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， 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 一种环腺苷酸结合蛋白。 这种蛋白质是必需的， 环磷酸腺苷的生物学功能，在某些情况下， 也参与调节环AMP合成。 知识 环磷酸腺苷结合蛋白的水平被控制 是理解这个关键控制 元素在细胞中发挥作用。 我们已经开始研究 对E.杆菌 我们 初步调查显示，有一种独特的机制， CRP操纵子的表达。 该机制涉及 通过环AMP和CRP激活发散转录的RNA 在crp转录开始时启动， 相反的链。 该RNA阻断crp mRNA的合成。 有证据表明，体内CRP的自身调节也涉及 这个机制。 我们希望继续这些研究， 和体内技术来证明这种新的机制调节 crp表达和了解其分子基础， 行动上 体外工作将包括定点诱变， 转录的趋异RNA的影响和实验， 检测趋异RNA是否与crp的5'末端形成双链体 mRNA。 体内实验将集中在使用克隆的 crp和趋异启动子的片段，以评估 体内CRP调节中的趋异转录物。 其他系统 将进行研究，以确定这种新的调节机制， 参与控制其他基因的表达。

Cyclic AMP is a key compound in many organisms involved in regulation 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 low 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. Evidence suggests that autoregulation of crp in vivo also involves this mechanism. 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 of 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 transcript in crp regulation in vivo. Other systems will be examined to determine if this novel regulatory mechanism is involved in the control of the expression of additional genes.