F FACTOR MEDIATED ABORTIVE INFECTION

这项提议的总体目标是理解分子 限制T7噬菌体感染雄性的机制 大肠杆菌菌株。这一现象也被称为流产 感染。一种新的方法正在被应用来帮助解决一个旧的和 有争议的问题。我们已经通过体内重组获得了 实验，T7噬菌体与相关噬菌体T3之间的杂交。鉴于T7 受到雄性的限制，T3不受限制，这些杂交噬菌体，它们是 在起源上主要是T7，包含必要的T3功能 流产的感染。我们最近还分离出了T3的突变体 似乎完全受到雄性品系的限制。在这里提出的是一种更 环状噬菌体的详细遗传和生理特征， 特别设计用来分离由提供的两个基本功能 T3。这些衍生品将独立地表征感染 无论是雄株还是雌株。类似地，现有的T3突变体一起 与其他将被隔离的人，将以遗传， 身体和生理标准。特别是考虑到这些数据， 确切地知道哪些基因产物在T3突变体中有缺陷，或者 由于F的存在而被阻止运行(在T7的情况下)我们可以 然后研究流产感染本身。这是第一次 现象可以通过使用噬菌体突变体来研究，因此 积累了大量的知识，特别是在T7基因产物上， 可应用于了解F因子介导的原因 流产感染。

The overall objective of this proposal is to understand the molecular mechanism whereby bacteriophage T7 is restricted upon infection of a male strain of E. coli. This phenomenom is also known as the abortive infection. A new approach is being applied to help solve an old and controversial problem. We have made, via an in vivo recombination experiment, hybrid phages between T7 and the related phage T3. Whereas T7 is restricted by males, T3 is not and these hybrid phages, which are predominately T7 in origin, contain the T3 functions necessary to overcome the abortive infection. We have also recently isolated mutants of T3 which appear to be fully restricted by male strains. Proposed here is a more detailed genetic and physiological characterization of the gybrid phages, designed in particular to separate the two essential functions supplied by T3. These derivatives will be characterized independently on infections of both male and female strains. Similarly the existing T3 mutants, together with others that will be isolated, will be characterized by genetic, physical and physiological criteria. Given these data, in particular knowing precisely which gene products are defective in the T3 mutants, or prevented from functioning (in the case of T7) by the presence of F we can then study the abortive infection itself. For the first time this phenomenom can be investigated by the use of phage mutants and thus the extensive body of knowldege accumulated, on T7 gene products in particular, can be applied to an understanding of the cause of the F factor-mediated abortive infection.