MECHANISM OF SELECTIVE EXPRESSION OF TRNA GENES

TRNA基因选择性表达机制

• 批准号: 3282019
• 负责人: KAREN U SPRAGUE
• 金额: $ 15.85万
• 依托单位: UNIVERSITY OF OREGON
• 依托单位国家: 美国
• 财政年份: 1983
• 资助国家: 美国
• 起止时间: 1983-12-01 至 1994-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3282019
• 关键词: Bombycidae; DNA directed RNA polymerase; DNA footprinting; alanine; binding proteins; cell differentiation; cell free system; developmental genetics; endocrine gland /system; eukaryote; gene expression; genetic manipulation; genetic transcription; genome; immunochemistry; microinjections; nucleic acid probes; nucleic acid sequence; radiotracer; transcription factor; transfer RNA

The goal of this work is to discover the mechanism of differential transcription in vitro of two kinds of tRNA genes. These genes encode alanine tRNA in the silkworm, Bombyx mori, and they differentially regulated in this organism. One class (tRNAAlaC genes) encodes alanine tRNA that is common to all silkworm cell types. The other class (tRNAAlaSG genes) encodes a distinct alanine tRNA that is found only the silkgland. The proposed study addresses the general problem of eukaryotic gene control, and the specific problem of transcription by RNA polymerase III. Since RNA polymerase III acts in all cells of all eukaryotes, understanding its function has broad biological and medical significance. The transcription properties displayed by tRNAAlaSG genes in vitro are very different from those displayed by tRNAAlaC genes -- and probably provide the basis for differential regulation in vivo. Therefore, a mechanistic analysis of these in vitro properties is biologically relevant. The interesting features of tRNAAlaSG transcription in vitro are 1.) It is extremely inefficient (relative to tRNAAlaC transcription) under standard conditions, and 2.) It is as efficient as tRNAAlaC transcription under special conditions. These two states could correspond to the inactivity of tRNAAlaSG genes in most silkworm cell types, and their high level of activity (equivalent to tRNAAlaC genes) in the silkgland. The molecular basis of both of these properties will be investigated. Specifically, the proposed experiments will identify the interaction(s) with the transcription machinery, and the step in the transduction cycle that is less efficient for tRNAAlaSG templates. When the defect in tRNAAlaSG transcription has been localized, the mechanism for overcoming it will be analyzed. To determine whether specific stimulation of tRNAAlaSG transcription in vitro is due to a qualitative or a quantitative change in the transcription machinery, the stimulatory component(s) will be resolved from the remainder of the transcription machinery, and tested for its specific activity on the two kinds of tRNAAla genes.

这项工作的目标是发现差异的机制。 两种tRNA基因的体外转录。这些基因编码 家蚕体内的丙氨酸tRNA和它们的差异 在这种有机体中被调节的。一类(tRNAAlaC基因)编码丙氨酸 所有家蚕细胞类型所共有的tRNA。另一个类(tRNAAlaSG 基因)编码一种独特的丙氨酸tRNA，这种tRNA只存在于丝腺中。 拟议的研究解决了真核基因的一般问题。 控制，以及RNA聚合酶III转录的特定问题。 由于RNA聚合酶III在所有真核生物的所有细胞中发挥作用，因此理解 其功能具有广泛的生物学和医学意义。 TRNAAlaSG基因在体外表现出很强的转录特性 与tRNAAlaC基因显示的不同--可能提供了 体内差异调控的基础。因此，一个机械主义者 对这些体外特性的分析具有生物学意义。这个 TRNAAlaSG体外转录的有趣特征如下：1)它是 标准下效率极低(相对于tRNAAlaC转录) 条件，以及2.)它与tRNAAlaC转录一样有效 有特殊情况。这两种状态可以对应于 TRNAAlaSG基因在大多数家蚕细胞类型中的高水平 丝腺中的活性(相当于tRNAAlaC基因)。 这两种特性的分子基础将被研究。 具体地说，拟议的实验将确定相互作用(S) 转录机制，以及转导周期中的步骤 这对于tRNAAlaSG模板来说效率较低。当存在缺陷时， TRNAAlaSG转录已经本地化，克服它的机制 将会被分析。确定tRNAAlaSG的特异性刺激是否 在体外转录是由于一个质的或量的变化 转录机制，刺激成分(S)将被解析 从转录机器的其余部分，并测试其 两种tRNAAla基因的比活性。