Reexamination of phenotypic defects in rec-1 and rec-2 mutants of Haemophilus influenzae Rd.
Radiolabeled donor DNA is efficiently taken up into competent H. influenzae Rd rec-2 mutant cells but does not undergo the rapid degradation observed in wild-type cells. Furthermore, donor label is not recovered in the chromosome even after 1 h. The donor DNA appears to remain in a protected state in a compartment that can be separated from the rest of the cell. We interpret this as a failure of the donor DNA to be translocated out of the transformasome. In contrast, rec-1 cells translocate labeled donor DNA normally. The donor label accumulates in the recipient chromosome, but, as expected for cells with a recombination defect, there is no preferential localization of the label in sites homologous to the donor DNA. In addition, we have observed two enzymatic activities that act on transformasome-associated DNA of rec-2 cells, an endonuclease which may play a role in the translocation of closed circular DNA and a phosphatase.
D000255:Adenosine Triphosphate / Q000378:metabolism; D001435:Bacteriophages / Q000235:genetics; D001482:Base Composition; D001483:Base Sequence; D001692:Biological Transport; D004269:DNA, Bacterial / Q000378:metabolism*; D006193:Haemophilus influenzae / Q000235:genetics*; D009154:Mutation; D010641:Phenotype; D010761:Phosphorus Radioisotopes; D010957:Plasmids; D014176:Protein Biosynthesis; D014169:Transformation, Bacterial
D004269:DNA, Bacterial; D010761:Phosphorus Radioisotopes; D000255:Adenosine Triphosphate