REGULATION OF MICROBIAL NITROGEN METABOLISM

这项研究的总体目标是了解基因表达是如何 是对氮等全球调控信号的反应而激活的 饿死了。特别是，本研究的重点是如何不同 正激活剂、NAC和CAP-cAMP(对氮和碳的响应 饥饿)可以各自激活相同的转录 启动子，胡图族组氨酸利用操纵子的启动子。 NaC对反应动力学参数(速率常数和屈服常数)的影响 用于RNA聚合酶的转录启动。这些影响将是 与NAC激活的al嵌合Hut-lac启动子上的基因相比 从LacZ启动子转录而来。同样，CAP-cAMP的作用 关于胡图族启动者的决定将被确定为与NAC和 解释胡图族内两个不同的CAP结合位点的影响 推动者。一组平行的实验将检验相互作用。 在NAC和RNA聚合酶之间，特别是集中在C- A亚基的末端结构域。 此外，NAC抑制某些基因转录的能力 (例如，ghdA基因)将被检查以解释为什么NAC的压制 似乎比激活更复杂。新来港定居人士的架构 蛋白质本身将通过组合物理方法(例如 NAC最小活性结构域的结晶学和鉴定 和遗传方法(识别与DNA、RNA相互作用的结构域 聚合酶等)。 最后，这一项目将导致继续改善 产气克雷比氏菌遗传分析工具，包括对 噬菌体lambda的一种新的溶源模式及一种新形式的分析 不依赖于NTR的氮素调节。

The overall goal of this research is to understand how gene expression is activated in response to global regulatory signals like nitrogen starvation. In particular, this research focuses on how to different positive activators, NAC and CAP-cAMP (responding to nitrogen and carbon starvation respectively) can each activate transcription from the same promoter, the hutU promoter of the histidine utilization operons. The effects of NAC on the kinetic parameters (rate and yield constants) for transcription initiation by RNA Polymerase. These effects will be compared with those at al chimeric hut-lac promoter where NAC activates transcription from the lacZ promoter. Similarly, the effects of CAP-cAMP on the hutU promoter will be determined both to compare with NAC and to explain the effects of two different CAP-binding sites within the hutU promoter. A parallel set of experiments will examine the interactions between NAC and RNA Polymerase, concentrating especially on the C- terminus domain of the a subunit. In addition, the ability of NAC to repress transcription of some genes (e.g. the ghdA gene) will be examined to explain why repression by NAC appears to be more complex than activation. The structure of the NAC protein itself will be probed by a combination of physical methods (e.g. crystallography and identification of the smallest active domain of NAC) and genetic approaches (to identify domains that interact with DNA, RNA Polymerase, etc). Finally this project will result in the continued improvement of the tools for genetic analysis of Klebisella aerogenes, including a study of a novel mode of lysogeny for phage lambda, and an analysis of a new form of NTR-independent nitrogen regulation.