REGULATORY MUTATIONS IN THE THREONINE OPERON

影响Thr操纵子衰减的调节性突变体 以寡核苷酸为导向构建大肠杆菌 诱变和直接合成程序。我们会 在前导肽编码中引入移码突变 序列以确定哪个区域(S)是调控的关键区域。 我们还将构建影响RNA的替换突变 次级结构被认为是重要的 监管。此外，我们还将研究dna超螺旋的影响。 密度和终止因子对转录终止的影响 体外培养。这项工作的长期目标是理解 调节转录终止的分子事件 三个衰减器。 第二个项目涉及到的分子机制。 噬菌体lambda定点重组。突变将会 在体外被引入到重组的结合部位 蛋白质在重组过程中结合。突变将会是 以它们对重组的影响和它们的 DNA保护中与重组蛋白的相互作用 化验。我们还将构建新的DNA底物来研究 枝条迁移和DNA-DNA相互作用在植物生长发育中的作用 重组。这项研究的长期目标是 了解链交换的分子机制，并 获取有关组织和组装的信息 重组复合体。

Regulatory mutants which affect attenuation of the thr operon of Escherichia coli will be constructed by oligonucleotide-directed mutagenesis and by direct synthesis procedures. We will introduce frameshift mutations into the leader peptide coding sequence to determine which region(s) are critical for regulation. We will also construct substitution mutations which affect RNA secondary structures that are thought to be important for regulation. In addition, we will study the effects DNA superhelix density and termination factors on transcription termination in vitro. The long range goal of this work is to understand the molecular events that regulate transcription termination at the thr attenuator. A second project is concerned with the molecular mechanism of bacteriophage lambda site-specific recombination. Mutations will be introduced in vitro into the binding sites where recombination proteins bind during recombination. The mutations will be characterized by their effects on recombination and by their interactions with recombination proteins in DNA protection assays. We will also construct novel DNA substrates to study the roles of branch migration and DNA-DNA interactions during recombination. The long range goal of this research is to understand the molecular mechanism of strand exchange and to gain information on the organization and assembly of recombination complexes.