Effect of Rec − Mutations on the Activity of Colicinogenic Factors

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Abstract
The effect of two Rec − mutations (AB2463 and JC1553) on the ability of a cell to accept, maintain, and express the colicinogenic factors ColE 1 , ColE 2 , 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 E 1 and E 2 which are determined by the ColE 1 and ColE 2 factors, respectively. The two Rec − mutations had no apparent effect on the ability of the cells to acquire, maintain, or transfer the ColE 1 and ColE 2 factors. These mutations did not affect the expression of immunity by any of the three Col factors. ColE 1 and ColE 2 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.