MOLECULAR BIOLOGY OF THE DELTA AGENT

Delta Agent 的分子生物学

• 批准号: 3146056
• 负责人: HUGH D ROBERTSON
• 金额: $ 25.22万
• 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/3146056
• 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.

类病毒和类病毒病原体--特别是 负责丁型肝炎-提供RNA种类的例子， 依赖于细胞成分的生命周期， 这些成分和细胞病理学的潜在失衡。 几 几年前，我们提出了一个1700个碱基的基因组RNA的两域模型， δ因子，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”结构域，现在已知其包含： RNA切割核酶的活动，我们已经表明，含有一个共同的 基序并能够反式切割;与具有相同基序的序列同源的区域， 丰富的细胞RNA（SRP RNA）;两个替代的二级 结构;和至少一个局部三级结构的元素。 这些 的特点，以及一个显着的保护区的一个地区， 在十多个delta菌株中测序的类病毒结构域， 表明该RNA结构域具有多种功能，包括 细胞蛋白质的结合位点。 我们认为，许多 这一小RNA区域的功能--以及它进行结构化改造的能力， 变化--是相关的;而从一个变化到另一个变化的控制 另一种结构也可以控制生物功能。 我们的具体目标是（i）进行详细的结构：功能 类δ病毒RNA保守区的研究 为了解释其结构特征如何与核酶作用相关， 和对照、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一努力的关键; (ii)研究δ发病机制，以确定细胞的COM- 组分（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 发现在三角洲肝炎;和（iii）研究细胞成分， 参与delta RNA复制的delta RNA结构。