RNA POLYMERASE II ELONGATION COMPLEX STRUCTURE/FUNCTION

基因的表达在一定程度上是通过调节RNA的能力来控制的 聚合酶II转录全长初级转录本。延伸率是 不仅仅是在不断增长的链条上增加单个核糖核苷酸单位； 相反，它的特点是在结构和结构上具有惊人的可塑性 RNA聚合酶可以承担的功能替代物。最新进展 已经确定了新的结构和功能中间体，它们是 监管事件的目标。转录过程可以通过以下方式阻止 称为基因内滞留位点和DNA结合的特定DNA元件 中断伸长的配基。只有少数几个逮捕地点是已知的 决定性的DNA序列还没有被解析。比伸长率 各种因素提高了核糖核酸链的合成效率。这样的两个因素， TFIIF和SIII(细长蛋白)与人类疾病有关，包括 癌症，表明转录聚合的扰动是 可能是有害的。这两个因素增加了平均链条 RNA聚合酶的延伸率II.一个额外的延伸率， SII，解救无法延长RNA的“受阻”RNA聚合酶II 链接，但仍保持模板使用状态。它通过激活一个新的 描述了在延伸复合体中发现的核糖核酸酶活性，范围为 细菌传给人类。TFIIF、SII和SIII可能控制 许多基因的输出，但几乎对其光谱一无所知 其表达依赖于这些和其他伸长的基因 各种因素。 我们建议通过系统的突变来定义被捕的人，并 建立一种测试它们在活细胞中的功能的方法。映射 实验将使我们能够定义分子的结构 RNA聚合酶II对催化链起重要作用的部分 伸长，并含有新生的RNA。实验计划是为了 观察不断增长的RNA链与RNA之间的变化关系 聚合酶II提议在复合体中发生，因为它们失去了延伸性 能力和能力来依靠延伸率因素拯救。我们将使用 在酵母中发现的易于停滞的突变RNA聚合酶II，以及 延长机制中的其他已知突变，以定义体内 对伸长因子和DNA序列的要求 在基因表达过程中对延伸因子辅助的要求。这个 将确定人类SII基因的细胞遗传学位置以确定 如果是S，那就是任何已知遗传性疾病的候选基因。本研究 将对RNA合成的基本过程提供有价值的见解 这将提高我们对正常和疾病状态的理解 分子水平。

Gene expression is controlled in part by regulating the ability of RNA polymerase II to transcribe full length primary transcripts. Elongation is not simply the addition of single ribonucleotide units to a growing chain; instead, it is characterized by a striking plasticity in structural and functional alternatives that RNA polymerases can assume. Recent advances have identified new structural and functional intermediates that are the target of regulatory events. The transcription process can be blocked by specific DNA elements called arrest sites within genes and DNA binding ligands that interrupt elongation. Only a few arrest sites are known and the defining DNA sequence has not been resolved. Specific elongation factors improve the efficiency of RNA chain synthesis. Two such factors, TFIIF and SIII (elongin), are implicated in human diseases including cancer, demonstrating that perturbation of transcript polymerization is potentially deleterious. These two factors increase the average chain elongation rate of RNA polymerase II. An additional elongation factor, SII, rescues "arrested" RNA polymerase iI that is unable to elongate RNA chains but remains template engaged. It does so by activating a newly described ribonuclease activity found in elongation complexes ranging from bacteria to humans. TFIIF, SII, and SIII can potentially control the output of many genes, yet virtually nothing is known about the spectrum of genes whose expression is dependent upon these, and other, elongation factors. We propose to define arrest sties by systematic mutagenesis and to establish an assay that measures their function in living cells. Mapping experiments will enable us to define the molecular architecture of the portions of RNA polymerase Ii that ar important for catalyzing chain elongation and harboring the nascent RNA. Experiments are planned to observe the changing relationship between the growing RNA chain and RNA polymerase Ii proposed to take place in complexes as they lose elongation competence and come to rely on elongation factor rescue. We will use an arrest-prone mutant RNA polymerase II identified in yeast, and yeast with other known mutations in the elongation machinery, to define the in vivo requirements for elongation factors and DNA sequences that precipitate a requirement for elongation factor assistance during gene expression. The cytogenetic location of the human SII gene will be identified to determine if it s a candidate gene for any known inheritable diseases. This study will provide valuable insight into the fundamental process of RNA synthesis which will improve our understanding of normal and disease states at the molecular level.