The role of the interaction between the C-terminal domain of RNA pol II and a his

RNA pol II C 端结构域与组氨酸之间相互作用的作用

• 批准号: 8125891
• 负责人: Uchechi E Ukaegbu
• 金额: $ 5.13万
• 依托单位: WEILL MEDICAL COLL OF CORNELL UNIV
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-06-01 至 2013-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8125891
• 关键词: Acute; Adhesives; Adopted; Africa South of the Sahara; Antigenic Variation; Binding; Biochemical; Birds; C-terminal; Cell surface; Cells; Cessation of life; Child; Chiroptera; Chromatin; Chronic; Circular Dichroism; DNA Polymerase II; Data; Development; Disease; Dominant-Negative Mutation; Enzymes; Epigenetic Process; Epitopes; Erythrocyte Membrane; Erythrocytes; Eukaryota; Falciparum Malaria; Gene Expression; Gene Expression Regulation; Gene Family; Genes; Genetic; Genetic Transcription; Genome; Goals; Histones; Human; Immune; Immune system; In Vitro; Individual; Infection; Knock-out; Lead; Maintenance; Malaria; Mediating; Membrane Proteins; Memory; Methyltransferase; Molecular Conformation; Parasitemia; Parasites; Pharmaceutical Preparations; Phosphorylation; Phylogenetic Analysis; Plasmodium falciparum; Play; Polymerase; Population; Primates; Property; Proteins; RNA; RNA Polymerase II; RNA polymerase II largest subunit; Recombinants; Recruitment Activity; Rodent; Role; Switch Genes; System; Time; Vaccines; Virulence; Virulent; Work; Yeasts; base; chromatin modification; flexibility; histone methyltransferase; histone modification; member; mutant

DESCRIPTION (provided by applicant): The role of the interaction between the C-terminal domain of RNA pol II and a histone methyltransferase in mediating epigenetic memory in malaria virulence genes Plasmodium falciparum is responsible for the most acute and severe form of human malaria. This protozoan parasite infects the circulating red blood cells of its human host, placing on the infected cell surface the primary virulence and antigenic determinant, an adhesive protein called PfEMP1. Different forms of PfEMP1 are encoded by individual members of the large, multicopy var gene family. Only a single var gene is expressed at a time. Switching which var gene is expressed aids the parasite in its ability to evade clearance by the immune system and is referred to as antigenic variation. The mechanism by which the expression of individual var genes is regulated is poorly understood, however recent work has demonstrated that histone modifications play a significant role. Once a var gene is activated, it tends to remain active for many cellular divisions, a property referred to as "epigenetic memory." Studies have also shown that active transcription by RNA polymerase II is required for the maintenance of epigenetic memory of P. falciparum var genes, suggesting that the polymerase itself might play a role in maintaining the necessary chromatin modifications required for regulating var gene expression. In addition, it was recently shown that rodent parasites do not utilize epigenetic memory to control the expression of their virulence genes. Phylogenetic comparisons reveal an unusual expansion of the C-terminal domain (CTD) of the largest subunit of RNA pol II of primate parasites that is not found in parasites of rodents, birds or bats. Further, this region of RNA pol II has been shown to interact with chromatin modifying enzymes in higher eukaryotes, suggesting that it could be involved in maintenance of epigenetic memory. Interestingly, two specific histone modifying proteins, the histone methyltransferase PfSet2 and its cognate demethylase PfJmjC1, are similarly only found in primate parasites. Previous structural and biochemical work in yeast has shown that the phosphorylated form of the RNA pol II CTD can directly interact with Set2 to recruit it to actively transcribed genes, thus helping to maintain active chromatin at highly transcribed regions of the genome. Our hypothesis is that PfSet2 is recruited to transcriptionally active var genes through interactions with the phosphorylated CTD of P. falciparum RNA pol II to enforce epigenetic memory. The goal of this study is to determine if PfSet2 directly interacts with the CTD using biochemical and structural approaches, and to investigate the role of this interaction in the maintenance of epigenetic memory of var genes by introducing mutant forms of PfSet2 in P. falciparum. The long term goal is to determine the role of the interaction between the CTD and PfSet2 in promoting virulent mechanisms such as antigenic variation in P. falciparum. PUBLIC HEALTH RELEVANCE: Each year, millions of people worldwide are afflicted with P. falciparum malaria resulting in approximately a million deaths of mostly young children in sub-Saharan Africa. Previous work demonstrated that placement of an antigenic determinant called PfEMP1 on human red blood cells is essential for P. falciparum survival, and is regulated by a var gene switching mechanism that aids the parasite in its ability to evade the immune system. Understanding the regulation of this gene switching mechanism can lead to the development of more efficient drugs and possibly a vaccine against this acute and severe disease.

描述（由申请人提供）：RNA pol II的C末端结构域与组蛋白甲基转移酶之间的相互作用在介导恶性疟原虫疟疾毒力基因中的表观遗传记忆中的作用是导致最急性和最严重形式的人类疟疾的原因。这种原生动物寄生虫感染其人类宿主的循环红细胞，将主要毒力和抗原决定簇（称为PfEMP 1的粘附蛋白）置于受感染的细胞表面。不同形式的PfEMP 1由大的多拷贝var基因家族的个体成员编码。一次只表达一个var基因。转换var基因的表达有助于寄生虫逃避免疫系统清除的能力，被称为抗原变异。人们对单个var基因表达的调节机制知之甚少，但最近的工作表明组蛋白修饰发挥着重要作用。一旦var基因被激活，它往往会在许多细胞分裂中保持活性，这种特性被称为“表观遗传记忆”。“研究还表明，RNA聚合酶II的主动转录是维持恶性疟原虫var基因的表观遗传记忆所必需的，这表明聚合酶本身可能在维持调节var基因表达所需的染色质修饰方面发挥作用。此外，最近的研究表明，啮齿类寄生虫不利用表观遗传记忆来控制其毒力基因的表达。系统发育比较揭示了灵长类动物寄生虫的RNA聚合酶II的最大亚基的C-末端结构域（CTD）的不寻常的扩展，这在啮齿动物、鸟类或蝙蝠的寄生虫中没有发现。此外，RNA聚合酶II的这一区域已被证明与高等真核生物中的染色质修饰酶相互作用，这表明它可能参与维持表观遗传记忆。有趣的是，两个特定的组蛋白修饰蛋白，组蛋白甲基转移酶PfSet 2和它的同源脱甲基酶PfJmjC 1，同样只在灵长类寄生虫中发现。先前在酵母中的结构和生物化学工作已经表明，RNA pol II CTD的磷酸化形式可以直接与Set 2相互作用，将其募集到活跃转录的基因中，从而有助于在基因组的高度转录区域保持活性染色质。 我们的假设是PfSet 2通过与恶性疟原虫RNA pol II的磷酸化CTD相互作用被招募到转录活性var基因中，以加强表观遗传记忆。本研究的目的是确定PfSet 2是否直接相互作用的CTD使用生化和结构的方法，并调查这种相互作用的作用，在维护表观遗传记忆的var基因引入突变形式的PfSet 2恶性疟原虫。长期目标是确定CTD和PfSet 2之间的相互作用在促进恶性疟原虫中的毒力机制如抗原变异中的作用。 公共卫生相关性：每年，全世界有数百万人患有恶性疟原虫疟疾，导致大约100万人死亡，其中大多数是撒哈拉以南非洲的幼儿。以前的工作表明，在人类红细胞上放置一种称为PfEMP 1的抗原决定簇对恶性疟原虫的生存至关重要，并且受到var基因转换机制的调节，该机制有助于寄生虫逃避免疫系统的能力。了解这种基因转换机制的调节可以导致开发更有效的药物，并可能开发针对这种急性和严重疾病的疫苗。