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：1982
卷号：79
期号：2
页码：515-519
DOI：10.1073/pnas.79.2.515
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Satellite phage P4 has two known options for propagation. In its lytic cycle, its regulatory functions can act in trans to alter the actions of a helper virus (P2), which then provides necessary gene products, including capsid proteins. P4 also can be propagated in the absence of a helper as a prophage, with distinct sites for integration within the Escherichia coli chromosome. We determined that a single spontaneous mutation (vir1) of phage P4 allows a third mode of propagation: as a plasmid (along with continued integration into the host chromosome). Hence, the P4 regulatory element is capable of (i) temperate; (ii) lytic, helper-dependent; and (iii) plasmid modes of development. These findings emphasize the close relationship between defective viruses and plasmids.
