Interaction Between Colicinogenic Factor V and the Integrated F Factor in an Hfr Strain of Escherichia coli

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Kahn, Phyllis L. (Princeton University, Princeton, N.J.), and Donald R. Helinski. Interaction between colicinogenic factor V and the integrated F factor in an Hfr strain of Escherichia coli. J. Bacteriol. 90:1276–1282. 1965.—The production of colicin V by strains of Escherichia coli is determined by a colicinogenic factor, colV. The colV factor possesses a genetic determinant of fertility, Fv. V+Fv+ cells are characteristically susceptible to a male-specific phage, μ, and able to transfer the colV factor and chromosomal markers to recipient cells. The present work describes an interaction of the colV factor with the chromosome of the Hfr strain, HfrH. A colV-containing HfrH strain, designated HfrHV+Fv+(l), was isolated and shown to be insensitive to phage μ and impaired in its fertility properties. Loss of the colV factor by this strain, either spontaneous or induced by acridine orange, resulted in a further 103- or 104-fold loss in fertility. This additional loss of fertility was restored by reinfection of these strains with the colV factor. The colV interaction with the HfrH chromosome also can result in defects in the fertility properties of the colV factor. Altered colV factors were found in recombinants isolated from a cross between the HfrHV+Fv+(l) strain and F− recipients. It is postulated that in the HfrHV+Fv+(l) strain an interaction of the colV episome with the integrated F region of the chromosome occurs, with a resulting modification of the fertility properties of the HfrH strain. This interaction can also result in a defect in certain properties of the colV factor.

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