TRANSLOCATION OF DNA ACROSS BACTERIAL-MEMBRANES

DNA translocation across bacterial membranes occurs during the biologi cal processes of infection by bacteriophages, conjugative DNA transfer of plasmids, T-DNA transfer, and genetic transformation. The mechanis m of DNA translocation in these systems is not fully understood, but d uring the last few years extensive data about genes and gene products involved in the translocation processes have accumulated. One reason f or the increasing interest in this topic is the discussion about horiz ontal gene transfer and transkingdom sex. Analyses of genes and gene p roducts involved in DNA transfer suggest that DNA is transferred throu gh a protein channel spanning the bacterial envelope. No common model exists for DNA translocation during phage infection. Perhaps various m echanisms are necessary as a result of the different morphologies of b acteriophages. The DNA translocation processes during conjugation, T-D NA transfer, and transformation are more consistent and may even be co mpared to the excretion of some proteins. On the basis of analogies an d homologies between the proteins involved in DNA translocation and pr otein secretion, a common basic model for these processes is presented .