BACTERIOPHAGE P22 ESSENTIAL RECOMBINATION FUNCTION

这项研究的长期目标是了解 基因重组的机制。重组是一个过程 在基因变异的产生中具有根本的重要性， 在高等生物中，免疫反应的多样性。这个 所要研究的系统是同源重组系统。 噬菌体P22，由四种蛋白产物组成 噬菌体基因：ERF是关键成分，是一种链交换蛋白； ARF(辅助重组功能)，增强ERF活性 以及ABC1和ABC2(抗RecBCD)，它们调节 宿主细胞RecBCD蛋白的活性，将其转移到 噬菌体重组途径。 P22进行同源重组的机制 系统将通过生化和遗传手段进行研究。活体内 噬菌体之间的重组试验将被用来检查 双链断裂在ERF系统中的作用，并测试 Arf在促进同源重组中的作用 系统。重组系统的各个组件将 被提纯并具有生化特征：结构和 ABC对RecBCD功能的改变(通过GAM蛋白的分析) 噬菌体lambda)、Arf对Erf活性的调节以及其功能 Erf的羧基末端结构域的部分将在 很特别。将尝试从提纯的 体外成分、忠实模仿的系统和子系统 体内P22同源重组的活性。这个 这些体系对底物dna的作用将通过凝胶来研究。 电泳法和电子显微镜技术，目的是 建立过程的各个步骤，并 描述形成的中间体的特征。

The long-term goal of this research is an understanding of the mechanisms of genetic recombination. Recombination is a process of fundamental importance in the generation of genetic variation, and, in higher organisms, of diversity in the immune response. The system to be studied is the homologous recombination system of bacteriophage P22, which consists of the protein products of four phage genes: Erf, the key component, a strand-exchanging protein; Arf (accessory recombination function), which enhances Erf activity in vivo; and Abc1 and Abc2 (anti-RecBCD), which modulate the activity of the host cell RecBCD protein, diverting it into the phage recombination pathway. The mechanism of homologous recombination carried out by the P22 system will be studied by biochemical and genetic means. In vivo assays of recombination between phages will pe employed to examine the role of double-chain breaks in the Erf system, and to test the activity of Arf in promoting homologous recombination by other systems. Individual components of the recombination system will be purified and characterized biochemically: structural and functional alteration of RecBCD by Abc (ana by the Gam protein of phage lambda), modulation of Erf activity by Arf, and the function of the carboxy-terminal domain of Erf will be examined in particular. Attempts will be made to assemble, from purified components in vitro, systems and sub-systems that faithfully mimic the activity of the P22 homologous recombination in vivo. The actions of these systems on substrate DNA will be studied by gel electrophoretic and electron microscopic techniques, with the aim of establishing the individual steps of the process and characterizing the intermediates formed.