four specific aims: (1) Characterization of the roles served by core promoter elements in our model promoter - alpha-2 tubulin. (2) Characterization of cryptic promoter elements. (3) Functional rharacterization of a homologue of TATA binding protein (TBP). (4) Examination of transcriptional regulation at the chromatin and nuclear level. These studies will build an understanding of transcription in Giardia lamblia and lay foundations for study of the role of the regulation of gene expression in disease.