Membrane protein biosynthesis in T5 bacteriophage-infected Escherichia coli

After infection of Escherichia coli with bacteriophage T5, a major new protein species, as indicated by polyacrylamide-gel electrophoresis, appears in the whole membrane fraction of the infected cells. Ultraviolet-irradiated phage do not induce the synthesis of this protein. The time course of synthesis of the protein as well as its appearance in cells infected in the presence of chloramphenicol and then blended and in infected cells containing the Col Ib factor are consistent with it being a pre-early protein; i.e., a protein induced by the spontaneously injected 8% piece of T5-DNA, the transcription and translation of which is necessary for the entry of the whole DNA molecule into the cell. The protein is found in both inner and outer membrane fractions of E. coli but appears as only one band in two gel systems. Some evidence indicates that the protein exists in a soluble form in the cytoplasm prior to incorporation into the cell membrane and that it can be incorporated into a membrane fraction in an in vitro system.