Transfer-positive J-independent revertants of the F factor inEscherichia coliK 12

Abstract

SUMMARY: Cells carryingtraJ⁻mutants of F are transfer-deficient and are good recipients in conjugation (Achtman, Willets & Clark, 1972). In addition, thetraJgene product is involved in pilus- and in plasmid-specificity (Willetts, 1971). J-independent mutants were isolated as revertants of atraJ⁻mutant; they still carry thetraJ⁻mutation but also carry at least one other mutation which results in transfer in the absence of thetraJgene product. J-independent transfer of these mutants is not inhibited by the R 100 repressor. Various models are presented which can account for the properties oftraJ⁻mutants and of these J-independent revertants.