GENE CONTROL IN INFECTION AND LYSOGENY BY PHAGE LAMBDA

我们将研究E。 这是在所有细胞中进行基因调控的模型。 1.噬菌体lambda基因Q编码的蛋白调用噬菌体晚期 在特定操纵子中作为转录因子的基因表达 反终结者。反终止是一种重要的调节机制 细菌，可能存在于所有细胞和病毒中。我们将决定如何 Lambda Q蛋白是由RNA聚合酶在基因组特定的位置激活的 启动子附近，使用化学和核酸酶保护方法进行探测 它与DNA的相互作用，利用突变，我们将改变这一点 以特定方式进行交互。我们将确定Q蛋白如何修饰 RNA聚合酶的特性使其能够通过转录终止子， 以及它是如何改变RNA聚合酶在特性上暂停的能力 网站。我们将研究转录因子Nusa的作用 抗流产中的蛋白质。 2.除了催化基因重组中的DNA链交换外， 大肠杆菌RecA蛋白介导SOS基因的诱导，包括 最重要的是突变所需的DNA修复功能 致癌物质。致癌物也是SOS基因(和噬菌体)的诱导者 Lambda)，因为它们导致RecA蛋白的激活以结合和 通过蛋白水解性切割破坏SOS基因的LexA抑制子，如 以及温和的噬菌体抑制因子。为了测试归纳的模型 当染色体复制发现DNA在以下位置的间隙时发生 致癌物诱导的损伤，我们将确定LexA与 卵裂和DNA复制。为了检验这一规定的普遍性， 我们将研究RecA蛋白在远亲中的类似物 枯草杆菌。

We will investigate two fundamental processes of genetic control in E. coli, which are models for genetic regulation in all cells. 1. The protein encoded by bacteriophage lambda gene Q invokes phage late gene expression by acting in a specific operon as a transcription antiterminator. Antitermination is an important mechanism of regulation in bacteria, and possibly in all cells and viruses. We will determine how lambda Q protein is engaged by RNA polymerase at a genome-specific site near the promoter, using chemical and nuclease protection methods to probe its interaction with DNA, and using mutations we will make that change this interaction in specific ways. We will determine how Q protein modifies the properties of RNA polymerase to allow it to pass transcription terminators, and how it changes the ability of RNA polymerase to pause at characteristic sites. We will investigate the role of the transcription factor NusA protein in antitermination. 2. In addition to catalyzing DNA strand exchange in genetic recombination, the E. coli RecA protein mediates induction of the SOS genes, which include DNA repair functions required for mutagenesis by most important carcinogens. Carcinogens are also inducers of SOS genes (and phage lambda), because they lead to activation of RecA protein to bind and destroy by proteolytic cleavage the LexA repressor of the SOS genes, as well as temperate phage repressors. To test the model that induction occurs when chromosome replication uncovers gaps in DNA at the sites of carcinogen-induced lesions, we will determine the relation between LexA cleavage and DNA replication. To test the universality of this regulation, we will study an analogue of RecA protein in the distantly related bacterium B. subtilis.