期刊名称:Proceedings of the National Academy of Sciences
印刷版ISSN:0027-8424
电子版ISSN:1091-6490
出版年度:1978
卷号:75
期号:11
页码:5594-5598
DOI:10.1073/pnas.75.11.5594
语种:English
出版社:The National Academy of Sciences of the United States of America
摘要:We describe the dissection and reconstruction of a complex control circuit, the P1 immunity system, by a method that involves inserting EcoRI-generated fragments of P1 DNA into lambda vectors that can then be sequentially inserted into a bacterial cell. Using these techniques we have isolated lambda-P1 hybrid phages that express the products of P1 genes c1, c4, ant, and ban and, in appropriately constructed lysogens, confirmed the roles played by the first three of these products in phage immunity. In addition we have localized to particular P1 fragments the sites requisite for expression and repression of these gene products. The analysis leads to the conclusion that gpant acts in trans to antagonize repression mediated by gpc1, in support of one of two proposed models for gpant action. Moreover, two features of the immunity system are revealed: (i) a hitherto unknown component that effects gpc1 repression; and (ii) an unexpected ability of gpc4 to channel a superinfecting c1+ phage into the lysogenic state, which suggests that gpc4 activity regulates the establishment phase of lysogeny.