MOLECULAR BIOLOGY OF THE DELTA AGENT

Delta Agent 的分子生物学

• 批准号: 2066065
• 负责人: HUGH D ROBERTSON
• 金额: $ 27.41万
• 依托单位: WEILL MEDICAL COLL OF CORNELL UNIV
• 依托单位国家: 美国
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-07-01 至 1997-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2066065
• 关键词: RNA; RNase protection assay; binding proteins; chemical binding; chemical cleavage; chemical kinetics; chemical structure function; enzyme mechanism; enzyme substrate; genetic mapping; genome; hepatitis; molecular biology; nucleic acid biosynthesis; nucleic acid sequence; nucleic acid structure; pancreatic ribonuclease; pathologic process; protein signal sequence; radiotracer; receptor; ribozymes; tissue /cell culture

The viroids and viroid-like pathogens--and particularly the agent responsible for delta hepatitis--provide examples of RNA species heavily dependent on cellular components for their life cycles, creating potential imbalances in these components and cellular pathology. Several years ago we proposed a two-domain model for the 1700-base genomic RNA of the delta agent, in which the non-coding RNA was highly conserved and contained most or all of the functional domains needed for replication. This model has received wide support, and the non-coding domain has been named the "viroid-like" domain, which is now known to contain: RNA-cleaving ribozyme activities, which we have shown to contain a common motif and to be capable of trans cleavage; a region of homology with an abundant cellular RNA (the SRP RNA); two alternative secondary structures; and at least one element of local tertiary structure. These features, together with a remarkable conservation of a region of the viroid-like domain in more than ten delta strains sequenced, strongly suggest multiple functions for this RNA domain which could include binding sites for cellular proteins. We believe that many of the functions of this small RNA region--and its ability to undergo structural variation--are related; and that control of the transition from one structure to another may also control biological function. Our specific goals are (i) to carry out detailed structure:function studies on the conserved region of the delta viroid-like RNA domain in order to explain how its structural features relate to ribozyme action and control, cellular protein binding, and functional RNA transitions. The newly discovered trans ribozyme reactions will be key to this effort; (ii) to study delta pathogenesis in order to identify the cellular com- ponents (such as RNA or proteins from the SRP particles or cellular antiviral factors) which could explain the severe symptoms sometimes found in delta hepatitis; and (iii) to study cellular components and delta RNA structure involved in delta RNA replication.

类病毒和类类病毒病原体——特别是病原体 造成丁型肝炎的原因——大量提供 RNA 种类的例子 其生命周期依赖于细胞成分，创造 这些成分和细胞病理学的潜在不平衡。 一些 几年前，我们提出了 1700 个碱基的基因组 RNA 的双结构域模型 delta 剂，其中非编码 RNA 高度保守， 包含复制所需的大部分或全部功能域。 该模型得到了广泛的支持，非编码域已被 命名为“类病毒”域，目前已知包含： RNA 切割核酶活性，我们已证明其包含一个常见的 基序并能够进行反式切割；同源区域 丰富的细胞RNA（SRP RNA）；两个替代次要 结构；以及至少一种局部三级结构元素。 这些 特色，以及对该地区的显着保护 已测序的十多个 delta 菌株中的类病毒结构域，强烈 建议该 RNA 结构域具有多种功能，其中可能包括 细胞蛋白质的结合位点。 我们相信，许多 这个小RNA区域的功能——以及它进行结构性改变的能力 变异——相关；以及对从一个过渡的控制 结构与另一种结构也可能控制生物功能。 我们的具体目标是（i）进行详细的结构：功能 δ类病毒RNA结构域保守区的研究 以解释其结构特征与核酶作用的关系 和控制、细胞蛋白结合和功能性 RNA 转换。 新发现的反式核酶反应将是这项工作的关键； (ii) 研究 Delta 发病机制，以确定细胞成分 成分（例如来自 SRP 颗粒或细胞的 RNA 或蛋白质） 抗病毒因素）有时可以解释严重的症状 见于丁型肝炎； (iii) 研究细胞成分和 参与 delta RNA 复制的 delta RNA 结构。