DNA transfer occurs during a cell surface contact stage of F sex factor-mediated bacterial conjugation.
Donor bacteria containing JCFL39, a temperature-sensitive traD mutant of the F sex factor, were used at the nonpermissive temperature to accumulate stable mating pairs with recipient cells. At this stage in conjugation, extracellular F pili were removed by treatment with 0.01% sodium dodecyl sulfate. Upon then shifting to the permissive temperature for JCFL39, transfer of the F plasmid was observed. The mating pairs that were accumulated with JCFL39 at the nonpermissive temperature were readily observed by electron microscopy in wall-to-wall contact with the recipient bacteria. These results demonstrate that the traD product, which is known to be required in transferring DNA to a recipient bacterium, acts after the stage at which extracellular F pili are required. In addition, we concluded that DNA transfer takes place while donor and recipient cells are in surface contact and not necessarily through an extended F pilus as envisioned in some models of bacterial conjugation.
Panicker
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Minkley
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D000268:Adhesiveness; D001426:Bacterial Proteins / Q000235:genetics; D003227:Conjugation, Genetic; D004269:DNA, Bacterial / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics*; D005144:F Factor; D010861:Fimbriae, Bacterial / Q000502:physiology; D005798:Genes, Bacterial; D008854:Microscopy, Electron; D009154:Mutation; D013997:Time Factors
D001426:Bacterial Proteins; D004269:DNA, Bacterial