AUTOREGULATION AND GLOBAL CONTROL OF THE CRP OPERON

环磷酸腺苷是许多生物体中的关键化合物，参与调节 正常和异常细胞生长的许多方面和 差异化。在大多数系统中，这种控制是由循环AMP介导的 结合蛋白。这种蛋白质是生物功能所必需的。 环状AMP，在某些情况下，该蛋白质还参与调节 环状AMP合成。了解循环AMP的水平如何 结合蛋白的调控是理解结合蛋白如何被控制的一个重要方面 该关键控制元素在单元格中起作用。我们已经开始研究…… 大肠杆菌中环磷酸腺苷结合蛋白(CRP)的调控。我们的 初步研究表明，表达控制有一种独特的机制 C反应蛋白操纵子。这一机制涉及到环磷酸腺苷的激活。 和CRP的差异转录的RNA，在接近开始的时候开始 C反应蛋白转录，但在相反的链上。这种RNA阻止了 C反应蛋白基因的合成。我们希望通过体外实验继续这些研究。 以及体内技术来证明这一新的机制调节CRP 并了解其作用的分子基础。离体 工作将包括定点突变，即分化的影响 RNA的转录和实验，以测试发散的RNA是否形成 C-反应蛋白基因5‘端的双链。活体实验将重点放在 利用C反应蛋白和发散启动子的克隆片段评价 分化转录在体内调节CRP中的作用。

Cyclic AMP is a key compound in many organisms involved in regulating numerous aspects of normal and abnormal cellular growth and differentiation. In most systems this control is mediated by a cyclic AMP binding protein. This protein is necessary for the biological function of cyclic AMP and, in some cases, the protein is also involved in regulating cyclic AMP synthesis. A knowledge of how the levels of the cyclic AMP binding protein is controlled is an important aspect of understanding how this key control element functions in the cell. We have begun a study of the regulation of the cyclic AMP binding protein (CRP) in E. coli. Our initial investigations suggest a unique mechanism for control of expression of the crp operon. This mechanism involves the activation by cyclic AMP and CRP of a divergently transcribed RNA that initiates close to the start of crp transcription but on the opposite strand. This RNA blocks the synthesis of crp mRNA. We wish to continue these studies using in vitro and in vivo techniques to prove that this novel mechanism regulates crp expression and to understand the molecular basis for its action. In vitro work will include site directed mutagenesis, the effect of the divergent RNA on transcription and experiments to test if the divergent RNA forms a duplex with the 5' end of crp mRNA. In vivo experiments will focus on the use of cloned fragments of the crp and divergent promoter to assess the role of the divergent transcription in crp regulation in vivo.