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Effect of Rec^– Mutations on the Activity of Colicinogenic Factors

University of California, San Diego, Department of Biology, Revelle College, La Jolla, California 92037

ABSTRACT

The effect of two Rec^– mutations (AB2463 and JC1553) on the ability of a cell to accept, maintain, and express the colicinogenic factors ColE₁, ColE₂, and ColV was examined in Escherichia coli. These mutations had no observable effect on the colicinogenic properties of the ColV factor, but prevented the spontaneous and induced production of colicins E₁ and E₂ which are determined by the ColE₁ and ColE₂ factors, respectively. The two Rec^– mutations had no apparent effect on the ability of the cells to acquire, maintain, or transfer the ColE₁ and ColE₂ factors. These mutations did not affect the expression of immunity by any of the three Col factors. ColE₁ and ColE₂ were also shown to be indirectly induced by mating F^– cells carrying these Col factors with ultraviolet-irradiated, non-colicinogenic, Hfr and F⁺ cells. Indirect induction of colicin production occurred when either an irradiated F⁺ Rec⁺ or F⁺ Rec^– strain was employed as the donor strain.