Abstract
In this communication we describe the events occurring during the injection step in the infection of Escherichia coli Hfr cells with the RNA bacteriophage f2. The phage RNA is partially injected into the F-pilus of the Hfr cell. This step was found to be necessary for f2 RNA to block the penetration of the DNA phage f1. A cold sensitive mutant of f2 is described. It is able to inject its RNA at 41° but not at 31°.
After contact is made between the phage RNA and the F-pilus, the coat protein of the phage desorbs from the F-pilus as an empty shell, leaving the RNA free to enter the cell. In the absence of divalent metals, however, the phage RNA is unable to leave the shell. When the shell desorbs from the F-pilus, the RNA remains inside in a ribonuclease sensitive state. A small fraction of the RNA in cultures depleted of divalent metal ions remains bound to the cell. It is sensitive to ribonuclease and is removed from the cell by treatments which remove F-pili.
* Present address: Albert Einstein College of Medicine, Department of Molecular Biology, Bronx, New York, N.Y. 10461, U.S.A.