EFFECT OF DRUG-RESISTANCE FACTOR R ON THE F PROPERTIES OF ESCHERICHIA COLI

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Abstract
Infection of Escherichia coli male cells (Hfr or F+) with resistance factor R results in the co-ordinate inhibition of several distinct functions of F factor: mating capacity to transfer chromosome by conjugation, production of f+ antigen, and formation of receptors for the male-specific bacteriophages, f1 and ribonucleic acid phage. The i" mutant (R100-1) of R factor, which was isolated from wild-type R factor (R100), shows no inhibition of these F properties. Male R+l00-l cells were autoagglutinable but the f+ antigen was still present. When R-infected female cells had acquired the ability to form recombinants with an F" strain, they also had become autoagglutinable. The question of the presence of f+ antigen in these strains was not solved. The cause of the autoagglutinability is not known, but it is not the result of loss of O antigen (rough autoagglutinability). Sensitivity to a phage tau, which can form plaques on female cells only, is not affected by the presence or absence of R factor. No difference in the pattern of segregation of recombinants was observed between the cross of Hfr R X F and that of Hfr R+ X F. These results indicate that R factor controls a key mechanism in the synthesis of "F substances" formed on the cell surface by the F factor.

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