GENE CONTROL IN INFECTION AND LYSOGENY BY PHAGE LAMBDA

我们的目的是了解E.大肠杆菌被修饰 通过由噬菌体λ基因Q编码的转录抗终止子。 抗终止作用是遗传调节的重要机制， 细菌，以及真核生物-例如在艾滋病毒的生长。 此外，许多细胞基因的表达可能受到以下因素的控制 在转录延长水平起作用的相关过程。的 所有RNA聚合酶的大亚基的广泛保守， 它们主要负责酶的运动和RNA链的生长， 这表明，将有重要的共同特点的机制， 在许多生物体中的伸长控制。E.杆菌RNA 聚合酶与单一的23 kD Q多肽，沿着与辅助 蛋白质NusA，改变酶的延伸特性， 通过转录终止子， 诱导暂停的信号。Q修饰RNA聚合酶在一个明确定义的 包括晚期基因启动子的位点，DNA中的Q结合位点，和 一种诱导转录暂停的DNA信号;这种信号起作用 主要通过与hon转录链的相互作用。的 Q对在该位点暂停的酶的作用可以模拟Q功能， 终止符，因为它通过停顿促进延长。我们将 描述这种相互作用并确定其与活动的关系 的Q蛋白在终止子，并表征终止的过程 本身我们将解剖Q蛋白，以确定参与 DNA结合及其与RNA聚合酶的相互作用， 遗传学和生物化学方法。我们将决定如何修改 由Q诱导的持续存在于启动子相关的接合位点 在转录延伸的整个过程中。

Our objective is to understand how RNA polymerase of E. coli is modified by the transcription antiterminator encoded by the phage lambda gene Q. Antitermination is an important mechanism of genetic regulation in bacteria, as well as eukaryotes - for example in the growth of HIV. Furthermore, expression of many cellular genes may be controlled by related processes that act at the level of transcript elongation. The extensive conservation of the large subunits of all RNA polymerases, which are mostly responsible for enzyme movement and RNA chain growth, suggests that there will be important common features in mechanisms of elongation control in many organisms. Interaction of E. coli RNA polymerase with the single 23 kD Q polypeptide, along with the accessory protein NusA, changes the elongation properties of the enzyme so that it goes through transcription terminators, and is less susceptible to some signals that induce pausing. Q modifies RNA polymerase at a well defined site that includes the late gene promoter, a Q binding site in DNA, and a DNA signal that induces transcriptional pausing; this signal acts primarily through interactions with the hon-transcribed strand. The action of Q on enzyme paused at this site may simulate Q function at terminators, because it promotes elongation through the pause. We will characterize this interaction and determine its relation to the activity of Q protein at terminators, and characterize the process of termination itself. We will dissect the Q protein to identify portions involved in DNA binding and in its interaction with RNA polymerase, using both genetic and biochemical methods. We will determine how the modification induced by Q persists from the promoter-associated engagement site throughout the process of transcription elongation.